1
|
Moscovitz S, Glassner H, Wokam Njomgang RM, Aflalo ED, Ovadia O, Sagi A. Community composition of invasive, outbreak, and non-pest snail species along a source spring-to-fishpond gradient in a spatially structured aquacultural region. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 351:119653. [PMID: 38070421 DOI: 10.1016/j.jenvman.2023.119653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 11/16/2023] [Accepted: 11/16/2023] [Indexed: 01/14/2024]
Abstract
Agricultural lands are integrated into and interact with natural areas. Such is the case of Emek HaMa'ayanot, northern Israel, comprising a springs-rich area characterized by multiple land-uses, including spring-water-based aquaculture, recreational springs, and nature reserves. Aquacultural farms suffer from pest snails that carry fish disease; in the study region, these species are invasive (Thiara scabra, Tarebia granifera, Pseudosuccinea columella) and outbreak endemic (Melanoides tuberculata). Previous snail control efforts have focused on individual fishponds without considering management on larger environmental scales in the waterways from the source springs to the fish farms. To broaden our understanding of the status of the pest snail problem in the study area prior to suggesting environmental managerial solutions, we quantified changes in the community composition of snail species along the springs-to-fishponds gradients in a spatially explicit system. We found a remarkable increase in pest snail abundances along these gradients, indicating that pest snails might be invading upstream towards the springs. There were always nearly 100% pest snails in the endpoint sites for water tracks that ended in fishponds. Moreover, pest snails dominated the site when it was used as a fishpond, even though the site was also a spring. In contrast, in a water track that does not end in a fish farm, the relative abundances of non-pest snail species was similar between the source spring and the downstream endpoint, in spite of an increase in pest snail abundance at a midpoint site. These results suggest that invasive pest snails are actively moving upstream and that the fishponds have a marked upstream effect on the ability of non-pest snails to resist pest species invasions. We suggest further investigation of possible strategies for biocontrol of the observed invasion of the snails into natural areas as a basis for environmental management efforts. Finally, the observations made during this study could have practical global implications for snail management in aquaculture and agriculture, and for the control of snails and snail vectors implicated in animal and human diseases.
Collapse
Affiliation(s)
- Sharon Moscovitz
- Department of Life Sciences, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva, 84105, Israel
| | - Hanoch Glassner
- Eden Research Station, Mobile Post Beit Shean, 11710, Israel
| | | | - Eliahu D Aflalo
- Department of Life Sciences, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva, 84105, Israel; Department of Life Sciences, Achva Academic College, Mobile Post Shikmim, 79800, Israel
| | - Ofer Ovadia
- Department of Life Sciences, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva, 84105, Israel; Goldman Sonnenfeldt School of Sustainability and Climate Change, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva, 84105, Israel.
| | - Amir Sagi
- Department of Life Sciences, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva, 84105, Israel; National Institute for Biotechnology in the Negev (NIBN), Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva, 84105, Israel.
| |
Collapse
|
2
|
Bio-efficacy of Soil Actinomycetes and an Isolated Molecule 1,2-Benzenedicarboxylic Acid from Nonomuraea sp. Against Culex quinquefasciatus Say and Aedes aegypti L. Mosquitoes (Diptera: Culicidae). Appl Biochem Biotechnol 2021; 194:4765-4782. [PMID: 34806140 DOI: 10.1007/s12010-021-03766-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 11/08/2021] [Indexed: 10/19/2022]
Abstract
Vector-borne diseases such as filariasis and dengue that contribute significantly to disease burden, death, poverty, and social frailty are still a major public healthcare problem worldwide. Currently, synthetic chemicals have been used in mosquito control programs. However, repeated use of chemical insecticides causes environmental pollution and harmful effects on non-target organisms. Therefore, alternative ecofriendly sources from biological source are urgently needed to manage mosquitoes. In this respect, the present study was aimed to evaluate mosquito larvicidal and pupicidal activities of 22 crude extracts of soil actinomycetes on Culex quinquefasciatus and Aedes aegypti and to identify the active molecule. Briefly, the crude ethyl acetate extract and fractions were tested at 62.5, 125, 250, and 500 ppm and 2.5, 5.0, 7.5, and 10.0 ppm concentrations on larval and pupal stages of Cx. quinquefasciatus and Ae. aegypti. The larval and pupal mortality was assessed after 24 h of treatment. Among the 22 isolates screened, Nonomuraea sp. VAS-16 exhibited significant larvicidal and pupicidal activities against the tested mosquito species. Among the 18 fractions screened, fraction-6 showed strong larvicidal and pupicidal activities with the LC50 and LC90 values of 9.1, 18.7, 9.82, and 22.85 ppm against the larvae and LC50 and LC90 values of 10.5, 23.1, 12.3, and 24.13 ppm against the pupae of Cx. quinquefasciatus and Ae. aegypti, respectively. Fascinatingly, the isolated compound 1,2-benzenedicarboxylic acid from fraction-6 at 0.5, 1.0, 1.5, and 2.0 ppm concentration recorded lower LC50 and LC90 values of 4.27, 14.90, 4.67, and 11.90 ppm against the larvae and LC50 and LC90 values of 4.58, 12.06, 5.36, and 13.07 ppm against the pupae of Cx. quinquefasciatus and Ae. aegypti, respectively. On the other hand, the compound recorded less ovicidal activity of 11.0% and 10.3% at 2 ppm against the eggs of Cx. quinquefasciatus and Ae. aegypti, respectively. The present study clearly shows that the crude extract and the compound from Nonomuraea sp. VAS-16 can be used as an effective biopesticide in integrated mosquito management program.
Collapse
|
3
|
Andreazza F, Oliveira EE, Martins GF. Implications of Sublethal Insecticide Exposure and the Development of Resistance on Mosquito Physiology, Behavior, and Pathogen Transmission. INSECTS 2021; 12:insects12100917. [PMID: 34680686 PMCID: PMC8539869 DOI: 10.3390/insects12100917] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 10/03/2021] [Accepted: 10/04/2021] [Indexed: 12/31/2022]
Abstract
Simple Summary Mosquitoes are one of the greatest threats to human lives; they transmit a wide range of pathogens, including viruses that cause lethal diseases. Mosquitoes are found in both aquatic (as larvae or pupae) and terrestrial (as adults) environments during their complex life cycle. For decades, insecticides have been systematically used on mosquitoes with the aim to reduce their population. Little is known about how the stress resulting from the exposure of mosquitoes to insecticides impacts the tri-partite relationship between the mosquitoes, their vertebrate hosts, and the pathogens they transmit. In this work, we review existing experimental evidence to obtain a broad picture on the potential effects of the (sub)lethal exposure of hematophagous mosquitoes to different insecticides. We have focused on studies that have advanced our understanding of their physiological and behavioral responses (including the mechanisms behind insecticide resistance) and the spread of pathogens by these vectors—understudied but critically important issues for epidemiology. Studying these exposure-related effects is of paramount importance for predicting how they respond to insecticide exposure and whether this exposure makes them more or less likely to transmit pathogens. Abstract For many decades, insecticides have been used to control mosquito populations in their larval and adult stages. Although changes in the population genetics, physiology, and behavior of mosquitoes exposed to lethal and sublethal doses of insecticides are expected, the relationships between these changes and their abilities to transmit pathogens remain unclear. Thus, we conducted a comprehensive review on the sublethal effects of insecticides and their contributions to insecticide resistance in mosquitoes, with the main focus on pyrethroids. We discuss the direct and acute effects of sublethal concentrations on individuals and populations, the changes in population genetics caused by the selection for resistance after insecticide exposure, and the major mechanisms underlying such resistance. Sublethal exposures negatively impact the individual’s performance by affecting their physiology and behavior and leaving them at a disadvantage when compared to unexposed organisms. How these sublethal effects could change mosquito population sizes and diversity so that pathogen transmission risks can be affected is less clear. Furthermore, despite the beneficial and acute aspects of lethality, exposure to higher insecticide concentrations clearly impacts the population genetics by selecting resistant individuals, which may bring further and complex interactions for mosquitoes, vertebrate hosts, and pathogens. Finally, we raise several hypotheses concerning how the here revised impacts of insecticides on mosquitoes could interplay with vector-mediated pathogens’ transmission.
Collapse
Affiliation(s)
- Felipe Andreazza
- Departamento de Entomologia, Universidade Federal de Viçosa, Viçosa 36570-900, MG, Brazil; (F.A.); (E.E.O.)
| | - Eugênio E. Oliveira
- Departamento de Entomologia, Universidade Federal de Viçosa, Viçosa 36570-900, MG, Brazil; (F.A.); (E.E.O.)
| | - Gustavo Ferreira Martins
- Departamento de Biologia Geral, Universidade Federal de Viçosa, Viçosa 36570-900, MG, Brazil
- Correspondence:
| |
Collapse
|
4
|
Carrillo-Bilbao G, Martin-Solano S, Saegerman C. Zoonotic Blood-Borne Pathogens in Non-Human Primates in the Neotropical Region: A Systematic Review. Pathogens 2021; 10:1009. [PMID: 34451473 PMCID: PMC8400055 DOI: 10.3390/pathogens10081009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2021] [Revised: 07/29/2021] [Accepted: 08/05/2021] [Indexed: 01/17/2023] Open
Abstract
Background: Understanding which non-human primates (NHPs) act as a wild reservoir for blood-borne pathogens will allow us to better understand the ecology of diseases and the role of NHPs in the emergence of human diseases in Ecuador, a small country in South America that lacks information on most of these pathogens. Methods and principal findings: A systematic review was carried out using PRISMA guidelines from 1927 until 2019 about blood-borne pathogens present in NHPs of the Neotropical region (i.e., South America and Middle America). Results: A total of 127 publications were found in several databases. We found in 25 genera (132 species) of NHPs a total of 56 blood-borne pathogens in 197 records where Protozoa has the highest number of records in neotropical NHPs (n = 128) compared to bacteria (n = 12) and viruses (n = 57). Plasmodium brasilianum and Trypanosoma cruzi are the most recorded protozoa in NHP. The neotropical primate genus with the highest number of blood-borne pathogens recorded is Alouatta sp. (n = 32). The use of non-invasive samples for neotropical NHPs remains poor in a group where several species are endangered or threatened. A combination of serological and molecular techniques is common when detecting blood-borne pathogens. Socioecological and ecological risk factors facilitate the transmission of these parasites. Finally, a large number of countries remain unsurveyed, such as Ecuador, which can be of public health importance. Conclusions and significance: NHPs are potential reservoirs of a large number of blood-borne pathogens. In Ecuador, research activities should be focused on bacteria and viruses, where there is a gap of information for neotropical NHPs, in order to implement surveillance programs with regular and effective monitoring protocols adapted to NHPs.
Collapse
Affiliation(s)
- Gabriel Carrillo-Bilbao
- Research Unit of Epidemiology and Risk Analysis Applied to Veterinary Sciences (UREAR-ULiège), Fundamental and Applied Research for Animal and Health (FARAH) Center, Department of Infections and Parasitic Diseases, Faculty of Veterinary Medicine, University of Liège, 4000 Liège, Belgium;
- Facultad de Filosofía y Letras y Ciencias de la Educación, Universidad Central del Ecuador, 170521 Quito, Ecuador
- Instituto de Investigación en Zoonosis (CIZ), Universidad Central del Ecuador, 170521 Quito, Ecuador;
| | - Sarah Martin-Solano
- Instituto de Investigación en Zoonosis (CIZ), Universidad Central del Ecuador, 170521 Quito, Ecuador;
- Grupo de Investigación en Sanidad Animal y Humana (GISAH), Carrera Ingeniería en Biotecnología, Departamento de Ciencias de la Vida y la Agricultura, Universidad de las Fuerzas Armadas—ESPE, 171103 Sangolquí, Ecuador
| | - Claude Saegerman
- Research Unit of Epidemiology and Risk Analysis Applied to Veterinary Sciences (UREAR-ULiège), Fundamental and Applied Research for Animal and Health (FARAH) Center, Department of Infections and Parasitic Diseases, Faculty of Veterinary Medicine, University of Liège, 4000 Liège, Belgium;
| |
Collapse
|
5
|
Reegan AD, Kumar PS, Asharaja AC, Devi C, Jameela S, Balakrishna K, Ignacimuthu S. Larvicidal and ovicidal activities of phenyl acetic acid isolated from Streptomyces collinus against Culex quinquefasciatus Say and Aedes aegypti L. (Diptera: Culicidae). Exp Parasitol 2021; 226-227:108120. [PMID: 34089701 DOI: 10.1016/j.exppara.2021.108120] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 03/26/2021] [Accepted: 05/30/2021] [Indexed: 11/19/2022]
Abstract
The bio-efficacy of crude ethyl acetate extract, fractions and a compound phenyl acetic acid from the ethyl acetate extract of Streptomyces collinus was evaluated on Culex quinquefasciatus Say and Aedes aegypti L. mosquitoes (Diptera: Culicidae). The larvae were exposed to concentrations of 2.5, 5.0, 7.5 and 10.0 ppm for fractions and 0.5, 1.0, 1.5 and 2.0 ppm for compound. After 24 h, the larval mortality was assessed and the LC₅₀ and LC90 values were calculated. Similarly, per cent ovicidal activity was calculated for eggs after 120 h post treatment for phenyl acetic acid. Among the eleven fractions screened, fraction 7 from the ethyl acetate extract of Streptomyces collinus exhibited good larvicidal activity against both mosquito species. The LC50 and LC90 values of fraction 7 were 4.42, 6.23 ppm against Cx. quinquefasciatus larvae and 5.13, 14.51 ppm against Ae. aegypti larvae, respectively. Further, the isolated compound, phenyl acetic acid from fraction 7 recorded 100% larvicidal activity at 2 ppm concentration with LC50 and LC90 values of 2.07, 4.87 ppm on Cx. quinquefasciatus larvae and 3.81, 9.87 ppm on Ae. aegypti larvae, respectively. Phenyl acetic acid presented 50.3% and 42.0% ovicidal activity against Cx. quinquefasciatus and Ae. aegypti eggs at 2 ppm concentration after 120 h post treatment. The compound, phenyl acetic acid could be used in mosquito control programme.
Collapse
Affiliation(s)
- Appadurai Daniel Reegan
- National Centre for Disease Control, NTI Campus, Bellary Road, Bangalore, 560 003, Karnataka, India.
| | - Pachaiyappan Saravana Kumar
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510 301, Guangdong, China.
| | - Antony Cruz Asharaja
- P.G. and Research Department of Zoology, Pasumpon Muthuramalinga Thevar College, Melaneelithanallur, Tenkasi, 627 953, Tamil Nadu, India
| | - Chitra Devi
- Department of Zoology, Sadakathullah Appa College (Autonomous), Rahmath Nagar, Tirunelveli, 627 011, Tamil Nadu, India
| | - Sithi Jameela
- Department of Zoology, Sadakathullah Appa College (Autonomous), Rahmath Nagar, Tirunelveli, 627 011, Tamil Nadu, India
| | - Kedike Balakrishna
- Entomology Research Institute, Loyola College, Chennai, 600 034, Tamil Nadu, India
| | | |
Collapse
|
6
|
Dumonteil E, Pronovost H, Bierman EF, Sanford A, Majeau A, Moore R, Herrera C. Interactions among Triatoma sanguisuga blood feeding sources, gut microbiota and Trypanosoma cruzi diversity in southern Louisiana. Mol Ecol 2020; 29:3747-3761. [PMID: 32749727 DOI: 10.1111/mec.15582] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 07/20/2020] [Accepted: 07/27/2020] [Indexed: 12/15/2022]
Abstract
Integrating how biodiversity and infectious disease dynamics are linked at multiple levels and scales is highly challenging. Chagas disease is a vector-borne disease, with specificities of the triatomine vectors and Trypanosoma cruzi parasite life histories resulting in a complex multihost and multistrain life cycle. Here, we tested the hypothesis that T. cruzi transmission cycles are shaped by triatomine host communities and gut microbiota composition by comparing the integrated interactions of Triatoma sanguisuga in southern Louisiana with feeding hosts, T. cruzi parasite and bacterial microbiota in two habitats. Bugs were collected from resident's houses and animal shelters and analysed for genetic structure, blood feeding sources, T. cruzi parasites, and bacterial diversity by PCR amplification of specific DNA markers followed by next-generation sequencing, in an integrative metabarcoding approach. T. sanguisuga feeding host communities appeared opportunistic and defined by host abundance in each habitat, yielding distinct parasite transmission networks among hosts. The circulation of a large diversity of T. cruzi DTUs was also detected, with TcII and TcV detected for the first time in triatomines in the US. The bacterial microbiota was highly diverse and varied significantly according to the DTU infecting the bugs, indicating specific interactions among them in the gut. Expanding such studies to multiple habitats and additional triatomine species would be key to further refine our understanding of the complex life cycles of multihost, multistrain parasites such as T. cruzi, and may lead to improved disease control strategies.
Collapse
Affiliation(s)
- Eric Dumonteil
- Department of Tropical Medicine, School of Public Health and Tropical Medicine, and Vector-Borne and Infectious Disease Research Center, Tulane University, New Orleans, LA, USA
| | - Henry Pronovost
- Department of Tropical Medicine, School of Public Health and Tropical Medicine, and Vector-Borne and Infectious Disease Research Center, Tulane University, New Orleans, LA, USA
| | - Eli F Bierman
- Department of Tropical Medicine, School of Public Health and Tropical Medicine, and Vector-Borne and Infectious Disease Research Center, Tulane University, New Orleans, LA, USA
| | - Anna Sanford
- Department of Tropical Medicine, School of Public Health and Tropical Medicine, and Vector-Borne and Infectious Disease Research Center, Tulane University, New Orleans, LA, USA
| | - Alicia Majeau
- Department of Tropical Medicine, School of Public Health and Tropical Medicine, and Vector-Borne and Infectious Disease Research Center, Tulane University, New Orleans, LA, USA
| | - Ryan Moore
- Department of Tropical Medicine, School of Public Health and Tropical Medicine, and Vector-Borne and Infectious Disease Research Center, Tulane University, New Orleans, LA, USA
| | - Claudia Herrera
- Department of Tropical Medicine, School of Public Health and Tropical Medicine, and Vector-Borne and Infectious Disease Research Center, Tulane University, New Orleans, LA, USA
| |
Collapse
|
7
|
da Costa KS, Galúcio JM, da Costa CHS, Santana AR, dos Santos Carvalho V, do Nascimento LD, Lima e Lima AH, Neves Cruz J, Alves CN, Lameira J. Exploring the Potentiality of Natural Products from Essential Oils as Inhibitors of Odorant-Binding Proteins: A Structure- and Ligand-Based Virtual Screening Approach To Find Novel Mosquito Repellents. ACS OMEGA 2019; 4:22475-22486. [PMID: 31909330 PMCID: PMC6941369 DOI: 10.1021/acsomega.9b03157] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 11/29/2019] [Indexed: 05/31/2023]
Abstract
Odorant-binding proteins (OBPs) are the main olfactory proteins of mosquitoes, and their structures have been widely explored to develop new repellents. In the present study, we combined ligand- and structure-based virtual screening approaches using as a starting point 1633 compounds from 71 botanical families obtained from the Essential Oil Database (EssOilDB). Using as reference the crystallographic structure of N,N-diethyl-meta-toluamide interacting with the OBP1 homodimer of Anopheles gambiae (AgamOBP1), we performed a structural and pharmacophoric similarity search to select potential natural products from the library. Thymol acetate, 4-(4-methyl phenyl)-pentanal, thymyl isovalerate, and p-cymen-8-yl demonstrated a favorable chemical correlation with DEET and also had high-affinity interactions with the OBP binding pocket that molecular dynamics simulations showed to be stable. To the best of our knowledge, this is the first study to evaluate on a large scale the potentiality of NPs from essential oils as inhibitors of the mosquito OBP1 using in silico approaches. Our results could facilitate the design of novel repellents with improved selectivity and affinity to the protein binding pocket and can shed light on the mechanism of action of these compounds against insect olfactory recognition.
Collapse
Affiliation(s)
- Kauȇ Santana da Costa
- Institute
of Biodiversity, Federal University of Western
Pará, 68035-110 Santarém, Pará, Brazil
| | - João Marcos Galúcio
- Institute
of Biodiversity, Federal University of Western
Pará, 68035-110 Santarém, Pará, Brazil
| | | | - Amanda Ruslana Santana
- Department
of Pharmaceutical Sciences, Federal University
of Pará, 66060-902 Belém, Pará, Brazil
| | - Vitor dos Santos Carvalho
- Institute of Exact and Natural
Sciences and Institute of Biological Sciences, Federal
University of Pará, 66075-110 Belém, Pará, Brazil
| | | | - Anderson Henrique Lima e Lima
- Institute of Exact and Natural
Sciences and Institute of Biological Sciences, Federal
University of Pará, 66075-110 Belém, Pará, Brazil
| | - Jorddy Neves Cruz
- Department
of Pharmaceutical Sciences, Federal University
of Pará, 66060-902 Belém, Pará, Brazil
| | - Claudio Nahum Alves
- Institute of Exact and Natural
Sciences and Institute of Biological Sciences, Federal
University of Pará, 66075-110 Belém, Pará, Brazil
| | - Jerônimo Lameira
- Institute of Exact and Natural
Sciences and Institute of Biological Sciences, Federal
University of Pará, 66075-110 Belém, Pará, Brazil
| |
Collapse
|
8
|
Flores-Ferrer A, Waleckx E, Rascalou G, Dumonteil E, Gourbière S. Trypanosoma cruzi transmission dynamics in a synanthropic and domesticated host community. PLoS Negl Trop Dis 2019; 13:e0007902. [PMID: 31834879 PMCID: PMC6934322 DOI: 10.1371/journal.pntd.0007902] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Revised: 12/27/2019] [Accepted: 11/04/2019] [Indexed: 12/26/2022] Open
Abstract
Trypanosoma cruzi is the causative agent of Chagas disease, a Neglected Tropical Disease affecting 8 million people in the Americas. Triatomine hematophagous vectors feed on a high diversity of vertebrate species that can be reservoirs or dead-end hosts, such as avian species refractory to T. cruzi. To understand its transmission dynamics in synanthropic and domesticated species living within villages is essential to quantify disease risk and assess the potential of zooprophylaxis. We developed a SI model of T. cruzi transmission in a multi-host community where vector reproduction and parasite transmission depend on a triatomine blood-feeding rate accounting for vector host preferences and interference while feeding. The model was parameterized to describe T. cruzi transmission in villages of the Yucatan peninsula, Mexico, using the information about Triatoma dimidiata vectors and host populations accumulated over the past 15 years. Extensive analyses of the model showed that dogs are key reservoirs and contributors to human infection, as compared to synanthropic rodents and cats, while chickens or other domesticated avian hosts dilute T. cruzi transmission despite increasing vector abundance. In this context, reducing the number of dogs or increasing avian hosts abundance decreases incidence in humans by up to 56% and 39%, respectively, while combining such changes reduces incidence by 71%. Although such effects are only reached over >10-years periods, they represent important considerations to be included in the design of cost-effective Integrated Vector Management. The concomitant reduction in T. cruzi vector prevalence estimated by simulating these zooprophylactic interventions could indeed complement the removal of colonies from the peridomiciles or the use of insect screens that lower vector indoor abundance by ~60% and ~80%. These new findings reinforce the idea that education and community empowerment to reduce basic risk factors is a cornerstone to reach and sustain the key objective of interrupting Chagas disease intra-domiciliary transmission.
Collapse
Affiliation(s)
- Alheli Flores-Ferrer
- UMR5096 ‘Laboratoire Génome et Développement des Plantes’, Université de Perpignan Via Domitia, Perpignan, France
| | - Etienne Waleckx
- Institut de Recherche pour le Développement, UMR INTERTRYP IRD, CIRAD, Université de Montpellier, Montpellier, France
- Laboratorio de Parasitología, Centro de Investigaciones Regionales ‘Dr. Hideyo Noguchi’, Universidad Autónoma deYucatán, Mérida, Yucatán, México
| | - Guilhem Rascalou
- UMR5096 ‘Laboratoire Génome et Développement des Plantes’, Université de Perpignan Via Domitia, Perpignan, France
| | - Eric Dumonteil
- Department of Tropical Medicine, School of Public Health and Tropical Medicine, and Vector-Borne and Infectious Disease Research Center, Tulane University, New Orleans, Louisiana, United States of America
| | - Sébastien Gourbière
- UMR5096 ‘Laboratoire Génome et Développement des Plantes’, Université de Perpignan Via Domitia, Perpignan, France
- Centre for the Study of Evolution, School of Life Sciences, University of Sussex, Brighton, United Kingdom
| |
Collapse
|
9
|
Wahid I, Ishak H, Hafid A, Fajri M, Sidjal S, Nurdin A, Azikin NT, Sudirman R, Hasan H, Yusuf M, Bachtiar I, Hawley WA, Rosenberg R, Lobo NF. Integrated vector management with additional pre-transmission season thermal fogging is associated with a reduction in dengue incidence in Makassar, Indonesia: Results of an 8-year observational study. PLoS Negl Trop Dis 2019; 13:e0007606. [PMID: 31381570 PMCID: PMC6695203 DOI: 10.1371/journal.pntd.0007606] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 08/15/2019] [Accepted: 07/05/2019] [Indexed: 02/08/2023] Open
Abstract
Dengue virus transmission is endemic in Makassar, Indonesia, with the majority of cases reported soon after the start of the annual rainy season. Before 2006, larval source reduction, larvaciding, and reactive routine, outdoor, insecticide fogging campaigns did not result in a reduction in seasonal dengue incidence. Beginning in 2006, village volunteers conducted comprehensive surveys for immature Aedes during the dry season, when vector populations were at their lowest. Based on this pre-season vector data, a single additional pre-emptive outdoor fogging with Malathion was conducted once annually before the rains began in villages with a pre-defined proportion of sampled houses positive for Aedes immatures. This additional procedure was associated with reduced temporal larval indices as well as an 83% reduction in reported cases during the transmission season over the 8-year period of implementation. Two cities adjacent to Makassar experienced substantial but smaller reductions in dengue incidence; while other cities further from the intervention area did not. This represents the first time an integrated intervention strategy has been coupled with substantially reduced dengue transmission in Indonesia.
Collapse
Affiliation(s)
- Isra Wahid
- Faculty of Medicine, Universitas Hasanuddin, Makassar, Indonesia
| | - Hasanuddin Ishak
- Faculty of Public Health, Universitas Hasanuddin, Makassar, Indonesia
| | | | | | | | | | | | - Rusdyah Sudirman
- Faculty of Medicine, Universitas Hasanuddin, Makassar, Indonesia
| | - Hajar Hasan
- Faculty of Medicine, Universitas Hasanuddin, Makassar, Indonesia
| | - Muhammad Yusuf
- Faculty of Medicine, Universitas Hasanuddin, Makassar, Indonesia
| | - Imam Bachtiar
- Faculty of Medicine, Universitas Hasanuddin, Makassar, Indonesia
| | - William A. Hawley
- Centers for Disease Control and Prevention, Atlanta, GA, United States of America
- Unicef, Jakarta, Indonesia
| | - Ronald Rosenberg
- Centers for Disease Control and Prevention, Fort Collins, CO, United States of America
| | - Neil F. Lobo
- Eck Institute for Global Health, University of Notre Dame, Notre Dame, Indiana, United States of America
| |
Collapse
|
10
|
Detailed ecological associations of triatomines revealed by metabarcoding and next-generation sequencing: implications for triatomine behavior and Trypanosoma cruzi transmission cycles. Sci Rep 2018. [PMID: 29515202 PMCID: PMC5841364 DOI: 10.1038/s41598-018-22455-x] [Citation(s) in RCA: 78] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Trypanosoma cruzi is the agent of Chagas disease, transmitted by hematophagous triatomine vectors. Establishing transmission cycles is key to understand the epidemiology of the disease, but integrative assessments of ecological interactions shaping parasite transmission are still limited. Current approaches also lack sensitivity to assess the full extent of this ecological diversity. Here we developed a metabarcoding approach based on next-generation sequencing to identify triatomine gut microbiome, vertebrate feeding hosts, and parasite diversity and their potential interactions. We detected a dynamic microbiome in Triatoma dimidiata, including 23 bacterial orders, which differed according to blood sources. Fourteen vertebrate species served as blood sources, corresponding to domestic, synantropic and sylvatic species, although four (human, dog, cow and mice) accounted for over 50% of blood sources. Importantly, bugs fed on multiple hosts, with up to 11 hosts identified per bug, indicating very frequent host-switching. A high clonal diversity of T. cruzi was detected, with up to 20 haplotypes per bug. This analysis provided much greater sensitivity to detect multiple blood meals and multiclonal infections with T. cruzi, which should be taken into account to develop transmission networks, and characterize the risk for human infection, eventually leading to a better control of disease transmission.
Collapse
|
11
|
Flores-Ferrer A, Marcou O, Waleckx E, Dumonteil E, Gourbière S. Evolutionary ecology of Chagas disease; what do we know and what do we need? Evol Appl 2017; 11:470-487. [PMID: 29636800 PMCID: PMC5891055 DOI: 10.1111/eva.12582] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Accepted: 11/19/2017] [Indexed: 01/02/2023] Open
Abstract
The aetiological agent of Chagas disease, Trypanosoma cruzi, is a key human pathogen afflicting most populations of Latin America. This vectorborne parasite is transmitted by haematophageous triatomines, whose control by large‐scale insecticide spraying has been the main strategy to limit the impact of the disease for over 25 years. While those international initiatives have been successful in highly endemic areas, this systematic approach is now challenged by the emergence of insecticide resistance and by its low efficacy in controlling species that are only partially adapted to human habitat. In this contribution, we review evidences that Chagas disease control shall now be entering a second stage that will rely on a better understanding of triatomines adaptive potential, which requires promoting microevolutionary studies and –omic approaches. Concomitantly, we show that our knowledge of the determinants of the evolution of T. cruzi high diversity and low virulence remains too limiting to design evolution‐proof strategies, while such attributes may be part of the future of Chagas disease control after the 2020 WHO's target of regional elimination of intradomiciliary transmission has been reached. We should then aim at developing a theory of T. cruzi virulence evolution that we anticipate to provide an interesting enrichment of the general theory according to the specificities of transmission of this very generalist stercorarian trypanosome. We stress that many ecological data required to better understand selective pressures acting on vector and parasite populations are already available as they have been meticulously accumulated in the last century of field research. Although more specific information will surely be needed, an effective research strategy would be to integrate data into the conceptual and theoretical framework of evolutionary ecology and life‐history evolution that provide the quantitative backgrounds necessary to understand and possibly anticipate adaptive responses to public health interventions.
Collapse
Affiliation(s)
- Alheli Flores-Ferrer
- UMR 228, ESPACE-DEV-IMAGES, 'Institut de Modélisation et d'Analyses en Géo-Environnement et Santé'Université de Perpignan Via Domitia Perpignan France.,UMR 5096 'Laboratoire Génome et Développement des Plantes' Université de Perpignan Via Domitia Perpignan France
| | - Olivier Marcou
- UMR 228, ESPACE-DEV-IMAGES, 'Institut de Modélisation et d'Analyses en Géo-Environnement et Santé'Université de Perpignan Via Domitia Perpignan France
| | - Etienne Waleckx
- Laboratorio de Parasitología, Centro de Investigaciones Regionales "Dr. Hideyo Noguchi" Universidad Autónoma de Yucatán Mérida Mexico
| | - Eric Dumonteil
- Department of Tropical Medicine School of Public Health and Tropical Medicine Tulane University New Orleans LA USA
| | - Sébastien Gourbière
- UMR 228, ESPACE-DEV-IMAGES, 'Institut de Modélisation et d'Analyses en Géo-Environnement et Santé'Université de Perpignan Via Domitia Perpignan France.,UMR 5096 'Laboratoire Génome et Développement des Plantes' Université de Perpignan Via Domitia Perpignan France
| |
Collapse
|
12
|
Lana RM, Riback TIS, Lima TFM, da Silva-Nunes M, Cruz OG, Oliveira FGS, Moresco GG, Honório NA, Codeço CT. Socioeconomic and demographic characterization of an endemic malaria region in Brazil by multiple correspondence analysis. Malar J 2017; 16:397. [PMID: 28969634 PMCID: PMC5625626 DOI: 10.1186/s12936-017-2045-z] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Accepted: 09/23/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND In the process of geographical retraction of malaria, some important endemicity pockets remain. Here, we report results from a study developed to obtain detailed community data from an important malaria hotspot in Latin America (Alto Juruá, Acre, Brazil), to investigate the association of malaria with socioeconomic, demographic and living conditions. METHODS A household survey was conducted in 40 localities (n = 520) of Mâncio Lima and Rodrigues Alves municipalities, Acre state. Information on previous malaria, schooling, age, gender, income, occupation, household structure, habits and behaviors related to malaria exposure was collected. Multiple correspondence analysis (MCA) was applied to characterize similarities between households and identify gradients. The association of these gradients with malaria was assessed using regression. RESULTS The first three dimensions of MCA accounted for almost 50% of the variability between households. The first dimension defined an urban/rurality gradient, where urbanization was associated with the presence of roads, basic services as garbage collection, water treatment, power grid energy, and less contact with the forest. There is a significant association between this axis and the probability of malaria at the household level, OR = 1.92 (1.23-3.02). The second dimension described a gradient from rural settlements in agricultural areas to those in forested areas. Access via dirt road or river, access to electricity power-grid services and aquaculture were important variables. Malaria was at lower risk at the forested area, OR = 0.55 (1.23-1.12). The third axis detected intraurban differences and did not correlate with malaria. CONCLUSIONS Living conditions in the study area are strongly geographically structured. Although malaria is found throughout all the landscapes, household traits can explain part of the variation found in the odds of having malaria. It is expected these results stimulate further discussions on modelling approaches targeting a more systemic and multi-level view of malaria dynamics.
Collapse
Affiliation(s)
- Raquel M Lana
- Programa de Pós-Graduação em Epidemilogia em Saúde Pública, Escola Nacional de Saúde Pública Sérgio Arouca, Fundação Oswaldo Cruz, Rua Leopoldo Bulhões, 1480, Manguinhos, Rio de Janeiro, RJ, 21041-210, Brazil. .,Programa de Computação Científica, Fundação Oswaldo Cruz, Residência Oficial, Avenida Brasil, 4365, Manguinhos, Rio de Janeiro, RJ, 21040-360, Brazil.
| | - Thais I S Riback
- Programa de Computação Científica, Fundação Oswaldo Cruz, Residência Oficial, Avenida Brasil, 4365, Manguinhos, Rio de Janeiro, RJ, 21040-360, Brazil
| | - Tiago F M Lima
- Laboratório de Engenharia e Desenvolvimento de Sistemas, Departamento de Computação e Sistemas, Instituto de Ciências Exatas e Aplicadas, Universidade Federal de Ouro Preto., Rua 36, n. 115, Loanda, João Monlevade, MG, 35931-008, Brazil
| | - Mônica da Silva-Nunes
- Centro de Ciências da Saúde, Universidade Federal do Acre, Campus Universitário-BR 364, km 4-Distrito Industrial, Rio Branco, AC, 69920-900, Brazil
| | - Oswaldo G Cruz
- Programa de Computação Científica, Fundação Oswaldo Cruz, Residência Oficial, Avenida Brasil, 4365, Manguinhos, Rio de Janeiro, RJ, 21040-360, Brazil
| | - Francisco G S Oliveira
- Campus Cruzeiro do Sul, Universidade Federal do Acre, Estrada do Canela Fina, s/n, Cruzeiro do Sul, AC, 69980-000, Brazil
| | - Gilberto G Moresco
- Coordenação Geral dos Programas Nacionais de Controle e Prevenção da Malária e das Doenças transmitidas pelo Aedes, Departamento de Vigilância das Doenças Transmissíveis, Secretaria de Vigilância em Saúde-Ministério da Saúde, SRTV 702, Via W 5 Norte, Ed. PO700-6 andar, Brasília, DF, 70723-040, Brazil
| | - Nildimar A Honório
- Laboratório de Mosquitos Transmissores de Hematozoários-Lathema, Instituto Oswaldo Cruz, FIOCRUZ, Avenida Brasil, 4365, Manguinhos, Rio de Janeiro, RJ, 21040-360, Brazil.,Núcleo Operacional Sentinela de Mosquitos Vetores-Nosmove/FIOCRUZ, Avenida Brasil, 4365, Manguinhos, Rio de Janeiro, RJ, 21040-360, Brazil
| | - Cláudia T Codeço
- Programa de Computação Científica, Fundação Oswaldo Cruz, Residência Oficial, Avenida Brasil, 4365, Manguinhos, Rio de Janeiro, RJ, 21040-360, Brazil
| |
Collapse
|
13
|
Assan B, Nyabadza F, Landi P, Hui C. Modeling the transmission of Buruli ulcer in fluctuating environments. INT J BIOMATH 2017. [DOI: 10.1142/s1793524517500632] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The transmission dynamics of Buruli ulcer (BU) largely depends on environmental changes. In this paper a deterministic model for the transmission of BU in fluctuating environments is proposed. The model incorporates periodicity in the disease transmission pathways and the Mycobacterium ulcerans density that are thought to vary seasonally. Two reproduction numbers, the time-averaged reproduction number [Formula: see text] and the basic reproduction number [Formula: see text], are determined and compared. It is shown that the time-averaged reproduction underestimates the number of infections. Numerical simulations confirmed that if [Formula: see text] the infection is sustained seasonally. The model outcome suggests that environmental fluctuations should be taken into consideration in designing policies aimed at BU control and management.
Collapse
Affiliation(s)
- Belthasara Assan
- Department of Mathematical Sciences, Stellenbosch University, Private Bag X1, Matieland, Cape Town 7602, South Africa
| | - Farai Nyabadza
- Department of Mathematical Sciences, Stellenbosch University, Private Bag X1, Matieland, Cape Town 7602, South Africa
| | - Pietro Landi
- Department of Mathematical Sciences, Stellenbosch University, Private Bag X1, Matieland, Cape Town 7602, South Africa
| | - Cang Hui
- Department of Mathematical Sciences, Stellenbosch University, Private Bag X1, Matieland, Cape Town 7602, South Africa
- African Institute for Mathematical Sciences (AIMS), Cape Town 7945, South Africa
| |
Collapse
|
14
|
Tomasini N, Ragone PG, Gourbière S, Aparicio JP, Diosque P. Epidemiological modeling of Trypanosoma cruzi: Low stercorarian transmission and failure of host adaptive immunity explain the frequency of mixed infections in humans. PLoS Comput Biol 2017; 13:e1005532. [PMID: 28481887 PMCID: PMC5440054 DOI: 10.1371/journal.pcbi.1005532] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 05/22/2017] [Accepted: 04/24/2017] [Indexed: 01/27/2023] Open
Abstract
People living in areas with active vector-borne transmission of Chagas disease have multiple contacts with its causative agent, Trypanosoma cruzi. Reinfections by T. cruzi are possible at least in animal models leading to lower or even hardly detectable parasitaemia. In humans, although reinfections are thought to have major public health implications by increasing the risk of chronic manifestations of the disease, there is little quantitative knowledge about their frequency and the timing of parasite re-inoculation in the course of the disease. Here, we implemented stochastic agent-based models i) to estimate the rate of re-inoculation in humans and ii) to assess how frequent are reinfections during the acute and chronic stages of the disease according to alternative hypotheses on the adaptive immune response following a primary infection. By using a hybrid genetic algorithm, the models were fitted to epidemiological data of Argentinean rural villages where mixed infections by different genotypes of T. cruzi reach 56% in humans. To explain this percentage, the best model predicted 0.032 (0.008-0.042) annual reinfections per individual with 98.4% of them occurring in the chronic phase. In addition, the parasite escapes to the adaptive immune response mounted after the primary infection in at least 20% of the events of re-inoculation. With these low annual rates, the risks of reinfection during the typically long chronic stage of the disease stand around 14% (4%-18%) and 60% (21%-70%) after 5 and 30 years, with most individuals being re-infected 1-3 times overall. These low rates are better explained by the weak efficiency of the stercorarian mode of transmission than a highly efficient adaptive immune response. Those estimates are of particular interest for vaccine development and for our understanding of the higher risk of chronic disease manifestations suffered by infected people living in endemic areas.
Collapse
Affiliation(s)
- Nicolás Tomasini
- Instituto de Patología Experimental, Facultad de Ciencias de la Salud, CONICET, Universidad Nacional de Salta, Salta, Argentina
| | - Paula Gabriela Ragone
- Instituto de Patología Experimental, Facultad de Ciencias de la Salud, CONICET, Universidad Nacional de Salta, Salta, Argentina
| | - Sébastien Gourbière
- UMR 228 ESPACE-DEV-IMAGES, ‘Institut de Modélisation et d'Analyses en Géo-Environnement et Santé’, Université de Perpignan Via Domitia, Perpignan, France
| | - Juan Pablo Aparicio
- Instituto de Investigaciones en Energía no Convencional, CONICET, Universidad Nacional de Salta, Salta, Argentina
| | - Patricio Diosque
- Instituto de Patología Experimental, Facultad de Ciencias de la Salud, CONICET, Universidad Nacional de Salta, Salta, Argentina
| |
Collapse
|
15
|
Modeling Chagas disease in Chile: From vector to congenital transmission. Biosystems 2017; 156-157:63-71. [PMID: 28435013 DOI: 10.1016/j.biosystems.2017.04.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 03/27/2017] [Accepted: 04/14/2017] [Indexed: 11/30/2022]
Abstract
Chagaś disease is a human health problem in Latin America. It is highly prevalent in northern Chile between the Arica-Parinacota and Coquimbo regions, with reported incidence of 3-11/100000 inhabitants and mortality of 0.3-0.4/100000. The interruption of vector transmission was reported in 1999 by means of the elimination of the primary vector, Triatoma infestans, from human dwellings, thus the epidemiologic dynamics of this disease should be modified. Here we model the dynamics of Chagaś disease based on previous models for vector and congenital transmission, propose a model that includes both transmission forms and perform simulations. We derive useful relationships for the reproductive number (R0) showing that it may be expressed as the sum of the vector (R0V) and congenital (R0C) contributions. The vector contribution is larger than the congenital one; without the former Chagaś disease vanishes exponentially in two to three generations. Sensitivity analyses showed that the main parameters that intervene are the human bite rate, the density of vectors per human and the mortality rate of the insect vectors. Our model showed that the success of the eradication of Chagaś disease is based on the interruption of domestic transmission. Once this is obtained, the control strategies should focus on avoiding the domiciliation of wild vectors, re-colonization by the primary vector, and an adequate coverage of congenital case treatment.
Collapse
|
16
|
Mesk M, Mahdjoub T, Gourbière S, Rabinovich JE, Menu F. Invasion speeds of Triatoma dimidiata, vector of Chagas disease: An application of orthogonal polynomials method. J Theor Biol 2016; 395:126-143. [PMID: 26807809 DOI: 10.1016/j.jtbi.2016.01.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 12/12/2015] [Accepted: 01/06/2016] [Indexed: 11/18/2022]
Abstract
Demographic processes and spatial dispersal of Triatoma dimidiata, a triatomine species vector of Chagas disease, are modeled by integrodifference equations to estimate invasion capacity of this species under different ecological conditions. The application of the theory of orthogonal polynomials and the steepest descent method applied to these equations, allow a good approximation of the abundance of the adult female population and the invasion speed. We show that: (1) under the same mean conditions of demography and dispersal, periodic spatial dispersal results in an invasion speed 2.5 times larger than the invasion speed when spatial dispersal is continuous; (2) when the invasion speed of periodic spatial dispersal is correlated to adverse demographic conditions, it is 34.7% higher as compared to a periodic dispersal that is correlated to good demographic conditions. From our results we conclude, in terms of triatomine population control, that the invasive success of T. dimidiata may be most sensitive to the probability of transition from juvenile to adult stage. We discuss our main theoretical predictions in the light of observed data in different triatomines species found in the literature.
Collapse
Affiliation(s)
- Mohammed Mesk
- Laboratoire d'Analyse Non Linéaire et Mathématiques Appliquées, Université de Tlemcen, BP 119 Imama (Pôle2), Tlemcen 13000, Algeria.
| | - Tewfik Mahdjoub
- Laboratoire d'Analyse Non Linéaire et Mathématiques Appliquées, Université de Tlemcen, BP 119 Imama (Pôle2), Tlemcen 13000, Algeria.
| | - Sébastien Gourbière
- Université de Perpignan Via Domitia, EA 4218 ׳Institut de Modélisation et d׳Analyse en Géo-Environnements et Santé' (IMAGES), Perpignan 66100, France.
| | - Jorge E Rabinovich
- Centro de Estudios Parasitológicos y de Vectores, Universidad Nacional de La Plata, La Plata, Provincia de Buenos Aires, Argentina.
| | - Frédéric Menu
- Laboratoire de Biométrie et Biologie Evolutive (UMR 5558), Université de Lyon, Université Lyon 1, UMR CNRS 5558, 43 Bd du 11 Novembre 1918, 69 622 Villeurbanne Cedex, France.
| |
Collapse
|
17
|
Péneau J, Nguyen A, Flores-Ferrer A, Blanchet D, Gourbière S. Amazonian Triatomine Biodiversity and the Transmission of Chagas Disease in French Guiana: In Medio Stat Sanitas. PLoS Negl Trop Dis 2016; 10:e0004427. [PMID: 26867025 PMCID: PMC4750908 DOI: 10.1371/journal.pntd.0004427] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Accepted: 01/12/2016] [Indexed: 12/22/2022] Open
Abstract
The effects of biodiversity on the transmission of infectious diseases now stand as a cornerstone of many public health policies. The upper Amazonia and Guyana shield are hot-spots of biodiversity that offer genuine opportunities to explore the relationship between the risk of transmission of Chagas disease and the diversity of its triatomine vectors. Over 730 triatomines were light-trapped in four geomorphological landscapes shaping French-Guiana, and we determined their taxonomic status and infection by Trypanosoma cruzi. We used a model selection approach to unravel the spatial and temporal variations in species abundance, diversity and infection. The vector community in French-Guiana is typically made of one key species (Panstrongylus geniculatus) that is more abundant than three secondary species combined (Rhodnius pictipes, Panstrongylus lignarius and Eratyrus mucronatus), and four other species that complete the assemblage. Although the overall abundance of adult triatomines does not vary across French-Guiana, their diversity increases along a coastal-inland gradient. These variations unravelled a non-monotonic relationship between vector biodiversity and the risk of transmission of Chagas disease, so that intermediate biodiversity levels are associated with the lowest risks. We also observed biannual variations in triatomine abundance, representing the first report of a biannual pattern in the risk of Chagas disease transmission. Those variations were highly and negatively correlated with the average monthly rainfall. We discuss the implications of these patterns for the transmission of T. cruzi by assemblages of triatomine species, and for the dual challenge of controlling Amazonian vector communities that are made of both highly diverse and mostly intrusive species.
Collapse
Affiliation(s)
- Julie Péneau
- UMR 228 ESPACE-DEV-IMAGES, ‘Institut de Modélisation et d'Analyses en Géo-Environnement et Santé’, Université de Perpignan Via Domitia, Perpignan, France
- Laboratoire de Parasitologie-Mycologie, Centre Hospitalier de Cayenne and Faculté de Médecine, Equipe « Ecosystèmes Amazoniens et Pathologie Tropicale » (EA3593), Université de Antilles et de la Guyane, Cayenne, French Guiana
| | - Anne Nguyen
- UMR 228 ESPACE-DEV-IMAGES, ‘Institut de Modélisation et d'Analyses en Géo-Environnement et Santé’, Université de Perpignan Via Domitia, Perpignan, France
| | - Alheli Flores-Ferrer
- UMR 228 ESPACE-DEV-IMAGES, ‘Institut de Modélisation et d'Analyses en Géo-Environnement et Santé’, Université de Perpignan Via Domitia, Perpignan, France
| | - Denis Blanchet
- Laboratoire de Parasitologie-Mycologie, Centre Hospitalier de Cayenne and Faculté de Médecine, Equipe « Ecosystèmes Amazoniens et Pathologie Tropicale » (EA3593), Université de Antilles et de la Guyane, Cayenne, French Guiana
| | - Sébastien Gourbière
- UMR 228 ESPACE-DEV-IMAGES, ‘Institut de Modélisation et d'Analyses en Géo-Environnement et Santé’, Université de Perpignan Via Domitia, Perpignan, France
| |
Collapse
|
18
|
Breyta R, McKenney D, Tesfaye T, Ono K, Kurath G. Increasing virulence, but not infectivity, associated with serially emergent virus strains of a fish rhabdovirus. Virus Evol 2016; 2:vev018. [PMID: 27774291 PMCID: PMC4989874 DOI: 10.1093/ve/vev018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Surveillance and genetic typing of field isolates of a fish rhabdovirus, infectious hematopoietic necrosis virus (IHNV), has identified four dominant viral genotypes that were involved in serial viral emergence and displacement events in steelhead trout (Oncorhynchus mykiss) in western North America. To investigate drivers of these landscape-scale events, IHNV isolates designated 007, 111, 110, and 139, representing the four relevant genotypes, were compared for virulence and infectivity in controlled laboratory challenge studies in five relevant steelhead trout populations. Viral virulence was assessed as mortality using lethal dose estimates (LD50), survival kinetics, and proportional hazards analysis. A pattern of increasing virulence for isolates 007, 111, and 110 was consistent in all five host populations tested, and correlated with serial emergence and displacements in the virus-endemic lower Columbia River source region during 1980-2013. The fourth isolate, 139, did not have higher virulence than the previous isolate 110. However, the mG139M genotype displayed a conditional displacement phenotype in that it displaced type mG110M in coastal Washington, but not in the lower Columbia River region, indicating that factors other than evolution of higher viral virulence were involved in some displacement events. Viral infectivity, measured as infectious dose (ID50), did not correlate consistently with virulence or with viral emergence, and showed a narrow range of variation relative to the variation observed in virulence. Comparison among the five steelhead trout populations confirmed variation in resistance to IHNV, but correlations with previous history of virus exposure or with sites of viral emergence varied between IHNV source and sink regions. Overall, this study indicated increasing viral virulence over time as a potential driver for emergence and displacement events in the endemic Lower Columbia River source region where these IHNV genotypes originated, but not in adjacent sink regions.
Collapse
Affiliation(s)
- Rachel Breyta
- US Geological Survey, Western Fisheries Research Center, 6505 NE 65th St., Seattle, WA 98115 and; School of Aquatic and Fishery Sciences, University of Washington, 1122 NE Boat St., Seattle, WA 98105, USA
| | - Doug McKenney
- US Geological Survey, Western Fisheries Research Center, 6505 NE 65th St., Seattle, WA 98115 and
| | - Tarin Tesfaye
- US Geological Survey, Western Fisheries Research Center, 6505 NE 65th St., Seattle, WA 98115 and
| | - Kotaro Ono
- School of Aquatic and Fishery Sciences, University of Washington, 1122 NE Boat St., Seattle, WA 98105, USA
| | - Gael Kurath
- US Geological Survey, Western Fisheries Research Center, 6505 NE 65th St., Seattle, WA 98115 and
| |
Collapse
|
19
|
de la Escosura-Muñiz A, Baptista-Pires L, Serrano L, Altet L, Francino O, Sánchez A, Merkoçi A. Magnetic Bead/Gold Nanoparticle Double-Labeled Primers for Electrochemical Detection of Isothermal Amplified Leishmania DNA. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2016; 12:205-213. [PMID: 26578391 DOI: 10.1002/smll.201502350] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Revised: 09/26/2015] [Indexed: 06/05/2023]
Abstract
A novel methodology for the isothermal amplification of Leishmania DNA using labeled primers combined with the advantages of magnetic purification/preconcentration and the use of gold nanoparticle (AuNP) tags for the sensitive electrochemical detection of such amplified DNA is developed. Primers labeled with AuNPs and magnetic beads (MBs) are used for the first time for the isothermal amplification reaction, being the amplified product ready for the electrochemical detection. The electrocatalytic activity of the AuNP tags toward the hydrogen evolution reaction allows the rapid quantification of the DNA on screen-printed carbon electrodes. Amplified products from the blood of dogs with Leishmania (positive samples) are discriminated from those of healthy dogs (blank samples). Quantitative studies demonstrate that the optimized method allows us to detect less than one parasite per microliter of blood (8 × 10(-3) parasites in the isothermal amplification reaction). This pioneering approach is much more sensitive than traditional methods based on real-time polymerase chain reaction (PCR), and is also more rapid, cheap, and user-friendly.
Collapse
Affiliation(s)
- Alfredo de la Escosura-Muñiz
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and Barcelona Institute of Science and Technology, Campus UAB, 08193, Barcelona, Spain
| | - Luis Baptista-Pires
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and Barcelona Institute of Science and Technology, Campus UAB, 08193, Barcelona, Spain
| | - Lorena Serrano
- Vetgenomics, Edifici Eureka, Parc de Recerca UAB, 08193, Bellaterra (Barcelona), Spain
| | - Laura Altet
- Vetgenomics, Edifici Eureka, Parc de Recerca UAB, 08193, Bellaterra (Barcelona), Spain
| | - Olga Francino
- Vetgenomics, Edifici Eureka, Parc de Recerca UAB, 08193, Bellaterra (Barcelona), Spain
- Department of Animal and Food Science, Autonomous University of Barcelona, Campus UAB, 08193, Bellaterra (Barcelona), Spain
| | - Armand Sánchez
- Department of Animal and Food Science, Autonomous University of Barcelona, Campus UAB, 08193, Bellaterra (Barcelona), Spain
- Centre for Research in Agricultural Genomics-CSIC-IRTA-UAB-UB, Campus UAB, 08193, Cerdanyola del Valles, Catalonia, Spain
| | - Arben Merkoçi
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and Barcelona Institute of Science and Technology, Campus UAB, 08193, Barcelona, Spain
- ICREA-Institucio Catalana de Recerca i Estudis Avançats, 08010, Barcelona, Spain
| |
Collapse
|
20
|
Ramirez-Sierra MJ, Dumonteil E. Infection Rate by Trypanosoma cruzi and Biased Vertebrate Host Selection in the Triatoma dimidiata (Hemiptera: Reduvidae) Species Complex. JOURNAL OF MEDICAL ENTOMOLOGY 2016; 53:20-25. [PMID: 26474882 DOI: 10.1093/jme/tjv157] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Accepted: 09/17/2015] [Indexed: 06/05/2023]
Abstract
Chagas disease is a vector-borne disease, caused by the protozoan parasite Trypanosoma cruzi and transmitted by hematophagous insects. Triatoma dimidiata (Hemiptera: Reduvidae (Latreille 1811)) is one of the main vectors, and recent molecular studies indicate that it is a species complex, with potentially different vectorial competences. We investigated the differences in natural T. cruzi infection rate within T. dimidiata complex in Yucatan, Mexico. ITS-2 hybrid bugs had a twofold higher infection rate than ITS-2 Groups 2 and 3 bugs, and this pattern was consistent over time and in several villages. To test if T. dimidiata ITS-2 hybrid bugs could feed more frequently on T. cruzi-infected hosts, we evaluated their host-seeking behavior in a dual-choice chamber. Group 2 and 3 bugs were equally attracted to T. cruzi-infected or uninfected mice. On the contrary, ITS-2 hybrid bugs reached three times more frequently the T. cruzi-infected mouse, compared to the uninfected one, indicating a significant bias toward an infected host. This behavior may explain in part their higher natural infection rate. Further studies should explore the complex and unique interactions among T. cruzi, triatomines vectors, and mammalian hosts, as this may led to new strategies to interfere with transmission cycles and improve Chagas disease control.
Collapse
Affiliation(s)
- M J Ramirez-Sierra
- Laboratorio de Parasitología, Centro de Investigaciones Regionales ''Dr. Hideyo Noguchi'', Universidad Autónoma de Yucatán, 97000 Mérida, Yucatán, México
| | - E Dumonteil
- Laboratorio de Parasitología, Centro de Investigaciones Regionales ''Dr. Hideyo Noguchi'', Universidad Autónoma de Yucatán, 97000 Mérida, Yucatán, México , Department of Tropical Medicine, School of Public Health and Tropical Medicine, Tulane University, 70112, New Orleans, LA, and
| |
Collapse
|
21
|
Nyabadza F, Bonyah E. On the transmission dynamics of Buruli ulcer in Ghana: Insights through a mathematical model. BMC Res Notes 2015; 8:656. [PMID: 26545356 PMCID: PMC4636839 DOI: 10.1186/s13104-015-1619-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Accepted: 10/26/2015] [Indexed: 04/29/2023] Open
Abstract
Background Mycobacterium ulcerans is know to cause the Buruli ulcer. The association between the ulcer and environmental exposure has been documented. However, the epidemiology of the ulcer is not well understood. A hypothesised transmission involves humans being bitten by the water bugs that prey on mollusks, snails and young fishes. Methods In this paper, a model for the transmission of Mycobacterium ulcerans to humans in the presence of a preventive strategy is proposed and analysed. The model equilibria are determined and conditions for the existence of the equilibria established. The model analysis is carried out in terms of the reproduction number \documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$\mathcal{R}_0$$\end{document}R0. The disease free equilibrium is found to be locally asymptotically stable for \documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$\mathcal{R}_0<1.$$\end{document}R0<1. The model is fitted to data from Ghana. Results The model is found to exhibit a backward
bifurcation and the endemic equilibrium point is globally stable when \documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$\mathcal{R}_0>1.$$\end{document}R0>1. Sensitivity analysis showed that the Buruli ulcer epidemic is highly influenced by the shedding and clearance rates of Mycobacterium ulcerans in the environment. The model is found to fit reasonably well to data from Ghana and projections on the future of the Buruli ulcer epidemic are also made. Conclusions The model reasonably fitted data from Ghana. The fitting process showed data that appeared to have reached a steady state and projections showed that the epidemic levels will remain the same for the projected time. The implications of the results to policy and future management of the disease are discussed.
Collapse
Affiliation(s)
- Farai Nyabadza
- Department of Mathematical Sciences, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa.
| | - Ebenezer Bonyah
- Department of Mathematics and Statistics, Kumasi Polytechnic, P. O. Box 854, Kumasi, Ghana.
| |
Collapse
|
22
|
Berger R, Wasserberg G, Warburg A, Orshan L, Kotler BP. Zoonotic disease in a peripheral population: persistence and transmission of Leishmania major in a putative sink-source system in the Negev Highlands, Israel. Vector Borne Zoonotic Dis 2015; 14:592-600. [PMID: 25072990 DOI: 10.1089/vbz.2013.1535] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Populations at the edge of their geographic distributions are referred to as peripheral populations. Very little attention has been given to this topic in the context of persistence of infectious disease in natural populations. In this study, we examined this question using zoonotic cutaneous leishmaniasis (ZCL) caused by Leishmania major in the Negev Desert of Israel as a model system. Here, we suggest that the regional persistence of Phlebotomus papatasi populations and L. major transmission in the Sede Boqer region could be explained through processes akin to sink-source and/or mainland-island metapopulation dynamics. Given its potentially enzootically superior ecological conditions, we hypothesize that the Zin Valley ecotope constitutes the "mainland" or the "source" patch for the Sede Boqer area where L. major transmission is persistent and resistant to local extinctions (die-outs) whereas the local sand fly populations on the Zin Plateau ("island patch" or "sink patch") are more prone to local extinctions. Between 2007 and 2008, we trapped sand flies and sand rats in the two areas and compared sand fly abundance and L. major infection prevalence in both. In both 2007 and 2008, sand fly abundance was high and continuous in the Zin Wadi but low and discontinuous in the Zin Plateau. Infection prevalence of sand rats was significantly higher in the Wadi (13%) compared with the Zin Plateau (3%). Minimum infection rate in sand flies did not differ significantly between the two areas. Overall, our results are consistent with the premise that the Zin Valley population is relatively robust in terms of L. major transmission, whereas transmission is potentially more tenuous in the plateau. Understanding the biotic and abiotic processes enabling the persistence of L. major and other vector-borne diseases in peripheral disease foci is important for predicting the effect of anthropogenic land use and climate change.
Collapse
Affiliation(s)
- Ruti Berger
- 1 Mitrani Department of Desert Ecology, Jacob Blaustein Institute for Desert Research, Ben-Gurion University of the Negev , Midreshet Ben-Gurion, Israel
| | | | | | | | | |
Collapse
|
23
|
Waleckx E, Gourbière S, Dumonteil E. Intrusive versus domiciliated triatomines and the challenge of adapting vector control practices against Chagas disease. Mem Inst Oswaldo Cruz 2015; 110:324-38. [PMID: 25993504 PMCID: PMC4489470 DOI: 10.1590/0074-02760140409] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Accepted: 03/09/2015] [Indexed: 11/22/2022] Open
Abstract
Chagas disease prevention remains mostly based on triatomine vector control to reduce or eliminate house infestation with these bugs. The level of adaptation of triatomines to human housing is a key part of vector competence and needs to be precisely evaluated to allow for the design of effective vector control strategies. In this review, we examine how the domiciliation/intrusion level of different triatomine species/populations has been defined and measured and discuss how these concepts may be improved for a better understanding of their ecology and evolution, as well as for the design of more effective control strategies against a large variety of triatomine species. We suggest that a major limitation of current criteria for classifying triatomines into sylvatic, intrusive, domiciliary and domestic species is that these are essentially qualitative and do not rely on quantitative variables measuring population sustainability and fitness in their different habitats. However, such assessments may be derived from further analysis and modelling of field data. Such approaches can shed new light on the domiciliation process of triatomines and may represent a key tool for decision-making and the design of vector control interventions.
Collapse
Affiliation(s)
- Etienne Waleckx
- Laboratorio de Parasitología, Centro de Investigaciones Regionales Dr
Hideyo Noguchi, Universidad Autónoma de Yucatán, Mérida, Yucatán, Mexico
| | - Sébastien Gourbière
- Institut de Modélisation et d’Analyses en Géo-Environnement et Santé,
Université de Perpignan Via Domitia, Perpignan, France
| | - Eric Dumonteil
- Laboratorio de Parasitología, Centro de Investigaciones Regionales Dr
Hideyo Noguchi, Universidad Autónoma de Yucatán, Mérida, Yucatán, Mexico
| |
Collapse
|
24
|
Nouvellet P, Cucunubá ZM, Gourbière S. Ecology, evolution and control of Chagas disease: a century of neglected modelling and a promising future. ADVANCES IN PARASITOLOGY 2015; 87:135-91. [PMID: 25765195 DOI: 10.1016/bs.apar.2014.12.004] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
More than 100 years after its formal description, Chagas disease remains a major public health concern in Latin America with a yearly burden of 430,000 Disability-Adjusted Life Years (DALYs). The aetiological agent, a protozoan named Trypanosoma cruzi, is mainly transmitted to mammalian hosts by triatomine vectors. Multiple species of mammals and triatomines can harbour and transmit the parasite, and the feeding range of triatomine species typically includes many noncompetent hosts. Furthermore, the transmission of the pathogen can occur via several routes including the typical vector's faeces, but also oral, congenital and blood transfusion routes. These ecological and epidemiological complexities of the disease have hindered many control initiatives. In such a context, mathematical models provide invaluable tools to explore and understand the dynamics of T. cruzi transmission, and to design, optimize and monitor the efficacy of control interventions. We intend here to provide the first review of the mathematical models of Chagas disease, focussing on how they have contributed to our understanding of (1) the population dynamics and control of triatomine vectors, and (2) the epidemiology of T. cruzi infections. We also aim at suggesting promising lines of modelling that could further improve our understanding of the ecology, evolution, and control of the disease.
Collapse
Affiliation(s)
- Pierre Nouvellet
- Medical Research Council Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, Imperial College London, London, UK
| | - Zulma M Cucunubá
- Grupo de Parasitología, Instituto Nacional de Salud, Colombia; Department of Infectious Disease Epidemiology, Imperial College London, London, UK
| | - Sébastien Gourbière
- Institut de Modélisation et d'Analyse en Géo-Environnements et Santé (IMAGES), Université de Perpignan Via Domitia, Perpignan, France
| |
Collapse
|
25
|
Gourbière S, Morand S, Waxman D. Fundamental factors determining the nature of parasite aggregation in hosts. PLoS One 2015; 10:e0116893. [PMID: 25689685 PMCID: PMC4331092 DOI: 10.1371/journal.pone.0116893] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Accepted: 12/16/2014] [Indexed: 01/01/2023] Open
Abstract
The distribution of parasites in hosts is typically aggregated: a few hosts harbour many parasites, while the remainder of hosts are virtually parasite free. The origin of this almost universal pattern is central to our understanding of host-parasite interactions; it affects many facets of their ecology and evolution. Despite this, the standard statistical framework used to characterize parasite aggregation does not describe the processes generating such a pattern. In this work, we have developed a mathematical framework for the distribution of parasites in hosts, starting from a simple statistical description in terms of two fundamental processes: the exposure of hosts to parasites and the infection success of parasites. This description allows the level of aggregation of parasites in hosts to be related to the random variation in these two processes and to true host heterogeneity. We show that random variation can generate an aggregated distribution and that the common view, that encounters and success are two equivalent filters, applies to the average parasite burden under neutral assumptions but it does not apply to the variance of the parasite burden, and it is not true when heterogeneity between hosts is incorporated in the model. We find that aggregation decreases linearly with the number of encounters, but it depends non-linearly on parasite success. We also find additional terms in the variance of the parasite burden which contribute to the actual level of aggregation in specific biological systems. We have derived the formal expressions of these contributions, and these provide new opportunities to analyse empirical data and tackle the complexity of the origin of aggregation in various host-parasite associations.
Collapse
Affiliation(s)
- Sébastien Gourbière
- Université de Perpignan Via Domitia, EA 4218, ‘Institut de Modélisation et d’Analyse en Géo-Environnements et Santé’ (IMAGES), Perpignan 66100, France
- University of Sussex, School of Life Sciences, Centre for the Study of Evolution, Brighton BN1 9QG, UK
| | - Serge Morand
- Institut des Sciences de l’Evolution—CNRS, Département Génétique Environnement, CC065, Université Montpellier 2, 34095, Montpellier cedex 05, France
| | - David Waxman
- Centre for Computational Systems Biology, Fudan University, Shanghai 200433, PRC
- * E-mail:
| |
Collapse
|
26
|
Savić S, Vidić B, Grgić Z, Potkonjak A, Spasojevic L. Emerging Vector-Borne Diseases - Incidence through Vectors. Front Public Health 2014; 2:267. [PMID: 25520951 PMCID: PMC4251170 DOI: 10.3389/fpubh.2014.00267] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Accepted: 11/17/2014] [Indexed: 11/14/2022] Open
Abstract
Vector-borne diseases use to be a major public health concern only in tropical and subtropical areas, but today they are an emerging threat for the continental and developed countries also. Nowadays, in intercontinental countries, there is a struggle with emerging diseases, which have found their way to appear through vectors. Vector-borne zoonotic diseases occur when vectors, animal hosts, climate conditions, pathogens, and susceptible human population exist at the same time, at the same place. Global climate change is predicted to lead to an increase in vector-borne infectious diseases and disease outbreaks. It could affect the range and population of pathogens, host and vectors, transmission season, etc. Reliable surveillance for diseases that are most likely to emerge is required. Canine vector-borne diseases represent a complex group of diseases including anaplasmosis, babesiosis, bartonellosis, borreliosis, dirofilariosis, ehrlichiosis, and leishmaniosis. Some of these diseases cause serious clinical symptoms in dogs and some of them have a zoonotic potential with an effect to public health. It is expected from veterinarians in coordination with medical doctors to play a fundamental role at primarily prevention and then treatment of vector-borne diseases in dogs. The One Health concept has to be integrated into the struggle against emerging diseases. During a 4-year period, from 2009 to 2013, a total number of 551 dog samples were analyzed for vector-borne diseases (borreliosis, babesiosis, ehrlichiosis, anaplasmosis, dirofilariosis, and leishmaniasis) in routine laboratory work. The analysis was done by serological tests – ELISA for borreliosis, dirofilariosis, and leishmaniasis, modified Knott test for dirofilariosis, and blood smear for babesiosis, ehrlichiosis, and anaplasmosis. This number of samples represented 75% of total number of samples that were sent for analysis for different diseases in dogs. Annually, on average more then half of the samples brought to the laboratory to analysis for different infectious diseases are analyzed for vector-borne diseases. In the region of Vojvodina (northern part of Serbia), the following vector-borne infectious diseases have been found in dogs so far borreliosis, babesiosis, dirofilariosis, leishmaniasis, and anaplasmosis.
Collapse
Affiliation(s)
- Sara Savić
- Scientific Veterinary Institute , Novi Sad , Serbia
| | - Branka Vidić
- Scientific Veterinary Institute , Novi Sad , Serbia
| | | | - Aleksandar Potkonjak
- Department of Veterinary Medicine, Faculty of Agriculture, University of Novi Sad , Novi Sad , Serbia
| | - Ljubica Spasojevic
- Department of Veterinary Medicine, Faculty of Agriculture, University of Novi Sad , Novi Sad , Serbia
| |
Collapse
|
27
|
Cantas L, Suer K. Review: the important bacterial zoonoses in "one health" concept. Front Public Health 2014; 2:144. [PMID: 25353010 PMCID: PMC4196475 DOI: 10.3389/fpubh.2014.00144] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 09/01/2014] [Indexed: 01/31/2023] Open
Abstract
UNLABELLED An infectious disease that is transmitted from animals to humans, sometimes by a vector, is called zoonosis. The focus of this review article is on the most common emerging and re-emerging bacterial zoonotic diseases. The role of "One Health" approach, public health education, and some measures that can be taken to prevent zoonotic bacterial infections are discussed. KEY POINTS A zoonotic bacterial disease is a disease that can be very commonly transmitted between animals and humans. Global climate changes, overuse of antimicrobials in medicine, more intensified farm settings, and closer interactions with animals facilitate emergence or re-emergence of bacterial zoonotic infections.The global "One Health" approach, which requires interdisciplinary collaborations and communications in all aspects of health care for humans, animals, and the environment, will support public health in general.New strategies for continuous dissemination of multidisciplinary research findings related to zoonotic bacterial diseases are hence needed.
Collapse
Affiliation(s)
- Leon Cantas
- Norwegian Private Veterinary Services, MicroLab, Hammerfest, Norway
- Department of Medical Microbiology, Faculty of Medicine, Near East University, Nicosia, Cyprus
| | - Kaya Suer
- Department of Infectious Diseases and Clinical Microbiology, Faculty of Medicine, Near East University, Nicosia, Cyprus
| |
Collapse
|
28
|
A theoretical model for the transmission dynamics of the Buruli ulcer with saturated treatment. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2014; 2014:576039. [PMID: 25214885 PMCID: PMC4158283 DOI: 10.1155/2014/576039] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Revised: 08/05/2014] [Accepted: 08/06/2014] [Indexed: 11/17/2022]
Abstract
The management of the Buruli ulcer (BU) in Africa is often accompanied by limited resources, delays in treatment, and macilent capacity in medical facilities. These challenges limit the number of infected individuals that access medical facilities. While most of the mathematical models with treatment assume a treatment function proportional to the number of infected individuals, in settings with such limitations, this assumption may not be valid. To capture these challenges, a mathematical model of the Buruli ulcer with a saturated treatment function is developed and studied. The model is a coupled system of two submodels for the human population and the environment. We examine the stability of the submodels and carry out numerical simulations. The model analysis is carried out in terms of the reproduction number of the submodel of environmental dynamics. The dynamics of the human population submodel, are found to occur at the steady states of the submodel of environmental dynamics. Sensitivity analysis is carried out on the model parameters and it is observed that the BU epidemic is driven by the dynamics of the environment. The model suggests that more effort should be focused on environmental management. The paper is concluded by discussing the public implications of the results.
Collapse
|
29
|
Rascalou G, Gourbière S. Competition, virulence, host body mass and the diversification of macro-parasites. J R Soc Interface 2014; 11:20131108. [PMID: 24522783 PMCID: PMC3928941 DOI: 10.1098/rsif.2013.1108] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Accepted: 01/13/2014] [Indexed: 12/17/2022] Open
Abstract
Adaptive speciation has been much debated in recent years, with a strong emphasis on how competition can lead to the diversification of ecological and sexual traits. Surprisingly, little attention has been paid to this evolutionary process to explain intrahost diversification of parasites. We expanded the theory of competitive speciation to look at the effect of key features of the parasite lifestyle, namely fragmentation, aggregation and virulence, on the conditions and rate of sympatric speciation under the standard 'pleiotropic scenario'. The conditions for competitive speciation were found similar to those for non-parasite species, but not the rate of diversification. Adaptive evolution proceeds faster in highly fragmented parasite populations and for weakly aggregated and virulent parasites. Combining these theoretical results with standard empirical allometric relationships, we showed that parasite diversification can be faster in host species of intermediate body mass. The increase in parasite load with body mass, indeed, fuels evolution by increasing mutants production, but because of the deleterious effect of virulence, it simultaneously weakens selection for resource specialization. Those two antagonistic effects lead to optimal parasite burden and host body mass for diversification. Data on the diversity of fishes' gills parasites were found consistent with the existence of such optimum.
Collapse
Affiliation(s)
- Guilhem Rascalou
- Centre for the Study of Evolution, School of Life Sciences, University of Sussex, Brighton BN1 9QG, UK
- Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle (MIVEGEC), UMR Universités Montpellier 1 and 2, CNRS 5290, IRD 224, Montpellier, France
| | - Sébastien Gourbière
- Centre for the Study of Evolution, School of Life Sciences, University of Sussex, Brighton BN1 9QG, UK
- Université de Perpignan Via Domitia, EA 4218 Institut de Modélisation et d'Analyse en Géo-Environnements et Santé (IMAGES), Perpignan 66100, France
| |
Collapse
|
30
|
Nouvellet P, Dumonteil E, Gourbière S. The improbable transmission of Trypanosoma cruzi to human: the missing link in the dynamics and control of Chagas disease. PLoS Negl Trop Dis 2013; 7:e2505. [PMID: 24244766 PMCID: PMC3820721 DOI: 10.1371/journal.pntd.0002505] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Accepted: 09/16/2013] [Indexed: 01/13/2023] Open
Abstract
Chagas disease has a major impact on human health in Latin America and is becoming of global concern due to international migrations. Trypanosoma cruzi, the etiological agent of the disease, is one of the rare human parasites transmitted by the feces of its vector, as it is unable to reach the salivary gland of the insect. This stercorarian transmission is notoriously poorly understood, despite its crucial role in the ecology and evolution of the pathogen and the disease. The objective of this study was to quantify the probability of T. cruzi vectorial transmission to humans, and to use such an estimate to predict human prevalence from entomological data. We developed several models of T. cruzi transmission to estimate the probability of transmission from vector to host. Using datasets from the literature, we estimated the probability of transmission per contact with an infected triatomine to be 5.8 × 10(-4) (95%CI: [2.6 ; 11.0] × 10(-4)). This estimate was consistent across triatomine species, robust to variations in other parameters, and corresponded to 900-4,000 contacts per case. Our models subsequently allowed predicting human prevalence from vector abundance and infection rate in 7/10 independent datasets covering various triatomine species and epidemiological situations. This low probability of T. cruzi transmission reflected well the complex and unlikely mechanism of transmission via insect feces, and allowed predicting human prevalence from basic entomological data. Although a proof of principle study would now be valuable to validate our models' predictive ability in an even broader range of entomological and ecological settings, our quantitative estimate could allow switching the evaluation of disease risk and vector control program from purely entomological indexes to parasitological measures, as commonly done for other major vector borne diseases. This might lead to different quantitative perspectives as these indexes are well known not to be proportional one to another.
Collapse
Affiliation(s)
- Pierre Nouvellet
- Laboratorio de Parasitología, Centro de Investigaciones Regionales "Dr. Hideyo Noguchi", Universidad Autónoma de Yucatán, Mérida, Yucatán, Mexico ; EA 4218 UPVD 'Institut de Modélisation et d'Analyses en Géo-Environnement et Santé', Université de Perpignan Via Domitia, Perpignan, France ; Medical Research Council Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | | | | |
Collapse
|
31
|
Kamiabi F, Jaal Z, Keng CL. Bioefficacy of crude extract of Cyperus aromaticus (Family: Cyperaceae) cultured cells, against Aedes aegypti and Aedes albopictus mosquitoes. Asian Pac J Trop Biomed 2013; 3:767-75. [PMID: 24075340 DOI: 10.1016/s2221-1691(13)60153-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Revised: 07/08/2013] [Accepted: 08/20/2013] [Indexed: 11/24/2022] Open
Abstract
OBJECTIVE To evaluate the growth inhibition activity of the crude extract of Cyperus aromaticus (C. aromaticus) cultured cells against the 3rd instar larvae of Aedes aegypti (Linn.) and Aedes albopictus Skuse (Ae. albopictus) under laboratory conditions, and determine the sublethal effects (EI50) of the crude extract of C. aromaticus cultured cells on some biological and morphological parameters of both Aedes mosquito species during two generations as well. METHODS The cell suspension cultures of C. aromaticus were activated from five callus lines (P4, Pa, Z1, Z6 and Ml) derived from the root explants of in vitro plantlets. The cultured cells were extracted in chloroform and used as plant material for the present study. For detection of juvenile hormone III, the crude extracts were analyzed by HPLC. Then the crude extracts of the three C. aromaticus cultured cell lines which contained varied amounts of juvenile hormone III [high level (P4 cell line), medium level (Z1 cell line) and low level (Ml cell line)] were tested against Aedes mosquito species. Laboratory evaluation was performed against late third instar larvae of the Vector Control Research Unit strains of Ae. aegypti and Ae. albopictus using the standard WHO method. The effects of EI50 of the C. aromaticus cultured P4 cells on fecundity, fertility, growth period, sex ratio, adult size and longevity of Aedes mosquitoes were assessed. RESULTS Bioassay tests presented the remarkable growth inhibition activity of the crude extracts of C. aromaticus cultured cells against the two Aedes mosquitoes. Between the two mosquito species, Ae. albopictus was more susceptible to the crude extracts with lower EI50 values. EI50 of the crude extract of C. aromaticus cultured cells (P4) increased the sterility indices in the parental generation females in both Aedes mosquito species. A significant delay in the pupal formation and adult emergence were observed in the parental generation of the both mosquito species. The sex ratio of the adult population either parental or F1 generation of the Aedes mosquito species was not significantly affected by the EI50 dosage of the crude extract of C. aromaticus cultured P4 cells. A significant decrease in the wing length of the treated adult (female and male) of Aedes aegypti as well as the treated female of Ae. albopictus were observed. Longevity of the adult female of the parental generation of both Aedes mosquitoes as well as females of F1 generation of Ae. albopictus were significantly decreased. CONCLUSIONS The present study revealed the potential of the crude extract of C. aromaticus cultured cells in controlling vector mosquito populations in the effort to reduce the transmission of vector borne diseases.
Collapse
Affiliation(s)
- Fatemeh Kamiabi
- School of Biological Sciences, Universiti Sains Malaysia, Penang, Malaysia; Faculty of Health, Kerman University of Medical Sciences, Kerman, Iran.
| | | | | |
Collapse
|
32
|
Dumonteil E, Nouvellet P, Rosecrans K, Ramirez-Sierra MJ, Gamboa-León R, Cruz-Chan V, Rosado-Vallado M, Gourbière S. Eco-bio-social determinants for house infestation by non-domiciliated Triatoma dimidiata in the Yucatan Peninsula, Mexico. PLoS Negl Trop Dis 2013; 7:e2466. [PMID: 24086790 PMCID: PMC3784500 DOI: 10.1371/journal.pntd.0002466] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Accepted: 08/23/2013] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Chagas disease is a vector-borne disease of major importance in the Americas. Disease prevention is mostly limited to vector control. Integrated interventions targeting ecological, biological and social determinants of vector-borne diseases are increasingly used for improved control. METHODOLOGY/PRINCIPAL FINDINGS We investigated key factors associated with transient house infestation by T. dimidiata in rural villages in Yucatan, Mexico, using a mixed modeling approach based on initial null-hypothesis testing followed by multimodel inference and averaging on data from 308 houses from three villages. We found that the presence of dogs, chickens and potential refuges, such as rock piles, in the peridomicile as well as the proximity of houses to vegetation at the periphery of the village and to public light sources are major risk factors for infestation. These factors explain most of the intra-village variations in infestation. CONCLUSIONS/SIGNIFICANCE These results underline a process of infestation distinct from that of domiciliated triatomines and may be used for risk stratification of houses for both vector surveillance and control. Combined integrated vector interventions, informed by an Ecohealth perspective, should aim at targeting several of these factors to effectively reduce infestation and provide sustainable vector control.
Collapse
Affiliation(s)
- Eric Dumonteil
- Laboratorio de Parasitología, Centro de Investigaciones Regionales “Dr. Hideyo Noguchi”, Universidad Autónoma de Yucatán, Mérida, Yucatán, Mexico
- Department of Tropical Medicine, School of Public Health and Tropical Medicine, Tulane University, New Orleans, Louisiana, United States of America
- * E-mail:
| | - Pierre Nouvellet
- Laboratorio de Parasitología, Centro de Investigaciones Regionales “Dr. Hideyo Noguchi”, Universidad Autónoma de Yucatán, Mérida, Yucatán, Mexico
- UMR 5244 CNRS-UPVD ‘Ecologie et Evolution des Interactions’, Université de Perpignan Via Domitia, Perpignan, France
- Medical Research Council Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - Kathryn Rosecrans
- Laboratorio de Parasitología, Centro de Investigaciones Regionales “Dr. Hideyo Noguchi”, Universidad Autónoma de Yucatán, Mérida, Yucatán, Mexico
| | - Maria Jesus Ramirez-Sierra
- Laboratorio de Parasitología, Centro de Investigaciones Regionales “Dr. Hideyo Noguchi”, Universidad Autónoma de Yucatán, Mérida, Yucatán, Mexico
| | - Rubi Gamboa-León
- Laboratorio de Parasitología, Centro de Investigaciones Regionales “Dr. Hideyo Noguchi”, Universidad Autónoma de Yucatán, Mérida, Yucatán, Mexico
| | - Vladimir Cruz-Chan
- Laboratorio de Parasitología, Centro de Investigaciones Regionales “Dr. Hideyo Noguchi”, Universidad Autónoma de Yucatán, Mérida, Yucatán, Mexico
| | - Miguel Rosado-Vallado
- Laboratorio de Parasitología, Centro de Investigaciones Regionales “Dr. Hideyo Noguchi”, Universidad Autónoma de Yucatán, Mérida, Yucatán, Mexico
| | - Sébastien Gourbière
- UMR 5244 CNRS-UPVD ‘Ecologie et Evolution des Interactions’, Université de Perpignan Via Domitia, Perpignan, France
| |
Collapse
|
33
|
Pelosse P, Kribs-Zaleta CM, Ginoux M, Rabinovich JE, Gourbière S, Menu F. Influence of vectors' risk-spreading strategies and environmental stochasticity on the epidemiology and evolution of vector-borne diseases: the example of Chagas' disease. PLoS One 2013; 8:e70830. [PMID: 23951018 PMCID: PMC3738595 DOI: 10.1371/journal.pone.0070830] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Accepted: 06/23/2013] [Indexed: 11/18/2022] Open
Abstract
Insects are known to display strategies that spread the risk of encountering unfavorable conditions, thereby decreasing the extinction probability of genetic lineages in unpredictable environments. To what extent these strategies influence the epidemiology and evolution of vector-borne diseases in stochastic environments is largely unknown. In triatomines, the vectors of the parasite Trypanosoma cruzi, the etiological agent of Chagas’ disease, juvenile development time varies between individuals and such variation most likely decreases the extinction risk of vector populations in stochastic environments. We developed a simplified multi-stage vector-borne SI epidemiological model to investigate how vector risk-spreading strategies and environmental stochasticity influence the prevalence and evolution of a parasite. This model is based on available knowledge on triatomine biodemography, but its conceptual outcomes apply, to a certain extent, to other vector-borne diseases. Model comparisons between deterministic and stochastic settings led to the conclusion that environmental stochasticity, vector risk-spreading strategies (in particular an increase in the length and variability of development time) and their interaction have drastic consequences on vector population dynamics, disease prevalence, and the relative short-term evolution of parasite virulence. Our work shows that stochastic environments and associated risk-spreading strategies can increase the prevalence of vector-borne diseases and favor the invasion of more virulent parasite strains on relatively short evolutionary timescales. This study raises new questions and challenges in a context of increasingly unpredictable environmental variations as a result of global climate change and human interventions such as habitat destruction or vector control.
Collapse
Affiliation(s)
- Perrine Pelosse
- Laboratoire de Biométrie et Biologie Evolutive UMR 5558, Centre National de la Recherche Scientifique, Université Lyon 1, Villeurbanne, France.
| | | | | | | | | | | |
Collapse
|
34
|
Nouvellet P, Gourbière S. Biased sex-ratio and sex-biased heterozygote disadvantage affect the maintenance of a genetic polymorphism and the properties of hybrid zones. J Evol Biol 2013; 26:1774-83. [PMID: 23837902 DOI: 10.1111/jeb.12180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Revised: 02/22/2013] [Accepted: 03/28/2013] [Indexed: 12/01/2022]
Abstract
The evolution of biodiversity is a major issue of modern biology, and it is becoming increasingly topical as the ongoing erosion of diversity puts serious threats on human well-being. An elementary mechanism that allows maintaining diversity is the interplay between dispersal and heterozygote selective disadvantage, which can lead to self-sustainable spatial genetic structures and is central to the stability of hybrid zones. Theoretical studies supporting the importance of this mechanism assume a balanced sex-ratio and a heterozygote disadvantage equally affecting both sexes, despite the multiplicity of empirical evidence that (i) adult sex-ratio is usually biased towards either male or female and that (ii) heterozygote disadvantage often affects a single sex. We expanded the existing theory by weighting the strength of selection against heterozygote according to the biased in sex-ratio and in heterozygote disadvantage. The range of conditions allowing for the maintenance of polymorphism can then either double or vanish. We discuss the implications of such finding for birds, mammals and insects diversity. Finally, we provide simple analytical predictions about the effect of those biased on the width and speed of hybrid zones and on the time for the spread of beneficial mutations through such zones.
Collapse
Affiliation(s)
- P Nouvellet
- MRC Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, Faculty of Medicine, School of Public Health, Imperial College, London, UK
| | | |
Collapse
|
35
|
Killeen GF, Seyoum A, Sikaala C, Zomboko AS, Gimnig JE, Govella NJ, White MT. Eliminating malaria vectors. Parasit Vectors 2013; 6:172. [PMID: 23758937 PMCID: PMC3685528 DOI: 10.1186/1756-3305-6-172] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Accepted: 06/03/2013] [Indexed: 01/24/2023] Open
Abstract
Malaria vectors which predominantly feed indoors upon humans have been locally eliminated from several settings with insecticide treated nets (ITNs), indoor residual spraying or larval source management. Recent dramatic declines of An. gambiae in east Africa with imperfect ITN coverage suggest mosquito populations can rapidly collapse when forced below realistically achievable, non-zero thresholds of density and supporting resource availability. Here we explain why insecticide-based mosquito elimination strategies are feasible, desirable and can be extended to a wider variety of species by expanding the vector control arsenal to cover a broader spectrum of the resources they need to survive. The greatest advantage of eliminating mosquitoes, rather than merely controlling them, is that this precludes local selection for behavioural or physiological resistance traits. The greatest challenges are therefore to achieve high biological coverage of targeted resources rapidly enough to prevent local emergence of resistance and to then continually exclude, monitor for and respond to re-invasion from external populations.
Collapse
Affiliation(s)
- Gerry F Killeen
- Environmental Health & Ecological Sciences, Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania.
| | | | | | | | | | | | | |
Collapse
|
36
|
Vector migration and dispersal rates for sylvatic Trypanosoma cruzi transmission. ECOLOGICAL COMPLEXITY 2013. [DOI: 10.1016/j.ecocom.2012.11.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
37
|
Predicted distribution of major malaria vectors belonging to the Anopheles dirus complex in Asia: ecological niche and environmental influences. PLoS One 2012; 7:e50475. [PMID: 23226292 PMCID: PMC3511573 DOI: 10.1371/journal.pone.0050475] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Accepted: 10/24/2012] [Indexed: 11/19/2022] Open
Abstract
Methods derived from ecological niche modeling allow to define species distribution based on presence-only data. This is particularly useful to develop models from literature records such as available for the Anopheles dirus complex, a major group of malaria mosquito vectors in Asia. This research defines an innovative modeling design based on presence-only model and hierarchical framework to define the distribution of the complex and attempt to delineate sibling species distribution and environmental preferences. At coarse resolution, the potential distribution was defined using slow changing abiotic factors such as topography and climate representative for the timescale covered by literature records of the species. The distribution area was then refined in a second step using a mask of current suitable land cover. Distribution area and ecological niche were compared between species and environmental factors tested for relevance. Alternatively, extreme values at occurrence points were used to delimit environmental envelopes. The spatial distribution for the complex was broadly consistent with its known distribution and influencing factors included temperature and rainfall. If maps developed from environmental envelopes gave similar results to modeling when the number of sites was high, the results were less similar for species with low number of recorded presences. Using presence-only models and hierarchical framework this study not only predicts the distribution of a major malaria vector, but also improved ecological modeling analysis design and proposed final products better adapted to malaria control decision makers. The resulting maps can help prioritizing areas which need further investigation and help simulate distribution under changing conditions such as climate change or reforestation. The hierarchical framework results in two products one abiotic based model describes the potential maximal distribution and remains valid for decades and the other including a biotic mask easy to update with frequently available information gives current species distribution.
Collapse
|
38
|
Guilhem R, Šimková A, Morand S, Gourbière S. Within-host competition and diversification of macro-parasites. J R Soc Interface 2012; 9:2936-46. [PMID: 22696483 PMCID: PMC3479921 DOI: 10.1098/rsif.2012.0358] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Accepted: 05/16/2012] [Indexed: 01/14/2023] Open
Abstract
Although competitive speciation is more and more regarded as a plausible mechanism for sympatric speciation of non-parasite species, virtually no empirical or theoretical study has considered this evolutionary process to explain intra-host diversification of parasites. We expanded the theory of competitive speciation to parasite species looking at the effect of macro-parasite life history on the conditions for sympatric speciation under the so-called pleiotropic scenario. We included within-host competition in the classical Anderson and May framework assuming that individuals exploit within-host resources according to a quantitative trait. We derived the invasion fitness function of mutants considering different distributions of individuals among hosts. Although the mutant fitness depends on parameters describing the key features of macro-parasite life history, and on the relative distributions of mutant and residents in hosts, the conditions for competitive speciation of macro-parasites are exactly the same as those previously established for free-living species. As an interesting by-product, within-host competitive speciation is expected not to depend on the aggregation level of the parasites. This theoretical pattern is confirmed by comparing the speciation rate of weakly and strongly aggregated monogenean parasites.
Collapse
Affiliation(s)
- Rascalou Guilhem
- UMR 5244 CNRS-UPVD ‘Ecologie et Evolution des Interactions’, Université de Perpignan Via Domitia, Perpignan 66100, France
| | - Andrea Šimková
- Department of Botany and Zoology, Faculty of Science, Masaryk University, Kotlářská 2, 611 37 Brno, Czech Republic
| | - Serge Morand
- Institut des Sciences de l'Evolution—CNRS, Département Génétique Environnement, CC065, Université Montpellier 2, 34095 Montpellier cedex 05, France
| | - Sébastien Gourbière
- UMR 5244 CNRS-UPVD ‘Ecologie et Evolution des Interactions’, Université de Perpignan Via Domitia, Perpignan 66100, France
- School of Life Sciences, Centre for the Study of Evolution, University of Sussex, Brighton BN1 9QG, UK
| |
Collapse
|
39
|
Grazú V, Silber AM, Moros M, Asín L, Torres TE, Marquina C, Ibarra MR, Goya GF. Application of magnetically induced hyperthermia in the model protozoan Crithidia fasciculata as a potential therapy against parasitic infections. Int J Nanomedicine 2012; 7:5351-60. [PMID: 23071396 PMCID: PMC3469100 DOI: 10.2147/ijn.s35510] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Background Magnetic hyperthermia is currently a clinical therapy approved in the European Union for treatment of tumor cells, and uses magnetic nanoparticles (MNPs) under time-varying magnetic fields (TVMFs). The same basic principle seems promising against trypanosomatids causing Chagas disease and sleeping sickness, given that the therapeutic drugs available have severe side effects and that there are drug-resistant strains. However, no applications of this strategy against protozoan-induced diseases have been reported so far. In the present study, Crithidia fasciculata, a widely used model for therapeutic strategies against pathogenic trypanosomatids, was targeted with Fe3O4 MNPs in order to provoke cell death remotely using TVMFs. Methods Iron oxide MNPs with average diameters of approximately 30 nm were synthesized by precipitation of FeSO4 in basic medium. The MNPs were added to C. fasciculata choanomastigotes in the exponential phase and incubated overnight, removing excess MNPs using a DEAE-cellulose resin column. The amount of MNPs uploaded per cell was determined by magnetic measurement. The cells bearing MNPs were submitted to TVMFs using a homemade AC field applicator (f = 249 kHz, H = 13 kA/m), and the temperature variation during the experiments was measured. Scanning electron microscopy was used to assess morphological changes after the TVMF experiments. Cell viability was analyzed using an MTT colorimetric assay and flow cytometry. Results MNPs were incorporated into the cells, with no noticeable cytotoxicity. When a TVMF was applied to cells bearing MNPs, massive cell death was induced via a nonapoptotic mechanism. No effects were observed by applying TVMF to control cells not loaded with MNPs. No macroscopic rise in temperature was observed in the extracellular medium during the experiments. Conclusion As a proof of principle, these data indicate that intracellular hyperthermia is a suitable technology to induce death of protozoan parasites bearing MNPs. These findings expand the possibilities for new therapeutic strategies combating parasitic infection.
Collapse
Affiliation(s)
- V Grazú
- Instituto de Nanociencia de Aragón (INA), Universidad de Zaragoza, Zaragoza, Spain
| | | | | | | | | | | | | | | |
Collapse
|