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Shaw JJ, Marinho-Júnior JF, Courtenay O, Brandão-Filho SP. Assessing reservoir host status in leishmaniasis with special reference to the infectiousness of Leishmania (Viannia) braziliensis infections in wild rodents. Rev Soc Bras Med Trop 2023; 56:0503. [PMID: 38126376 PMCID: PMC10726968 DOI: 10.1590/0037-8682-0503-2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Accepted: 11/29/2023] [Indexed: 12/23/2023] Open
Abstract
Molecular methods have been responsible for a notable increase in the detection of Leishmaniinae infections in wild animals. Determining their infectiousness is of paramount importance in evaluating their epidemiological significance. One of the most efficient ways of determining infectiousness for vector borne diseases is xenodiagnosis with the appropriate vector. However, this is logistically very difficult to accomplish in the field, and an ideal solution is to find a molecular surrogate for xenodiagnosis. In this review we discuss different approaches to the problem by focusing on the infectiousness of Leishmania (Viannia) braziliensis in rodents under laboratory and field conditions. Comparisons with similar studies for other Leishmania species emphasizes that there are pivotal differences in the infectiousness and the importance of asymptomatic infections in different hosts. Potentially the most promising surrogate is the real time quantitative PCR (qPCR). However, its success depends on choosing a tissue that relates to the vector's feeding location and the parasite's tissue tropism. This requires detailed knowledge of the infection of each species in its wild hosts. We conclude that for L. (V.) braziliensis infections in wild rodents the tissue of choice for a molecular xenodiagnostic test, based on the qPCR is blood, providing that a significant number of samples must be examined.
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Affiliation(s)
- Jeffrey J. Shaw
- Universidade de São Paulo, Instituto de Ciências Biomédicas, Departamento de Parasitologia, São Paulo, SP, Brasil. Universidade de São PauloInstituto de Ciências BiomédicasDepartamento de ParasitologiaSão PauloSPBrasil
| | - José F. Marinho-Júnior
- Fundação Oswaldo Cruz, Instituto Aggeu Magalhães, Recife, PE, Brasil. Fundação Oswaldo CruzInstituto Aggeu MagalhãesRecifePEBrasil
| | - Orin Courtenay
- University of Warwick, School of Life Sciences and the Zeeman Institute, Coventry, United Kingdom.University of WarwickSchool of Life Sciences and the Zeeman InstituteCoventryUnited Kingdom
| | - Sinval P. Brandão-Filho
- Fundação Oswaldo Cruz, Instituto Aggeu Magalhães, Recife, PE, Brasil. Fundação Oswaldo CruzInstituto Aggeu MagalhãesRecifePEBrasil
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Jibreel T, Khogali A, Jiménez M, Raiyed A, Dakein O, Alsharif B, Khalid NM, Osman OF, Nour BYM, Mohamed GH, Molina R, Vidal-López A, Díaz-Regañón R, den Boer M, Alvar J, Courtenay O, Elnaiem DE. Host preference and human blood index of Phlebotomus orientalis, an exophilic sand fly vector of visceral leishmaniasis in eastern Sudan. Med Vet Entomol 2023; 37:782-792. [PMID: 37540228 DOI: 10.1111/mve.12683] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Accepted: 07/10/2023] [Indexed: 08/05/2023]
Abstract
Visceral leishmaniasis (VL, kala azar), caused by Leishmania donovani, transmitted by Phlebotomus orientalis, is a serious systemic disease that causes high morbidity and mortality rates in Sudan and other parts of East Africa and the world. Despite progress in understanding the epidemiology of the disease in East Africa, little is known about the host preference of P. orientalis in kala azar endemic villages of Sudan, which have some of the highest VL incidence rates in the world. The present study used host choice experiments and blood-meal identification approaches to determine the host preference of P. orientalis in kala azar endemic villages in Gedarif state, eastern Sudan. In the host choice experiment, tent traps were used to compare the attractiveness of cows, donkeys, sheep and goats for host-seeking P. orientalis. In the blood-meal identification study, blood-fed P. orientalis females, captured inside houses and peri-domestic habitats, were subjected to molecular typing using cytochrome b gene (cyt b) amplification and sequence analysis. Cows and donkeys were the most attractive to blood-seeking P. orientalis, followed by goats. Similarly, the blood-meal analysis of P. orientalis showed that the vector preferentially feeds on cows, followed by donkeys, humans and goats. The human blood index of P. orientalis was 19.4% (42/216), indicating a high zoophilic habit of the vector, both inside and outside the houses. Although the order of host preference varied by location, it was clear that cows are the most preferred host of P. orientalis in the area. Results are discussed in relation to the role of domestic/livestock animals in VL zoopotentiation and zooprophylaxis. Inference is made on the potential impact of insecticide treatment of cows in control of the vector and the transmission of VL in Sudan and other parts of East Africa.
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Affiliation(s)
- Tayseer Jibreel
- Blue Nile National Institute for Communicable Diseases, University of Gezira, Wad Medani, Sudan
| | - Altayeb Khogali
- Blue Nile National Institute for Communicable Diseases, University of Gezira, Wad Medani, Sudan
| | - Maribel Jiménez
- Laboratorio de Entomología Médica, Servicio de Parasitología, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Infecciosas (CIBERINFEC), Instituto de Salud Carlos III, Madrid, Spain
| | - Adeel Raiyed
- Department of Zoology, Faculty of Science, University of Khartoum, Khartoum, Sudan
| | - Osman Dakein
- Kala azar Research Centre, Faculty of Medicine and Health Sciences, University of Gedarif, Gedarif, Sudan
| | - Bashir Alsharif
- Medical Entomology Department, Federal Ministry of Health, Khartoum, Sudan
| | | | - Omran F Osman
- Department of Zoology, Faculty of Science, University of Khartoum, Khartoum, Sudan
| | - Bakri Y M Nour
- Department of Medical Parasitology, Faculty of Medical Laboratory Sciences, University of Gezira, Wad Medani, Sudan
| | - Gamal Hassan Mohamed
- Department of Biostatistics, Epidemiology and Scientific Computing, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Ricardo Molina
- Laboratorio de Entomología Médica, Servicio de Parasitología, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Infecciosas (CIBERINFEC), Instituto de Salud Carlos III, Madrid, Spain
| | - Ana Vidal-López
- Laboratorio de Entomología Médica, Servicio de Parasitología, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Infecciosas (CIBERINFEC), Instituto de Salud Carlos III, Madrid, Spain
| | - Ramón Díaz-Regañón
- Laboratorio de Entomología Médica, Servicio de Parasitología, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Infecciosas (CIBERINFEC), Instituto de Salud Carlos III, Madrid, Spain
| | | | | | - Orin Courtenay
- Zeeman Institute and School of Life Sciences, University of Warwick, Coventry, UK
| | - Dia-Eldin Elnaiem
- Department of Natural Sciences, University of Maryland Eastern Shore, Princess Anne, Maryland, USA
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Courtenay O, Marinho-Júnior JF, Brito MEF, Monteiro JFCLS, Shaw JJ, Brandão-Filho SP. Incidence of Human and Free-Ranging Wild Rodent Infections with Leishmania ( Viannia) braziliensis, Aetiological Agent of Cutaneous Leishmaniasis. Pathogens 2023; 12:1395. [PMID: 38133280 PMCID: PMC10746019 DOI: 10.3390/pathogens12121395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Revised: 11/06/2023] [Accepted: 11/19/2023] [Indexed: 12/23/2023] Open
Abstract
BACKGROUND Human and wild rodent infection rates with Leishmania (Viannia) braziliensis are needed to differentiate transmission pathways in anthropogenically altered habitats. METHODS Human participants in northeast Brazil were tested by the leishmanin skin test (LST) and inspected for lesions/scars characteristic of American clinical leishmaniasis (ACL). Molecular (PCR/qPCR) test records of free-ranging rodents were available from a concurrent capture-mark-recapture study. Force of Infection (λ) and recovery (ρ) rates were estimated from cross-sectional and longitudinal datasets. RESULTS Cumulative prevalences of human LST+ves and ACL scar+ves were 0.343-0.563 (n = 503 participants) and 0.122-0.475 (n = 503), respectively. Active ACL lesions were not detected. Annual rates of LST conversions were λ = 0.03-0.15 and ρ = 0.02-0.07. The probability of infection was independent of sex and associated with increasing age in addition to the period of exposure. Rodents (n = 596 individuals of 6 species) showed high rates of exclusively asymptomatic infection (λ = 0.222/month) and potential infectiousness to the sand fly vector. Spatially concurrent rodent and household human infection prevalences were correlated. CONCLUSIONS Human exposure to L. (V.) braziliensis continues to be high despite the substantial drop in reported ACL cases in recent years. Spill-over transmission risk to humans from rodents in peridomestic habitats is likely supported by a rodent infection/transmission corridor linking houses, plantations, and the Atlantic Forest.
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Affiliation(s)
- Orin Courtenay
- Zeeman Institute for Systems Biology & Infectious Disease Epidemiology Research, and School of Life Sciences, University of Warwick, Coventry CV8 2PB, UK
| | - José F. Marinho-Júnior
- Departament of Immunology, Instituto Aggeu Magalhães/FIOCRUZ, Cidade Universitária, Recife 50740-465, PE, Brazil; (J.F.M.-J.); (M.E.F.B.); (J.F.C.L.S.M.); (S.P.B.-F.)
| | - Maria Edileuza F. Brito
- Departament of Immunology, Instituto Aggeu Magalhães/FIOCRUZ, Cidade Universitária, Recife 50740-465, PE, Brazil; (J.F.M.-J.); (M.E.F.B.); (J.F.C.L.S.M.); (S.P.B.-F.)
| | - Juliana F. C. L. S. Monteiro
- Departament of Immunology, Instituto Aggeu Magalhães/FIOCRUZ, Cidade Universitária, Recife 50740-465, PE, Brazil; (J.F.M.-J.); (M.E.F.B.); (J.F.C.L.S.M.); (S.P.B.-F.)
| | - Jeffrey J. Shaw
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo 03001-000, SP, Brazil;
| | - Sinval P. Brandão-Filho
- Departament of Immunology, Instituto Aggeu Magalhães/FIOCRUZ, Cidade Universitária, Recife 50740-465, PE, Brazil; (J.F.M.-J.); (M.E.F.B.); (J.F.C.L.S.M.); (S.P.B.-F.)
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Marinho-Júnior JF, Monteiro JFCLS, Sales de Carvalho AW, de Carvalho FG, de Paiva Cavalcanti M, Shaw J, Courtenay O, Brandão-Filho SP. High levels of infectiousness of asymptomatic Leishmania (Viannia) braziliensis infections in wild rodents highlights their importance in the epidemiology of American Tegumentary Leishmaniasis in Brazil. PLoS Negl Trop Dis 2023; 17:e0010996. [PMID: 36716345 PMCID: PMC9910795 DOI: 10.1371/journal.pntd.0010996] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 02/09/2023] [Accepted: 11/29/2022] [Indexed: 02/01/2023] Open
Abstract
BACKGROUND The epidemiological significance of wildlife infections with aetiological agents causing human infectious diseases is largely determined by their infection status, contact potential with humans (via vectors for vector-borne diseases), and their infectiousness to maintain onward transmission. This study quantified these parameters in wild and synanthropic naturally infected rodent populations in an endemic region of tegumentary leishmaniasis in northeast Brazil. METHODS Capture-mark-recapture (CMR) of rodents was conducted over 27 months in domestic/peri domestic environs, household plantations and nearby Atlantic Forest (9,920 single trap nights). Rodent clinical samples (blood and ear tissue) were tested for infection by conventional PCR and quantitative PCR (qPCR) for Leishmania (Viannia) braziliensis, and xenodiagnosis to measure infectiousness to the local sand fly vector. RESULTS A total 603 individuals of 8 rodent species were (re)captured on 1,051 occasions. The most abundant species were Nectomys squamipes (245 individuals, 41% of the total catch), Rattus rattus (148, 25%), and Necromys lasiurus (83, 14%). All species were captured in greater relative frequencies in plantations; R. rattus was the only species captured in all three habitats including in and around houses. Four species, comprising 22.6% of individuals captured at least twice, were geolocated in more than one habitat type; 78.6% were infected with L. (V.) braziliensis, facilitating inter-species and inter-habitat transmission. Species specific period prevalence ranged between 0%-62% being significantly higher in N. squamipes (54-62%) and Hollochillus sciureus (43-47%). Xenodiagnosis was performed on 41 occasions exposing 1,879 Nyssomyia whitmani sand flies to five rodent species (37 individuals). Similar mean levels of infectiousness amongst the more common rodent species were observed. Longitudinal xenodiagnosis of the N. squamipes population revealed a persistent level of infectiousness over 13 months follow-up, infecting a median 48% (IQR: 30.1%-64.2%) of exposed blood-fed vectors. The proportion of exposed flies infected was greater in the low compared to in the high seasonal period of vector abundance. L. (V.) braziliensis parasite loads in rodent blood quantified by qPCR were similar across rodent species but did not represent a reliable quantitative marker of infectiousness to sand flies. The standardised risk of rodent infection in plantations was 70.3% relative to 11.3% and 18.4% in peri domestic and forest habitats respectively. R. rattus was the only exception to this trend indicating greatest risk in the peri domestic environment. CONCLUSIONS The results support the view that a collective assemblage of wild and synanthropic rodent species is an important wild reservoir of L. (V.) braziliensis in this region, with N. squamipes and R. rattus probably playing a key role in transmission within and between habitat types and rodent species. Rodents, and by implication humans, are at risk of infection in all sampled habitats, but more so in homestead plantations. These conclusions are based on one of the longest CMR study of small rodents in an American Tegumentary Leishmaniasis (ATL) foci.
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Affiliation(s)
| | | | | | - Francisco Gomes de Carvalho
- Department of Immunology, Instituto Aggeu Magalhães/FIOCRUZ, Cidade Universitária, Recife, Pernambuco, Brazil
| | - Milena de Paiva Cavalcanti
- Department of Immunology, Instituto Aggeu Magalhães/FIOCRUZ, Cidade Universitária, Recife, Pernambuco, Brazil
| | - Jeffrey Shaw
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, São Paulo, Brazil
| | - Orin Courtenay
- The Zeeman Institute and School of Life Sciences, University of Warwick, Coventry, United Kingdom
- * E-mail: (SPBF); (OC)
| | - Sinval Pinto Brandão-Filho
- Department of Immunology, Instituto Aggeu Magalhães/FIOCRUZ, Cidade Universitária, Recife, Pernambuco, Brazil
- * E-mail: (SPBF); (OC)
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Willen L, Milton P, Hamley JID, Walker M, Osei-Atweneboana MY, Volf P, Basáñez MG, Courtenay O. Demographic patterns of human antibody levels to Simulium damnosum s.l. saliva in onchocerciasis-endemic areas: An indicator of exposure to vector bites. PLoS Negl Trop Dis 2022; 16:e0010108. [PMID: 35020729 PMCID: PMC8789114 DOI: 10.1371/journal.pntd.0010108] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 01/25/2022] [Accepted: 12/17/2021] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND In onchocerciasis endemic areas in Africa, heterogenous biting rates by blackfly vectors on humans are assumed to partially explain age- and sex-dependent infection patterns with Onchocerca volvulus. To underpin these assumptions and further improve predictions made by onchocerciasis transmission models, demographic patterns in antibody responses to salivary antigens of Simulium damnosum s.l. are evaluated as a measure of blackfly exposure. METHODOLOGY/PRINCIPAL FINDINGS Recently developed IgG and IgM anti-saliva immunoassays for S. damnosum s.l. were applied to blood samples collected from residents in four onchocerciasis endemic villages in Ghana. Demographic patterns in antibody levels according to village, sex and age were explored by fitting generalized linear models. Antibody levels varied between villages but showed consistent patterns with age and sex. Both IgG and IgM responses declined with increasing age. IgG responses were generally lower in males than in females and exhibited a steeper decline in adult males than in adult females. No sex-specific difference was observed in IgM responses. CONCLUSIONS/SIGNIFICANCE The decline in age-specific antibody patterns suggested development of immunotolerance or desensitization to blackfly saliva antigen in response to persistent exposure. The variation between sexes, and between adults and youngsters may reflect differences in behaviour influencing cumulative exposure. These measures of antibody acquisition and decay could be incorporated into onchocerciasis transmission models towards informing onchocerciasis control, elimination, and surveillance.
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Affiliation(s)
- Laura Willen
- Department of Parasitology, Faculty of Science, Charles University, Prague, Czech Republic
- Centre for the Evaluation of Vaccinations, Vaccine and Infectious Disease Institute, University of Antwerp, Wilrijk, Belgium
- * E-mail: (LW); (OC)
| | - Philip Milton
- MRC Centre for Global Infectious Disease Analysis and London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, United Kingdom
| | - Jonathan I. D. Hamley
- MRC Centre for Global Infectious Disease Analysis and London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, United Kingdom
| | - Martin Walker
- London Centre for Neglected Tropical Disease Research and Department of Pathobiology and Population Sciences, Royal Veterinary College, Hatfield, United Kingdom
| | | | - Petr Volf
- Department of Parasitology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Maria-Gloria Basáñez
- MRC Centre for Global Infectious Disease Analysis and London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, United Kingdom
| | - Orin Courtenay
- Zeeman Institute for Systems Biology & Infectious Disease Epidemiology Research and School of Life Sciences, University of Warwick, Coventry, United Kingdom
- * E-mail: (LW); (OC)
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Gonçalves R, Landivar D, Grover Sañez Liendo E, Mamani Fernandez J, Ismail HM, Paine MJI, Courtenay O, Bern C. Improving houses in the Bolivian Chaco increases effectiveness of residual insecticide spraying against infestation with Triatoma infestans, vector of Chagas disease. Trop Med Int Health 2021; 26:1127-1138. [PMID: 34114721 DOI: 10.1111/tmi.13640] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVE Failure to control domestic Triatoma infestans in the Chaco is attributed to vulnerable adobe construction, which provides vector refuges and diminishes insecticide contact. We conducted a pilot to test the impact of housing improvement plus indoor residual spraying (IRS) on house infestation and vector abundance in a rural community in the Bolivian Chaco. METHODS The intervention included three arms: housing improvement + IRS [HI], assisted IRS [AS] in which the team helped to clear the house pre-IRS and routine IRS [RS]. HI used locally available materials, traditional construction techniques and community participation. Vector parameters were assessed by Timed Manual Capture for 2 person-hours per house at baseline and medians of 114, 173, 314, 389 and 445 days post-IRS-1. A second IRS round was applied at a median of 314 days post-IRS-1. RESULTS Post-intervention infestation indices and abundance fell in all three arms. The mean odds of infestation was 0.29 (95% CL 0.124, 0.684) in the HI relative to the RS arm. No difference was observed between AS and RS. Vector abundance was reduced by a mean 44% (24.8, 58.0) in HI compared to RS, with no difference between AS and RS. Median delivered insecticide concentrations per house were lower than the target of 50 mg/m2 in >90% of houses in all arms. CONCLUSION Housing improvement using local materials and community participation is a promising strategy to improve IRS effectiveness in the Bolivian Chaco. A larger trial is needed to quantify the impact on reinfestation over time.
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Affiliation(s)
- Raquel Gonçalves
- Zeeman Institute and School of Life Sciences, University of Warwick, Coventry, UK
| | | | | | | | - Hanafy M Ismail
- Liverpool School of Tropical Medicine, Department of Vector Biology, Liverpool, UK
| | - Mark J I Paine
- Liverpool School of Tropical Medicine, Department of Vector Biology, Liverpool, UK
| | - Orin Courtenay
- Zeeman Institute and School of Life Sciences, University of Warwick, Coventry, UK
| | - Caryn Bern
- Department of Epidemiology and Biostatistics, School of Medicine, University of California San Francisco, San Francisco, CA, USA
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Gonçalves R, Logan RAE, Ismail HM, Paine MJI, Bern C, Courtenay O. Indoor residual spraying practices against Triatoma infestans in the Bolivian Chaco: contributing factors to suboptimal insecticide delivery to treated households. Parasit Vectors 2021; 14:327. [PMID: 34134775 PMCID: PMC8207695 DOI: 10.1186/s13071-021-04831-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Accepted: 06/09/2021] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Indoor residual spraying (IRS) of insecticides is a key method to reduce vector transmission of Trypanosoma cruzi, causing Chagas disease in a large part of South America. However, the successes of IRS in the Gran Chaco region straddling Bolivia, Argentina, and Paraguay, have not equalled those in other Southern Cone countries. AIMS This study evaluated routine IRS practices and insecticide quality control in a typical endemic community in the Bolivian Chaco. METHODS Alpha-cypermethrin active ingredient (a.i.) captured onto filter papers fitted to sprayed wall surfaces, and in prepared spray tank solutions, were measured using an adapted Insecticide Quantification Kit (IQK™) validated against HPLC quantification methods. The data were analysed by mixed-effects negative binomial regression models to examine the delivered insecticide a.i. concentrations on filter papers in relation to the sprayed wall heights, spray coverage rates (surface area / spray time [m2/min]), and observed/expected spray rate ratios. Variations between health workers and householders' compliance to empty houses for IRS delivery were also evaluated. Sedimentation rates of alpha-cypermethrin a.i. post-mixing of prepared spray tanks were quantified in the laboratory. RESULTS Substantial variations were observed in the alpha-cypermethrin a.i. concentrations delivered; only 10.4% (50/480) of filter papers and 8.8% (5/57) of houses received the target concentration of 50 mg ± 20% a.i./m2. The delivered concentrations were not related to those in the matched spray tank solutions. The sedimentation of alpha-cypermethrin a.i. in the surface solution of prepared spray tanks was rapid post-mixing, resulting in a linear 3.3% loss of a.i. content per minute and 49% loss after 15 min. Only 7.5% (6/80) of houses were sprayed at the WHO recommended rate of 19 m2/min (± 10%), whereas 77.5% (62/80) were sprayed at a lower than expected rate. The median a.i. concentration delivered to houses was not significantly associated with the observed spray coverage rate. Householder compliance did not significantly influence either the spray coverage rates or the median alpha-cypermethrin a.i. concentrations delivered to houses. CONCLUSIONS Suboptimal delivery of IRS is partially attributable to the insecticide physical characteristics and the need for revision of insecticide delivery methods, which includes training of IRS teams and community education to encourage compliance. The IQK™ is a necessary field-friendly tool to improve IRS quality and to facilitate health worker training and decision-making by Chagas disease vector control managers.
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Affiliation(s)
- Raquel Gonçalves
- Zeeman Institute and School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK
| | - Rhiannon A E Logan
- Liverpool School of Tropical Medicine, Department of Vector Biology, Faculty of Biological Sciences, Pembroke Place, Liverpool, L3 5QA, UK
| | - Hanafy M Ismail
- Liverpool School of Tropical Medicine, Department of Vector Biology, Faculty of Biological Sciences, Pembroke Place, Liverpool, L3 5QA, UK
| | - Mark J I Paine
- Liverpool School of Tropical Medicine, Department of Vector Biology, Faculty of Biological Sciences, Pembroke Place, Liverpool, L3 5QA, UK
| | - Caryn Bern
- Department of Epidemiology and Biostatistics, School of Medicine, University of California San Francisco, San Francisco, CA, USA
| | - Orin Courtenay
- Zeeman Institute and School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK.
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Retkute R, Dilger E, Hamilton JGC, Keeling MJ, Courtenay O. Modelling Sand Fly Lutzomyia longipalpis Attraction to Host Odour: Synthetic Sex-Aggregation Pheromone Dominates the Response. Microorganisms 2021; 9:microorganisms9030602. [PMID: 33804003 PMCID: PMC7999287 DOI: 10.3390/microorganisms9030602] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Accepted: 03/12/2021] [Indexed: 11/22/2022] Open
Abstract
Zoontic visceral leishmaniasis (ZVL) due to Leishmania infantum is a potentially fatal protozoan parasitic disease of humans and dogs. In the Americas, dogs are the reservoir and the sand fly, Lutzomyia longipalpis, the principal vector. A synthetic version of the male sand fly produced sex-aggregation pheromone attracts both female and male conspecifics to co-located insecticide, reducing both reservoir infection and vector abundance. However the effect of the synthetic pheromone on the vector’s “choice“ of host (human, animal reservoir, or dead-end host) for blood feeding in the presence of the pheromone is less well understood. In this study, we developed a modelling framework to allow us to predict the relative attractiveness of the synthetic pheromone and potential alterations in host choice. Our analysis indicates that the synthetic pheromone can attract 53% (95% CIs: 39%–86%) of host-seeking female Lu. longipalpis and thus it out-competes competing host odours. Importantly, the results suggest that the synthetic pheromone can lure vectors away from humans and dogs, such that when co-located with insecticide, it provides protection against transmission leading to human and canine ZVL.
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Affiliation(s)
- Renata Retkute
- The Zeeman Institute for Systems Biology and Infectious Disease Epidemiology Research (SBIDER), The University of Warwick, Coventry CV4 7AL, UK; (E.D.); (M.J.K.)
- Epidemiology and Modelling Group, Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, UK
- Correspondence: (R.R.); (O.C.)
| | - Erin Dilger
- The Zeeman Institute for Systems Biology and Infectious Disease Epidemiology Research (SBIDER), The University of Warwick, Coventry CV4 7AL, UK; (E.D.); (M.J.K.)
- School of Life Sciences, The University of Warwick, Coventry CV4 7AL, UK
| | - James G. C. Hamilton
- Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancashire LA1 4YG, UK;
| | - Matt J. Keeling
- The Zeeman Institute for Systems Biology and Infectious Disease Epidemiology Research (SBIDER), The University of Warwick, Coventry CV4 7AL, UK; (E.D.); (M.J.K.)
| | - Orin Courtenay
- The Zeeman Institute for Systems Biology and Infectious Disease Epidemiology Research (SBIDER), The University of Warwick, Coventry CV4 7AL, UK; (E.D.); (M.J.K.)
- School of Life Sciences, The University of Warwick, Coventry CV4 7AL, UK
- Correspondence: (R.R.); (O.C.)
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Gonçalves R, de Souza CF, Rontani RB, Pereira A, Farnes KB, Gorsich EE, Silva RA, Brazil RP, Hamilton JGC, Courtenay O. Community deployment of a synthetic pheromone of the sand fly Lutzomyia longipalpis co-located with insecticide reduces vector abundance in treated and neighbouring untreated houses: Implications for control of Leishmania infantum. PLoS Negl Trop Dis 2021; 15:e0009080. [PMID: 33534804 PMCID: PMC7886189 DOI: 10.1371/journal.pntd.0009080] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 02/16/2021] [Accepted: 12/17/2020] [Indexed: 01/29/2023] Open
Abstract
Background The rising incidence of visceral leishmaniasis due to Leishmania infantum requires novel methods to control transmission by the sand fly vector. Indoor residual spraying of insecticide (IRS) against these largely exophilic / exophagic vectors may not be the most effective method. A synthetic copy of the male sex-aggregation pheromone of the key vector species Lutzomyia longipalpis in the Americas, was co-located with residual pyrethroid insecticide, and tested for its effects on vector abundance, hence potential transmission, in a Brazilian community study. Methods Houses within eight defined semi-urban blocks in an endemic municipality in Brazil were randomised to synthetic pheromone + insecticide or to placebo treatments. A similar number of houses located >100m from each block were placebo treated and considered as “True Controls” (thus, analysed as three trial arms). Insecticide was sprayed on a 2.6m2 surface area of the property boundary or outbuilding wall, co-located within one metre of 50mg synthetic pheromone in controlled-release dispensers. Vector numbers captured in nearby CDC light traps were recorded at monthly intervals over 3 months post intervention. Recruited sentinel houses under True Control and pheromone + insecticide treatments were similarly monitored at 7–9 day intervals. The intervention effects were estimated by mixed effects negative binomial models compared to the True Control group. Results Dose-response field assays using 50mg of the synthetic pheromone captured a mean 4.8 (95% C.L.: 3.91, 5.80) to 6.3 (95% C.L.: 3.24, 12.11) times more vectors (female Lu. longipalpis) than using 10mg of synthetic pheromone. The intervention reduced household female vector abundance by 59% (C.L.: 48.7, 66.7%) (IRR = 0.41) estimated by the cross-sectional community study, and by 70% (C.L.: 56.7%, 78.8%) estimated by the longitudinal sentinel study. Similar reductions in male Lu. longipalpis were observed. Beneficial spill-over intervention effects were also observed at nearby untreated households with a mean reduction of 24% (95% C.L.: 0.050%, 39.8%) in female vectors. The spill-over effect in untreated houses was 44% (95% C.L.: 29.7%, 56.1%) as effective as the intervention in pheromone-treated houses. Ownership of chickens increased the intervention effects in both treated and untreated houses, attributed to the suspected synergistic attraction of the synthetic pheromone and chicken kairomones. The variation in IRR between study blocks was not associated with inter-household distances, household densities, or coverage (proportion of total households treated). Conclusions The study confirms the entomological efficacy of the lure-and-kill method to reduce the abundance of this important sand fly vector in treated and untreated homesteads. The outcomes were achieved by low coverage and using only 1–2% of the quantity of insecticide as normally required for IRS, indicating the potential cost-effectiveness of this method. Implications for programmatic deployment of this vector control method are discussed. The predominant sand fly vector of the intracellular parasite Leishmania infantum, that causes human and canine visceral leishmaniasis in the Americas, is Lutzomyia longipalpis. Vector control tools to reduce transmission are needed. A sex-aggregation pheromone released by male Lu. longipalpis attracts female conspecifics which facilitates blood-feeding and transmission. This study, conducted in Brazil, quantifies the effects of community deployment of a synthetic version of the sex-aggregation pheromone, in a controlled-release dispenser, and co-located with lethal insecticide applied to a small area of the household compound or outbuilding wall. 50mg synthetic pheromone dispensers were used since they attracted substantially more vectors than 10mg dispensers. Deploying this novel lure-and-kill method to houses in eight replicate study blocks in two suburban endemic areas, demonstrated that it reduces vector numbers at both pheromone + insecticide treated houses, and neighbouring untreated houses. The presence of chickens (a known additional attraction to blood-seeking female Lu. longipalpis) increased the beneficial effects of the intervention. The method used only 1–2% of the quantity of insecticide necessary for IRS for an average sized house. The results demonstrate the efficacy and potential cost-effectiveness of this novel lure-and-kill control method.
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Affiliation(s)
- Raquel Gonçalves
- Zeeman Institute and School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Cristian F. de Souza
- Laboratório de Doenças Parasitárias, Instituto Oswaldo Cruz, FIOCRUZ, Rio de Janeiro, Brazil
| | - Reila B. Rontani
- Laboratório de Doenças Parasitárias, Instituto Oswaldo Cruz, FIOCRUZ, Rio de Janeiro, Brazil
| | - Alisson Pereira
- Laboratório de Doenças Parasitárias, Instituto Oswaldo Cruz, FIOCRUZ, Rio de Janeiro, Brazil
| | - Katie B. Farnes
- Zeeman Institute and School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Erin E. Gorsich
- Zeeman Institute and School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Rafaella A. Silva
- Núcleo de Medicina Tropical, Universidade de Brasilia, Brasília, Federal District, Brazil
- Ministério da Saúde, Departamento de Imunização e Doenças Transmissíveis, Secretaria de Vigilância em Saúde, Brasília, Federal District, Brazil
| | - Reginaldo P. Brazil
- Laboratório de Doenças Parasitárias, Instituto Oswaldo Cruz, FIOCRUZ, Rio de Janeiro, Brazil
| | - James G. C. Hamilton
- Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Bailrigg, Lancaster, Lancashire, United Kingdom
- * E-mail: (JH); (OC)
| | - Orin Courtenay
- Zeeman Institute and School of Life Sciences, University of Warwick, Coventry, United Kingdom
- * E-mail: (JH); (OC)
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González MA, Dilger E, Ronderos MM, Spinelli GR, Courtenay O, Hamilton JGC. Significant reduction in abundance of peridomestic mosquitoes (Culicidae) and Culicoides midges (Ceratopogonidae) after chemical intervention in western São Paulo, Brazil. Parasit Vectors 2020; 13:549. [PMID: 33160407 PMCID: PMC7648319 DOI: 10.1186/s13071-020-04427-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Accepted: 10/24/2020] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND We assessed the impact of two sand fly insecticide interventions (insecticide spraying and insecticide-impregnated dog collars) on the peridomestic abundance and distribution of mosquitoes (Culicidae) and biting midges (Ceratopogonidae) in western São Paulo (Brazil) in a long-term (42-month) evaluation. Both of these dipteran groups are vectors of diseases of medical and veterinary relevance to humans and domestic animals in Brazil. METHODS The interventions in the 3-arm stratified randomised control trial were: pheromone + insecticide (PI) (chicken roosts were sprayed with microencapsulated lambda-cyhalothrin; pheromone lure has no effect on the Diptera pests studied here); dog-collars (DC) (dogs fitted with deltamethrin-impregnated collars); and control (C) (unexposed to pyrethroids) were extended by 12 months. During that time, adult mosquitoes and midges were sampled along 280 households at three household locations (inside human dwellings, dog sleeping sites and chicken roosts). RESULTS We collected 3145 culicids (9 genera, 87.6% Culex spp.) distributed relatively uniformly across all 3 arms: 41.9% at chicken roosts; 37.7% inside houses; and 20.3% at dog sleeping sites. We collected 11,464 Culicoides (15 species) found mostly at chicken roosting sites (84.7%) compared with dog sleeping sites (12.9%) or houses (2.4%). Mosquitoes and Culicoides were most abundant during the hot and rainy season. Increased daytime temperature was marginally associated with increased mosquito abundance (Z = 1.97, P = 0.049) and Culicoides abundance (Z = 1.71, P = 0.087). There was no significant association with daily average rainfall for either group. Household-level mosquito and midge numbers were both significantly reduced by the PI intervention 56% [incidence rate ratio, IRR = 0.54 (95% CI: 0.30-0.97), P ≤ 0.05] and 53% [IRR = 0.47 (95% CI: 0.26-0.85), P ≤ 0.05], respectively, compared to the control intervention. The abundance of both dipteran groups at dog sleeping sites was largely unaffected by the PI and DC interventions. The PI intervention significantly reduced abundance of mosquitoes inside houses (41%) and at chicken roosting sites (48%) and reduced midge abundance by 51% in chicken roosting sites. CONCLUSIONS Sprayed insecticide at chicken roosting sites reduced the abundance of mosquitoes and midges at the peridomestic level while dog collars had no effect on numbers for any group.
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Affiliation(s)
- Mikel A. González
- Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Bailrigg, LA1 4YG Lancashire UK
- Present Address: Departamento de Sanidad Animal, Instituto Vasco de Investigación y Desarrollo Agrario (NEIKER), Derio, Bizkaia Spain
| | - Erin Dilger
- Zeeman Institute and School of Life Sciences, Gibbet Hill Campus, University of Warwick, Coventry, CV4 7AL UK
| | - María M. Ronderos
- División Entomología, Museo de La Plata, Paseo del Bosque s/n, 1900 La Plata, Buenos Aires Argentina
| | - Gustavo R. Spinelli
- División Entomología, Museo de La Plata, Paseo del Bosque s/n, 1900 La Plata, Buenos Aires Argentina
| | - Orin Courtenay
- Zeeman Institute and School of Life Sciences, Gibbet Hill Campus, University of Warwick, Coventry, CV4 7AL UK
| | - James G. C. Hamilton
- Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Bailrigg, LA1 4YG Lancashire UK
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Elnaiem DEA, Dakein O, Alawad AMA, Alsharif B, Khogali A, Jibreel T, Osman OF, Has’san H, Atia AM, Elhag M, Den Boer M, Ritmeijer K, Bern C, Alvar J, Khalid N, Courtenay O. Outdoor Residual Insecticide Spraying (ODRS), a New Approach for the Control of the Exophilic Vectors of Human Visceral Leishmaniasis: Phlebotomus orientalis in East Africa. PLoS Negl Trop Dis 2020; 14:e0008774. [PMID: 33079934 PMCID: PMC7598920 DOI: 10.1371/journal.pntd.0008774] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 10/30/2020] [Accepted: 09/04/2020] [Indexed: 01/18/2023] Open
Abstract
Visceral Leishmaniasis (VL) due to Leishmania donovani is a neglected protozoan parasitic disease in humans, which is usually fatal if untreated. Phlebotomus orientalis, the predominant VL vector in East Africa, is a highly exophilic/exophagic species that poses a major challenge to current Integrated Vector Management (IVM). Here we report results of pilot studies conducted in rural villages in Gedarif state, Sudan, to evaluate outdoor residual spraying of 20mg active ingredient (a.i.) /m2 deltamethrin insecticide applied to the characteristic household compound boundary reed fence and to the outside of household buildings (Outdoor Residual Insecticide Spraying, ODRS), and as an alternative, spraying restricted to the boundary fence only (Restricted Outdoor Residual Insecticide Spraying, RODRS). Four to six clusters of 20 households were assigned to insecticide treatments or control in three experiments. Changes in sand fly numbers were monitored over 2,033 trap-nights over 43–76 days follow-up in four sentinel houses per cluster relative to unsprayed control clusters. Sand fly numbers were monitored by sticky traps placed on the ground on the inside (“outdoor”) and the outside (“peridomestic”) of the boundary fence, and by CDC light traps suspended outdoors in the household compound. The effects of ODRS on sand fly numbers inside sleeping huts were monitored by insecticide knockdown. After a single application, ODRS reduced P. orientalis abundance by 83%-99% in outdoor and peridomestic trap locations. ODRS also reduced numbers of P. orientalis found resting inside sleeping huts. RODRS reduced outdoor and peridomestic P. orientalis by 60%-88%. By direct comparison, RODRS was 58%-100% as effective as ODRS depending on the trapping method. These impacts were immediate on intervention and persisted during follow-up, representing a large fraction of the P. orientalis activity season. Relative costs of ODRS and RODRS delivery were $5.76 and $3.48 per household, respectively. The study demonstrates the feasibility and high entomological efficacy of ODRS and RODRS, and the expected low costs relative to current IVM practises. These methods represent novel sand fly vector control tools against predominantly exophilic/exophagic sand fly vectors, aimed to lower VL burdens in Sudan, with potential application in other endemic regions in East Africa. Phlebotomus orientalis is the predominant vector of visceral leishmaniasis (VL, kala azar) in Sudan and other countries of East Africa, where the disease causes high morbidity and mortality. This sylvatic sand fly species is abundant in wild habitats characterized by presence of black cotton soil and vegetation dominated by Balanites aegyptiaca and/or Acacia seyal trees. In villages, the vector bites people in the household yard and in nearby peri-domestic locations, exhibiting limited indoor resting behaviour. The marked exophagic and exophilic behaviours of P. orientalis represent a profound challenge for VL control by excluding indoor residual spraying of insecticides (IRS) and compromising the efficacy of insecticide-impregnated bednets (ITNs). In this study, we evaluated the entomological efficacy of residual pyrethroid applied outdoors to household boundary fences and the exterior walls of household huts (outdoor residual insecticide spraying, ODRS), to reduce the abundance of P. orientalis inside and outside houses. We also evaluated the entomological impact of a restricted outdoor residual insecticide spraying (RODRS), whereby insecticide was applied only to the boundary fence. The study was carried out in June 2016-June 2017 in Jebel-Algana and Umsalala villages, Gedarif state, eastern Sudan, which are highly endemic for VL. The results showed that a single ODRS application of 20mg a.i. /m2 2.8% deltamethrin provided average reductions of 83%-99% in outdoor and peridomestic P. orientalis sand fly numbers relative to unsprayed control clusters. RODRS reduced outdoor and peridomestic P. orientalis by 60%-88%. The average cost of ODRS and RODRS per household were $5.76 and $3.48, respectively. The costs of these community-based control measures were substantially lower than the costs of LLINs, which is the only evidence-based tool used to protect against VL in the area. Future studies should evaluate the impact of ODRS/RODRS transmission of VL incidence in endemic villages and in seasonal agricultural farms.
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Affiliation(s)
- Dia-Eldin A. Elnaiem
- Department of Natural Sciences, University of Maryland Eastern Shore, MD, United States of America
- * E-mail: (DEAE); (OC)
| | - Osman Dakein
- Department of Zoology, Faculty of Science, University of Khartoum, Sudan
- Kala azar Research Centre, Faculty of Medicine and Health Sciences, University for Gedarif, Gedarif, Sudan
| | - Ahmed Mohammed-Ali Alawad
- Ministry of Health, Gedarif state, Sudan
- Blue Nile Health Institute, Gezira University, Wad Medani, Sudan
| | - Bashir Alsharif
- Departamento de Entomologia, CPqAM, Fundação Oswaldo Cruz, Recife, Brasil and Dept of Medical Entomology, National Public Health Laboratory, Ministry of Health, Sudan
| | - Altayeb Khogali
- Blue Nile Health Institute, Gezira University, Wad Medani, Sudan
| | - Tayseer Jibreel
- Blue Nile Health Institute, Gezira University, Wad Medani, Sudan
| | - Omran F. Osman
- Department of Zoology, Faculty of Science, University of Khartoum, Sudan
| | - Hassan Has’san
- Ministry of Health, Gedarif state, Sudan
- Blue Nile Health Institute, Gezira University, Wad Medani, Sudan
| | | | - Mousab Elhag
- Director, Directorate of Communicable Diseases, Federal Ministry of Health, Khartoum, Sudan
| | | | | | - Caryn Bern
- University of California San Francisco, San Francisco, California, United States of America
| | - Jorge Alvar
- Drugs for Neglected Diseases initiative, Geneva, Switzerland
| | - Noteila Khalid
- Department of Zoology, Ibn Sina University, Khartoum, Sudan
| | - Orin Courtenay
- Zeeman Institute and School of Life Sciences, University of Warwick, Coventry, CV4 7AL, United Kingdom
- * E-mail: (DEAE); (OC)
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González MA, Bell M, Souza CF, Maciel-de-Freitas R, Brazil RP, Courtenay O, Hamilton JGC. Synthetic sex-aggregation pheromone of Lutzomyia longipalpis, the South American sand fly vector of Leishmania infantum, attracts males and females over long-distance. PLoS Negl Trop Dis 2020; 14:e0008798. [PMID: 33079936 PMCID: PMC7598924 DOI: 10.1371/journal.pntd.0008798] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 10/30/2020] [Accepted: 09/16/2020] [Indexed: 01/22/2023] Open
Abstract
Background In South America the sand fly Lutzomyia longipalpis is the predominant vector of Leishmania infantum, the parasite that causes canine and human visceral leishmaniasis. Co-location of synthetic male sex-aggregation pheromone with an insecticide provided protection against canine seroconversion, parasite infection, reduced tissue parasite loads, and female sand fly densities at households. Optimising the sex-aggregation pheromone + insecticide intervention requires information on the distance over which female and male Lu. longipalpis would be attracted to the synthetic pheromone in the field. Methodology/Principal findings Wild Lu. longipalpis were collected at two peridomestic study sites in Governador Valadares (Minas Gerais, Brazil). Sand flies were marked with coloured fluorescent powder using an improved protocol and then released into an existing domestic chicken shed at two independent sites, followed by recapture at synthetic-pheromone host-odour baited traps placed up to 30 metres distant from the release point. In total 1704 wild-caught Lu. longipalpis were released into the two chicken sheds. Overall 4.3% of the marked flies were recaptured in the pheromone baited experimental chicken sheds compared to no marked flies recaptured in the control sheds. At the first site, 14 specimens (10.4% of the marked and released specimens) were recaptured at 10m, 36 (14.8%) at 20m, and 15 (3.4%) at 30m. At the second site, lower recapture rates were recorded; 8 marked specimens (1.3%) were recaptured at 5 and 10m and no marked specimens were recaptured at 15m. Approximately 7x more marked males than females were recaptured although males were only 2x as common as females in the released population. 52% of the marked Lu. longipalpis were collected during the first night of sampling, 32% on the second night, and 16% on the third night. Conclusions/Significance The study established that both male and female sand flies can be attracted to the synthetic sex-aggregation pheromone in the presence of host odour over distances up to at least 30m in the field depending on local environmental and meterological conditions. Visceral leishmaniasis (VL) is a disease caused by an insect transmitted protist parasite. In South America and Brazil in particular, it causes significant morbidity and mortality, with thousands of human cases and deaths reported every year. Domestic dogs are the most important source of human infection. Controlling the sand flies that transmit the parasite is one way to reduce the number of VL cases and recent research has shown the potential for a new pheromone-based approach to vector control. In a recent cluster-randomised control trial, co-location of a synthetic copy of the male sand fly sex-aggregation pheromone with pyrethroid insecticide reduced numbers of sand flies in households and provided protection for dogs against leishmaniasis infection incidence. The current study was carried out to determine the distance over which the synthetic sex-aggregation pheromone could attract Lu. longipalpis in a peridomestic environment in a Brazilian city. Male and female Lu. longipalpis were attracted up to 30m in one night towards a source of the pheromone. This information will help to inform the optimisation of placement of sex pheromone/insecticide intervention in Brazil.
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Affiliation(s)
- Mikel A. González
- Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Bailrigg, Lancashire, United Kingdom
| | - Melissa Bell
- Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Bailrigg, Lancashire, United Kingdom
| | - Cristian F. Souza
- Laboratório Doenças Parasitárias, Instituto Oswaldo Cruz—Fiocruz, Pavilhão Arthur Neiva, Av. Brasil, Rio de Janeiro, RJ, Brazil
| | - Rafael Maciel-de-Freitas
- Laboratório de Mosquitos Transmissores de Hematozoários, Instituto Oswaldo Cruz, Pavilhão Carlos Chagas, Av. Brasil, Rio de Janeiro, RJ, Brazil
| | - Reginaldo P. Brazil
- Laboratório Doenças Parasitárias, Instituto Oswaldo Cruz—Fiocruz, Pavilhão Arthur Neiva, Av. Brasil, Rio de Janeiro, RJ, Brazil
| | - Orin Courtenay
- Zeeman Institute and School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - James G. C. Hamilton
- Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Bailrigg, Lancashire, United Kingdom
- * E-mail:
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Dantas-Torres F, Nogueira FDS, Menz I, Tabanez P, da Silva SM, Ribeiro VM, Miró G, Cardoso L, Petersen C, Baneth G, Oliva G, Solano-Gallego L, Ferrer L, Pennisi MG, Bourdeau P, Maia C, Otranto D, Gradoni L, Courtenay O, Costa CHN. Vaccination against canine leishmaniasis in Brazil. Int J Parasitol 2020; 50:171-176. [PMID: 32126240 DOI: 10.1016/j.ijpara.2020.01.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Revised: 12/29/2019] [Accepted: 01/02/2020] [Indexed: 12/13/2022]
Abstract
Prevention of canine Leishmania infantum infection is critical to management of visceral leishmaniasis in people living in endemic areas of Brazil. A bill (PL 1738/11), currently under consideration, proposes to establish a national vaccination policy against canine leishmaniasis in Brazil. However, there is no solid scientific evidence supporting the idea that this could reduce transmission from infected vaccinated dogs to sand flies to a level that would significantly reduce the risk of L. infantum infection or visceral leishmaniasis in humans. Thus, we advocate that insecticide-impregnated collars should the first line protective measure for public health purposes and that vaccines are applied on a case-by-case, optional basis for individual dog protection.
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Affiliation(s)
- Filipe Dantas-Torres
- Department of Immunology, Aggeu Magalhães Institute, Oswaldo Cruz Foundation, Recife, Brazil.
| | | | - Ingrid Menz
- Self-employed Veterinarian, Campinas, Brazil
| | | | - Sydnei Magno da Silva
- Department of Immunology, Microbiology and Parasitology, Institute of Biomedical Sciences, Federal University of Uberlândia, Uberlândia, Brazil
| | - Vitor Márcio Ribeiro
- Veterinary School, Pontifical Catholic University of Minas Gerais, Betim, Brazil
| | - Guadalupe Miró
- Department of Animal Health, Veterinary Faculty, Universidad Complutense de Madrid, Madrid, Spain
| | - Luís Cardoso
- Department of Veterinary Sciences, and Animal and Veterinary Research Centre, University of Trás-os-Montes e Alto Douro (UTAD), Vila Real, Portugal
| | - Christine Petersen
- Department of Epidemiology, College of Public Health, University of Iowa, Iowa City, United States
| | - Gad Baneth
- Koret School of Veterinary Medicine, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Gaetano Oliva
- Department of Veterinary Medicine and Food Production, University of Naples Federico II, Naples, Italy
| | - Laia Solano-Gallego
- Departament de Medicina i Cirurgia Animals, Facultat de Veterinària, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Lluís Ferrer
- Departament de Medicina i Cirurgia Animals, Facultat de Veterinària, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Maria Grazia Pennisi
- Department of Veterinary Sciences, University of Messina, Polo Universitario Annunziata, Messina, Italy
| | - Patrick Bourdeau
- Veterinary School of Nantes ONIRIS, University of Nantes, LUNAM, Nantes, France
| | - Carla Maia
- Global Health and Tropical Medicine (GHTM), Instituto de Higiene e Medicina Tropical (IHMT), Universidade Nova de Lisboa (UNL), Lisbon, Portugal
| | - Domenico Otranto
- Department of Veterinary Medicine, University of Bari, Valenzano, Italy
| | - Luigi Gradoni
- Unit of Vector-borne Diseases, Department of Infectious Diseases, Istituto Superiore di Sanità, Rome, Italy
| | - Orin Courtenay
- Zeeman Institute, and School of Life Sciences, University of Warwick, Coventry, United Kingdom
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Wilson AL, Courtenay O, Kelly-Hope LA, Scott TW, Takken W, Torr SJ, Lindsay SW. The importance of vector control for the control and elimination of vector-borne diseases. PLoS Negl Trop Dis 2020; 14:e0007831. [PMID: 31945061 PMCID: PMC6964823 DOI: 10.1371/journal.pntd.0007831] [Citation(s) in RCA: 251] [Impact Index Per Article: 62.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Vector-borne diseases (VBDs) such as malaria, dengue, and leishmaniasis exert a huge burden of morbidity and mortality worldwide, particularly affecting the poorest of the poor. The principal method by which these diseases are controlled is through vector control, which has a long and distinguished history. Vector control, to a greater extent than drugs or vaccines, has been responsible for shrinking the map of many VBDs. Here, we describe the history of vector control programmes worldwide from the late 1800s to date. Pre 1940, vector control relied on a thorough understanding of vector ecology and epidemiology, and implementation of environmental management tailored to the ecology and behaviour of local vector species. This complex understanding was replaced by a simplified dependency on a handful of insecticide-based tools, particularly for malaria control, without an adequate understanding of entomology and epidemiology and without proper monitoring and evaluation. With the rising threat from insecticide-resistant vectors, global environmental change, and the need to incorporate more vector control interventions to eliminate these diseases, we advocate for continued investment in evidence-based vector control. There is a need to return to vector control approaches based on a thorough knowledge of the determinants of pathogen transmission, which utilise a range of insecticide and non-insecticide-based approaches in a locally tailored manner for more effective and sustainable vector control.
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Affiliation(s)
- Anne L. Wilson
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Orin Courtenay
- Zeeman Institute and School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Louise A. Kelly-Hope
- Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Thomas W. Scott
- Department of Entomology and Nematology, University of California Davis, Davis, California, United States of America
| | - Willem Takken
- Department of Plant Sciences, Wageningen University and Research, Wageningen, the Netherlands
| | - Steve J. Torr
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Steve W. Lindsay
- Department of Biosciences, Durham University, Durham, United Kingdom
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Courtenay O, Dilger E, Calvo-Bado LA, Kravar-Garde L, Carter V, Bell MJ, Alves GB, Goncalves R, Makhdoomi MM, González MA, Nunes CM, Bray DP, Brazil RP, Hamilton JGC. Sand fly synthetic sex-aggregation pheromone co-located with insecticide reduces the incidence of infection in the canine reservoir of visceral leishmaniasis: A stratified cluster randomised trial. PLoS Negl Trop Dis 2019; 13:e0007767. [PMID: 31652261 PMCID: PMC6834291 DOI: 10.1371/journal.pntd.0007767] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 11/06/2019] [Accepted: 09/09/2019] [Indexed: 12/20/2022] Open
Abstract
OBJECTIVE To evaluate the efficacy of a synthetic sex-aggregation pheromone of the sand fly vector Lu. longipalpis, co-located with residual insecticide, to reduce the infection incidence of Leishmania infantum in the canine reservoir. METHODS A stratified cluster randomised trial was designed to detect a 50% reduction in canine incident infection after 24 months in 42 recruited clusters, randomly assigned to one of three intervention arms (14 cluster each): synthetic pheromone + insecticide, insecticide-impregnated dog collars, or placebo control. Infection incidence was measured by seroconversion to anti-Leishmania serum antibody, Leishmania parasite detection and canine tissue parasite loads. Changes in relative Lu. longipalpis abundance within households were measured by setting three CDC light traps per household. RESULTS A total 1,454 seronegative dogs were followed-up for a median 15.2 (95% C.I.s: 14.6, 16.2) months per cluster. The pheromone + insecticide intervention provided 13% (95% C.I. 0%, 44.0%) protection against anti-Leishmania antibody seroconversion, 52% (95% C.I. 6.2%, 74·9%) against parasite infection, reduced tissue parasite loads by 53% (95% C.I. 5.4%, 76.7%), and reduced household female sand fly abundance by 49% (95% C.I. 8.2%, 71.3%). Variation in the efficacy against seroconversion varied between trial strata. Equivalent protection attributed to the impregnated-collars were 36% (95% C.I. 14.4%, 51.8%), 23% (95% C.I. 0%, 57·5%), 48% (95% C.I. 0%, 73.4%) and 43% (95% C.I. 0%, 67.9%), respectively. Comparison of the two interventions showed no statistically consistent differences in their efficacies; however, the errors were broad for all outcomes. Reductions in sand fly numbers were predominant where insecticide was located (chicken and dog sleeping sites), with no evidence of insecticide-induced repellence onto humans or dogs. CONCLUSION The synthetic pheromone co-located with insecticide provides protection particularly against canine L. infantum parasite transmission and sand fly vector abundance. The effect estimates are not dissimilar to those of the insecticide-impregnated collars, which are documented to reduce canine infection incidence, human infection and clinical VL disease incidence, in different global regions. The trialled novel lure-and-kill approach is a low-cost potential vector control tool against ZVL in the Americas.
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Affiliation(s)
- Orin Courtenay
- Zeeman Institute and School of Life Sciences, University of Warwick, Coventry, United Kingdom
- * E-mail: (OC); (JGCH)
| | - Erin Dilger
- Zeeman Institute and School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Leo A. Calvo-Bado
- Zeeman Institute and School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Lidija Kravar-Garde
- Zeeman Institute and School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Vicky Carter
- School of Life Sciences, Institute of Science & Technology in Medicine, Keele University, Keele, Staffordshire, United Kingdom
| | - Melissa J. Bell
- Zeeman Institute and School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Graziella B. Alves
- School of Life Sciences, Institute of Science & Technology in Medicine, Keele University, Keele, Staffordshire, United Kingdom
| | - Raquel Goncalves
- Zeeman Institute and School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Muhammad M. Makhdoomi
- Zeeman Institute and School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Mikel A. González
- Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Bailrigg, Lancaster, Lancashire, United Kingdom
| | - Caris M. Nunes
- Faculdade de Medicina Veterinária, Universidade Estadual Paulista (UNESP), Araçatuba, São Paulo, Brazil
| | - Daniel P. Bray
- School of Life Sciences, Institute of Science & Technology in Medicine, Keele University, Keele, Staffordshire, United Kingdom
| | - Reginaldo P. Brazil
- Laboratório de Doenças Parasitárias, Instituto Oswaldo Cruz, Rio de Janeiro, Brazil
| | - James G. C. Hamilton
- Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Bailrigg, Lancaster, Lancashire, United Kingdom
- * E-mail: (OC); (JGCH)
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Gomez SA, Chapman LAC, Dilger E, Courtenay O, Picado A. Correction: Estimating the efficacy of community-wide use of systemic insecticides in dogs to control zoonotic visceral leishmaniasis: A modelling study in a Brazilian scenario. PLoS Negl Trop Dis 2019; 13:e0007452. [PMID: 31136590 PMCID: PMC6538138 DOI: 10.1371/journal.pntd.0007452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Buckingham-Jeffery E, Hill EM, Datta S, Dilger E, Courtenay O. Spatio-temporal modelling of Leishmania infantum infection among domestic dogs: a simulation study and sensitivity analysis applied to rural Brazil. Parasit Vectors 2019; 12:215. [PMID: 31064395 PMCID: PMC6505121 DOI: 10.1186/s13071-019-3430-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 04/04/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The parasite Leishmania infantum causes zoonotic visceral leishmaniasis (VL), a potentially fatal vector-borne disease of canids and humans. Zoonotic VL poses a significant risk to public health, with regions of Latin America being particularly afflicted by the disease. Leishmania infantum parasites are transmitted between hosts during blood-feeding by infected female phlebotomine sand flies. With a principal reservoir host of L. infantum being domestic dogs, limiting prevalence in this reservoir may result in a reduced risk of infection for the human population. To this end, a primary focus of research efforts has been to understand disease transmission dynamics among dogs. One way this can be achieved is through the use of mathematical models. METHODS We have developed a stochastic, spatial, individual-based mechanistic model of L. infantum transmission in domestic dogs. The model framework was applied to a rural Brazilian village setting with parameter values informed by fieldwork and laboratory data. To ensure household and sand fly populations were realistic, we statistically fitted distributions for these entities to existing survey data. To identify the model parameters of highest importance, we performed a stochastic parameter sensitivity analysis of the prevalence of infection among dogs to the model parameters. RESULTS We computed parametric distributions for the number of humans and animals per household and a non-parametric temporal profile for sand fly abundance. The stochastic parameter sensitivity analysis determined prevalence of L. infantum infection in dogs to be most strongly affected by the sand fly associated parameters and the proportion of immigrant dogs already infected with L. infantum parasites. CONCLUSIONS Establishing the model parameters with the highest sensitivity of average L. infantum infection prevalence in dogs to their variation helps motivate future data collection efforts focusing on these elements. Moreover, the proposed mechanistic modelling framework provides a foundation that can be expanded to explore spatial patterns of zoonotic VL in humans and to assess spatially targeted interventions.
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Affiliation(s)
- Elizabeth Buckingham-Jeffery
- School of Mathematics, University of Manchester, Manchester, UK.
- Zeeman Institute: SBIDER (Systems Biology & Infectious Disease Epidemiology Research), University of Warwick, Coventry, UK.
| | - Edward M Hill
- Zeeman Institute: SBIDER (Systems Biology & Infectious Disease Epidemiology Research), University of Warwick, Coventry, UK
- Warwick Mathematics Institute, University of Warwick, Coventry, UK
| | - Samik Datta
- Population Modelling Group, National Institute of Water and Atmospheric Research, Wellington, New Zealand
- Zeeman Institute: SBIDER (Systems Biology & Infectious Disease Epidemiology Research), University of Warwick, Coventry, UK
| | - Erin Dilger
- Zeeman Institute: SBIDER (Systems Biology & Infectious Disease Epidemiology Research), University of Warwick, Coventry, UK
- School of Life Sciences, University of Warwick, Coventry, UK
| | - Orin Courtenay
- Zeeman Institute: SBIDER (Systems Biology & Infectious Disease Epidemiology Research), University of Warwick, Coventry, UK
- School of Life Sciences, University of Warwick, Coventry, UK
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González MA, Bell MJ, Bernhardt SA, Brazil RP, Dilger E, Courtenay O, Hamilton JGC. Susceptibility of wild-caught Lutzomyia longipalpis (Diptera: Psychodidae) sand flies to insecticide after an extended period of exposure in western São Paulo, Brazil. Parasit Vectors 2019; 12:110. [PMID: 30871639 PMCID: PMC6419423 DOI: 10.1186/s13071-019-3364-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2018] [Accepted: 02/26/2019] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND In Brazil, members of the sand fly species complex Lutzomyia longipalpis transmit Leishmania infantum, a protist parasite that causes visceral leishmaniasis. Male Lu. longipalpis produce a sex pheromone that is attractive to both females and males. During a cluster randomised trial, to determine the combined effect of synthetic sex-aggregation pheromone and insecticide on Le. infantum transmission Lu. longipalpis had been continuously exposed to insecticide for 30 months. The objective of this study was to determine the effect of continuous exposure to the insecticides used in the trial on the susceptibility of Lu. longipalpis population. METHODS During the trial the sand flies had been exposed to either lambda-cyhalothrin [pheromone + residual insecticide spray (PI)], deltamethrin [dog collars (DC)] or no insecticide [control (C)], for 30 months (November 2012 to April 2015). The insecticide treatment regime was kept in place for an additional 12 months (May 2015-April 2016) during this susceptibility study. Sand flies collected from the field were exposed to WHO insecticide-impregnated papers cyhalothrin (0.05%), deltamethrin (0.5%) and control (silicone oil) in a modified WHO insecticide exposure trial to determine their susceptibility. RESULTS We collected 788 Lu. longipalpis using CDC-light traps in 31 municipalities across the three trial arms. Probit analysis showed that the knockdown times (KDTs) of Lu. longipalpis collected from the lambda-cyhalothrin exposed PI-arm [KDT50: 31.1 min, confidence interval (CI): 29.6-32.6 and KDT90: 44.2 min, CI: 42.1-46.7] were longer than the KDTs from the non-insecticide-treated C-arm (KDT50: 26.3 min, CI: 25.1-27.6 and KDT90: 38.2, CI: 36.5-40.2) (no-overlapping 95% CIs). KDTs of Lu. longipalpis collected from the deltamethrin exposed DC-arm had similar values (KDT50: 13.7 min, CI: 10.1-16.2 and KDT90: 26.7 min, CI: 21.8-30.6) to those for the C-arm (KDT50: 13.5 min; CI: 12.2-14.8 and KDT90: 23.2 min, CI: 21.4-25.4) (overlapping CIs). The wild-caught unexposed Lu. longipalpis (C-arm), took approximately twice as long to knock down as laboratory-colonised specimens for both insecticides. CONCLUSIONS Our study reveals slight changes in KDT, in sand flies after prolonged exposure to lambda-cyhalothrin in the presence of pheromone. These changes are not considered to have reached the reference levels indicative of resistance in sand flies suggesting that pheromone and insecticide treatment at the level indicated in this study do not constitute a significant risk of increased insecticide resistance. Prolonged exposure to deltamethrin in dog collars did not result in changes to KDT.
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Affiliation(s)
- Mikel A. González
- Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancashire, LA1 4YG UK
- Present Address: Departamento de Sanidad Animal, Instituto Vasco de Investigación y Desarrollo Agrario (NEIKER-Teknalia), Derio, 48160 Biscay Spain
| | - Melissa J. Bell
- Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancashire, LA1 4YG UK
| | | | - Reginaldo P. Brazil
- Laboratório de Doenças Parasitárias, Instituto Oswaldo Cruz, Fundaçao Oswaldo Cruz, Av. Brasil, Manguinhos, Rio de Janeiro, RJ 4365 Brazil
| | - Erin Dilger
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL UK
| | - Orin Courtenay
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL UK
| | - James G. C. Hamilton
- Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancashire, LA1 4YG UK
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Courtenay O, Bazmani A, Parvizi P, Ready PD, Cameron MM. Insecticide-impregnated dog collars reduce infantile clinical visceral leishmaniasis under operational conditions in NW Iran: A community-wide cluster randomised trial. PLoS Negl Trop Dis 2019; 13:e0007193. [PMID: 30830929 PMCID: PMC6417739 DOI: 10.1371/journal.pntd.0007193] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 03/14/2019] [Accepted: 01/28/2019] [Indexed: 02/07/2023] Open
Abstract
OBJECTIVE To assess the effectiveness of community-wide deployment of insecticide-impregnated collars for dogs- the reservoir of Leishmania infantum-to reduce infantile clinical visceral leishmaniasis (VL). METHODS A pair matched-cluster randomised controlled trial involving 40 collared and 40 uncollared control villages (161 [95% C.L.s: 136, 187] children per cluster), was designed to detect a 55% reduction in 48 month confirmed VL case incidence. The intervention study was designed by the authors, but implemented by the Leishmaniasis Control Program in NW Iran, from 2002 to 2006. RESULTS The collars provided 50% (95% C.I. 17·8%-70·0%) protection against infantile VL incidence (0·95/1000/yr compared to 1·75/1000/yr). Reductions in incidence were observed across 76% (22/29) of collared villages compared to pair-matched control villages, with 31 fewer cases by the end of the trial period. In 11 paired villages, no further cases were recorded post-intervention, whereas in 7 collared villages there were 9 new clinical cases relative to controls. Over the trial period, 6,835 collars were fitted at the beginning of the 4 month sand fly season, of which 6.9% (95% C.I. 6.25%, 7.56%) were lost but rapidly replaced. Collar coverage (percent dogs collared) per village varied between 66% and 100%, with a mean annual coverage of 87% (95% C.I. 84·2, 89·0%). The variation in post-intervention clinical VL incidence was not associated with collar coverage, dog population size, implementation logistics, dog owner compliance, or other demographic variables tested. Larger reductions and greater persistence in incident case numbers (indicative of transmission) were observed in villages with higher pre-existing VL case incidence. CONCLUSION Community-wide deployment of collars can provide a significant level of protection against infantile clinical VL, achieved in this study by the local VL Control Program, demonstrating attributes desirable of a sustainable public health program. The effectiveness is not dissimilar to the community-level protection provided against human and canine infection with L. infantum.
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Affiliation(s)
- Orin Courtenay
- Zeeman Institute, and School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Ahad Bazmani
- Infectious and Tropical Diseases Research Centre, Tabriz University of Medical Sciences, Tabriz, Iran
| | | | - Paul D. Ready
- London School of Hygiene and Tropical Medicine, Keppel Street, London, United Kingdom
| | - Mary M. Cameron
- London School of Hygiene and Tropical Medicine, Keppel Street, London, United Kingdom
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Bell MJ, Sedda L, Gonzalez MA, de Souza CF, Dilger E, Brazil RP, Courtenay O, Hamilton JGC. Attraction of Lutzomyia longipalpis to synthetic sex-aggregation pheromone: Effect of release rate and proximity of adjacent pheromone sources. PLoS Negl Trop Dis 2018; 12:e0007007. [PMID: 30566503 PMCID: PMC6300254 DOI: 10.1371/journal.pntd.0007007] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Accepted: 11/17/2018] [Indexed: 12/01/2022] Open
Abstract
In South America, the Protist parasite that causes visceral leishmaniasis, a potentially fatal human disease, is transmitted by blood-feeding female Lutzomyia longipalpis sand flies. A synthetic copy of the male produced sex-aggregation pheromone offers new opportunities for vector control applications. We have previously shown that the pheromone placed in plastic sachets (lures) can attract both females and males to insecticide treated sites for up to 3 months. To use the pheromone lure in a control program we need to understand how the application of lures in the field can be optimised. In this study we investigated the effect of increasing the number of lures and their proximity to each other on their ability to attract Lu. longipalpis. Also for the first time we applied a Bayesian log-linear model rather than a classic simple (deterministic) log-linear model to fully exploit the field-collected data. We found that sand fly response to pheromone is significantly related to the quantity of pheromone and is not influenced by the proximity of other pheromone sources. Thus sand flies are attracted to the pheromone source at a non-linear rate determined by the amount of pheromone being released. This rate is independent of the proximity of other pheromone releasing traps and indicates the role of the pheromone in aggregation formation. These results have important implications for optimisation of the pheromone as a vector control tool and indicate that multiple lures placed in relatively close proximity to each other (5 m apart) are unlikely to interfere with one another. Lutzomyia longipalpis sand flies are the insect vectors of the Protist parasite Leishmania infantum which causes visceral leishmaniasis (VL) in Brazil. Control of VL has focussed on vector and infected reservoir control, but despite the sustained efforts of the Brazilian Health authorities the disease burden doubled between 1990 to 2016. New approaches to VL control are urgently needed. We previously demonstrated that Lu. longipalpis synthetic sex-aggregation pheromone placed alongside insecticide sprayed surfaces can attract and kill female sand flies. However, before the synthetic pheromone can be effectively exploited in any VL control program it is essential to understand how it might be deployed. In this study we investigated the effect of different amounts of pheromone and the spatial relationship between different pheromone sources on Lu. longipalpis catches. We developed a robust Bayesian analysis to fully exploit the field data which showed that optimal use of the pheromone could be achieved by placing individual or small numbers of pheromone releasing devices (lures) within the peridomestic environment and these can be positioned relatively closely without competing with each other. The results also revealed the significance of the pheromone in maintaining aggregations of Lu. longipalpis and suggested that Lu. longipalpis may be more evenly distributed in the peridomestic environment than previously recognised.
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Affiliation(s)
- Melissa J. Bell
- Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancashire, United Kingdom
| | - Luigi Sedda
- Centre for Health Informatics Computation and Statistics (CHICAS), Lancaster Medical School, Faculty of Health and Medicine, Lancaster University, Lancashire, United Kingdom
| | - Mikel A. Gonzalez
- Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancashire, United Kingdom
| | - Cristian F. de Souza
- Laboratório de Doenças Parasitárias, Instituto Oswaldo Cruz, FIOCRUZ, Rio de Janeiro, Brazil
| | - Erin Dilger
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Reginaldo P. Brazil
- Laboratório de Doenças Parasitárias, Instituto Oswaldo Cruz, FIOCRUZ, Rio de Janeiro, Brazil
| | - Orin Courtenay
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - James G. C. Hamilton
- Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancashire, United Kingdom
- * E-mail:
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Duthie MS, Lison A, Courtenay O. Advances toward Diagnostic Tools for Managing Zoonotic Visceral Leishmaniasis. Trends Parasitol 2018; 34:881-890. [PMID: 30131210 PMCID: PMC6168404 DOI: 10.1016/j.pt.2018.07.012] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Revised: 07/23/2018] [Accepted: 07/24/2018] [Indexed: 11/20/2022]
Abstract
Visceral leishmaniasis (VL) is a life-threatening outcome of Leishmania infantum or Leishmania donovani infection. Dogs are the primary domestic reservoir of L. infantum parasites, and ownership of infected dogs increases the risk of human VL. Controlling infection within dog populations is regarded as critical to VL management in endemic countries, both preventing progression of canine disease and limiting parasite transmission to humans and dogs. Here we discuss various strategies that are used to diagnose canine visceral leishmaniasis (CVL) and the possibilities of adapting these for use within population screening and control programs. In addition, given the variable transmissibility of L. infantum to the sand fly vector, we outline some possibilities for the preferential identification of 'super-spreader' dogs among the overall infected population.
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Affiliation(s)
- Malcolm S Duthie
- Infectious Disease Research Institute, 1616 Eastlake Ave E, Suite 400, Seattle, WA 98102, USA.
| | - Aurore Lison
- School of Life Sciences, University of Warwick, Coventry, UK
| | - Orin Courtenay
- School of Life Sciences, University of Warwick, Coventry, UK
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Gomez SA, Chapman LAC, Dilger E, Courtenay O, Picado A. Estimating the efficacy of community-wide use of systemic insecticides in dogs to control zoonotic visceral leishmaniasis: A modelling study in a Brazilian scenario. PLoS Negl Trop Dis 2018; 12:e0006797. [PMID: 30222756 PMCID: PMC6160230 DOI: 10.1371/journal.pntd.0006797] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 09/27/2018] [Accepted: 08/28/2018] [Indexed: 12/31/2022] Open
Abstract
Systemic insecticides in dogs have been suggested as a public health intervention to prevent human cases of Zoonotic Visceral Leishmaniasis (ZVL). But, currently there are no systemic insecticides for dogs registered against zoo-anthropophilic pool blood feeding phlebotomine flies. We predict the impact of community-wide use of systemic insecticide in dog populations as a public health measure to control transmission of Leishmania infantum to humans using a mathematical model. We developed a Susceptible-Exposed-Infected (SEI) compartmental model to describe L. infantum transmission dynamics in dogs, with a vectorial capacity term to represent transmission between L. infantum-hosting dogs via phlebotomine flies. For Infected (I) dogs two levels of infectiousness were modelled, high infectiousness and low infectiousness. Human incidence was estimated through its relationship to infection in the dog population. We evaluated outcomes from a wide range of scenarios comprising different combinations of initial insecticide efficacy, duration of insecticide efficacy over time, and proportion of the dog population treated (60%, 70% & 80%). The same reduction in human infection incidence can be achieved via different combinations of insecticide efficacy, duration and dog coverage. For example, a systemic insecticide with an initial efficacy of 80% and 6 months above 65% efficacy would require treating at least 70% of the dogs to reduce the human infection incidence by 50%. Sensitivity analysis showed that the model outcome was most sensitive to baseline values of phlebotomine fly daily survival rate and insecticide coverage. Community-wide use of systemic insecticides applied to the “L. infantum canine reservoir” can significantly reduce human incidence of L. infantum infection. The results of this mathematical model can help defining the insecticide target product profile and how the insecticide should be applied to maximise effectiveness. Zoonotic visceral leishmaniasis (ZVL) is a potentially deadly disease in humans caused by Leishmania infantum. This leishmania species can be delivered by pool blood feeding zoo-anthropophilic phlebotomine flies to several mammals, the dog population being recognized as the main reservoir. Transmission from infected dogs to humans is through the bite of female phlebotomine sand flies. The disease is endemic in several countries and Brazil has a high prevalence of cases with over 3000 ZVL cases reported per year. The main, inefficient and highly controversial, control measure in Brazil has been culling sero-positive dogs. The community-wide use of systemic insecticides in dogs could be an alternative to control L. infantum transmission from phlebotomine flies to humans. The rationale is that phlebotomine flies which sampled their blood meals from dogs treated with systemic insecticides would die reducing the risk of L. infantum transmission. To reduce the number of ZVL cases, a large proportion of dogs in the community should be treated and the systemic insecticide used should be effective in killing phlebotomine flies acting as vectors of L. infantum parasites for a significant amount of time. We used a mathematical model mimicking L. infantum transmission to show that this novel vector control strategy could be effective. We identified the combination of different key parameters (e.g. insecticide efficacy, duration and proportion of dogs treated) that could lead to a significant reduction of the risk of L. infantum infection in humans.
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Affiliation(s)
- Sonia A. Gomez
- ISGlobal-Hospital Clínic, Universitat de Barcelona, Barcelona, Spain
- * E-mail: (AP); (SAG)
| | - Lloyd A. C. Chapman
- Department of Global Health and Development, London School of Hygiene and Tropical Medicine, London, United Kingdom
- School of Life Sciences, University of Warwick, Gibbet Hill Campus, Coventry, United Kingdom
| | - Erin Dilger
- School of Life Sciences, University of Warwick, Gibbet Hill Campus, Coventry, United Kingdom
| | - Orin Courtenay
- School of Life Sciences, University of Warwick, Gibbet Hill Campus, Coventry, United Kingdom
| | - Albert Picado
- ISGlobal-Hospital Clínic, Universitat de Barcelona, Barcelona, Spain
- * E-mail: (AP); (SAG)
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Jervis S, Chapman LAC, Dwivedi S, Karthick M, Das A, Le Rutte EA, Courtenay O, Medley GF, Banerjee I, Mahapatra T, Chaudhuri I, Srikantiah S, Hollingsworth TD. Variations in visceral leishmaniasis burden, mortality and the pathway to care within Bihar, India. Parasit Vectors 2017; 10:601. [PMID: 29216905 PMCID: PMC5719561 DOI: 10.1186/s13071-017-2530-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2016] [Accepted: 11/12/2017] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Visceral leishmaniasis (VL) has been targeted by the WHO for elimination as a public health problem (< 1 case/10,000 people/year) in the Indian sub-continent (ISC) by 2020. Bihar State in India, which accounts for the majority of cases in the ISC, remains a major target for this elimination effort. However, there is considerable spatial, temporal and sub-population variation in occurrence of the disease and the pathway to care, which is largely unexplored and a threat to achieving the target. METHODS Data from 6081 suspected VL patients who reported being clinically diagnosed during 2012-2013 across eight districts in Bihar were analysed. Graphical comparisons and Chi-square tests were used to determine differences in the burden of identified cases by season, district, age and sex. Log-linear regression models were fitted to onset (of symptoms)-to-diagnosis and onset-to-treatment waiting times to estimate their associations with age, sex, district and various socio-economic factors (SEFs). Logistic regression models were used to identify factors associated with mortality. RESULTS Comparisons of VL caseloads suggested an annual cycle peaking in January-March. A 17-fold variation in the burden of identified cases across districts and under-representation of young children (0-5 years) relative to age-specific populations in Bihar were observed. Women accounted for a significantly lower proportion of the reported cases than men (41 vs 59%, P < 0.0001). Age, district of residence, house wall materials, caste, treatment cost, travelling for diagnosis and the number of treatments for symptoms before diagnosis were identified as correlates of waiting times. Mortality was associated with age, district of residence, onset-to-treatment waiting time, treatment duration, cattle ownership and cost of diagnosis. CONCLUSIONS The distribution of VL in Bihar is highly heterogeneous, and reported caseloads and associated mortality vary significantly across different districts, posing different challenges to the elimination campaign. Socio-economic factors are important correlates of these differences, suggesting that elimination will require tailoring to population and sub-population circumstances.
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Affiliation(s)
- Sarah Jervis
- School of Life Sciences, University of Warwick, Gibbet Hill Campus, Coventry, CV4 7AL, UK.
| | - Lloyd A C Chapman
- School of Life Sciences, University of Warwick, Gibbet Hill Campus, Coventry, CV4 7AL, UK.
| | - Shweta Dwivedi
- CARE India Solutions for Sustainable Development, Patna, Bihar, India
| | - Morchan Karthick
- CARE India Solutions for Sustainable Development, Patna, Bihar, India
| | - Aritra Das
- CARE India Solutions for Sustainable Development, Patna, Bihar, India
| | - Epke A Le Rutte
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, PO Box 2040, 3000, CA, Rotterdam, The Netherlands
| | - Orin Courtenay
- School of Life Sciences, University of Warwick, Gibbet Hill Campus, Coventry, CV4 7AL, UK
| | - Graham F Medley
- London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | | | - Tanmay Mahapatra
- CARE India Solutions for Sustainable Development, Patna, Bihar, India
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González MA, Bandi KK, Bell MJ, Brazil RP, Dilger E, Guerrero A, Courtenay O, Hamilton JGC. A temporal comparison of sex-aggregation pheromone gland content and dynamics of release in three members of the Lutzomyia longipalpis (Diptera: Psychodidae) species complex. PLoS Negl Trop Dis 2017; 11:e0006071. [PMID: 29194438 PMCID: PMC5745125 DOI: 10.1371/journal.pntd.0006071] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2017] [Revised: 12/27/2017] [Accepted: 10/25/2017] [Indexed: 11/19/2022] Open
Abstract
Background Lutzomyia longipalpis is the South American vector of Leishmania infantum, the etiologic agent of visceral leishmaniasis (VL). Male L. longipalpis produce a sex-aggregation pheromone that is critical in mating, yet very little is known about its accumulation over time or factors involved in release. This laboratory study aimed to compare accumulation of pheromone over time and determine factors that might influence release in three members of the L. longipalpis species complex. Methodology/Principal findings We investigated male sex-aggregation pheromone gland content at different ages and the release rate of pheromone in the presence or absence of females under different light conditions by gas chromatography-mass spectrometry (GC-MS). Pheromone gland content was determined by extraction of whole males and pheromone release rate was determined by collection of headspace volatiles. Pheromone gland content appeared age-related and pheromone began to accumulate between 6 to 12 h post eclosion and gradually increased until males were 7–9 days old. The greatest amount was detected in 9-day old Campo Grande males ((S)-9-methylgermacrene-B; X ± SE: 203.5 ± 57.4 ng/male) followed by Sobral 2S males (diterpene; 199.9 ± 34.3) and Jacobina males ((1S,3S,7R)-3-methyl-α-himachalene; 128.8 ± 30.3) at 7 days old. Pheromone release was not continuous over time. During a 4-hour period, the greatest quantities of pheromone were released during the first hour, when wing beating activity was most intense. It was then substantially diminished for the remainder of the time. During a 24 h period, 4–5 day old male sand flies released approximately 63 ± 11% of the pheromone content of their glands, depending on the chemotype. The presence of females significantly increased pheromone release rate. The light regime under which the sand flies were held had little influence on pheromone release except on Sobral 2S chemotype. Conclusions/Significance Accumulation of pheromone appears to occur at different rates in the different chemotypes examined and results in differing amounts being present in glands over time. Release of accumulated pheromone is not passive, but depends on biotic (presence of females) and abiotic (light) circumstances. There are marked differences in content and release between the members of the complex suggesting important behavioural, biosynthetic and ecological differences between them. The Dipteran subfamily Phlebotominae includes the genera Lutzomyia and Phlebotomus among which several species are important vectors of parasitic and bacterial pathogens. The sand fly Lutzomyia longipalpis is considered the main vector of visceral leishmaniasis (VL) in the New World. Based on the main component of the male sex-aggregation pheromone gland, different sex pheromone-producing populations (chemotypes) of L. longipalpis are recognized in Brazil. Given the importance of the sex-aggregation pheromones in the biology of this species complex, we present here the first attempt to study how pheromone accumulates in the glands over time and factors that might influence its release in the three most common chemotypes from Brazil. Our results demonstrated that pheromone first starts to accumulate a few hours post-eclosion (6–12 h) and this continues over 15 days. Pheromone release is a dynamic process which varies between the 3 chemotypes depending on biotic factors, such as light regime and presence/absence of conspecific females. This work provides valuable information, critical to our understanding of the behaviour and ecology of L. longipalpis sand flies and which will contribute to investigations to improve field-based pheromone control and monitoring of L. longipalpis sand flies.
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Affiliation(s)
- Mikel A. González
- Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancashire, United Kingdom
| | - Krishna K. Bandi
- Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancashire, United Kingdom
| | - Melissa J. Bell
- Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancashire, United Kingdom
| | - Reginaldo P. Brazil
- Laboratório de Doenças Parasitárias, Instituto Oswaldo Cruz, FIOCRUZ, Rio de Janeiro, Brazil
| | - Erin Dilger
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Angel Guerrero
- Department of Biological Chemistry and Molecular Modelling, IQAC (CSIC), Barcelona, Spain
| | - Orin Courtenay
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - James G. C. Hamilton
- Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancashire, United Kingdom
- * E-mail:
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25
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Courtenay O, Peters NC, Rogers ME, Bern C. Combining epidemiology with basic biology of sand flies, parasites, and hosts to inform leishmaniasis transmission dynamics and control. PLoS Pathog 2017; 13:e1006571. [PMID: 29049371 PMCID: PMC5648254 DOI: 10.1371/journal.ppat.1006571] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Quantitation of the nonlinear heterogeneities in Leishmania parasites, sand fly vectors, and mammalian host relationships provides insights to better understand leishmanial transmission epidemiology towards improving its control. The parasite manipulates the sand fly via production of promastigote secretory gel (PSG), leading to the “blocked sand fly” phenotype, persistent feeding attempts, and feeding on multiple hosts. PSG is injected into the mammalian host with the parasite and promotes the establishment of infection. Animal models demonstrate that sand flies with the highest parasite loads and percent metacyclic promastigotes transmit more parasites with greater frequency, resulting in higher load infections that are more likely to be both symptomatic and efficient reservoirs. The existence of mammalian and sand fly “super-spreaders” provides a biological basis for the spatial and temporal clustering of clinical leishmanial disease. Sand fly blood-feeding behavior will determine the efficacies of indoor residual spraying, topical insecticides, and bed nets. Interventions need to have sufficient coverage to include transmission hot spots, especially in the absence of field tools to assess infectiousness. Interventions that reduce sand fly densities in the absence of elimination could have negative consequences, for example, by interfering with partial immunity conferred by exposure to sand fly saliva. A deeper understanding of both sand fly and host biology and behavior is essential to ensuring effectiveness of vector interventions. We review recent research that sheds light on the quantitative biology of leishmanial transmission between sand flies and mammalian hosts and use these insights to better understand transmission, the observed epidemiology of the disease, and their implications in choice of control strategy. Using animal models, we show how the parasite-induced processes manipulate sand fly blood-feeding behavior and the infectious metacyclic dose to promote host infection and to differentially regulate the onward transmission potential of individual vectors and hosts. The existence of subpopulations of mammalian and sand fly “super-spreaders” provides a biological basis for the spatial and temporal clustering of clinical leishmanial disease. While tools are unavailable to distinguish these individuals in mixed populations, blanket interventions will be necessary to ensure inclusion of transmission hot spots. Interventions that reduce sand fly densities without elimination could interfere with vector—host dynamics and conferred partial immunity to host populations.
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Affiliation(s)
- Orin Courtenay
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
- Zeeman Institute, University of Warwick, Coventry, United Kingdom
- * E-mail:
| | - Nathan C. Peters
- Snyder Institute for Chronic Diseases, University of Calgary, Calgary, Alberta, Canada
| | - Matthew E. Rogers
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Caryn Bern
- Department of Epidemiology and Biostatistics, School of Medicine, University of California San Francisco, San Francisco, California, United States of America
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Pereira-Fonseca DCM, Oliveira-Rovai FM, Rodas LAC, Beloti CAC, Torrecilha RBP, Ito PKRK, Avanço SV, Cipriano RS, Utsunomiya YT, Hiramoto RM, Calvo-Bado L, Courtenay O, Machado GF, Lima VMF, Nunes CM. Dog skin parasite load, TLR-2, IL-10 and TNF-α expression and infectiousness. Parasite Immunol 2017; 39. [DOI: 10.1111/pim.12493] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2016] [Accepted: 09/13/2017] [Indexed: 11/28/2022]
Affiliation(s)
- D. C. M. Pereira-Fonseca
- Department of Production and Animal Health; School of Veterinary Medicine; São Paulo State University (Unesp); Araçatuba São Paulo Brazil
| | - F. M. Oliveira-Rovai
- Department of Production and Animal Health; School of Veterinary Medicine; São Paulo State University (Unesp); Araçatuba São Paulo Brazil
| | - L. A. C. Rodas
- Department of Production and Animal Health; School of Veterinary Medicine; São Paulo State University (Unesp); Araçatuba São Paulo Brazil
| | - C. A. C. Beloti
- Department of Production and Animal Health; School of Veterinary Medicine; São Paulo State University (Unesp); Araçatuba São Paulo Brazil
| | - R. B. P. Torrecilha
- Department of Preventive Veterinary Medicine and Animal Reproduction; School of Agricultural and Veterinarian Science; São Paulo State University (Unesp); Jaboticabal São Paulo Brazil
| | - P. K. R. K. Ito
- Department of Production and Animal Health; School of Veterinary Medicine; São Paulo State University (Unesp); Araçatuba São Paulo Brazil
| | - S. V. Avanço
- Center for Zoonosis Control; Rua Doutor Luiz de Almeida; Araçatuba São Paulo Brazil
| | - R. S. Cipriano
- Center for Zoonosis Control; Rua Doutor Luiz de Almeida; Araçatuba São Paulo Brazil
| | - Y. T. Utsunomiya
- Department of Preventive Veterinary Medicine and Animal Reproduction; School of Agricultural and Veterinarian Science; São Paulo State University (Unesp); Jaboticabal São Paulo Brazil
| | | | - L. Calvo-Bado
- School of Life Sciences; The University of Warwick; Coventry UK
| | - O. Courtenay
- School of Life Sciences; The University of Warwick; Coventry UK
| | - G. F. Machado
- Department of Production and Animal Health; School of Veterinary Medicine; São Paulo State University (Unesp); Araçatuba São Paulo Brazil
| | - V. M. F. Lima
- Department of Production and Animal Health; School of Veterinary Medicine; São Paulo State University (Unesp); Araçatuba São Paulo Brazil
| | - C. M. Nunes
- Department of Production and Animal Health; School of Veterinary Medicine; São Paulo State University (Unesp); Araçatuba São Paulo Brazil
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27
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Loza A, Talaga A, Herbas G, Canaviri RJ, Cahuasiri T, Luck L, Guibarra A, Goncalves R, Pereira JA, Gomez SA, Picado A, Messenger LA, Bern C, Courtenay O. Systemic insecticide treatment of the canine reservoir of Trypanosoma cruzi induces high levels of lethality in Triatoma infestans, a principal vector of Chagas disease. Parasit Vectors 2017; 10:344. [PMID: 28724448 PMCID: PMC5518140 DOI: 10.1186/s13071-017-2278-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2017] [Accepted: 07/06/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Despite large-scale reductions in Chagas disease prevalence across Central and South America, Trypanosoma cruzi infection remains a considerable public health problem in the Gran Chaco region where vector-borne transmission persists. In these communities, peridomestic animals are major blood-meal sources for triatomines, and household presence of infected dogs increases T. cruzi transmission risk for humans. To address the pressing need for field-friendly, complementary methods to reduce triatomine infestation and interrupt T. cruzi transmission, this study evaluated the systemic activity of three commercial, oral, single dose insecticides Fluralaner (Bravecto®), Afoxolaner (NexGard®) and Spinosad (Comfortis®) in canine feed-through assays against Triatoma infestans, the principal domestic vector species in the Southern Cone of South America. METHODS Twelve healthy, outbred dogs were recruited from the Zoonosis Surveillance and Control Program in Santa Cruz, Bolivia, and randomized to three treatment groups, each containing one control and three treated dogs. Following oral drug administration, colony-reared second and third stage T. infestans instars were offered to feed on dogs for 30 min at 2, 7, 21, 34 and 51 days post-treatment. RESULTS Eighty-five per cent (768/907) of T. infestans successfully blood-fed during bioassays, with significantly higher proportions of bugs becoming fully-engorged when exposed to Bravecto® treated dogs (P < 0.001) for reasons unknown. Exposure to Bravecto® or NexGard® induced 100% triatomine mortality in fully- or semi-engorged bugs within 5 days of feeding for the entire follow-up period. The lethality effect for Comfortis® was much lower (50-70%) and declined almost entirely after 51 days. Instead Comfortis® treatment resulted in substantial morbidity; of these, 30% fully recovered whereas 53% remained morbid after 120 h, the latter subsequently unable to feed 30 days later. CONCLUSIONS A single oral dose of Fluralaner or Afoxolaner was safe and well tolerated, producing complete triatomine mortality on treated dogs over 7.3 weeks. While both drugs were highly efficacious, more bugs exposed to Fluralaner took complete blood-meals, and experienced rapid knock-down. Coupled with its longer residual activity, Fluralaner represents an ideal insecticide for development into a complementary, operationally-feasible, community-level method of reducing triatomine infestation and potentially controlling T. cruzi transmission, in the Gran Chaco region.
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Affiliation(s)
- Ariel Loza
- Facultad de Ciencias Veterinarias, Universidad Autonóma Gabriel René Moreno (UAGRM), Santa Cruz, Bolivia
| | - Adrianna Talaga
- University of Warwick, Gibbet Hill Campus, Coventry, CV4 7AL, UK
| | - Gladys Herbas
- Facultad de Ciencias Veterinarias, Universidad Autonóma Gabriel René Moreno (UAGRM), Santa Cruz, Bolivia
| | - Ruben Jair Canaviri
- Facultad de Ciencias Veterinarias, Universidad Autonóma Gabriel René Moreno (UAGRM), Santa Cruz, Bolivia
| | - Thalia Cahuasiri
- Facultad de Ciencias Veterinarias, Universidad Autonóma Gabriel René Moreno (UAGRM), Santa Cruz, Bolivia
| | - Laura Luck
- Facultad de Ciencias Veterinarias, Universidad Autonóma Gabriel René Moreno (UAGRM), Santa Cruz, Bolivia
| | - Alvaro Guibarra
- Facultad de Ciencias Veterinarias, Universidad Autonóma Gabriel René Moreno (UAGRM), Santa Cruz, Bolivia
| | - Raquel Goncalves
- University of Warwick, Gibbet Hill Campus, Coventry, CV4 7AL, UK
| | - Juan Antonio Pereira
- Facultad de Ciencias Veterinarias, Universidad Autonóma Gabriel René Moreno (UAGRM), Santa Cruz, Bolivia
| | - Sonia A Gomez
- ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clinic - Universitat de Barcelona, Rosello 132, 08036, Barcelona, Spain
| | - Albert Picado
- ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clinic - Universitat de Barcelona, Rosello 132, 08036, Barcelona, Spain
| | | | - Caryn Bern
- University of California-San Francisco, 550 16th St, 94158, San Francisco, CA, USA
| | - Orin Courtenay
- University of Warwick, Gibbet Hill Campus, Coventry, CV4 7AL, UK
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28
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King HC, Khera-Butler T, James P, Oakley BB, Erenso G, Aseffa A, Knight R, Wellington EM, Courtenay O. Environmental reservoirs of pathogenic mycobacteria across the Ethiopian biogeographical landscape. PLoS One 2017; 12:e0173811. [PMID: 28333945 PMCID: PMC5363844 DOI: 10.1371/journal.pone.0173811] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Accepted: 02/26/2017] [Indexed: 12/31/2022] Open
Abstract
The Mycobacterium genus comprises over one-hundred-and-fifty recognised species, the majority of which reside in the environment and many of which can be pathogenic to mammals. Some species of environmental mycobacteria may interfere with BCG vaccination efficacy and in tuberculin test interpretation. Examining biogeographic trends in the distribution of members of the mycobacteria across a number of physicochemical and spatial gradients in soil and water environments across Ethiopia using oligotyping identified differential distributions of pathogenic and significant species. The tuberculosis complex was identified in more than 90% of water samples and taxonomic groups implicated in lower BCG vaccine efficiency were core in both soil and water Mycobacterium communities. A reservoir of Mycobacterium bovis was identified in water, with up to 7.3×102 genome equivalents per ml. Elevation, temperature, habitat and vegetation type were important predictors of both soil and water Mycobacterium communities. These results represent the first step in understanding the potential risk of exposure to environmental mycobacteria that may undermine efforts to reduce disease incidence.
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Affiliation(s)
- Hayley C. King
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
- * E-mail:
| | - Tanya Khera-Butler
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Phillip James
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Brian B. Oakley
- College of Veterinary Medicine, Western University of Health Sciences, Pomona, California, United States of America
| | - Girume Erenso
- St. Paul’s Hospital Millennium Medical College, Department of Microbiology, Immunology and Parasitology, Addis Ababa, Ethiopia
- Armauer Hansen Research Institute (AHRI), ALERT Campus, Addis Ababa, Ethiopia
| | - Abraham Aseffa
- Armauer Hansen Research Institute (AHRI), ALERT Campus, Addis Ababa, Ethiopia
| | - Rob Knight
- Department of Pediatrics and Department of Computer Science, University of California, San Diego, California, United States of America
| | | | - Orin Courtenay
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
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29
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Kostalova T, Lestinova T, Maia C, Sumova P, Vlkova M, Willen L, Polanska N, Fiorentino E, Scalone A, Oliva G, Veronesi F, Cristóvão JM, Courtenay O, Campino L, Gradoni L, Gramiccia M, Volf P. The recombinant protein rSP03B is a valid antigen for screening dog exposure to Phlebotomus perniciosus across foci of canine leishmaniasis. Med Vet Entomol 2017; 31:88-93. [PMID: 27718267 DOI: 10.1111/mve.12192] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 05/25/2016] [Accepted: 06/05/2016] [Indexed: 06/06/2023]
Abstract
The frequency of sandfly-host contacts can be measured by host antibody levels against sandfly salivary proteins. Recombinant salivary proteins are suggested to represent a valid replacement for salivary gland homogenate (SGH); however, it is necessary to prove that such antigens are recognized by antibodies against various populations of the same species. Phlebotomus perniciosus (Diptera: Psychodidae) is the main vector of Leishmania infantum (Trypanosomatida: Trypanosomatidae) in southwest Europe and is widespread from Portugal to Italy. In this study, sera were sampled from naturally exposed dogs from distant regions, including Campania (southern Italy), Umbria (central Italy) and the metropolitan Lisbon region (Portugal), where P. perniciosus is the unique or principal vector species. Sera were screened for anti-P. perniciosus antibodies using SGH and 43-kDa yellow-related recombinant protein (rSP03B). A robust correlation between antibodies recognizing SGH and rSP03B was detected in all regions, suggesting substantial antigenic cross-reactivity among different P. perniciosus populations. No significant differences in this relationship were detected between regions. Moreover, rSP03B and the native yellow-related protein were shown to share similar antigenic epitopes, as canine immunoglobulin G (IgG) binding to the native protein was inhibited by pre-incubation with the recombinant form. These findings suggest that rSP03B should be regarded as a universal marker of sandfly exposure throughout the geographical distribution of P. perniciosus.
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Affiliation(s)
- T Kostalova
- Department of Parasitology, Faculty of Science, Charles University in Prague, Prague, Czech Republic
| | - T Lestinova
- Department of Parasitology, Faculty of Science, Charles University in Prague, Prague, Czech Republic
| | - C Maia
- Global Health and Tropical Medicine, Medical Parasitology Unit, Instituto de Higiene e Medicina Tropical, New University of Lisbon, Lisbon, Portugal
- Faculty of Veterinary Medicine, Lusophone University of Humanities and Technologies, Lisbon, Portugal
| | - P Sumova
- Department of Parasitology, Faculty of Science, Charles University in Prague, Prague, Czech Republic
| | - M Vlkova
- Department of Parasitology, Faculty of Science, Charles University in Prague, Prague, Czech Republic
| | - L Willen
- Department of Parasitology, Faculty of Science, Charles University in Prague, Prague, Czech Republic
| | - N Polanska
- Department of Parasitology, Faculty of Science, Charles University in Prague, Prague, Czech Republic
| | - E Fiorentino
- Unit of Vector-Borne Diseases and International Health, Istituto Superiore di Sanità, Rome, Italy
| | - A Scalone
- Unit of Vector-Borne Diseases and International Health, Istituto Superiore di Sanità, Rome, Italy
| | - G Oliva
- Department of Veterinary Medicine and Animal Production, University Federico II, Naples, Italy
| | - F Veronesi
- Department of Veterinary Medicine, University of Perugia, Perugia, Italy
| | - J M Cristóvão
- Global Health and Tropical Medicine, Medical Parasitology Unit, Instituto de Higiene e Medicina Tropical, New University of Lisbon, Lisbon, Portugal
| | - O Courtenay
- Warwick Infectious Disease Epidemiology Research (WIDER), School of Life Sciences, University of Warwick, Coventry, U.K
| | - L Campino
- Global Health and Tropical Medicine, Medical Parasitology Unit, Instituto de Higiene e Medicina Tropical, New University of Lisbon, Lisbon, Portugal
- Department of Biomedical and Medical Sciences, University of Algarve, Faro, Portugal
| | - L Gradoni
- Unit of Vector-Borne Diseases and International Health, Istituto Superiore di Sanità, Rome, Italy
| | - M Gramiccia
- Unit of Vector-Borne Diseases and International Health, Istituto Superiore di Sanità, Rome, Italy
| | - P Volf
- Department of Parasitology, Faculty of Science, Charles University in Prague, Prague, Czech Republic
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Abstract
The leishmaniases comprise a complex of diseases characterized by clinical outcomes that range from self-limiting to chronic, and disfiguring and stigmatizing to life threatening. Diagnostic methods, treatments, and vector and reservoir control options exist, but deciding the most effective interventions requires a quantitative understanding of the population level infection and disease dynamics. The effectiveness of any set of interventions has to be determined within the context of operational conditions, including economic and political commitment. Mathematical models are the best available tools for studying quantitative systems crossing disciplinary spheres (biology, medicine, economics) within environmental and societal constraints. In 2005, the World Health Assembly and government health ministers of India, Nepal, and Bangladesh signed a Memorandum of Understanding to eliminate the life threatening form of leishmaniasis, visceral leishmaniasis (VL), on the Indian subcontinent by 2015 through a combination of early case detection, improved treatments, and vector control. The elimination target is <1 case/10,000 population at the district or subdistrict level compared to the current 20/10,000 in the regions of highest transmission. Towards this goal, this chapter focuses on mathematical models of VL, and the biology driving those models, to enable realistic predictions of the best combination of interventions. Several key issues will be discussed which have affected previous modelling of VL and the direction future modelling may take. Current understanding of the natural history of disease, immunity (and loss of immunity), and stages of infection and their durations are considered particularly for humans, and also for dogs. Asymptomatic and clinical infection are discussed in the context of their relative roles in Leishmania transmission, as well as key components of the parasite-sandfly-vector interaction and intervention strategies including diagnosis, treatment and vector control. Gaps in current biological knowledge and potential avenues to improve model structures and mathematical predictions are identified. Underpinning the marriage between biology and mathematical modelling, the content of this chapter represents the first step towards developing the next generation of models for VL.
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Affiliation(s)
- K S Rock
- University of Warwick, Coventry, United Kingdom
| | | | - G F Medley
- London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - O Courtenay
- University of Warwick, Coventry, United Kingdom
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31
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Torrecilha RBP, Utsunomiya YT, Bosco AM, Almeida BF, Pereira PP, Narciso LG, Pereira DCM, Baptistiolli L, Calvo-Bado L, Courtenay O, Nunes CM, Ciarlini PC. Correlations between peripheral parasite load and common clinical and laboratory alterations in dogs with visceral leishmaniasis. Prev Vet Med 2016; 132:83-87. [PMID: 27664450 DOI: 10.1016/j.prevetmed.2016.08.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Revised: 08/22/2016] [Accepted: 08/23/2016] [Indexed: 10/21/2022]
Abstract
Intensity of peripheral parasite infection has an important role in the transmission of Leishmania spp. from one host to another. As parasite load quantification is still an expensive procedure to be used routinely in epidemiological surveillance, the use of surrogate predictors may be an important asset in the identification of dogs with high transmitting ability. The present study examined whether common clinical and laboratory alterations can serve as predictors of peripheral parasitism in dogs naturally infected with Leishmania spp. Thirty-seven dogs were examined in order to establish correlations between parasite load (PL) in multiple peripheral tissues and common clinical and laboratory findings in canine visceral leishmaniasis (CVL). Quantitative polymerase chain reaction was employed to determine PL in conjunctival swabs, ear skin, peripheral blood and buffy coat. Additionally, a series of hematological, biochemical and oxidative stress markers were quantified. Correlations between net peripheral infection and severity of clinical alterations and variation in laboratory parameters were assessed through a new analytical approach, namely Compressed Parasite Load Data (CPLD), which uses dimension reduction techniques from multivariate statistics to summarize PL across tissues into a single variable. The analysis revealed that elevation in PL is positively correlated with severity of clinical sings commonly observed in CVL, such as skin lesions, ophthalmic alterations, onycogriphosis, popliteal lymphadenomegaly and low body mass. Furthermore, increase in PL was found to be followed by intensification of non-regenerative anemia, neutrophilia, eosinopenia, hepatic injury and oxidative imbalance. These results suggest that routinely used clinical and laboratory exams can be predictive of intensity of peripheral parasite infection, which has an important implication in the identification of dogs with high transmitting ability.
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Affiliation(s)
- R B P Torrecilha
- Departamento de Clínica, Cirurgia e Reprodução Animal, Faculdade de Medicina Veterinária de Araçatuba, UNESP-Univ Estadual Paulista, Rua Clóvis Pestana 793, Dona Amélia, Araçatuba, SP, 16050-680, Brazil.
| | - Y T Utsunomiya
- Departamento de Medicina Veterinária Preventiva e Reprodução Animal, Faculdade de Ciências Agrárias e Veterinárias, UNESP- Univ Estadual Paulista, Via de Acesso Prof. Paulo Donato Castellane s/n, Jaboticabal, SP, 14884-900, Brazil
| | - A M Bosco
- Departamento de Clínica, Cirurgia e Reprodução Animal, Faculdade de Medicina Veterinária de Araçatuba, UNESP-Univ Estadual Paulista, Rua Clóvis Pestana 793, Dona Amélia, Araçatuba, SP, 16050-680, Brazil
| | - B F Almeida
- Departamento de Clínica, Cirurgia e Reprodução Animal, Faculdade de Medicina Veterinária de Araçatuba, UNESP-Univ Estadual Paulista, Rua Clóvis Pestana 793, Dona Amélia, Araçatuba, SP, 16050-680, Brazil
| | - P P Pereira
- Departamento de Clínica, Cirurgia e Reprodução Animal, Faculdade de Medicina Veterinária de Araçatuba, UNESP-Univ Estadual Paulista, Rua Clóvis Pestana 793, Dona Amélia, Araçatuba, SP, 16050-680, Brazil
| | - L G Narciso
- Departamento de Clínica, Cirurgia e Reprodução Animal, Faculdade de Medicina Veterinária de Araçatuba, UNESP-Univ Estadual Paulista, Rua Clóvis Pestana 793, Dona Amélia, Araçatuba, SP, 16050-680, Brazil
| | - D C M Pereira
- Departamento de Apoio, Produção e Saúde Animal, Faculdade de Medicina Veterinária de Araçatuba, UNESP- Univ Estadual Paulista, Rua Clóvis Pestana 793, Dona Amélia, Araçatuba, SP, 16050-680, Brazil
| | - L Baptistiolli
- Departamento de Clínica, Cirurgia e Reprodução Animal, Faculdade de Medicina Veterinária de Araçatuba, UNESP-Univ Estadual Paulista, Rua Clóvis Pestana 793, Dona Amélia, Araçatuba, SP, 16050-680, Brazil
| | - L Calvo-Bado
- School of Life Sciences and Warwick Infectious Disease and Epidemiology Research Group (WIDER), Gibbett Hill Road, CV47AL, Coventry, England, UK
| | - O Courtenay
- School of Life Sciences and Warwick Infectious Disease and Epidemiology Research Group (WIDER), Gibbett Hill Road, CV47AL, Coventry, England, UK
| | - C M Nunes
- Departamento de Apoio, Produção e Saúde Animal, Faculdade de Medicina Veterinária de Araçatuba, UNESP- Univ Estadual Paulista, Rua Clóvis Pestana 793, Dona Amélia, Araçatuba, SP, 16050-680, Brazil
| | - P C Ciarlini
- Departamento de Clínica, Cirurgia e Reprodução Animal, Faculdade de Medicina Veterinária de Araçatuba, UNESP-Univ Estadual Paulista, Rua Clóvis Pestana 793, Dona Amélia, Araçatuba, SP, 16050-680, Brazil.
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Cameron MM, Acosta-Serrano A, Bern C, Boelaert M, den Boer M, Burza S, Chapman LAC, Chaskopoulou A, Coleman M, Courtenay O, Croft S, Das P, Dilger E, Foster G, Garlapati R, Haines L, Harris A, Hemingway J, Hollingsworth TD, Jervis S, Medley G, Miles M, Paine M, Picado A, Poché R, Ready P, Rogers M, Rowland M, Sundar S, de Vlas SJ, Weetman D. Understanding the transmission dynamics of Leishmania donovani to provide robust evidence for interventions to eliminate visceral leishmaniasis in Bihar, India. Parasit Vectors 2016; 9:25. [PMID: 26812963 PMCID: PMC4729074 DOI: 10.1186/s13071-016-1309-8] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Accepted: 01/15/2016] [Indexed: 12/31/2022] Open
Abstract
Visceral Leishmaniasis (VL) is a neglected vector-borne disease. In India, it is transmitted to humans by Leishmania donovani-infected Phlebotomus argentipes sand flies. In 2005, VL was targeted for elimination by the governments of India, Nepal and Bangladesh by 2015. The elimination strategy consists of rapid case detection, treatment of VL cases and vector control using indoor residual spraying (IRS). However, to achieve sustained elimination of VL, an appropriate post elimination surveillance programme should be designed, and crucial knowledge gaps in vector bionomics, human infection and transmission need to be addressed. This review examines the outstanding knowledge gaps, specifically in the context of Bihar State, India.The knowledge gaps in vector bionomics that will be of immediate benefit to current control operations include better estimates of human biting rates and natural infection rates of P. argentipes, with L. donovani, and how these vary spatially, temporally and in response to IRS. The relative importance of indoor and outdoor transmission, and how P. argentipes disperse, are also unknown. With respect to human transmission it is important to use a range of diagnostic tools to distinguish individuals in endemic communities into those who: 1) are to going to progress to clinical VL, 2) are immune/refractory to infection and 3) have had past exposure to sand flies.It is crucial to keep in mind that close to elimination, and post-elimination, VL cases will become infrequent, so it is vital to define what the surveillance programme should target and how it should be designed to prevent resurgence. Therefore, a better understanding of the transmission dynamics of VL, in particular of how rates of infection in humans and sand flies vary as functions of each other, is required to guide VL elimination efforts and ensure sustained elimination in the Indian subcontinent. By collecting contemporary entomological and human data in the same geographical locations, more precise epidemiological models can be produced. The suite of data collected can also be used to inform the national programme if supplementary vector control tools, in addition to IRS, are required to address the issues of people sleeping outside.
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Affiliation(s)
- Mary M Cameron
- London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK.
| | | | - Caryn Bern
- UCSF School of Medicine, 550 16th Street, San Francisco, 94158, CA, USA.
| | | | | | - Sakib Burza
- London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK.
| | | | - Alexandra Chaskopoulou
- European Biological Control Laboratory, USDA-ARS, Tsimiski 43 Street, Thessaloniki, 54623, Greece.
| | - Michael Coleman
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.
| | - Orin Courtenay
- University of Warwick, Gibbet Hill Campus, Coventry, CV4 7AL, UK.
| | - Simon Croft
- London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK.
| | - Pradeep Das
- Rajendra Memorial Research Institute of Medical Sciences, Patna, India.
| | - Erin Dilger
- University of Warwick, Gibbet Hill Campus, Coventry, CV4 7AL, UK.
| | - Geraldine Foster
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.
| | | | - Lee Haines
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.
| | | | - Janet Hemingway
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.
| | | | - Sarah Jervis
- University of Warwick, Gibbet Hill Campus, Coventry, CV4 7AL, UK.
| | - Graham Medley
- London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK.
| | - Michael Miles
- London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK.
| | - Mark Paine
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.
| | - Albert Picado
- FIND, Campus Biotech, Chemin des Mines 9, 1202, Geneva, Switzerland.
| | - Richard Poché
- Genesis Laboratories, Inc., Wellington, CO, 80549, USA.
| | - Paul Ready
- London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK.
| | - Matthew Rogers
- London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK.
| | - Mark Rowland
- London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK.
| | - Shyam Sundar
- Institute of Medical Sciences, Banaras Hindu University, Varanasi, 221005, India.
| | - Sake J de Vlas
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands.
| | - David Weetman
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.
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Hollingsworth TD, Adams ER, Anderson RM, Atkins K, Bartsch S, Basáñez MG, Behrend M, Blok DJ, Chapman LAC, Coffeng L, Courtenay O, Crump RE, de Vlas SJ, Dobson A, Dyson L, Farkas H, Galvani AP, Gambhir M, Gurarie D, Irvine MA, Jervis S, Keeling MJ, Kelly-Hope L, King C, Lee BY, Le Rutte EA, Lietman TM, Ndeffo-Mbah M, Medley GF, Michael E, Pandey A, Peterson JK, Pinsent A, Porco TC, Richardus JH, Reimer L, Rock KS, Singh BK, Stolk W, Swaminathan S, Torr SJ, Townsend J, Truscott J, Walker M, Zoueva A. Quantitative analyses and modelling to support achievement of the 2020 goals for nine neglected tropical diseases. Parasit Vectors 2015; 8:630. [PMID: 26652272 PMCID: PMC4674954 DOI: 10.1186/s13071-015-1235-1] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Accepted: 12/01/2015] [Indexed: 12/30/2022] Open
Abstract
Quantitative analysis and mathematical models are useful tools in informing strategies to control or eliminate disease. Currently, there is an urgent need to develop these tools to inform policy to achieve the 2020 goals for neglected tropical diseases (NTDs). In this paper we give an overview of a collection of novel model-based analyses which aim to address key questions on the dynamics of transmission and control of nine NTDs: Chagas disease, visceral leishmaniasis, human African trypanosomiasis, leprosy, soil-transmitted helminths, schistosomiasis, lymphatic filariasis, onchocerciasis and trachoma. Several common themes resonate throughout these analyses, including: the importance of epidemiological setting on the success of interventions; targeting groups who are at highest risk of infection or re-infection; and reaching populations who are not accessing interventions and may act as a reservoir for infection,. The results also highlight the challenge of maintaining elimination 'as a public health problem' when true elimination is not reached. The models elucidate the factors that may be contributing most to persistence of disease and discuss the requirements for eventually achieving true elimination, if that is possible. Overall this collection presents new analyses to inform current control initiatives. These papers form a base from which further development of the models and more rigorous validation against a variety of datasets can help to give more detailed advice. At the moment, the models' predictions are being considered as the world prepares for a final push towards control or elimination of neglected tropical diseases by 2020.
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Affiliation(s)
| | - Emily R Adams
- Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | | | - Katherine Atkins
- London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK
| | - Sarah Bartsch
- Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, 21205, USA
| | | | | | - David J Blok
- Erasmus University Medical Center, 3015 CE, Rotterdam, Netherlands
| | | | - Luc Coffeng
- Erasmus University Medical Center, 3015 CE, Rotterdam, Netherlands
| | | | - Ron E Crump
- University of Warwick, Coventry, CV4 7AL, UK
| | - Sake J de Vlas
- Erasmus University Medical Center, 3015 CE, Rotterdam, Netherlands
| | - Andy Dobson
- Princeton University, New Jersey, NJ, 08544, USA
| | | | | | | | | | - David Gurarie
- Case Western Reserve University, Cleveland, OH, 44106, USA
| | | | | | | | | | - Charles King
- Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Bruce Y Lee
- Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, 21205, USA
| | - Epke A Le Rutte
- Erasmus University Medical Center, 3015 CE, Rotterdam, Netherlands
| | - Thomas M Lietman
- University of California, San Francisco, San Francisco, CA, 94143, USA
| | | | - Graham F Medley
- London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK
| | - Edwin Michael
- University of Notre Dame, South Bend, IN, 47556, USA
| | | | | | - Amy Pinsent
- Monash University, Melbourne, VIC, 3800, Australia
| | - Travis C Porco
- University of California, San Francisco, San Francisco, CA, 94143, USA
| | | | - Lisa Reimer
- Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Kat S Rock
- University of Warwick, Coventry, CV4 7AL, UK
| | | | - Wilma Stolk
- Erasmus University Medical Center, 3015 CE, Rotterdam, Netherlands
| | | | - Steve J Torr
- Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
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Chapman LAC, Dyson L, Courtenay O, Chowdhury R, Bern C, Medley GF, Hollingsworth TD. Quantification of the natural history of visceral leishmaniasis and consequences for control. Parasit Vectors 2015; 8:521. [PMID: 26490668 PMCID: PMC4618734 DOI: 10.1186/s13071-015-1136-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 10/03/2015] [Indexed: 01/20/2023] Open
Abstract
Background Visceral leishmaniasis has been targeted for elimination as a public health problem (less than 1 case per 10,000 people per year) in the Indian sub-continent by 2017. However, there is still a high degree of uncertainty about the natural history of the disease, in particular about the duration of asymptomatic infection and the proportion of asymptomatically infected individuals that develop clinical visceral leishmaniasis. Quantifying these aspects of the disease is key for guiding efforts to eliminate visceral leishmaniasis and maintaining elimination once it is reached. Methods Data from a detailed epidemiological study in Bangladesh in 2002–2004 was analysed to estimate key epidemiological parameters. The role of diagnostics in determining the probability and rate of progression to clinical disease was estimated by fitting Cox proportional hazards models. A multi-state Markov model of the natural history of visceral leishmaniasis was fitted to the data to estimate the asymptomatic infection period and the proportion of asymptomatic individuals going on to develop clinical symptoms. Results At the time of the study, individuals were taking several months to be diagnosed with visceral leishmaniasis, leading to many opportunities for ongoing transmission. The probability of progression to clinical disease was strongly associated with initial seropositivity and even more strongly with seroconversion, with most clinical symptoms developing within a year. The estimated average durations of asymptomatic infection and symptomatic infection for our model of the natural history are 147 days (95 % CI 130–166) and 140 days (95 % CI 123–160), respectively, and are significantly longer than previously reported estimates. We estimate from the data that 14.7 % (95 % CI 12.6-20.0 %) of asymptomatic individuals develop clinical symptoms—a greater proportion than previously estimated. Conclusions Extended periods of asymptomatic infection could be important for visceral leishmaniasis transmission, but this depends critically on the relative infectivity of asymptomatic and symptomatic individuals to sandflies. These estimates could be informed by similar analysis of other datasets. Our results highlight the importance of reducing times from onset of symptoms to diagnosis and treatment to reduce opportunities for transmission. Electronic supplementary material The online version of this article (doi:10.1186/s13071-015-1136-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Lloyd A C Chapman
- School of Life Sciences, University of Warwick, Gibbet Hill Campus, Coventry, CV4 7AL, UK.
| | - Louise Dyson
- School of Life Sciences, University of Warwick, Gibbet Hill Campus, Coventry, CV4 7AL, UK
| | - Orin Courtenay
- School of Life Sciences, University of Warwick, Gibbet Hill Campus, Coventry, CV4 7AL, UK
| | - Rajib Chowdhury
- Country Programme Manager - Bangladesh, KalaCORE Programme, Dhaka, Bangladesh.,Department of Medical Entomology, National Institute of Preventive and Social Medicine (NIPSOM), Mohakhali, Dhaka, Bangladesh
| | - Caryn Bern
- UCSF School of Medicine, 550 16th Street, San Francisco, CA, 94158, USA
| | - Graham F Medley
- London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
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Andrade MS, Courtenay O, F. Brito ME, Carvalho FG, Carvalho AWS, Soares F, Carvalho SM, Costa PL, Zampieri R, Floeter-Winter LM, Shaw JJ, Brandão-Filho SP. Infectiousness of Sylvatic and Synanthropic Small Rodents Implicates a Multi-host Reservoir of Leishmania (Viannia) braziliensis. PLoS Negl Trop Dis 2015; 9:e0004137. [PMID: 26448187 PMCID: PMC4598029 DOI: 10.1371/journal.pntd.0004137] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 09/10/2015] [Indexed: 11/28/2022] Open
Abstract
Background The possibility that a multi-host wildlife reservoir is responsible for maintaining transmission of Leishmania (Viannia) braziliensis causing human cutaneous and mucocutaneous leishmaniasis is tested by comparative analysis of infection progression and infectiousness to sandflies in rodent host species previously shown to have high natural infection prevalences in both sylvatic or/and peridomestic habitats in close proximity to humans in northeast Brazil. Methods The clinical and parasitological outcomes, and infectiousness to sandflies, were observed in 54 colonized animals of three species (18 Necromys lasiurus, 18 Nectomys squamipes and 18 Rattus rattus) experimentally infected with high (5.5×106/ml) or low (2.8×105/ml) dose L. (V.) braziliensis (MBOL/BR/2000/CPqAM95) inoculum. Clinical signs of infection were monitored daily. Whole animal xenodiagnoses were performed 6 months post inoculation using Lutzomyia longipalpis originating from flies caught in Passira, Pernambuco, after this parasite evaluation was performed at necropsy. Heterogeneities in Leishmania parasite loads were measured by quantitative PCR in ear skin, liver and spleen tissues. Results All three rodent species proved to establish infection characterized by short-term self-resolving skin lesions, located on ears and tail but not on footpads (one site of inoculation), and variable parasite loads detected in all three tissues with maximum burdens of 8.1×103 (skin), 2.8×103 (spleen), and 8.9×102 (liver). All three host species, 18/18 N. lasiurus, 10/18 N. squamipes and 6/18 R. rattus, also proved infectious to sandflies in cross-sectional study. R. rattus supported significantly lower tissue parasite loads compared to those in N. lasiurus and N. squamipes, and N. lasiurus appeared to be more infectious, on average, than either N. squamipes or R. rattus. Conclusions A multi-host reservoir of cutaneous leishmaniasis is indicated in this region of Brazil, though with apparent differences in the competence between the rodent species. The results provide preliminary insights into links between sylvatic and peri-domestic transmission cycles associated with overlaps in the rodent species’ ecological niches. Across the Americas, Leishmania (V.) braziliensis is the predominant Leishmania species causing cutaneous and mucocutaneous leishmaniasis in humans. Transmitted by Phlebotomine sandflies, questions remain about the epidemiological contributions of the numerous zoonotic and more domestic host species. Domestication of the principal vector and human infection patterns suggest that human infection risk is predominantly peridomestic, whereas control strategies will be more complex if there is a link to a wildlife transmission cycle. Almost no studies have been conducted on the transmission potential of natural hosts of L. (V.) braziliensis. This study evaluates the infectiousness of experimentally infected natural rodent host species, that in different ecological habitats are proposed to act as a single or a multi-host reservoir. Clinical and parasitological development, and the ability to transmit Leishmania to sandflies, was observed under experimental conditions using a single strain of L. (V.) braziliensis isolated from the wild rat, Necromys lasiurus. Xenodiagnoses were performed with laboratory bred sand fly females established from a local population of Lutzomyia longipalpis. All three rodent species developed disseminated subclinical parasitological infections, but clinical signs (lesions) were transient and self-resolving. N. squamipes, N. lasiurus and R. rattus were all infectious when asymptomatic, though their competence in transmission potential appears to differ with R. rattus showing signs of lower susceptibility. These results provide further evidence that a multi-host reservoir is responsible for maintaining transmission with a bridge between infectious sylvatic and peridomestic rodent populations.
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Affiliation(s)
- Maria S. Andrade
- Department of Immunology, Aggeu Magalhães Research Center-Oswaldo Cruz Foundation (FIOCRUZ), Recife, Pernambuco, Brazil
- University of Pernambuco, Recife, Pernambuco, Brazil
| | - Orin Courtenay
- Warwick Infectious Disease Epidemiology Research (WIDER) and School of Life Sciences, University Warwick, Coventry, United Kingdom
| | - Maria E. F. Brito
- Department of Immunology, Aggeu Magalhães Research Center-Oswaldo Cruz Foundation (FIOCRUZ), Recife, Pernambuco, Brazil
| | - Francisco G. Carvalho
- Department of Immunology, Aggeu Magalhães Research Center-Oswaldo Cruz Foundation (FIOCRUZ), Recife, Pernambuco, Brazil
| | - Ana Waléria S. Carvalho
- Department of Immunology, Aggeu Magalhães Research Center-Oswaldo Cruz Foundation (FIOCRUZ), Recife, Pernambuco, Brazil
| | - Fábia Soares
- Department of Immunology, Aggeu Magalhães Research Center-Oswaldo Cruz Foundation (FIOCRUZ), Recife, Pernambuco, Brazil
| | - Silvia M. Carvalho
- Department of Immunology, Aggeu Magalhães Research Center-Oswaldo Cruz Foundation (FIOCRUZ), Recife, Pernambuco, Brazil
| | - Pietra L. Costa
- Department of Immunology, Aggeu Magalhães Research Center-Oswaldo Cruz Foundation (FIOCRUZ), Recife, Pernambuco, Brazil
| | - Ricardo Zampieri
- Biosiences Institute, São Paulo University, São Paulo, São Paulo, Brazil
| | | | - Jeffrey J. Shaw
- Biomedical Institute, São Paulo University, São Paulo, São Paulo, Brazil
- * E-mail: (JJS); SPBF
| | - Sinval P. Brandão-Filho
- Department of Immunology, Aggeu Magalhães Research Center-Oswaldo Cruz Foundation (FIOCRUZ), Recife, Pernambuco, Brazil
- * E-mail: (JJS); SPBF
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King HC, Murphy A, James P, Travis E, Porter D, Hung YJ, Sawyer J, Cork J, Delahay RJ, Gaze W, Courtenay O, Wellington EM. The variability and seasonality of the environmental reservoir of Mycobacterium bovis shed by wild European badgers. Sci Rep 2015; 5:12318. [PMID: 26247348 PMCID: PMC4527091 DOI: 10.1038/srep12318] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 04/02/2015] [Indexed: 11/10/2022] Open
Abstract
The incidence of Mycobacterium bovis, the causative agent of bovine tuberculosis, has been increasing in UK cattle herds resulting in substantial economic losses. The European badger (Meles meles) is implicated as a wildlife reservoir of infection. One likely route of transmission to cattle is through exposure to infected badger urine and faeces. The relative importance of the environment in transmission remains unknown, in part due to the lack of information on the distribution and magnitude of environmental reservoirs. Here we identify potential infection hotspots in the badger population and quantify the heterogeneity in bacterial load; with infected badgers shedding between 1 × 10(3)- 4 × 10(5) M. bovis cells g(-1) of faeces, creating a substantial and seasonally variable environmental reservoir. Our findings highlight the potential importance of monitoring environmental reservoirs of M. bovis which may constitute a component of disease spread that is currently overlooked and yet may be responsible for a proportion of transmission amongst badgers and onwards to cattle.
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Affiliation(s)
- Hayley C. King
- University of Warwick, School of Life Sciences, Gibbet Hill Campus, Coventry, CV4 7AL
| | - Andrew Murphy
- University of Warwick, School of Life Sciences, Gibbet Hill Campus, Coventry, CV4 7AL
| | - Phillip James
- University of Warwick, School of Life Sciences, Gibbet Hill Campus, Coventry, CV4 7AL
| | - Emma Travis
- University of Warwick, School of Life Sciences, Gibbet Hill Campus, Coventry, CV4 7AL
| | - David Porter
- University of Warwick, School of Life Sciences, Gibbet Hill Campus, Coventry, CV4 7AL
| | - Yu-Jiun Hung
- University of Warwick, School of Life Sciences, Gibbet Hill Campus, Coventry, CV4 7AL
| | - Jason Sawyer
- Animal and Plant Health Agency, Weybridge, Woodham lane, New Haw, Addlestone, Surrey, KT15 3NB
| | - Jennifer Cork
- Animal and Plant Health Agency, Weybridge, Woodham lane, New Haw, Addlestone, Surrey, KT15 3NB
| | - Richard J. Delahay
- National Wildlife Management Centre, Animal and Plant Health Agency, Woodchester Park, Nympsfield, Gloucestershire, GL10 3UJ, UK
| | - William Gaze
- European Centre for Environmental and Human Health, University of Exeter Medical School, Knowledge Spa, Royal Cornwall Hospital, Truro, Cornwall, TR1 3HD
| | - Orin Courtenay
- University of Warwick, School of Life Sciences, Gibbet Hill Campus, Coventry, CV4 7AL
- Warwick Infectious Disease Epidemiology Research (WIDER), University of Warwick, Coventry, CV4 7AL
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Courtenay O, Carson C, Calvo-Bado L, Garcez LM, Quinnell RJ. Heterogeneities in Leishmania infantum infection: using skin parasite burdens to identify highly infectious dogs. PLoS Negl Trop Dis 2014; 8:e2583. [PMID: 24416460 PMCID: PMC3886905 DOI: 10.1371/journal.pntd.0002583] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Accepted: 10/29/2013] [Indexed: 11/18/2022] Open
Abstract
Background The relationships between heterogeneities in host infection and infectiousness (transmission to arthropod vectors) can provide important insights for disease management. Here, we quantify heterogeneities in Leishmania infantum parasite numbers in reservoir and non-reservoir host populations, and relate this to their infectiousness during natural infection. Tissue parasite number was evaluated as a potential surrogate marker of host transmission potential. Methods Parasite numbers were measured by qPCR in bone marrow and ear skin biopsies of 82 dogs and 34 crab-eating foxes collected during a longitudinal study in Amazon Brazil, for which previous data was available on infectiousness (by xenodiagnosis) and severity of infection. Results Parasite numbers were highly aggregated both between samples and between individuals. In dogs, total parasite abundance and relative numbers in ear skin compared to bone marrow increased with the duration and severity of infection. Infectiousness to the sandfly vector was associated with high parasite numbers; parasite number in skin was the best predictor of being infectious. Crab-eating foxes, which typically present asymptomatic infection and are non-infectious, had parasite numbers comparable to those of non-infectious dogs. Conclusions Skin parasite number provides an indirect marker of infectiousness, and could allow targeted control particularly of highly infectious dogs. Zoonotic visceral leishmaniasis is a sandfly-borne disease of humans and dogs caused by the intracellular parasite Leishmania infantum. Dogs are the proven reservoir. The disease is usually fatal unless treated, and is of global health significance. Diagnosis of canine infections relies on serum antibody-based tests that measure infection. In some endemic regions, a test-and-slaughter policy of seropositive dogs forms part of the national control policy to reduce human infection. However, this strategy is not considered effective. Since not all infected dogs are infectious to sandfly vectors, one option is to target control at infectious dogs, as only these dogs maintain transmission. We quantify Leishmania numbers in individual host tissues from time of infection using molecular methods. Comparing these results with their infectiousness to sandflies, we also evaluate the performance of molecular and immunological assays to identify infectious animals. Parasite numbers varied substantially between individuals, increasing with duration and severity of disease. Infectiousness to the sandfly vector was associated with high parasite numbers, and parasite loads in the skin was the best predictor of being infectious. The results suggest that molecular quantitation is useful in identifying individuals and populations responsible for maintaining transmission, with potential application in operational control programmes.
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Affiliation(s)
- Orin Courtenay
- School of Life Sciences, and Warwick Infectious Disease Epidemiology Research (WIDER), University of Warwick, Coventry, United Kingdom
- * E-mail:
| | - Connor Carson
- School of Life Sciences, and Warwick Infectious Disease Epidemiology Research (WIDER), University of Warwick, Coventry, United Kingdom
| | - Leo Calvo-Bado
- School of Life Sciences, and Warwick Infectious Disease Epidemiology Research (WIDER), University of Warwick, Coventry, United Kingdom
| | - Lourdes M. Garcez
- Laboratório de Epidemiologia e Imunologia aplicada às Leishmanioses, Seção de Parasitologia, Instituto Evandro Chagas, Belém, Pará, Brazil
- Centro do Ciências Biológicas e da Saúde, Universidade do Estado do Pará, Belém, Pará, Brazil
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Quinnell RJ, Carson C, Reithinger R, Garcez LM, Courtenay O. Evaluation of rK39 rapid diagnostic tests for canine visceral leishmaniasis: longitudinal study and meta-analysis. PLoS Negl Trop Dis 2013; 7:e1992. [PMID: 23326615 PMCID: PMC3542187 DOI: 10.1371/journal.pntd.0001992] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Accepted: 11/17/2012] [Indexed: 11/30/2022] Open
Abstract
Background There is a need for sensitive and specific rapid diagnostic tests (RDT) for canine visceral leishmaniasis. The aims of this study were to evaluate the diagnostic performance of immunochromatographic dipstick RDTs using rK39 antigen for canine visceral leishmaniasis by (i) investigating the sensitivity of RDTs to detect infection, disease and infectiousness in a longitudinal cohort study of natural infection in Brazil, and (ii) using meta-analysis to estimate the sensitivity and specificity of RDTs from published studies. Methodology We used a rK39 RDT (Kalazar Detect Canine Rapid Test; Inbios) to test sera collected from 54 sentinel dogs exposed to natural infection in an endemic area of Brazil. Dogs were sampled bimonthly for up to 27 months, and rK39 results compared to those of crude antigen ELISA, PCR, clinical status and infectiousness to sandflies. We then searched MEDLINE and Web of Knowledge (1993–2011) for original studies evaluating the performance of rK39 RDTs in dogs. Meta-analysis of sensitivity and specificity was performed using bivariate mixed effects models. Principal Findings The sensitivity of the rK39 RDT in Brazil to detect infection, disease and infectiousness was 46%, 77% and 78% respectively. Sensitivity increased with time since infection, antibody titre, parasite load, clinical score and infectiousness. Sixteen studies met the inclusion criteria for meta-analysis. The combined sensitivity of rK39 RDTs was 86.7% (95% CI: 76.9–92.8%) to detect clinical disease and 59.3% (37.9–77.6%) to detect infection. Combined specificity was 98.7% (89.5–99.9%). Both sensitivity and specificity varied considerably between studies. Conclusion The diagnostic performance of rK39 RDTs is reasonable for confirmation of infection in suspected clinical cases, but the sensitivity to detect infected dogs is too low for large-scale epidemiological studies and operational control programmes. Canine visceral leishmaniasis is a vector-borne disease caused by the intracellular parasite Leishmania infantum. It is an important veterinary disease, and dogs are also the main animal reservoir for human infection. The disease is widespread in the Mediterranean area, and parts of Asia and South and Central America, and is potentially fatal in both dogs and humans unless treated. Diagnosis of canine infections requires serological or molecular tests. Detection of infection in dogs is important prior to treatment, and in epidemiological studies and control programmes, and a sensitive and specific rapid diagnostic test would be very useful. Rapid diagnostic tests (RDTs) have been developed, but their diagnostic performance has been reported to be variable. We evaluated the sensitivity of a RDT based on serological detection of the rK39 antigen in a cohort of naturally infected Brazilian dogs. The sensitivity of the test to detect infection was relatively low, but increased with time since infection and the severity of infection. We then carried out a meta-analysis of published studies of rK39 RDTs, evaluating the sensitivity to detect disease and infection. The results suggest that rK39 RDTs may be useful in a veterinary clinical setting, but the sensitivity to detect infection is too low for operational control programmes.
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Pontiroli A, Travis ER, Sweeney FP, Porter D, Gaze WH, Mason S, Hibberd V, Holden J, Courtenay O, Wellington EMH. Pathogen quantitation in complex matrices: a multi-operator comparison of DNA extraction methods with a novel assessment of PCR inhibition. PLoS One 2011; 6:e17916. [PMID: 21448453 PMCID: PMC3063169 DOI: 10.1371/journal.pone.0017916] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2010] [Accepted: 02/15/2011] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Mycobacterium bovis is the aetiological agent of bovine tuberculosis (bTB), an important recrudescent zoonosis, significantly increasing in British herds in recent years. Wildlife reservoirs have been identified for this disease but the mode of transmission to cattle remains unclear. There is evidence that viable M. bovis cells can survive in soil and faeces for over a year. METHODOLOGY/PRINCIPAL FINDINGS We report a multi-operator blinded trial for a rigorous comparison of five DNA extraction methods from a variety of soil and faecal samples to assess recovery of M. bovis via real-time PCR detection. The methods included four commercial kits: the QIAamp Stool Mini kit with a pre-treatment step, the FastDNA® Spin kit, the UltraClean™ and PowerSoil™ soil kits and a published manual method based on phenol:chloroform purification, termed Griffiths. M. bovis BCG Pasteur spiked samples were extracted by four operators and evaluated using a specific real-time PCR assay. A novel inhibition control assay was used alongside spectrophotometric ratios to monitor the level of inhibitory compounds affecting PCR, DNA yield, and purity. There were statistically significant differences in M. bovis detection between methods of extraction and types of environmental samples; no significant differences were observed between operators. Processing times and costs were also evaluated. To improve M. bovis detection further, the two best performing methods, FastDNA® Spin kit and Griffiths, were optimised and the ABI TaqMan environmental PCR Master mix was adopted, leading to improved sensitivities. CONCLUSIONS M. bovis was successfully detected in all environmental samples; DNA extraction using FastDNA® Spin kit was the most sensitive method with highest recoveries from all soil types tested. For troublesome faecal samples, we have used and recommend an improved assay based on a reduced volume, resulting in detection limits of 4.25×10(5) cells g(-1) using Griffiths and 4.25×10(6) cells g(-1) using FastDNA® Spin kit.
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Bern C, Courtenay O, Alvar J. Of cattle, sand flies and men: a systematic review of risk factor analyses for South Asian visceral leishmaniasis and implications for elimination. PLoS Negl Trop Dis 2010; 4:e599. [PMID: 20161727 PMCID: PMC2817719 DOI: 10.1371/journal.pntd.0000599] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2009] [Accepted: 12/16/2009] [Indexed: 01/27/2023] Open
Abstract
BACKGROUND Studies performed over the past decade have identified fairly consistent epidemiological patterns of risk factors for visceral leishmaniasis (VL) in the Indian subcontinent. METHODS AND PRINCIPAL FINDINGS To inform the current regional VL elimination effort and identify key gaps in knowledge, we performed a systematic review of the literature, with a special emphasis on data regarding the role of cattle because primary risk factor studies have yielded apparently contradictory results. Because humans form the sole infection reservoir, clustering of kala-azar cases is a prominent epidemiological feature, both at the household level and on a larger scale. Subclinical infection also tends to show clustering around kala-azar cases. Within villages, areas become saturated over a period of several years; kala-azar incidence then decreases while neighboring areas see increases. More recently, post kala-azar dermal leishmaniasis (PKDL) cases have followed kala-azar peaks. Mud walls, palpable dampness in houses, and peri-domestic vegetation may increase infection risk through enhanced density and prolonged survival of the sand fly vector. Bed net use, sleeping on a cot and indoor residual spraying are generally associated with decreased risk. Poor micronutrient status increases the risk of progression to kala-azar. The presence of cattle is associated with increased risk in some studies and decreased risk in others, reflecting the complexity of the effect of bovines on sand fly abundance, aggregation, feeding behavior and leishmanial infection rates. Poverty is an overarching theme, interacting with individual risk factors on multiple levels. CONCLUSIONS Carefully designed demonstration projects, taking into account the complex web of interconnected risk factors, are needed to provide direct proof of principle for elimination and to identify the most effective maintenance activities to prevent a rapid resurgence when interventions are scaled back. More effective, short-course treatment regimens for PKDL are urgently needed to enable the elimination initiative to succeed.
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Affiliation(s)
- Caryn Bern
- Division of Parasitic Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA.
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Antoniou M, Messaritakis I, Christodoulou V, Ascoksilaki I, Kanavakis N, Sutton AJ, Carson C, Courtenay O. Increasing incidence of zoonotic visceral leishmaniasis on Crete, Greece. Emerg Infect Dis 2009; 15:932-4. [PMID: 19523295 PMCID: PMC2727332 DOI: 10.3201/eid1506.071666] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
To determine whether the incidence of canine leishmaniasis has increased on Crete, Greece, we fitted infection models to serodiagnostic records of 8,848 dog samples for 1990–2006. Models predicted that seroprevalence has increased 2.4% (95% confidence interval 1.61%–3.51%) per year and that incidence has increased 2.2- to 3.8-fold over this 17-year period.
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Courtenay O, Kovacic V, Gomes PAF, Garcez LM, Quinnell RJ. A long-lasting topical deltamethrin treatment to protect dogs against visceral leishmaniasis. Med Vet Entomol 2009; 23:245-256. [PMID: 19712155 DOI: 10.1111/j.1365-2915.2009.00815.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
To develop long-lasting, topical pour-on insecticides for dogs to control zoonotic visceral leishmaniasis, two deltamethrin-based formulations (emulsifiable concentrate [EC] and suspension concentrate [SC]) were tested for their efficacy against the phlebotomine sandfly Lutzomyia longipalpis Lutz & Neiva (Diptera: Psychodidae), vector of Leishmania infantum Nicolle (Kinetoplastida: Trypanosomatidae). The entomological outcomes tested were anti-feeding effect (proportion of female sandflies unfed), lethal effect (24-h female sandfly mortality) and these two effects combined, and the insecticide persistence time at 50% (residual activity, RA50) and 80% (RA80) efficacy. On initial application, the proportions of female flies that demonstrated anti-feeding activity or were killed were similar for both formulations, at 0.93 (95% confidence interval [CI] 0.856-0.977) vs. 0.81 (95% CI 0.763-0.858) (anti-feeding) and 0.86 (95% CI 0.787-0.920) vs. 0.76 (95% CI 0.698-0.817) (24-h mortality) for EC and SC, respectively. The RA(50) rates for anti-feeding and mortality caused by the EC formulation were 4.7 months (95% CI 4.18-5.84) and 2.5 months (95% CI 2.25-2.90), respectively, compared with 1.1 months (95% CI 0.96-1.15) and 0.6 months (95% CI 0.50-0.61), respectively, for the SC formulation. The RA(50) for the combined anti-feeding and mortality effects of EC was 5.2 months (95% CI 4.73-5.96), compared with only 0.9 months (95% CI 0.85-1.00) for the SC formulation. The four- to six-fold superior residual activity of the EC formulation was attributed to the addition of a solvent-soluble resin in the formulation which improved fur adhesion and acted as a reservoir for the slow release of the active ingredient. These results identify the potential of such a low-cost formulation to reduce the inter-intervention interval to 5-6 months, similar to that recommended for deltamethrin-impregnated dog collars or for re-impregnation of conventional bednets, both of which are currently used to combat Leishmania transmission. Finally, a novel bioassay was developed in which sandflies were exposed to fur from treated dogs, revealing no detectable tolerance (24-h mortality) in wild-caught sandflies to the insecticide formulations up to 8 months after the initiation of communitywide application of the insecticides to dogs.
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Affiliation(s)
- O Courtenay
- Populations and Disease Research Group, Department of Biological Sciences, University of Warwick, Coventry, UK.
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Carson C, Quinnell RJ, Day MJ, Courtenay O. Comparison of monoclonal and polyclonal antibodies for the detection of canine IgG1 and IgG2, and associations with infection outcome in Leishmania infantum naturally infected dogs. Vet Immunol Immunopathol 2009; 133:264-8. [PMID: 19726090 DOI: 10.1016/j.vetimm.2009.07.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2009] [Revised: 07/24/2009] [Accepted: 07/29/2009] [Indexed: 11/26/2022]
Abstract
In murine models of leishmaniasis, IgG subclass expression is a proxy measure for Th1/Th2 cellular immune response bias. However, in dogs, the reservoir of zoonotic visceral leishmaniasis, no consistent association has been described between IgG subclass ratios and disease resistance. Inconsistent results may reflect lack of specificity of commonly used commercial antibodies. Our aim was to measure IgG1 and IgG2 responses to crude Leishmania antigen using commercial polyclonal antibodies for comparison with a panel of commercially unavailable monoclonal antibodies, in a cohort of 60 naturally infected dogs, and to compare associations between subclass responses and clinical or parasitological outcomes. IgG1 and IgG2, measured by both antibodies, were higher in clinically symptomatic than in asymptomatic dogs (P</=0.03), reflecting general upregulation of IgG in infected dogs. Unlike the murine model, canine IgG2:IgG1 ratios were not predictive of clinical or parasitological outcomes of infection. Associations between subclass levels and positivity by bone marrow culture and PCR were not consistent when measured with different antibodies. Further research is needed to re-evaluate the specificity of commercially available IgG subclass antibodies.
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Affiliation(s)
- Connor Carson
- Populations and Disease Research Group, Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, UK.
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Carson C, Antoniou M, Christodoulou V, Messaritakis I, Quinnell RJ, Blackwell JM, Courtenay O. Selection of appropriate serological tests to measure the incidence of natural Leishmania infantum infection during DNA/MVA prime/boost canine vaccine trials. Vet Parasitol 2009; 162:207-13. [DOI: 10.1016/j.vetpar.2009.03.037] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2008] [Revised: 02/13/2009] [Accepted: 03/19/2009] [Indexed: 11/16/2022]
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Macdonald DW, Courtenay O. Enduring social relationships in a population of crab-eating zorros,Cerdocyon thous, in Amazonian Brazil (Carnivora, Canidae). J Zool (1987) 2009. [DOI: 10.1111/j.1469-7998.1996.tb05454.x] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Carson C, Antoniou M, Ruiz-Argüello MB, Alcami A, Christodoulou V, Messaritakis I, Blackwell JM, Courtenay O. A prime/boost DNA/Modified vaccinia virus Ankara vaccine expressing recombinant Leishmania DNA encoding TRYP is safe and immunogenic in outbred dogs, the reservoir of zoonotic visceral leishmaniasis. Vaccine 2009; 27:1080-6. [PMID: 19095029 PMCID: PMC2663027 DOI: 10.1016/j.vaccine.2008.11.094] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2008] [Revised: 11/19/2008] [Accepted: 11/27/2008] [Indexed: 01/28/2023]
Abstract
Previous studies demonstrated safety, immunogenicity and efficacy of DNA/modified vaccinia virus Ankara (MVA) prime/boost vaccines expressing tryparedoxin peroxidase (TRYP) and Leishmania homologue of the mammalian receptor for activated C kinase (LACK) against Leishmania major challenge in mice, which was consistent with results from TRYP protein/adjuvant combinations in non-human primates. This study aimed to conduct safety and immunogenicity trials of these DNA/MVA vaccines in dogs, the natural reservoir host of Leishmania infantum, followed-up for 4 months post-vaccination. In a cohort of 22 uninfected outbred dogs, blinded randomised administration of 1000 microg (high dose) or 100 microg (low dose) DNA prime (day 0) and 1x10(8)pfu MVA boost (day 28) was shown to be safe and showed no clinical side effects. High dose DNA/MVA vaccinated TRYP dogs produced statistically higher mean levels of the type-1 pro-inflammatory cytokine IFN-gamma than controls in whole blood assays (WBA) stimulated with the recombinant vaccine antigen TRYP, up to the final sampling at day 126, and in the absence of challenge with Leishmania. TRYP vaccinated dogs also demonstrated significantly higher TRYP-specific total IgG and IgG2 subtype titres than in controls, and positive in vivo intradermal reactions at day 156 in the absence of natural infection, observed in 6/8 TRYP vaccinated dogs. No significant increases in IFN-gamma in LACK-stimulated WBA, or in LACK-specific IgG levels, were detected in LACK vaccinated dogs compared to controls, and only 2/9 LACK vaccinated dogs demonstrated DTH responses at day 156. In all groups, IgG1 subclass responses and antigen-specific stimulation of IL-10 were similar to controls demonstrating an absence of Th2/T(reg) response, as expected in the absence of in vivo restimulation or natural/experimental challenge with Leishmania. These collective results indicate significant antigen-specific type-1 responses and in vivo memory phase cellular immune responses, consistent with superior potential for protective vaccine immunogenicity of DNA/MVA TRYP over LACK.
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MESH Headings
- Animals
- Antibodies, Protozoan/blood
- Antigens, Protozoan/genetics
- Antigens, Protozoan/immunology
- Dogs
- Immunization, Secondary/methods
- Immunoglobulin G/blood
- Interferon-gamma/metabolism
- Leishmania infantum/immunology
- Leishmaniasis Vaccines/administration & dosage
- Leishmaniasis Vaccines/adverse effects
- Leishmaniasis Vaccines/immunology
- Leishmaniasis, Visceral/immunology
- Leishmaniasis, Visceral/prevention & control
- Leukocytes, Mononuclear/immunology
- Peroxidases/genetics
- Peroxidases/immunology
- Protozoan Proteins/genetics
- Protozoan Proteins/immunology
- Vaccines, DNA/administration & dosage
- Vaccines, DNA/adverse effects
- Vaccines, DNA/immunology
- Vaccinia virus/genetics
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Affiliation(s)
- Connor Carson
- Populations and Disease Research Group, Department of Biological Sciences, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK.
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Parvizi P, Mazloumi-Gavgani A, Davies C, Courtenay O, Ready P. Two Leishmania species circulating in the Kaleybar focus of infantile visceral leishmaniasis, northwest Iran: implications for deltamethrin dog collar intervention. Trans R Soc Trop Med Hyg 2008; 102:891-7. [DOI: 10.1016/j.trstmh.2008.04.026] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2007] [Revised: 04/15/2008] [Accepted: 04/18/2008] [Indexed: 10/22/2022] Open
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Reilly LA, Favacho J, Garcez LM, Courtenay O. Preliminary evidence that synanthropic flies contribute to the transmission of trachoma- causing Chlamydia trachomatis in Latin America. CAD SAUDE PUBLICA 2008; 23:1682-8. [PMID: 17572818 DOI: 10.1590/s0102-311x2007000700020] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2006] [Accepted: 01/12/2006] [Indexed: 11/21/2022] Open
Abstract
Synanthropic flies have been shown to be important mechanical vectors of Chlamydia trachomatis, which causes trachoma. However entomological studies have not been forthcoming in Latin America. This study assesses the relationship between household dipteran fly densities and active childhood trachoma in a village on Marajó Island, Pará state, Brazil. For 78 households, members were examined for signs of trachoma, relative abundance of potential trachoma vectors (Diptera, Chloropidae and Diptera, Muscidae) was quantified by trap counts, and additional measures of household hygiene associated with C. trachomatis transmission were assessed. Active childhood trachoma prevalence was 24.1% (45/187), present in 46.2% of sampled households with evidence of case clustering. Childhood prevalence was positively associated with increased fly densities, whereas indirect measures of sanitary conditions (latrine ownership and perceived importance of flies) showed a protective effect. This study indicates that C. trachomatis can be transmitted by synanthropic flies in this region of Latin America.
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Affiliation(s)
- Lucy A Reilly
- Department of Biological Sciences, University of Warwick, Coventry, UK
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Courtenay O, Reilly LA, Sweeney FP, Macdonald DW, Delahay RJ, Wilson GJ, Cheeseman CL, Keeling MJ, Wellington EMH. Performance of an environmental test to detect Mycobacterium bovis infection in badger social groups. Vet Rec 2007; 161:817-818. [PMID: 18083981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Affiliation(s)
- O Courtenay
- Ecology and Epidemiology Group, Department of Biological Sciences, University of Warwick, Coventry cv4 7al
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Sweeney FP, Courtenay O, Hibberd V, Hewinson RG, Reilly LA, Gaze WH, Wellington EMH. Environmental monitoring of Mycobacterium bovis in badger feces and badger sett soil by real-time PCR, as confirmed by immunofluorescence, immunocapture, and cultivation. Appl Environ Microbiol 2007; 73:7471-3. [PMID: 17905874 PMCID: PMC2168199 DOI: 10.1128/aem.00978-07] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Real-time PCR was used to detect and quantify Mycobacterium bovis cells in naturally infected soil and badger feces. Immunomagnetic capture, immunofluorescence, and selective culture confirmed species identification and cell viability. These techniques will prove useful for monitoring M. bovis in the environment and for elucidating transmission routes between wildlife and cattle.
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Affiliation(s)
- F P Sweeney
- Microbiology Group, Department of Biological Sciences, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, United Kingdom.
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