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Msellemu D, Tanner M, Yadav R, Moore SJ. Occupational exposure to malaria, leishmaniasis and arbovirus vectors in endemic regions: A systematic review. CURRENT RESEARCH IN PARASITOLOGY & VECTOR-BORNE DISEASES 2024; 6:100185. [PMID: 39027087 PMCID: PMC11252614 DOI: 10.1016/j.crpvbd.2024.100185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Revised: 04/26/2024] [Accepted: 06/01/2024] [Indexed: 07/20/2024]
Abstract
Vector-borne diseases, including dengue, leishmaniasis and malaria, may be more common among individuals whose occupations or behaviours bring them into frequent contact with these disease vectors outside of their homes. A systematic review was conducted to ascertain at-risk occupations and situations that put individuals at increased risk of exposure to these disease vectors in endemic regions and identify the most suitable interventions for each exposure. The review was conducted in accordance with PRISMA guidelines on articles published between 1945 and October 2021, searched in 16 online databases. The primary outcome was incidence or prevalence of dengue, leishmaniasis or malaria. The review excluded ecological and qualitative studies, abstracts only, letters, commentaries, reviews, and studies of laboratory-acquired infections. Studies were appraised, data extracted, and a descriptive analysis conducted. Bite interventions for each risk group were assessed. A total of 1170 articles were screened and 99 included. Malaria, leishmaniasis and dengue were presented in 47, 41 and 24 articles, respectively; some articles presented multiple conditions. The most represented populations were soldiers, 38% (43 of 112 studies); refugees and travellers, 15% (17) each; migrant workers, 12.5% (14); miners, 9% (10); farmers, 5% (6); rubber tappers and missionaries, 1.8% (2) each; and forest workers, 0.9% (1). Risk of exposure was categorised into round-the-clock or specific times of day/night dependent on occupation. Exposure to these vectors presents a critical and understudied concern for outdoor workers and mobile populations. When devising interventions to provide round-the-clock vector bite protection, two populations are considered. First, mobile populations, characterized by their high mobility, may find potential benefits in insecticide-treated clothing, though more research and optimization are essential. Treated clothing offers personal vector protection and holds promise for economically disadvantaged individuals, especially when enabling them to self-treat their clothing to repel vectors. Secondly, semi-permanent and permanent settlement populations can receive a combination of interventions that offer both personal and community protection, including spatial repellents, suitable for extended stays. Existing research is heavily biased towards tourism and the military, diverting attention and resources from vulnerable populations where these interventions are most required like refugee populations as well as those residing in sub-Saharan Africa.
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Affiliation(s)
- Daniel Msellemu
- Vector Control Product Testing Unit, Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Tanzania
- Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123, Allschwil, Switzerland
- University of Basel, Petersplatz 1, 4003, Basel, Switzerland
| | - Marcel Tanner
- Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123, Allschwil, Switzerland
- University of Basel, Petersplatz 1, 4003, Basel, Switzerland
| | - Rajpal Yadav
- Department of Control of Neglected Tropical Diseases, World Health Organization, Geneva, Switzerland
- Academy of Public Health Entomology, Udaipur, 313 002, India
| | - Sarah J. Moore
- Vector Control Product Testing Unit, Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Tanzania
- Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123, Allschwil, Switzerland
- University of Basel, Petersplatz 1, 4003, Basel, Switzerland
- The Nelson Mandela African Institution of Science and Technology (NM-AIST), P.O. Box 447, Tengeru, Arusha, Tanzania
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Epidemiological profile of dengue in Champasak and Savannakhet provinces, Lao People's Democratic Republic, 2003-2020. Western Pac Surveill Response J 2022; 13:1-13. [PMID: 36817500 PMCID: PMC9912291 DOI: 10.5365/wpsar.2022.13.4.932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Dengue is a public health issue in tropical south-eastern Asia responsible for significant morbidity and mortality. Information on dengue epidemiology is necessary for developing strategies to control infections effectively. In the Lao People’s Democratic Republic (Lao PDR), Champasak and Savannakhet provinces account for around 30% of the national dengue burden. In this study, the dengue epidemiological profile in these two southern provinces of Lao PDR was described by analysing seasonal and spatial dengue notification data from 2003–2020 using the long-term mean (LTM) method. Savannakhet had a higher LTM (132.0 cases/month, 95% confidence interval [Cl]: 92.2–171.7) than Champasak (113.3 cases/month, 95% CI: 86.0–140.5), with peaks in dengue notifications following the rainy season in both provinces. The highest notification rates were observed in July to September; these months were also when the LTM was most frequently exceeded. Previously, dengue notifications were largely confined to the western districts of Savannakhet and the northern districts of Champasak, but more recently, notifications have increased in the eastern districts of Savannakhet and southern districts of Champasak. While the notification rate remained high in children and young adults (5–30 years), especially among students and farmers, a shift in the age structure of dengue cases was observed, with a greater proportion of notifications now occurring in those aged over 30 years. Community-based vector control and prevention programmes are needed to restrict the spread of dengue into new geographical areas in the southern provinces of Lao PDR.
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Cui G, Zhong S, Zheng T, Li Z, Zhang X, Li C, Hemming-Schroeder E, Zhou G, Li Y. Aedes albopictus life table: environment, food, and age dependence survivorship and reproduction in a tropical area. Parasit Vectors 2021; 14:568. [PMID: 34743753 PMCID: PMC8573987 DOI: 10.1186/s13071-021-05081-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2021] [Accepted: 10/26/2021] [Indexed: 11/29/2022] Open
Abstract
Background Environmental conditions affect the biology of mosquito vectors. Aedes albopictus is a major vector of many important diseases including dengue, Zika, and chikungunya in China. Understanding the development, fecundity, and survivorship of Ae. albopictus mosquitoes in different environmental conditions is beneficial for the implementation of effective vector control measures. Methods Aedes albopictus larval and adult life-table experiments were conducted under natural conditions in indoor, half-shaded, and fully shaded settings, simulating the three major habitat types in Hainan Province, a tropical island in the South China Sea. Temperature, humidity, and light intensity were recorded daily. Larval rearing used habitat water and tap water, with and without additional artificial food. Development time, survivorship, pupation rate, and adult emergence rates were monitored. Adult mosquito survivorship and fecundity were monitored daily and reproductive rates were determined, and age-dependent survivorship and reproduction were analyzed. Results The pupation time and male and female emergence times were significantly shorter in indoor conditions than in shaded and half-shaded conditions for both tap water with added food and habitat water with added food groups. For habitat water with added food, the shaded environment had the lowest pupation rate among the settings. For tap water with added food group, the shaded environment had the lowest pupation rate. The mean survival time of females was 27.3 ± 0.8 days in the indoor condition, which was significantly longer than that in the half-shaded (18.4 ± 0.6 days) and shaded (13.8 ± 1.2 days) conditions. Adult mortality was age-dependent, and the rate of change in mortality with age was not significantly different among different environmental conditions. The mean net replacement rate (R0) of female mosquitoes showed no significant difference among the three conditions, whereas the per capita intrinsic growth rate (r) in the shaded condition was 42.0% and 20.4% higher than that in the indoor and half-shaded conditions, respectively. Female daily egg mass was also age-dependent in all the settings, decaying exponentially with age. Conclusions Our results imply that half-shaded conditions are likely the best natural condition for adult emergence and female reproduction, and food supply is crucial for larval development and pupation. The results provide new avenues for integrated mosquito management in indoor and outdoor areas, especially in half-shaded areas. Graphical Abstract ![]()
Supplementary Information The online version contains supplementary material available at 10.1186/s13071-021-05081-x.
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Affiliation(s)
- Guzhen Cui
- Key Laboratory of Tropical Translational Medicine of Ministry of Education, Hainan Medical University, Haikou, 571199, China.,Key Laboratory of Medical Microbiology and Parasitology of Education Department of Guizhou, School of Basic Medical Science, Guizhou Medical University, Guiyang, 550025, China
| | - Saifeng Zhong
- Department of Pathogen Biology, Hainan Medical University, Haikou, 571199, China
| | - Tuquan Zheng
- Department of Pathogen Biology, Hainan Medical University, Haikou, 571199, China
| | - Zhangrui Li
- Department of Pathogen Biology, Hainan Medical University, Haikou, 571199, China
| | - Xu Zhang
- Department of Pathogen Biology, Hainan Medical University, Haikou, 571199, China
| | - Chuang Li
- Department of Pathogen Biology, Hainan Medical University, Haikou, 571199, China
| | - Elizabeth Hemming-Schroeder
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA, 92617, USA
| | - Guofa Zhou
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA, 92617, USA.
| | - Yiji Li
- Key Laboratory of Tropical Translational Medicine of Ministry of Education, Hainan Medical University, Haikou, 571199, China. .,Department of Pathogen Biology, Hainan Medical University, Haikou, 571199, China. .,Hainan Medical University-The University of Hong Kong Joint Laboratory of Tropical Infectious Diseases, Hainan Medical University, Haikou, 571199, China.
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Hii J, Hustedt J, Bangs MJ. Residual Malaria Transmission in Select Countries of Asia-Pacific Region: Old Wine in a New Barrel. J Infect Dis 2021; 223:S111-S142. [PMID: 33906222 PMCID: PMC8079134 DOI: 10.1093/infdis/jiab004] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Background Despite substantial reductions in malaria burden and improvement in case management, malaria remains a major public health challenge in the Asia-Pacific region. Residual malaria transmission (RMT) is the fraction of total transmission that persists after achievement of full operational coverage with effective insecticide-treated bed nets (ITNs)/long-lasting insecticidal nets (LLINs) and/or indoor residual spray interventions. There is a critical need to standardize and share best practices for entomological, anthropological, and product development investigative protocols to meet the challenges of RMT and elimination goals. Methods A systematic review was conducted to describe when and where RMT is occurring, while specifically targeting ownership and usage of ITN/LLINs, indoor residual spray application, insecticide susceptibility of vectors, and human and vector biting behavior, with a focus on nighttime activities. Results Sixty-six publications from 1995 to present met the inclusion criteria for closer review. Associations between local vector control coverage and use with behaviors of human and mosquito vectors varied by locality and circumstance. Consequently, the magnitude of RMT is insufficiently studied and analyzed with sparse estimates of individual exposure in communities, insufficient or incomplete observations of ITN/LLIN use, and the local human population movement into and from high-risk areas. Conclusions This review identified significant gaps or deficiencies that require urgent attention, namely, developing standardized procedures and methods to estimate risk exposure beyond the peridomestic setting, analytical approaches to measure key human-vector interactions, and seasonal location-specific agricultural or forest use calendars, and establishing the collection of longitudinal human and vector data close in time and location.
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Affiliation(s)
- Jeffrey Hii
- Malaria Consortium Asia, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.,College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Queensland, Australia
| | | | - Michael J Bangs
- Public Health and Malaria Control Department, PT Freeport Indonesia, International SOS, Jl. Kertajasa, Kuala Kencana, Papua, Indonesia.,Department of Entomology, Faculty of Agriculture, Kasertart University, Bangkok, Thailand
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Vantaux A, Riehle MM, Piv E, Farley EJ, Chy S, Kim S, Corbett AG, Fehrman RL, Pepey A, Eiglmeier K, Lek D, Siv S, Mueller I, Vernick KD, Witkowski B. Anopheles ecology, genetics and malaria transmission in northern Cambodia. Sci Rep 2021; 11:6458. [PMID: 33742030 PMCID: PMC7979810 DOI: 10.1038/s41598-021-85628-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 03/04/2021] [Indexed: 12/20/2022] Open
Abstract
In the Greater Mekong Subregion, malaria cases have significantly decreased but little is known about the vectors or mechanisms responsible for residual malaria transmission. We analysed a total of 3920 Anopheles mosquitoes collected during the rainy and dry seasons from four ecological settings in Cambodia (villages, forested areas near villages, rubber tree plantations and forest sites). Using odor-baited traps, 81% of the total samples across all sites were collected in cow baited traps, although 67% of the samples attracted by human baited traps were collected in forest sites. Overall, 20% of collected Anopheles were active during the day, with increased day biting during the dry season. 3131 samples were identified morphologically as 14 different species, and a subset was also identified by DNA amplicon sequencing allowing determination of 29 Anopheles species. The investigation of well characterized insecticide mutations (ace-1, kdr, and rdl genes) indicated that individuals carried mutations associated with response to all the different classes of insecticides. There also appeared to be a non-random association between mosquito species and insecticide resistance with Anopheles peditaeniatus exhibiting nearly fixed mutations. Molecular screening for Plasmodium sp. presence indicated that 3.6% of collected Anopheles were positive, most for P. vivax followed by P. falciparum. These results highlight some of the key mechanisms driving residual human malaria transmission in Cambodia, and illustrate the importance of diverse collection methods, sites and seasons to avoid bias and better characterize Anopheles mosquito ecology in Southeast Asia.
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Affiliation(s)
- Amélie Vantaux
- Malaria Molecular Epidemiology Unit, Institut Pasteur du Cambodge, Phnom Penh, Cambodia.
| | - Michelle M Riehle
- Department of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Eakpor Piv
- Malaria Molecular Epidemiology Unit, Institut Pasteur du Cambodge, Phnom Penh, Cambodia
| | - Elise J Farley
- Department of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Sophy Chy
- Malaria Molecular Epidemiology Unit, Institut Pasteur du Cambodge, Phnom Penh, Cambodia
| | - Saorin Kim
- Malaria Molecular Epidemiology Unit, Institut Pasteur du Cambodge, Phnom Penh, Cambodia
| | - Anneli G Corbett
- Department of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Rachel L Fehrman
- Department of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Anais Pepey
- Malaria Molecular Epidemiology Unit, Institut Pasteur du Cambodge, Phnom Penh, Cambodia
| | - Karin Eiglmeier
- Unit of Insect Vector Genetics and Genomics, Department of Parasites and Insect Vectors, Institut Pasteur, Paris, France.,CNRS Unit of Evolutionary Genomics, Modeling, and Health (UMR2000), Institut Pasteur, Paris, France
| | - Dysoley Lek
- National Center for Parasitology, Entomology and Malaria Control Program, Phnom Penh, Cambodia.,School of Public Health, National Institute of Public Health, Phnom Penh, Cambodia
| | - Sovannaroth Siv
- National Center for Parasitology, Entomology and Malaria Control Program, Phnom Penh, Cambodia
| | - Ivo Mueller
- Malaria: Parasites and Hosts Unit, Institut Pasteur, Paris, France
| | - Kenneth D Vernick
- Unit of Insect Vector Genetics and Genomics, Department of Parasites and Insect Vectors, Institut Pasteur, Paris, France.,CNRS Unit of Evolutionary Genomics, Modeling, and Health (UMR2000), Institut Pasteur, Paris, France
| | - Benoit Witkowski
- Malaria Molecular Epidemiology Unit, Institut Pasteur du Cambodge, Phnom Penh, Cambodia
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Chan EYY, Sham TST, Shahzada TS, Dubois C, Huang Z, Liu S, Hung KK, Tse SL, Kwok KO, Chung PH, Kayano R, Shaw R. Narrative Review on Health-EDRM Primary Prevention Measures for Vector-Borne Diseases. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:E5981. [PMID: 32824754 PMCID: PMC7459832 DOI: 10.3390/ijerph17165981] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 08/13/2020] [Accepted: 08/13/2020] [Indexed: 01/01/2023]
Abstract
Climate change is expanding the global at-risk population for vector-borne diseases (VBDs). The World Health Organization (WHO) health emergency and disaster risk management (health-EDRM) framework emphasises the importance of primary prevention of biological hazards and its value in protecting against VBDs. The framework encourages stakeholder coordination and information sharing, though there is still a need to reinforce prevention and recovery within disaster management. This keyword-search based narrative literature review searched databases PubMed, Google Scholar, Embase and Medline between January 2000 and May 2020, and identified 134 publications. In total, 10 health-EDRM primary prevention measures are summarised at three levels (personal, environmental and household). Enabling factor, limiting factors, co-benefits and strength of evidence were identified. Current studies on primary prevention measures for VBDs focus on health risk-reduction, with minimal evaluation of actual disease reduction. Although prevention against mosquito-borne diseases, notably malaria, has been well-studied, research on other vectors and VBDs remains limited. Other gaps included the limited evidence pertaining to prevention in resource-poor settings and the efficacy of alternatives, discrepancies amongst agencies' recommendations, and limited studies on the impact of technological advancements and habitat change on VBD prevalence. Health-EDRM primary prevention measures for VBDs require high-priority research to facilitate multifaceted, multi-sectoral, coordinated responses that will enable effective risk mitigation.
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Affiliation(s)
- Emily Ying Yang Chan
- Collaborating Centre for Oxford University and CUHK for Disaster and Medical Humanitarian Response (CCOUC), The Chinese University of Hong Kong, Hong Kong SAR, China; (Z.H.); (S.L.); (K.K.C.H.)
- Nuffield Department of Medicine, University of Oxford, Oxford OX37BN, UK
- JC School of Public Health and Primary Care, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong SAR, China; (T.S.T.S.); (T.S.S.); (S.L.A.T.); (K.O.K.); (P.-H.C.)
- GX Foundation, Hong Kong SAR, China;
- Accident & Emergency Medicine Academic Unit, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong SAR, China
| | - Tiffany Sze Tung Sham
- JC School of Public Health and Primary Care, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong SAR, China; (T.S.T.S.); (T.S.S.); (S.L.A.T.); (K.O.K.); (P.-H.C.)
- GX Foundation, Hong Kong SAR, China;
| | - Tayyab Salim Shahzada
- JC School of Public Health and Primary Care, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong SAR, China; (T.S.T.S.); (T.S.S.); (S.L.A.T.); (K.O.K.); (P.-H.C.)
- GX Foundation, Hong Kong SAR, China;
| | | | - Zhe Huang
- Collaborating Centre for Oxford University and CUHK for Disaster and Medical Humanitarian Response (CCOUC), The Chinese University of Hong Kong, Hong Kong SAR, China; (Z.H.); (S.L.); (K.K.C.H.)
- JC School of Public Health and Primary Care, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong SAR, China; (T.S.T.S.); (T.S.S.); (S.L.A.T.); (K.O.K.); (P.-H.C.)
| | - Sida Liu
- Collaborating Centre for Oxford University and CUHK for Disaster and Medical Humanitarian Response (CCOUC), The Chinese University of Hong Kong, Hong Kong SAR, China; (Z.H.); (S.L.); (K.K.C.H.)
- GX Foundation, Hong Kong SAR, China;
| | - Kevin K.C. Hung
- Collaborating Centre for Oxford University and CUHK for Disaster and Medical Humanitarian Response (CCOUC), The Chinese University of Hong Kong, Hong Kong SAR, China; (Z.H.); (S.L.); (K.K.C.H.)
- JC School of Public Health and Primary Care, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong SAR, China; (T.S.T.S.); (T.S.S.); (S.L.A.T.); (K.O.K.); (P.-H.C.)
- Accident & Emergency Medicine Academic Unit, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong SAR, China
| | - Shelly L.A. Tse
- JC School of Public Health and Primary Care, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong SAR, China; (T.S.T.S.); (T.S.S.); (S.L.A.T.); (K.O.K.); (P.-H.C.)
| | - Kin On Kwok
- JC School of Public Health and Primary Care, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong SAR, China; (T.S.T.S.); (T.S.S.); (S.L.A.T.); (K.O.K.); (P.-H.C.)
| | - Pui-Hong Chung
- JC School of Public Health and Primary Care, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong SAR, China; (T.S.T.S.); (T.S.S.); (S.L.A.T.); (K.O.K.); (P.-H.C.)
| | - Ryoma Kayano
- World Health Organization Centre for Health Development, Kobe 651-0073, Japan;
| | - Rajib Shaw
- Graduate School of Media and Governance, Keio University, Fujisawa 252-0882, Japan;
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Incidence and epidemiological features of dengue in Sabah, Malaysia. PLoS Negl Trop Dis 2020; 14:e0007504. [PMID: 32392222 PMCID: PMC7241834 DOI: 10.1371/journal.pntd.0007504] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2019] [Revised: 05/21/2020] [Accepted: 12/19/2019] [Indexed: 12/22/2022] Open
Abstract
In South East Asia, dengue epidemics have increased in size and geographical distribution in recent years. We examined the spatiotemporal distribution and epidemiological characteristics of reported dengue cases in the predominantly rural state of Sabah, in Malaysian Borneo-an area where sylvatic and urban circulation of pathogens are known to intersect. Using a public health data set of routinely notified dengue cases in Sabah between 2010 and 2016, we described demographic and entomological risk factors, both before and after a 2014 change in the clinical case definition for the disease. Annual dengue incidence rates were spatially variable over the 7-year study period from 2010-2016 (state-wide mean annual incidence of 21 cases/100,000 people; range 5-42/100,000), but were highest in rural localities in the western districts of the state (Kuala Penyu, Nabawan, Tenom and Kota Marudu). Eastern districts exhibited lower overall dengue rates, although a high proportion of severe (haemorrhagic) dengue cases (44%) were focused in Sandakan and Tawau. Dengue incidence was highest for those aged between 10 and 29 years (24/100,000), and was slightly higher for males compared to females. Available vector surveillance data indicated that during large outbreaks in 2015 and 2016 the mosquito Aedes albopictus was more prevalent in both urban and rural households (House Index of 64%) than Ae. aegypti (15%). Demographic patterns remained unchanged both before and after the dengue case definition was changed; however, in the years following the change, reported case numbers increased substantially. Overall, these findings suggest that dengue outbreaks in Sabah are increasing in both urban and rural settings. Future studies to better understand the drivers of risk in specific age groups, genders and geographic locations, and to test the potential role of Ae. albopictus in transmission, may help target dengue prevention and control efforts.
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Survey of asymptomatic malaria and mosquito vectors in Muang Khua District of Phongsaly Province, China-Laos Border. Int J Infect Dis 2020; 96:141-147. [PMID: 32251803 DOI: 10.1016/j.ijid.2020.03.066] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 02/22/2020] [Accepted: 03/25/2020] [Indexed: 12/17/2022] Open
Abstract
OBJECTIVES The China-Laos border has been identified as an important origin of imported malaria outside China. The aim of this study was to describe the asymptomatic malaria infections and epidemic trend of malaria in the China-Laos border region. METHODS A prevalence survey and surveillance of mosquito vectors was conducted in Muang Khua District of Phongsaly Province, China-Laos border, to determine the parasite carriage rate using nested PCR and microscopy. The species composition of malaria vectors was determined by overnight trapping. Blood samples were collected from 354 local residents aged 1-72 years in Sankang village in 2016. A total of 2430 adult mosquitoes were collected from four other villages in Muang Khua District from June to August 2016. RESULTS The parasite carriage rate was 7.63% (27/354) by microscopy or 7.91% (28/354) by nested PCR. The results of surveillance of the mosquito vectors revealed that the predominant genera of adult mosquitoes were Culex (69.92%, 1699/2430) and Anopheles (21.48%, 522/2430). Anopheles sinensis (82.95%, 433/522) was identified as the predominant species among the seven members of Anopheles found in this border region. CONCLUSIONS A high prevalence of asymptomatic malaria was present and the most important malaria vector was Anopheles sinensis, suggesting that the malaria epidemic situation on the China-Laos border is serious.
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Liu Y, Lillepold K, Semenza JC, Tozan Y, Quam MBM, Rocklöv J. Reviewing estimates of the basic reproduction number for dengue, Zika and chikungunya across global climate zones. ENVIRONMENTAL RESEARCH 2020; 182:109114. [PMID: 31927301 DOI: 10.1016/j.envres.2020.109114] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2019] [Revised: 01/01/2020] [Accepted: 01/02/2020] [Indexed: 05/14/2023]
Abstract
BACKGROUND Globally, dengue, Zika virus, and chikungunya are important viral mosquito-borne diseases that infect millions of people annually. Their geographic range includes not only tropical areas but also sub-tropical and temperate zones such as Japan and Italy. The relative severity of these arboviral disease outbreaks can vary depending on the setting. In this study we explore variation in the epidemiologic potential of outbreaks amongst these climatic zones and arboviruses in order to elucidate potential reasons behind such differences. METHODOLOGY We reviewed the peer-reviewed literature (PubMed) to obtain basic reproduction number (R0) estimates for dengue, Zika virus, and chikungunya from tropical, sub-tropical and temperate regions. We also computed R0 estimates for temperate and sub-tropical climate zones, based on the outbreak curves in the initial outbreak phase. Lastly we compared these estimates across climate zones, defined by latitude. RESULTS Of 2115 studies, we reviewed the full text of 128 studies and included 65 studies in our analysis. Our results suggest that the R0 of an arboviral outbreak depends on climate zone, with lower R0 estimates, on average, in temperate zones (R0 = 2.03) compared to tropical (R0 = 3.44) and sub-tropical zones (R0 = 10.29). The variation in R0 was considerable, ranging from 0.16 to 65. The largest R0 was for dengue (65) and was estimated by the Ross-Macdonald model in the tropical zone, whereas the smallest R0 (0.16) was for Zika virus and was estimated statistically from an outbreak curve in the sub-tropical zone. CONCLUSIONS The results indicate climate zone to be an important determinant of the basic reproduction number, R0, for dengue, Zika virus, and chikungunya. The role of other factors as determinants of R0, such as methods, environmental and social conditions, and disease control, should be further investigated. The results suggest that R0 may increase in temperate regions in response to global warming, and highlight the increasing need for strengthening preparedness and control activities.
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Affiliation(s)
- Ying Liu
- School of International Business, Xiamen University Tan Kah Kee College, Zhangzhou, 363105, China.
| | - Kate Lillepold
- European Centre for Disease Prevention and Control, Stockholm, Sweden
| | - Jan C Semenza
- European Centre for Disease Prevention and Control, Stockholm, Sweden
| | - Yesim Tozan
- New York University, College of Global Public Health, New York, NY, USA.
| | - Mikkel B M Quam
- Department of Public Health and Clinical Medicine, Section of Sustainable Health, Umeå University, Umeå, Sweden
| | - Joacim Rocklöv
- Department of Public Health and Clinical Medicine, Section of Sustainable Health, Umeå University, Umeå, Sweden.
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Motoki MT, Fonseca DM, Miot EF, Demari-Silva B, Thammavong P, Chonephetsarath S, Phommavanh N, Hertz JC, Kittayapong P, Brey PT, Marcombe S. Population genetics of Aedes albopictus (Diptera: Culicidae) in its native range in Lao People's Democratic Republic. Parasit Vectors 2019; 12:477. [PMID: 31610813 PMCID: PMC6792217 DOI: 10.1186/s13071-019-3740-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Accepted: 10/04/2019] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND The Asian tiger mosquito, Aedes (Stegomyia) albopictus (Skuse) is an important worldwide invasive species and can be a locally important vector of chikungunya, dengue and, potentially, Zika. This species is native to Southeast Asia where populations thrive in both temperate and tropical climates. A better understanding of the population structure of Ae. albopictus in Lao PDR is very important in order to support the implementation of strategies for diseases prevention and vector control. In the present study, we investigated the genetic variability of Ae. albopictus across a north-south transect in Lao PDR. METHODS We used variability in a 1337-bp fragment of the mitochondrial cytochrome c oxidase subunit 1 gene (cox1), to assess the population structure of Ae. albopictus in Lao PDR. For context, we also examined variability at the same genetic locus in samples of Ae. albopictus from Thailand, China, Taiwan, Japan, Singapore, Italy and the USA. RESULTS We observed very high levels of genetic polymorphism with 46 novel haplotypes in Ae. albopictus from 9 localities in Lao PDR and Thailand populations. Significant differences were observed between the Luangnamtha population and other locations in Lao PDR. However, we found no evidence of isolation by distance. There was overall little genetic structure indicating ongoing and frequent gene flow among populations or a recent population expansion. Indeed, the neutrality test supported population expansion in Laotian Ae. albopictus and mismatch distribution analyses showed a lack of low frequency alleles, a pattern often seen in bottlenecked populations. When samples from Lao PDR were analyzed together with samples from Thailand, China, Taiwan, Japan, Singapore, Italy and the USA, phylogenetic network and Bayesian cluster analysis showed that most populations from tropical/subtropical regions are more genetically related to each other, than populations from temperate regions. Similarly, most populations from temperate regions are more genetically related to each other, than those from tropical/subtropical regions. CONCLUSIONS Aedes albopictus in Lao PDR are genetically related to populations from tropical/subtropical regions (i.e. Thailand, Singapore, and California and Texas in the USA). The extensive gene flow among locations in Lao PDR indicates that local control is undermined by repeated introductions from untreated sites.
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Affiliation(s)
- Maysa Tiemi Motoki
- Medical Entomology and Vector Borne Disease Unit, Institut Pasteur du Laos, Vientiane, Lao People's Democratic Republic. .,Vysnova Partners Inc., Landover, MD, USA. .,Walter Reed Biosystematics Unit, Smithsonian Institution, Museum Support Center, MRC-534, Suitland, MD, 20746, USA.
| | - Dina Madera Fonseca
- Center for Vector Biology and Department of Entomology, Rutgers University, New Brunswick, NJ, USA
| | - Elliott Frederic Miot
- Medical Entomology and Vector Borne Disease Unit, Institut Pasteur du Laos, Vientiane, Lao People's Democratic Republic.,Université Pierre et Marie Curie, Cellule Pasteur UPMC, Paris, France.,Insect-Virus Interactions Group, Department of Genomes and Genetics, Institut Pasteur, Paris, France.,Centre National de la Recherche Scientifique, Unité Mixte de Recherche 2000, Paris, France
| | - Bruna Demari-Silva
- Department of Epidemiology, Faculty of Public Health, University of Sao Paulo, Sao Paulo, Brazil
| | - Phoutmany Thammavong
- Medical Entomology and Vector Borne Disease Unit, Institut Pasteur du Laos, Vientiane, Lao People's Democratic Republic
| | - Somsanith Chonephetsarath
- Medical Entomology and Vector Borne Disease Unit, Institut Pasteur du Laos, Vientiane, Lao People's Democratic Republic
| | - Nothasine Phommavanh
- Medical Entomology and Vector Borne Disease Unit, Institut Pasteur du Laos, Vientiane, Lao People's Democratic Republic
| | | | | | - Paul Trevor Brey
- Medical Entomology and Vector Borne Disease Unit, Institut Pasteur du Laos, Vientiane, Lao People's Democratic Republic
| | - Sebastien Marcombe
- Medical Entomology and Vector Borne Disease Unit, Institut Pasteur du Laos, Vientiane, Lao People's Democratic Republic
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11
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Saavedra MP, Conn JE, Alava F, Carrasco-Escobar G, Prussing C, Bickersmith SA, Sangama JL, Fernandez-Miñope C, Guzman M, Tong C, Valderrama C, Vinetz JM, Gamboa D, Moreno M. Higher risk of malaria transmission outdoors than indoors by Nyssorhynchus darlingi in riverine communities in the Peruvian Amazon. Parasit Vectors 2019; 12:374. [PMID: 31358033 PMCID: PMC6664538 DOI: 10.1186/s13071-019-3619-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Accepted: 07/19/2019] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND Malaria remains an important public health problem in Peru where incidence has been increasing since 2011. Of over 55,000 cases reported in 2017, Plasmodium vivax was the predominant species (76%), with P. falciparum responsible for the remaining 24%. Nyssorhynchus darlingi (previously Anopheles darlingi) is the main vector in Amazonian Peru, where hyperendemic Plasmodium transmission pockets have been found. Mazán district has pronounced spatial heterogeneity of P. vivax malaria. However, little is known about behavior, ecology or seasonal dynamics of Ny. darlingi in Mazán. This study aimed to gather baseline information about bionomics of malaria vectors and transmission risk factors in a hyperendemic malaria area of Amazonian Peru. METHODS To assess vector biology metrics, five surveys (two in the dry and three in the rainy season), including collection of sociodemographic information, were conducted in four communities in 2016-2017 on the Napo (Urco Miraño, URC; Salvador, SAL) and Mazán Rivers (Visto Bueno, VIB; Libertad, LIB). Human-biting rate (HBR), entomological inoculation rate (EIR) and human blood index (HBI) were measured to test the hypothesis of differences in entomological indices of Ny. darlingi between watersheds. A generalized linear mixed effect model (GLMM) was constructed to model the relationship between household risk factors and the EIR. RESULTS Nyssorhynchus darlingi comprised 95% of 7117 Anophelinae collected and its abundance was significantly higher along the Mazán River. The highest EIRs (3.03-4.54) were detected in March and June in URC, LIB and VIB, and significantly more Ny. darlingi were infected outdoors than indoors. Multivariate analysis indicated that the EIR was >12 times higher in URC compared with SAL. The HBI ranged from 0.42-0.75; humans were the most common blood source, followed by Galliformes and cows. There were dramatic differences in peak biting time and malaria incidence with similar bednet coverage in the villages. CONCLUSIONS Nyssorhynchus darlingi is the predominant contributor to malaria transmission in the Mazán District, Peru. Malaria risk in these villages is higher in the peridomestic area, with pronounced heterogeneities between and within villages on the Mazán and the Napo Rivers. Spatiotemporal identification and quantification of the prevailing malaria transmission would provide new evidence to orient specific control measures for vulnerable or at high risk populations.
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Affiliation(s)
- Marlon P. Saavedra
- Laboratorio ICEMR-Amazonia, Laboratorios de Investigacion y Desarrollo, Facultad de Ciencias y Filosofia, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Jan E. Conn
- Department of Biomedical Sciences, School of Public Health, State University of New York-Albany, Albany, NY USA
- Wadsworth Center, New York State Department of Health, Albany, NY USA
| | | | - Gabriel Carrasco-Escobar
- Laboratorio ICEMR-Amazonia, Laboratorios de Investigacion y Desarrollo, Facultad de Ciencias y Filosofia, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Catharine Prussing
- Department of Biomedical Sciences, School of Public Health, State University of New York-Albany, Albany, NY USA
| | | | - Jorge L. Sangama
- Laboratorio ICEMR-Amazonia, Laboratorios de Investigacion y Desarrollo, Facultad de Ciencias y Filosofia, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Carlos Fernandez-Miñope
- Laboratorio ICEMR-Amazonia, Laboratorios de Investigacion y Desarrollo, Facultad de Ciencias y Filosofia, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Mitchel Guzman
- Laboratorio ICEMR-Amazonia, Laboratorios de Investigacion y Desarrollo, Facultad de Ciencias y Filosofia, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Carlos Tong
- Laboratorio ICEMR-Amazonia, Laboratorios de Investigacion y Desarrollo, Facultad de Ciencias y Filosofia, Universidad Peruana Cayetano Heredia, Lima, Peru
| | | | - Joseph M. Vinetz
- Laboratorio ICEMR-Amazonia, Laboratorios de Investigacion y Desarrollo, Facultad de Ciencias y Filosofia, Universidad Peruana Cayetano Heredia, Lima, Peru
- Division of Infectious Diseases, Department of Medicine, University of California San Diego, La Jolla, CA USA
- Present Address: Section of Infectious Diseases, Yale University School of Medicine, New Haven, CT USA
| | - Dionicia Gamboa
- Laboratorio ICEMR-Amazonia, Laboratorios de Investigacion y Desarrollo, Facultad de Ciencias y Filosofia, Universidad Peruana Cayetano Heredia, Lima, Peru
- Departamento de Ciencias Celulares y Moleculares, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru
- Instituto de Medicinal Tropical “Alexander von Humboldt”, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Marta Moreno
- Division of Infectious Diseases, Department of Medicine, University of California San Diego, La Jolla, CA USA
- Present Address: Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, UK
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12
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Vilay P, Nonaka D, Senamonty P, Lao M, Iwagami M, Kobayashi J, Hernandez PM, Phrasisombath K, Kounnavong S, Hongvanthong B, Brey PT, Kano S. Malaria prevalence, knowledge, perception, preventive and treatment behavior among military in Champasak and Attapeu provinces, Lao PDR: a mixed methods study. Trop Med Health 2019; 47:11. [PMID: 30700970 PMCID: PMC6347756 DOI: 10.1186/s41182-019-0138-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Accepted: 01/14/2019] [Indexed: 11/10/2022] Open
Abstract
Background Malaria is a major health problem in Lao People's Democratic Republic (Lao PDR) with high transmission in remote and forest areas, particularly in the South. The military is at risk of malaria infection especially those deployed in forest areas. This study determined the prevalence of malaria infection and assessed knowledge, perception, and preventive and treatment behavior regarding malaria among military personnel in two southern provinces in Lao PDR. Methods Quantitative and qualitative approaches were undertaken in Champasak and Attapeu provinces in 2017. From 313 military personnel, quantitative data were collected through questionnaire-based interviews and blood samples used for parasite detection by polymerase chain reaction (PCR). Qualitative data were collected through 7 focus group discussions and 17 in-depth interviews among 49 military personnel. Fisher's exact test and Mann-Whitney U test were used to assess the association between malaria infection and participant characteristics. Content analysis for qualitative data was performed to explore perception and treatment behaviors regarding malaria. Results The prevalence of malaria infection was 11.2% (Plasmodium falciparum: 1.3%, Plasmodium vivax: 9.3% and mixed infections: 0.6%). Many participants understood that malaria is transmitted through mosquito bites, although they did not necessarily know the name of vector mosquitoes (Anopheles). Surprisingly, more than a half also believed that malaria is transmitted through drinking stream water. One-third of the participants used long-lasting insecticidal nets. Due to limited supply, participants were often unable to use mosquito repellent and coils when necessary. Because participants were unable to receive timely diagnosis and appropriate treatment for malaria in their camps, they commonly practiced self-treatment using antibiotics, painkillers, and/or traditional medicines. They only go to a healthcare facility through their supervisor if their conditions worsen. Conclusions The prevalence of symptomatic and asymptomatic malaria was conspicuous among military in forest areas. Many participants believed that malaria is transmitted not only by mosquito bites but also from drinking stream water. Preventive equipment was often insufficient. Self-treatment was practiced before referring to healthcare facility. To further prevent military from contracting malaria, the National Malaria Control Program and military body should provide adequate and suitable health education, protective equipment, and on-site malaria case management.
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Affiliation(s)
- Phoutnalong Vilay
- 1Department of Global Health, Graduate School of Health Sciences, University of the Ryukyus, 207 Uehara-cho, Okinawa, 903-0215 Japan.,2Center of Malariology, Parasitology and Entomology, Ministry of Health, Vientiane, Lao PDR.,SATREPS Project for Parasitic Diseases, Vientiane, Lao PDR
| | - Daisuke Nonaka
- 1Department of Global Health, Graduate School of Health Sciences, University of the Ryukyus, 207 Uehara-cho, Okinawa, 903-0215 Japan.,SATREPS Project for Parasitic Diseases, Vientiane, Lao PDR
| | - Phosadeth Senamonty
- Military Institute of Diseases Prevention, Department of Military Medical, Ministry of Defense, Vientiane, Lao PDR
| | - Malayvanh Lao
- Military Institute of Diseases Prevention, Department of Military Medical, Ministry of Defense, Vientiane, Lao PDR
| | - Moritoshi Iwagami
- SATREPS Project for Parasitic Diseases, Vientiane, Lao PDR.,5Department of Tropical Medicine and Malaria, Research Institute, National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku-ku, Tokyo, 162-8655 Japan.,6Institut Pasteur du Laos, Ministry of Health, Vientiane, Lao PDR
| | - Jun Kobayashi
- 1Department of Global Health, Graduate School of Health Sciences, University of the Ryukyus, 207 Uehara-cho, Okinawa, 903-0215 Japan.,SATREPS Project for Parasitic Diseases, Vientiane, Lao PDR
| | - Paul Michael Hernandez
- 1Department of Global Health, Graduate School of Health Sciences, University of the Ryukyus, 207 Uehara-cho, Okinawa, 903-0215 Japan.,7Department of Environmental and Occupational Health, College of Public Health, University of the Philippines Manila, 625 Pedro Gil Street, Ermita, 1000 Manila, Philippines
| | | | - Sengchanh Kounnavong
- SATREPS Project for Parasitic Diseases, Vientiane, Lao PDR.,9Lao Tropical and Public Health Institute, Ministry of Health, Vientiane, Lao PDR
| | - Bouasy Hongvanthong
- 2Center of Malariology, Parasitology and Entomology, Ministry of Health, Vientiane, Lao PDR.,SATREPS Project for Parasitic Diseases, Vientiane, Lao PDR
| | - Paul T Brey
- SATREPS Project for Parasitic Diseases, Vientiane, Lao PDR.,6Institut Pasteur du Laos, Ministry of Health, Vientiane, Lao PDR
| | - Shigeyuki Kano
- SATREPS Project for Parasitic Diseases, Vientiane, Lao PDR.,5Department of Tropical Medicine and Malaria, Research Institute, National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku-ku, Tokyo, 162-8655 Japan
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13
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Tangena JAA, Thammavong P, Chonephetsarath S, Logan JG, Brey PT, Lindsay SW. Field evaluation of personal protection methods against outdoor-biting mosquitoes in Lao PDR. Parasit Vectors 2018; 11:661. [PMID: 30558671 PMCID: PMC6296151 DOI: 10.1186/s13071-018-3239-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 11/28/2018] [Indexed: 11/10/2022] Open
Abstract
Background Protecting people outdoors against mosquito-borne diseases is a major challenge. Here we compared commercially available personal protection methods to identify the most effective method for outdoor use in northern Lao PDR. Methods From June to August 2016 the protective efficacy of treatments were compared in a secondary forest during the afternoon and a village during the evening. Comparisons were made using a replicated Latin square design between: (i) short permethrin-treated overalls; (ii) long permethrin-treated overalls; (iii) short untreated overalls with para-menthane-3,8-diol (PMD) applied topically; (iv) short permethrin-treated overalls plus PMD applied topically; (v) short untreated overalls with metofluthrin coils in a metal casing worn on a belt; and (vi) long untreated overalls. Short untreated overalls served as the control. Cone tests were conducted on the treated and untreated fabric before and after field experiments. A questionnaire survey was used to measure social acceptability. Results Mosquito coils in a metal casing worn on a belt resulted in 92.3% (95% confidence interval, CI: 88.9–94.6%). landing protection from female mosquitoes in the afternoon and 68.8% (95% CI: 41.7–83.3%) protection in the evening compared to short untreated clothing. PMD was protective both when combined with short permethrin-treated overalls (afternoon, 68.2%, 95% CI: 52.6–78.7%; evening, 52.3%, 95% CI: 33.8–65.7%) and when used in combination with short untreated overalls (afternoon, 55.0%, 95% CI: 41.7–65.2%; evening, 25.2%, 95% CI: 9.4–38.2%). Whilst long permethrin-treated overalls were protective (afternoon, 61.1%, 95% CI: 51.4–68.8%; evening, 43.0%, 95% CI: 25.5–56.4%), short permethrin-treated overalls and long untreated overalls were not. Exposure to new permethrin-treated fabric in cone tests resulted in 25.0% (95% CI, 17.8–32.2%) and 26.2% (95% CI 16.7–35.8%) mortality for susceptible Ae. albopictus and susceptible Ae. aegypti, respectively. There was a loss of efficacy of permethrin-treated clothing after use in the field, with 3 min knockdown rates of Ae. albopictus and 1 h knockdown of Ae. aegypti decreasing over time. Participants considered all treatments acceptable. Conclusions The portable mosquito coils were highly protective against outdoor biting mosquitoes, although there are safety concerns related to its use. The combination of permethrin-treated clothing and PMD repellent represent an alternative treatment for protection against outdoor-biting mosquitoes. Electronic supplementary material The online version of this article (10.1186/s13071-018-3239-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Julie-Anne A Tangena
- Medical Entomology & Biology of Disease Vectors Laboratory, Institut Pasteur du Laos, Vientiane, Lao PDR.
| | - Phoutmany Thammavong
- Medical Entomology & Biology of Disease Vectors Laboratory, Institut Pasteur du Laos, Vientiane, Lao PDR
| | - Somsanith Chonephetsarath
- Medical Entomology & Biology of Disease Vectors Laboratory, Institut Pasteur du Laos, Vientiane, Lao PDR
| | - James G Logan
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK.,ARCTEC, London School of Hygiene and Tropical Medicine, London, UK
| | - Paul T Brey
- Medical Entomology & Biology of Disease Vectors Laboratory, Institut Pasteur du Laos, Vientiane, Lao PDR
| | - Steve W Lindsay
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK.,Department of Biosciences, Durham University, Durham, UK
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14
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Tangena JAA, Marcombe S, Thammavong P, Chonephetsarath S, Somphong B, Sayteng K, Grandadam M, Sutherland IW, Lindsay SW, Brey PT. Bionomics and insecticide resistance of the arboviral vector Aedes albopictus in northern Lao PDR. PLoS One 2018; 13:e0206387. [PMID: 30359425 PMCID: PMC6201963 DOI: 10.1371/journal.pone.0206387] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 10/11/2018] [Indexed: 12/21/2022] Open
Abstract
In the last four decades there has been a staggering increase in the geographical range of the arboviral vector Aedes albopictus (Skuse, 1894). This species is now found in every continent except Antarctica, increasing the distribution of arboviral diseases such as dengue and chikungunya. In Lao PDR dengue epidemics occur regularly, with cases of chikungunya also reported. As treatment methods for arboviral diseases is limited, the control of the vector mosquitoes are essential. There is a paucity of information on the bionomics and resistance status of this mosquito for successful vector control efforts. Here we describe the bionomics and insecticide resistance status of Ae. albopictus in Laos to identify opportunities for control. Adult Ae. albopictus were collected using human-baited double bed net (HDN) traps in forests, villages and rubber plantations and tested for alpha- and flaviviruses with RT-PCR. Surveys were also conducted to identify larval habitats. Seven adult and larval populations originating from Vientiane Capital and Luang Prabang province were tested against DDT, malathion, permethrin, deltamethrin and, temephos following WHO protocols. Aedes albopictus were found throughout the year, but were six-fold greater in the rainy season than the dry season. Adult females were active for 24 hours, with peak of behaviour at 18.00 h. The secondary forest and rubber plantation samples showed evidence of Pan-flaviviruses, while samples from the villages did not. More than half of the emerged Ae. albopictus were collected from mature rubber plantations (53.9%; 1,533/2,845). Most Ae. albopictus mosquitoes emerged from latex collection cups (19.7%; 562/2,845), small water containers (19.7%; 562/2,845) and tyres (17.4%; 495/2,845). Adult mosquitoes were susceptible to pyrethroids, apart from one population in Vientiane city. All populations were resistant to DDT (between 27-90% mortality) and all except one were resistant to malathion (20-86%). Three of the seven larval populations were resistant to temephos (42-87%), with suspected resistance found in three other populations (92-98%).This study demonstrates that rural areas in northern Laos are potential hot spots for arboviral disease transmission. Multiple-insecticide resistance was found. Aedes albopictus control efforts in villages need to expand to include secondary forests and rubber plantations, with larval source management and limited use of insecticides.
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Affiliation(s)
- Julie-Anne A. Tangena
- Medical Entomology and Vector-Borne Disease Laboratory Institut Pasteur du Laos, Vientiane, Laos
| | - Sébastien Marcombe
- Medical Entomology and Vector-Borne Disease Laboratory Institut Pasteur du Laos, Vientiane, Laos
| | - Phoutmany Thammavong
- Medical Entomology and Vector-Borne Disease Laboratory Institut Pasteur du Laos, Vientiane, Laos
| | | | - Boudsady Somphong
- Medical Entomology and Vector-Borne Disease Laboratory Institut Pasteur du Laos, Vientiane, Laos
| | - Kouxiong Sayteng
- Arbovirology and Emerging Viruses Laboratory, Institut Pasteur du Laos, Vientiane, Laos
| | - Marc Grandadam
- Medical Entomology and Vector-Borne Disease Laboratory Institut Pasteur du Laos, Vientiane, Laos
| | - Ian W. Sutherland
- United States Naval Medical Research Center—Asia, PSA SEMBAWANG, Singapore
- United States Navy Entomology Center of Excellence, NAS Jacksonville, Florida, United States of America
| | - Steve W. Lindsay
- Department of Biosciences, Durham University, Durham, United Kingdom
| | - Paul T. Brey
- Medical Entomology and Vector-Borne Disease Laboratory Institut Pasteur du Laos, Vientiane, Laos
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15
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Tangena JAA, Thammavong P, Lindsay SW, Brey PT. Risk of exposure to potential vector mosquitoes for rural workers in Northern Lao PDR. PLoS Negl Trop Dis 2017; 11:e0005802. [PMID: 28742854 PMCID: PMC5544251 DOI: 10.1371/journal.pntd.0005802] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Revised: 08/04/2017] [Accepted: 07/12/2017] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND One major consequence of economic development in South-East Asia has been a rapid expansion of rubber plantations, in which outbreaks of dengue and malaria have occurred. Here we explored the difference in risk of exposure to potential dengue, Japanese encephalitis (JE), and malaria vectors between rubber workers and those engaged in traditional forest activities in northern Laos PDR. METHODOLOGY/PRINCIPAL FINDINGS Adult mosquitoes were collected for nine months in secondary forests, mature and immature rubber plantations, and villages. Human behavior data were collected using rapid participatory rural appraisals and surveys. Exposure risk was assessed by combining vector and human behavior and calculating the basic reproduction number (R0) in different typologies. Compared to those that stayed in the village, the risk of dengue vector exposure was higher for those that visited the secondary forests during the day (odds ratio (OR) 36.0), for those living and working in rubber plantations (OR 16.2) and for those that tapped rubber (OR 3.2). Exposure to JE vectors was also higher in the forest (OR 1.4) and, similar when working (OR 1.0) and living in the plantations (OR 0.8). Exposure to malaria vectors was greater in the forest (OR 1.3), similar when working in the plantations (OR 0.9) and lower when living in the plantations (OR 0.6). R0 for dengue was >2.8 for all habitats surveyed, except villages where R0≤0.06. The main malaria vector in all habitats was Anopheles maculatus s.l. in the rainy season and An. minimus s.l. in the dry season. CONCLUSIONS/SIGNIFICANCE The highest risk of exposure to vector mosquitoes occurred when people visit natural forests. However, since rubber workers spend long periods in the rubber plantations, their risk of exposure is increased greatly compared to those who temporarily enter natural forests or remain in the village. This study highlights the necessity of broadening mosquito control to include rubber plantations.
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Affiliation(s)
- Julie-Anne A. Tangena
- Department of Medical Entomology & Biology of Disease Vectors, Institut Pasteur du Laos, Vientiane, Lao PDR
- School of Biological and Biomedical Sciences, Durham University, Durham, United Kingdom
- * E-mail:
| | - Phoutmany Thammavong
- Department of Medical Entomology & Biology of Disease Vectors, Institut Pasteur du Laos, Vientiane, Lao PDR
| | - Steve W. Lindsay
- School of Biological and Biomedical Sciences, Durham University, Durham, United Kingdom
| | - Paul T. Brey
- Department of Medical Entomology & Biology of Disease Vectors, Institut Pasteur du Laos, Vientiane, Lao PDR
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