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Sun D, Jiang H, Wang G, Hu X, Wang S, Chen Y. Factors Contributing to the Pre-Elimination of Malaria from Hainan Island, China, 1986-2009. Am J Trop Med Hyg 2023; 109:1063-1071. [PMID: 37918006 PMCID: PMC10622475 DOI: 10.4269/ajtmh.23-0303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 08/17/2023] [Indexed: 11/04/2023] Open
Abstract
Malaria was endemic in Hainan Island, China, for a lengthy period before its elimination. Here, we aim to gain a better understanding of malaria elimination by assessing and quantifying the relative effects of longitudinal changes in specific antimalarial interventions, socioeconomic development approaches, and malaria vectors on malaria prevalence in Hainan during the 1986-2009 pre-elimination period. Annual data were collected on the incidence of malaria, the number of residents protected by drugs (RPD), the number of residents protected by vector control, the presence of Anopheles minimus and Anopheles dirus, the annual per capita income of rural residents, major cash crop (rubber plantation) areas, the literacy rate of adult rural residents, and the rate of reinforced concrete house construction in rural areas. Backward stepwise multiple linear regression models were developed to identify the factors associated with the annual malaria incidence (AMI). The AMI declined from 20.3 to 0.8 per 10,000 population from 1986 to 2009; this decrease was significantly associated with an increase in the number of RPD and improved literacy rate among rural adults. The results of this study implied that the sustained distribution of antimalarial drugs and increase in education levels in risk areas significantly impacted the reduction and elimination of malaria infection in Hainan. We suggest that these findings could be applicable to malaria-endemic areas in Southeast Asia with similar natural and socioeconomic environments to Hainan and where malaria incidence has decreased to a low level.
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Affiliation(s)
- Dingwei Sun
- Hainan Provincial Center for Disease Control and Prevention, Haikou, China
| | - Hongwei Jiang
- Graduate School of Humanities, Osaka University, Toyonaka City, Japan
- Research Institute for Humanity and Nature, Kyoto, Japan
| | - Guangze Wang
- Hainan Provincial Center for Disease Control and Prevention, Haikou, China
| | - Ximin Hu
- Hainan Provincial Center for Disease Control and Prevention, Haikou, China
| | - Shanqing Wang
- Hainan Provincial Center for Disease Control and Prevention, Haikou, China
| | - Yan Chen
- Hainan Provincial Center for Disease Control and Prevention, Haikou, China
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Olagunju EA. Is the presence of mosquitoes an indicator of poor environmental sanitation? JOURNAL OF WATER AND HEALTH 2023; 21:385-401. [PMID: 37338318 PMCID: wh_2023_280 DOI: 10.2166/wh.2023.280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/21/2023]
Abstract
The World Health Organization has designated mosquitoes as the most lethal animal since they are known to spread pathogen-transmitting organisms. Understanding the many environmental elements that contribute to the spread of these vectors is one of the many strategies used to stop them. If there are mosquitoes around people, it may indicate that there is not an appropriate environmental sanitation program in place in the community or region. Environmental sanitation involves improving any elements of the physical environment that could have a negative impact on a person's survival, health, or physical environment. Keywords containing 'Aedes,' 'Culex,' 'Anopheles,' 'dengue,' 'malaria,' 'yellow fever,' 'Zika,' 'West Nile,' 'chikungunya,' 'resident,' 'environment,' 'sanitation,' 'mosquito control,' and 'breeding sites' of published articles on PubMed, Google Scholar, and ResearchGate were reviewed. It was discovered that the general population should be involved in mosquito and mosquito-borne disease control. Collaboration between health professionals and the general population is essential. The purpose of this paper is to increase public awareness of environmental health issues related to diseases carried by mosquitoes.
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Affiliation(s)
- Emmanuel Ajibola Olagunju
- Department of Crop and Environmental Protection, Faculty of Agricultural Sciences, Ladoke Akintola University of Technology, Ogbomoso, Nigeria E-mail:
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3
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Geographical distribution of falciparum malaria in the world and its relationship with the human development index (HDI): countries based on the WHO report in 2017. J Public Health (Oxf) 2022. [DOI: 10.1007/s10389-020-01336-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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4
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Nguyen-Tien T, Bui AN, Ling J, Tran-Hai S, Pham-Thanh L, Bui VN, Dao TD, Hoang TT, Vu LT, Tran PV, Vu DT, Lundkvist Å, Nguyen-Viet H, Magnusson U, Lindahl JF. The Distribution and Composition of Vector Abundance in Hanoi City, Vietnam: Association with Livestock Keeping and Flavivirus Detection. Viruses 2021; 13:v13112291. [PMID: 34835097 PMCID: PMC8621768 DOI: 10.3390/v13112291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2021] [Revised: 11/12/2021] [Accepted: 11/14/2021] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Dengue virus and Japanese encephalitis virus are two common flaviviruses that are spread widely by Aedes and Culex mosquitoes. Livestock keeping is vital for cities; however, it can pose the risk of increasing the mosquito population. Our study explored how livestock keeping in and around a large city is associated with the presence of mosquitoes and the risk of them spreading flaviviruses. METHODS An entomological study was conducted in 6 districts with 233 households with livestock, and 280 households without livestock, in Hanoi city. BG-Sentinel traps and CDC light traps were used to collect mosquitoes close to animal farms and human habitats. Adult mosquitoes were counted, identified to species level, and grouped into 385 pools, which were screened for flaviviruses using a pan-flavivirus qPCR protocol and sequencing. RESULTS A total of 12,861 adult mosquitoes were collected at the 513 households, with 5 different genera collected, of which the Culex genus was the most abundant. Our study found that there was a positive association between livestock keeping and the size of the mosquito population-most predominantly between pig rearing and Culex species (p < 0.001). One pool of Cx. tritaeniorhynchus, collected in a peri-urban district, was found to be positive for Japanese encephalitis virus. CONCLUSIONS The risk of flavivirus transmission in urban areas of Hanoi city due to the spread of Culex and Aedes mosquitoes could be facilitated by livestock keeping.
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Affiliation(s)
- Thang Nguyen-Tien
- Zoonosis Science Center, Department of Medical Biochemistry and Microbiology, Uppsala University, 75237 Uppsala, Sweden; (J.L.); (L.P.-T.); (Å.L.); (J.F.L.)
- International Livestock Research Institute (ILRI), Hanoi 10000, Vietnam;
- Correspondence: or
| | - Anh Ngoc Bui
- National Institute of Veterinary Research, Hanoi 10000, Vietnam; (A.N.B.); (V.N.B.); (T.D.D.); (T.T.H.)
| | - Jiaxin Ling
- Zoonosis Science Center, Department of Medical Biochemistry and Microbiology, Uppsala University, 75237 Uppsala, Sweden; (J.L.); (L.P.-T.); (Å.L.); (J.F.L.)
| | - Son Tran-Hai
- National Institute of Hygiene and Epidemiology, Hanoi 10000, Vietnam; (S.T.-H.); (L.T.V.); (P.V.T.); (D.T.V.)
| | - Long Pham-Thanh
- Zoonosis Science Center, Department of Medical Biochemistry and Microbiology, Uppsala University, 75237 Uppsala, Sweden; (J.L.); (L.P.-T.); (Å.L.); (J.F.L.)
- International Livestock Research Institute (ILRI), Hanoi 10000, Vietnam;
- Department of Animal Health, Ministry of Agriculture and Rural Development, Hanoi 10000, Vietnam
| | - Vuong Nghia Bui
- National Institute of Veterinary Research, Hanoi 10000, Vietnam; (A.N.B.); (V.N.B.); (T.D.D.); (T.T.H.)
| | - Tung Duy Dao
- National Institute of Veterinary Research, Hanoi 10000, Vietnam; (A.N.B.); (V.N.B.); (T.D.D.); (T.T.H.)
| | - Thuy Thi Hoang
- National Institute of Veterinary Research, Hanoi 10000, Vietnam; (A.N.B.); (V.N.B.); (T.D.D.); (T.T.H.)
| | - Lieu Thi Vu
- National Institute of Hygiene and Epidemiology, Hanoi 10000, Vietnam; (S.T.-H.); (L.T.V.); (P.V.T.); (D.T.V.)
| | - Phong Vu Tran
- National Institute of Hygiene and Epidemiology, Hanoi 10000, Vietnam; (S.T.-H.); (L.T.V.); (P.V.T.); (D.T.V.)
| | - Duoc Trong Vu
- National Institute of Hygiene and Epidemiology, Hanoi 10000, Vietnam; (S.T.-H.); (L.T.V.); (P.V.T.); (D.T.V.)
| | - Åke Lundkvist
- Zoonosis Science Center, Department of Medical Biochemistry and Microbiology, Uppsala University, 75237 Uppsala, Sweden; (J.L.); (L.P.-T.); (Å.L.); (J.F.L.)
| | - Hung Nguyen-Viet
- International Livestock Research Institute (ILRI), Hanoi 10000, Vietnam;
| | - Ulf Magnusson
- Department of Clinical Sciences, Swedish University of Agricultural Sciences, 75007 Uppsala, Sweden;
| | - Johanna Frida Lindahl
- Zoonosis Science Center, Department of Medical Biochemistry and Microbiology, Uppsala University, 75237 Uppsala, Sweden; (J.L.); (L.P.-T.); (Å.L.); (J.F.L.)
- International Livestock Research Institute (ILRI), Hanoi 10000, Vietnam;
- Department of Clinical Sciences, Swedish University of Agricultural Sciences, 75007 Uppsala, Sweden;
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Kaindoa EW, Mmbando AS, Shirima R, Hape EE, Okumu FO. Insecticide-treated eave ribbons for malaria vector control in low-income communities. Malar J 2021; 20:415. [PMID: 34688285 PMCID: PMC8542300 DOI: 10.1186/s12936-021-03945-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Accepted: 10/06/2021] [Indexed: 12/03/2022] Open
Abstract
Supplementary tools are required to address the limitations of insecticide-treated nets (ITNs) and indoor residual spraying (IRS), which are currently the core vector control methods against malaria in Africa. The eave ribbons technology exploits the natural house-entry behaviours of major malaria vectors to deliver mosquitocidal or repellent actives around eave spaces through which the Anopheles mosquitoes usually enter human dwellings. They confer protection by preventing biting indoors and in the peri-domestic outdoor spaces, and also killing a significant proportion of the mosquitoes. Current versions of eave ribbons are made of low-cost hessian fabric infused with candidate insecticides and can be easily fitted onto multiple house types without any additional modifications. This article reviews the evidence for efficacy of the technology, and discusses its potential as affordable and versatile supplementary approach for targeted and efficient control of mosquito-borne diseases, particularly malaria. Given their simplicity and demonstrated potential in previous studies, future research should investigate ways to optimize scalability and effectiveness of the ribbons. It is also important to assess whether the ribbons may constitute a less-cumbersome, but more affordable substitute for other interventions, such as IRS, by judiciously using lower quantities of selected insecticides targeted around eave spaces to deliver equivalent or greater suppression of malaria transmission.
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Affiliation(s)
- Emmanuel W Kaindoa
- Environmental Health and Ecological Science Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania. .,School of Life Science and Bioengineering, The Nelson Mandela African Institution of Science and Technology, P. O. Box 447, Arusha, Tanzania.
| | - Arnold S Mmbando
- Environmental Health and Ecological Science Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania.,Department of Biosciences, Durham University, DH13LE, Durham, UK
| | - Ruth Shirima
- Environmental Health and Ecological Science Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania
| | - Emmanuel E Hape
- Environmental Health and Ecological Science Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania.,Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, G12 8QQ, Glasgow, UK
| | - Fredros O Okumu
- Environmental Health and Ecological Science Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania.,School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.,Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, G12 8QQ, Glasgow, UK.,School of Life Science and Bioengineering, The Nelson Mandela African Institution of Science and Technology, P. O. Box 447, Arusha, Tanzania
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6
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Mburu MM, Zembere K, Mzilahowa T, Terlouw AD, Malenga T, van den Berg H, Takken W, McCann RS. Impact of cattle on the abundance of indoor and outdoor resting malaria vectors in southern Malawi. Malar J 2021; 20:353. [PMID: 34446033 PMCID: PMC8390081 DOI: 10.1186/s12936-021-03885-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 08/16/2021] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Understanding the blood feeding preferences and resting habits of malaria vectors is important for assessing and designing effective malaria vector control tools. The presence of livestock, such as cattle, which are used as blood meal hosts by some malaria vectors, may impact malaria parasite transmission dynamics. The presence of livestock may provide sufficient blood meals for the vectors, thereby reducing the frequency of vectors biting humans. Alternatively, the presence of cattle may enhance the availability of blood meals such that infectious mosquitoes may survive longer, thereby increasing the risk of malaria transmission. This study assessed the effect of household-level cattle presence and distribution on the abundance of indoor and outdoor resting malaria vectors. METHODS Houses with and without cattle were selected in Chikwawa district, southern Malawi for sampling resting malaria vectors. Prokopack aspirators and clay pots were used for indoor and outdoor sampling, respectively. Each house was sampled over two consecutive days. For houses with cattle nearby, the number of cattle and the distances from the house to where the cattle were corralled the previous night were recorded. All data were analysed using generalized linear models fitted with Poisson distribution. RESULTS The malaria vectors caught resting indoors were Anopheles gambiae sensu stricto (s.s.), Anopheles arabiensis and Anopheles funestus s.s. Outdoor collections consisted primarily of An. arabiensis. The catch sizes of indoor resting An. gambiae sensu lato (s.l.) were not different in houses with and without cattle (P = 0.34). The presence of cattle near a house was associated with a reduction in the abundance of indoor resting An. funestus s.l. (P = 0.04). This effect was strongest when cattle were kept overnight ≤ 15 m away from the houses (P = 0.03). The blood meal hosts varied across the species. CONCLUSION These results highlight differences between malaria vector species and their interactions with potential blood meal hosts, which may have implications for malaria risk. Whereas An. arabiensis remained unaffected, the reduction of An. funestus s.s. in houses near cattle suggests a potential protective effect of cattle. However, the low abundance of mosquitoes reduced the power of some analyses and limited the generalizability of the results to other settings. Therefore, further studies incorporating the vectors' host-seeking behaviour/human biting rates are recommended to fully support the primary finding.
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Affiliation(s)
- Monicah M Mburu
- School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre, Malawi.
- Laboratory of Entomology, Wageningen University and Research, Wageningen, The Netherlands.
- Macha Research Trust, Choma, Zambia.
| | - Kennedy Zembere
- School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre, Malawi
- Malawi-Liverpool-Wellcome Trust, Blantyre, Malawi
| | - Themba Mzilahowa
- School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre, Malawi
- MAC Communicable Diseases Action Centre, Blantyre, Malawi
| | - Anja D Terlouw
- Malawi-Liverpool-Wellcome Trust, Blantyre, Malawi
- Liverpool School of Tropical Medicine, Liverpool, UK
| | - Tumaini Malenga
- School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Henk van den Berg
- Laboratory of Entomology, Wageningen University and Research, Wageningen, The Netherlands
| | - Willem Takken
- Laboratory of Entomology, Wageningen University and Research, Wageningen, The Netherlands
| | - Robert S McCann
- School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre, Malawi
- Laboratory of Entomology, Wageningen University and Research, Wageningen, The Netherlands
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, USA
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Cramer EY, Quang NX, Hertz JC, Van Nguyen D, Quang HH, Mendenhall I, Lover AA. Ivermectin Treatment for Cattle Reduced the Survival of Two Malaria Vectors, Anopheles dirus and Anopheles epiroticus, Under Laboratory Conditions in Central Vietnam. Am J Trop Med Hyg 2021; 104:2165-2168. [PMID: 33901003 PMCID: PMC8176477 DOI: 10.4269/ajtmh.20-1239] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 03/03/2021] [Indexed: 01/30/2023] Open
Abstract
Ivermectin is a low-cost and nontoxic mosquitocide that may have a role in malaria elimination. However, the extent to which this drug impacts the mortality of Anopheles dirus and Anopheles epiroticus, two important malaria vectors in Southeast Asia, is unknown. This study compared and quantified anopheline mortality after feeding on ivermectin-treated cattle and control cattle in Vietnam. Local anopheline colonies fed on cattle 1 to 3, 6 to 8, 13 to 15, 20 to 22, and 28 to 30 days after injection (DAI) with ivermectin (intervention) or saline (control). An. dirus that fed on ivermectin-treated cattle had higher mortality rates than controls for up to 20 DAI (P < 0.05); An. epiroticus that fed on ivermectin-treated cattle had consistently higher mortality rates than controls for up to 8 DAI (P < 0.05). Feeding on ivermectin-treated cattle increased the mortality rate of these vector species for biologically relevant time periods. Therefore, ivermectin has the potential to become an important tool for integrated vector management.
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Affiliation(s)
- Estee Y Cramer
- 1Department of Biostatistics and Epidemiology, School of Public Health and Health Sciences, University of Massachusetts-Amherst, Amherst, Massachusetts
| | - Nguyen Xuan Quang
- 2Institute for Malariology, Parasitology and Entomology, Ministry of Health, Quy Nhon, Vietnam
| | | | - Do Van Nguyen
- 2Institute for Malariology, Parasitology and Entomology, Ministry of Health, Quy Nhon, Vietnam
| | - Huynh Hong Quang
- 2Institute for Malariology, Parasitology and Entomology, Ministry of Health, Quy Nhon, Vietnam
| | - Ian Mendenhall
- 4Programme in Emerging Infectious Diseases, Duke-NUS Medical School, Singapore
| | - Andrew A Lover
- 1Department of Biostatistics and Epidemiology, School of Public Health and Health Sciences, University of Massachusetts-Amherst, Amherst, Massachusetts
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Jones RT, Tusting LS, Smith HMP, Segbaya S, Macdonald MB, Bangs MJ, Logan JG. The Role of the Private Sector in Supporting Malaria Control in Resource Development Settings. J Infect Dis 2021; 222:S701-S708. [PMID: 33119094 PMCID: PMC7594257 DOI: 10.1093/infdis/jiaa488] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Industrial operations of the private sector, such as extraction, agriculture, and construction, can bring large numbers of people into new settlement areas and cause environmental change that promotes the transmission of vector-borne diseases. Industry-related workers and communities unduly exposed to infection risk typically lack the knowledge and means to protect themselves. However, there is a strong business rationale for protecting local resident employees through integrated vector control programs, as well as an ethical responsibility to care for these individuals and the affected communities. We discuss the role and challenges of the private sector in developing malaria control programs, which can include extensive collaborations with the public sector that go on to form the basis of national vector control programs or more broadly support local healthcare systems.
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Affiliation(s)
- Robert T Jones
- Arthropod Control Product Test Centre, London School of Hygiene & Tropical Medicine, London, United Kingdom.,Department of Disease Control, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Lucy S Tusting
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Hugh M P Smith
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | | | | | - Michael J Bangs
- lnternational SOS, Ltd., Timika, Papua Province, Indonesia.,International SOS, Ltd., Kolwesi, Lualaba Province, Democratic Republic of Congo
| | - James G Logan
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, United Kingdom
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Aung PL, Soe MT, Oo TL, Khin A, Thi A, Zhao Y, Cao Y, Cui L, Kyaw MP, Parker DM. Predictors of malaria rapid diagnostic test positivity in a high burden area of Paletwa Township, Chin State in Western Myanmar. Infect Dis Poverty 2021; 10:6. [PMID: 33431057 PMCID: PMC7802189 DOI: 10.1186/s40249-020-00787-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 12/16/2020] [Indexed: 12/05/2022] Open
Abstract
Background Despite major reductions in malaria burden across Myanmar, clusters of the disease continue to persist in specific subregions. This study aimed to assess the predictors of test positivity among people living in Paletwa Township of Chin State, an area of persistently high malaria burden. Methods Four villages with the highest malaria incidence from Paletwa Township were purposively selected. The characteristics of 1045 subjects seeking malaria diagnosis from the four assigned village health volunteers from January to December, 2018 were retrospectively analyzed. Their household conditions and surroundings were also recorded using a checklist. Descriptive statistics and logistic regression models were applied to investigate potential associations between individual and household characteristics and malaria diagnosis. Results In 2017, the Paletwa township presented 20.9% positivity and an annual parasite index of 46.9 cases per 1000 people. Plasmodium falciparum was the predominant species and accounted for more than 80.0% of all infections. Among 1045 people presenting at a clinic with malaria symptoms, 31.1% were diagnosed with malaria. Predictors for test positivity included living in a hut [adjusted odds ratios (a OR): 2.3, 95% confidence intervals (CI): 1.2–4.6], owning farm animals (aOR: 1.7, 95% CI: 1.1–3.6), using non-septic type of toilets (aOR: 1.9, 95% CI: 1.1–8.4), presenting with fever (aOR: 1.9, 95% CI: 1.1–3.0), having a malaria episode within the last year (aOR: 2.9, 95% CI: 1.4–5.8), traveling outside the village in the previous 14 days (aOR: 4.5, 95% CI: 1.5–13.4), and not using bed nets (a OR: 3.4, 95% CI: 2.3–5.1). There were no statistically significant differences by age or gender in this present analysis. Conclusions The results from this study, including a high proportion of P. falciparum infections, little difference in age, sex, or occupation, suggest that malaria is a major burden for these study villages. Targeted health education campaigns should be introduced to strengthen synchronous diagnosis-seeking behaviors, tighten treatment adherence, receiving a diagnosis after traveling to endemic regions, and using bed nets properly. We suggest increased surveillance, early diagnosis, and treatment efforts to control the disease and then to consider the local elimination.![]()
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Affiliation(s)
| | - Myat Thu Soe
- Myanmar Health Network Organization, Yangon, Myanmar
| | - Thit Lwin Oo
- Myanmar Health Network Organization, Yangon, Myanmar
| | - Aung Khin
- Myanmar Health Assistant Association, Yangon, Myanmar
| | - Aung Thi
- Department of Public Health, Ministry of Health and Sports, NayPyiTaw, Myanmar
| | - Yan Zhao
- Department of Immunology, College of Basic Medical Science, China Medical University, Shenyang, 110122, Liaoning, China
| | - Yaming Cao
- Department of Immunology, College of Basic Medical Science, China Medical University, Shenyang, 110122, Liaoning, China
| | - Liwang Cui
- Division of Infectious Diseases and International Medicine, Department of Internal Medicine, Morsani College of Medicine, University of South Florida, 3720 Spectrum Boulevard, Suite 304, Tampa, FL, 33612, USA
| | | | - Daniel M Parker
- Department of Population Health and Disease Prevention, Department of Epidemiology, University of California, Irvine, USA.
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Madewell ZJ, López MR, Espinosa-Bode A, Brouwer KC, Sánchez CG, McCracken JP. Inverse association between dengue, chikungunya, and Zika virus infection and indicators of household air pollution in Santa Rosa, Guatemala: A case-control study, 2011-2018. PLoS One 2020; 15:e0234399. [PMID: 32559225 PMCID: PMC7304608 DOI: 10.1371/journal.pone.0234399] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 05/24/2020] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Dengue, chikungunya, and Zika viruses are increasingly important public health problems. Burning vegetation, leaves, and other plant products have been shown to be effective mosquito repellents for their vector, Aedes spp., but there has been scant research on whether firewood cooking smoke in households influences mosquito populations or mosquito-borne diseases. About 2.9 billion people worldwide use biomass fuel for household cooking and heating, resulting in an estimated 1.6 million deaths annually from household air pollution (HAP)-related diseases. Global health agencies now encourage households to transition from biomass to clean fuels, but it is unclear whether such interventions may actually increase risk for mosquito-borne diseases. This retrospective case-control study evaluated associations between arboviral infections and cooking with firewood in Santa Rosa, Guatemala. METHOD Vigilancia Integrada Comunitaria (VICo) was a prospective public health surveillance system for bacterial, parasitic, and viral causes of diarrheal, neurological, respiratory, and febrile illnesses in hospitals and clinics in the department of Santa Rosa, Guatemala. Enrolled VICo in-patients and out-patients during 2011-2018 were interviewed using standardized questionnaires on demographics and household characteristics. Blood and stool specimens were collected and tested to identify the etiologies presenting symptoms. Cases were defined as laboratory-positive for dengue, chikungunya, or Zika virus infections. Controls were laboratory-positive for bacterial and viral diarrheal illnesses (e.g., Salmonella, Shigella, Campylobacter, Escherichia coli, rotavirus, norovirus, sapovirus, or astrovirus). Cooking with firewood, kitchen location, stove type, and firewood cooking frequency were the independent exposure variables. Logistic regression models were used to analyze unadjusted and adjusted associations between arboviral infections and exposures of interest. RESULT There were 311 arboviral cases and 1,239 diarrheal controls. Arboviral infections were inversely associated with cooking with firewood in the main house (AOR: 0.22; 95% CI: 0.08-0.57), cooking with firewood on an open hearth (AOR: 0.50; 95% CI: 0.33-0.78), and cooking with firewood ≥5 times per week (AOR: 0.54; 95% CI: 0.36-0.81), adjusting for age, sex, ethnicity, socioeconomic status index, number of people per household, community population density, community elevation, recruitment location, season, and admission year. CONCLUSION Several primary determinants of HAP exposure were inversely associated with arboviral infections. Additional studies are needed to understand whether interventions to reduce HAP might actually increase risk for mosquito-borne infectious diseases, which would warrant improved education and mosquito control efforts in conjunction with fuel interventions.
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Affiliation(s)
- Zachary J. Madewell
- Centro de Estudios en Salud, Universidad del Valle de Guatemala, Guatemala City, Guatemala
- PhD Program in Public Health (Epidemiology), University of California, San Diego, CA, United States of America
- San Diego State University, San Diego, CA, United States of America
| | - María Reneé López
- Centro de Estudios en Salud, Universidad del Valle de Guatemala, Guatemala City, Guatemala
| | - Andrés Espinosa-Bode
- Division of Global Health Protection, Centers for Disease Control and Prevention, Atlanta, GA, United States of America
| | - Kimberly C. Brouwer
- Division of Global Health, Department of Family Medicine & Public Health, University of California, San Diego, CA, United States of America
| | - César G. Sánchez
- Ministerio de Salud Pública y Asistencia Social, Guatemala City, Guatemala
| | - John P. McCracken
- Centro de Estudios en Salud, Universidad del Valle de Guatemala, Guatemala City, Guatemala
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Semifield Evaluation of Improved Passive Outdoor Host Seeking Device (POHD) for Outdoor Control of Anopheles arabiensis Mosquitoes. ScientificWorldJournal 2020; 2020:8938309. [PMID: 32547328 PMCID: PMC7271259 DOI: 10.1155/2020/8938309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2019] [Revised: 03/07/2020] [Accepted: 04/13/2020] [Indexed: 12/03/2022] Open
Abstract
Despite the considerable progress made so far, the effectiveness and mass application of odour-baited outdoor mosquito control devices in pipelines is limited by several factors. These include the design and size of the devices, optimal placement of attractive blends, and nature of materials into which the blends are impregnated. The primary aim of this study was to manipulate these factors to improve the attractiveness of our recently developed passive outdoor host seeking device (POHD) to outdoor biting Anopheles arabiensis. Specifically, the study aimed to determine optimal placement of odour blends and killing bioactives in POHD for maximum attraction and killing of An. arabiensis and to assess the effects of blend types, formulation, and residual activity on attractiveness of the POHD to An. arabiensis. The POHDs baited with attractive blends, carbon dioxide (CO2), and bendiocarb-treated electrostatic netting were placed either towards the top or bottom openings, and other modifications were exposed to An. arabiensis under the semifield system at Ifakara Health Institute (IHI). Each night, a total of 100 starved female, 3–7-day-old, semifield reared An. arabiensis mosquitoes were released, collected the next morning (alive or dead), counted, and recorded. Live mosquitoes were maintained in the semifield insectary and monitored for 24 hours mortality. Each treatment combination of the POHD was tested in three replicates. Overall, the results indicated that the proportion of mosquitoes attracted to and killed in the POHD varied with position of attractants and killing agent (bendiocarb). The POHD with bottom placed attractants and bendiocarb attracted and killed higher proportion of mosquitoes compared to the POHD with top placed attractants and bendiocarb. The highest mortalities were observed when the POHD was baited with a combination of attractive blends and CO2. Moreover, the residual activity of attractive blends applied inside POHD varied with type and formulation of attractive blend. The POHD packed with Mbita and Ifakara blend in microencapsulated pellets (granules) attracted higher proportion of mosquitoes than that baited with soaked nylon-strip formulation of either blends. Interestingly, POHD baited with Mbita blend in microencapsulated pellets (granules) formulation attracted and killed higher proportion of mosquitoes (>90%) than that baited with Ifakara blend even 9 months after application. Conclusively, the POHD remained effective for a relatively longer period of time when baited with bottom placed synthetic blends and CO2 combination, thus warranting further trials under real life situations.
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12
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Lippi CA, Mao L, Stewart-Ibarra AM, Heydari N, Ayala EB, Burkett-Cadena ND, Blackburn JK, Ryan SJ. A network analysis framework to improve the delivery of mosquito abatement services in Machala, Ecuador. Int J Health Geogr 2020; 19:3. [PMID: 32046732 PMCID: PMC7014633 DOI: 10.1186/s12942-020-0196-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Accepted: 01/18/2020] [Indexed: 11/12/2022] Open
Abstract
Background Vector-borne disease places a high health and economic burden in the American tropics. Comprehensive vector control programs remain the primary method of containing local outbreaks. With limited resources, many vector control operations struggle to serve all affected communities within their districts. In the coastal city of Machala, Ecuador, vector control services, such as application of larvicides and truck-mounted fogging, are delivered through two deployment facilities managed by the Ecuadorian Ministry of Health. Public health professionals in Machala face several logistical issues when delivering mosquito abatement services, namely applying limited resources in ways that will most effectively suppress vectors of malaria, dengue, and encephalitis viruses. Methods Using a transportation network analysis framework, we built models of service areas and optimized delivery routes based on distance costs associated with accessing neighborhoods throughout the city. Optimized routes were used to estimate the relative cost of accessing neighborhoods for mosquito control services in Machala, creating a visual tool to guide decision makers and maximize mosquito control program efficiency. Location-allocation analyses were performed to evaluate efficiency gains of moving service deployment to other available locations with respect to distance to service hub, neighborhood population, dengue incidence, and housing condition. Results Using this framework, we identified different locations for targeting mosquito control efforts, dependent upon management goals and specified risk factors of interest, including human population, housing condition, and reported dengue incidence. Our models indicate that neighborhoods on the periphery of Machala with the poorest housing conditions are the most costly to access. Optimal locations of facilities for deployment of control services change depending on pre-determined management priorities, increasing the population served via inexpensive routes up to 34.9%, and reducing overall cost of accessing neighborhoods up to 12.7%. Conclusions Our transportation network models indicate that current locations of mosquito control facilities in Machala are not ideal for minimizing driving distances or maximizing populations served. Services may be optimized by moving vector control operations to other existing public health facilities in Machala. This work represents a first step in creating a spatial tool for planning and critically evaluating the systematic delivery of mosquito control services in Machala and elsewhere.
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Affiliation(s)
- Catherine A Lippi
- Quantitative Disease Ecology and Conservation (QDEC) Lab Group, Department of Geography, University of Florida, Gainesville, FL, USA. .,Emerging Pathogens Institute, University of Florida, Gainesville, FL, USA.
| | - Liang Mao
- Department of Geography, University of Florida, Gainesville, FL, USA
| | - Anna M Stewart-Ibarra
- InterAmerican Institute for Global Change Research, Department of Montevideo, Montevideo, Uruguay.,Institute for Global Health and Translational Science, State University of New York Upstate Medical University, Syracuse, NY, USA
| | - Naveed Heydari
- Institute for Global Health and Translational Science, State University of New York Upstate Medical University, Syracuse, NY, USA
| | - Efraín Beltrán Ayala
- Unidad Académica de Ciencias Químicas y de la Salud, Universidad Técnica de Machala, Machala, Ecuador
| | | | - Jason K Blackburn
- Emerging Pathogens Institute, University of Florida, Gainesville, FL, USA.,Spatial Epidemiology and Ecology Research (SEER) Laboratory, Department of Geography, University of Florida, Gainesville, FL, USA
| | - Sadie J Ryan
- Quantitative Disease Ecology and Conservation (QDEC) Lab Group, Department of Geography, University of Florida, Gainesville, FL, USA. .,Emerging Pathogens Institute, University of Florida, Gainesville, FL, USA.
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13
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Edwards HM, Sriwichai P, Kirabittir K, Prachumsri J, Chavez IF, Hii J. Transmission risk beyond the village: entomological and human factors contributing to residual malaria transmission in an area approaching malaria elimination on the Thailand-Myanmar border. Malar J 2019; 18:221. [PMID: 31262309 PMCID: PMC6604376 DOI: 10.1186/s12936-019-2852-5] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2019] [Accepted: 06/19/2019] [Indexed: 11/12/2022] Open
Abstract
Background A mixed methods study was conducted to look at the
magnitude of residual malaria transmission (RMT) and factors contributing to low (< 1% prevalence), but sustained transmission in rural communities on the Thai–Myanmar border. Methods A cross-sectional behaviour and net survey, observational surveys and entomological collections in both villages and forested farm huts frequented by community members for subsistence farming practices were conducted. Results Community members frequently stayed overnight at subsistence farm huts or in the forest. Entomological collections showed higher biting rates of primary vectors in forested farm hut sites and in a more forested village setting compared to a village with clustered housing and better infrastructure. Despite high levels of outdoor biting, biting exposure occurred predominantly indoors, particularly for non-users of long-lasting insecticidal nets (LLINs). Risk of biting exposure was exacerbated by sub-optimal coverage of LLINs, particularly in subsistence farm huts and in the forest. Furthermore, early waking hours when people had left the safety of their nets coincided with peaks in biting in later morning hours. Conclusions Entomological and epidemiological findings suggest drivers and modulators of sustained infection prevalence in the area to be: higher mosquito abundance in forested areas where LLINs were used less frequently or could not be used; late sleeping and waking times coinciding with peak biting hours; feeding preferences of Anopheles taking them away from contact with LLIN and indoor residual spraying (IRS), e.g. exophagy and zoophagy; non-use of LLIN and use of damaged/torn LLIN; high population movement across the border and into forested areas thereby increasing risk of exposure, decreasing use of protection and limiting access to healthcare; and, Plasmodium vivax predominance resulting in relapse(s) of previous infection. The findings highlight gaps in current intervention coverage beyond the village setting. Electronic supplementary material The online version of this article (10.1186/s12936-019-2852-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Hannah M Edwards
- Department of Disease Epidemiology, Imperial College London, London, UK. .,Malaria Consortium Asia, Faculty of Tropical Medicine, Mahidol University, 420/6 Rajvithi Road, Bangkok, 10400, Thailand.
| | - Patchara Sriwichai
- Department of Entomology, Faculty of Tropical Medicine, Mahidol University, 420/6 Rajvithi Road, Bangkok, 10400, Thailand
| | - Kirakorn Kirabittir
- Mahidol Vivax Research Unit, Faculty of Tropical Medicine, Mahidol University, 420/6 Rajvithi Road, Bangkok, 10400, Thailand
| | - Jetsumon Prachumsri
- Mahidol Vivax Research Unit, Faculty of Tropical Medicine, Mahidol University, 420/6 Rajvithi Road, Bangkok, 10400, Thailand
| | - Irwin F Chavez
- Department of Tropical Hygiene, Faculty of Tropical Medicine, Mahidol University, 420/6 Rajvithi Road, Bangkok, 10400, Thailand
| | - Jeffrey Hii
- Department of Disease Epidemiology, Imperial College London, London, UK
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14
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Motoki MT, Vongphayloth K, Rueda LM, Miot EF, Hiscox A, Hertz JC, Brey PT. New records and updated checklist of mosquitoes (Diptera: Culicidae) from Lao People's Democratic Republic, with special emphasis on adult and larval surveillance in Khammuane Province. JOURNAL OF VECTOR ECOLOGY : JOURNAL OF THE SOCIETY FOR VECTOR ECOLOGY 2019; 44:76-88. [PMID: 31124228 DOI: 10.1111/jvec.12331] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Accepted: 02/14/2019] [Indexed: 06/09/2023]
Abstract
A list of mosquitoes from the Nakai Nam Theun National Protected Area along the Nam Theun, Nam Mon, Nam Noy, and Nam On rivers, Nakai District, Khammuane Province, Lao People's Democratic Republic (Lao PDR) is presented. Fifty-four mosquito taxa were identified, including 15 new records in the Lao PDR. A fragment of the mtDNA cytochrome c oxidase subunit I (COI) gene, barcode region, was generated for 34 specimens, and together with four specimens already published, it represented 23 species in eight genera. In addition, an updated checklist of 170 mosquito taxa from Lao PDR is provided based on field collections from Khammuane Province, the literature, and specimens deposited in the Smithsonian Institution, National Museum of Natural History (SI-NMNH), Washington, DC, U.S.A. This paper provides additional information about the biodiversity of mosquito fauna in Lao PDR.
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Affiliation(s)
- Maysa T Motoki
- Medical Entomology and Vector-Borne Disease Unit, Institut Pasteur du Laos, Samsenthai Rd., Ban Kao-gnot, P.O. Box 3560, Vientiane, Lao PDR
- Walter Reed Biosystematics Unit, Entomology Department, Smithsonian Institution, MSC MRC 514, Suitland, MD, U.S.A
| | - Khamsing Vongphayloth
- Medical Entomology and Vector-Borne Disease Unit, Institut Pasteur du Laos, Samsenthai Rd., Ban Kao-gnot, P.O. Box 3560, Vientiane, Lao PDR
| | - Leopoldo M Rueda
- Walter Reed Biosystematics Unit, Entomology Department, Smithsonian Institution, MSC MRC 514, Suitland, MD, U.S.A
| | - Elliott F Miot
- Medical Entomology and Vector-Borne Disease Unit, Institut Pasteur du Laos, Samsenthai Rd., Ban Kao-gnot, P.O. Box 3560, Vientiane, Lao PDR
- 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
| | - Alexandra Hiscox
- Laboratory of Entomology, Wageningen University and Research, Wageningen, The Netherlands
| | | | - Paul T Brey
- Medical Entomology and Vector-Borne Disease Unit, Institut Pasteur du Laos, Samsenthai Rd., Ban Kao-gnot, P.O. Box 3560, Vientiane, Lao PDR
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15
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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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16
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Zhao Y, Zeng J, Zhao Y, Liu Q, He Y, Zhang J, Yang Z, Fan Q, Wang Q, Cui L, Cao Y. Risk factors for asymptomatic malaria infections from seasonal cross-sectional surveys along the China-Myanmar border. Malar J 2018; 17:247. [PMID: 29973194 PMCID: PMC6032786 DOI: 10.1186/s12936-018-2398-y] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 06/22/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Border malaria, a shared phenomenon in the Greater Mekong Sub-region of Southeast Asia, is a major obstacle for regional malaria elimination. Along the China-Myanmar border, an additional problem arose as a result of the settlement of internally displaced people (IDP) in the border region. Since asymptomatic malaria significantly impacts transmission dynamics, assessment of the prevalence, dynamics and risk factors of asymptomatic malaria infections is necessary. METHODS Cross-sectional surveys were carried out in 3 seasons (March and April, July and November) and 2 sites (villages and IDP camps) in 2015. A total of 1680 finger-prick blood samples were collected and used for parasite detection by microscopy and nested RT-PCR (nRT-PCR). Logistic regression models were used to explore the risk factors associated with asymptomatic malaria at individual and household levels. RESULTS The prevalence of asymptomatic Plasmodium infections was 23.3% by nRT-PCR, significantly higher than that detected by microscopy (1.5%). The proportions of Plasmodium vivax, Plasmodium falciparum and mixed-species infections were 89.6, 8.1 and 2.3%, respectively. Asymptomatic infections showed obvious seasonality with higher prevalence in the rainy season. Logistic regression analysis identified males and school children (≤ 15 years) as the high-risk populations. Vector-based interventions, including bed net and indoor residual spray, were found to have significant impacts on asymptomatic Plasmodium infections, with non-users of these measures carrying much higher risks of infection. In addition, individuals living in poorly constructed households or farther away from clinics were more prone to asymptomatic infections. CONCLUSIONS Sub-microscopic Plasmodium infections were highly prevalent in the border human populations from IDP camps and surrounding villages. Both individual- and household-level risk factors were identified, which provides useful information for identifying the high-priority populations to implement targeted malaria control.
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Affiliation(s)
- Yan Zhao
- Department of Immunology, College of Basic Medical Sciences, China Medical University, Shenyang, 110122, Liaoning, China
| | - Jie Zeng
- Department of Immunology, College of Basic Medical Sciences, China Medical University, Shenyang, 110122, Liaoning, China
| | - Yonghong Zhao
- Department of Immunology, College of Basic Medical Sciences, China Medical University, Shenyang, 110122, Liaoning, China
| | - Qingyang Liu
- Department of Immunology, College of Basic Medical Sciences, China Medical University, Shenyang, 110122, Liaoning, China
| | - Yang He
- Department of Immunology, College of Basic Medical Sciences, China Medical University, Shenyang, 110122, Liaoning, China
| | - Jiaqi Zhang
- Department of Pathogen Biology and Immunology, Kunming Medical University, Kunming, China
| | - Zhaoqing Yang
- Department of Pathogen Biology and Immunology, Kunming Medical University, Kunming, China
| | - Qi Fan
- Dalian Institute of Biotechnology, Dalian, Liaoning, China
| | - Qinghui Wang
- Department of Immunology, College of Basic Medical Sciences, China Medical University, Shenyang, 110122, Liaoning, China.
| | - Liwang Cui
- Department of Immunology, College of Basic Medical Sciences, China Medical University, Shenyang, 110122, Liaoning, China. .,Department of Entomology, Pennsylvania State University, University Park, State College, PA, 16802, USA.
| | - Yaming Cao
- Department of Immunology, College of Basic Medical Sciences, China Medical University, Shenyang, 110122, Liaoning, China.
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17
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Ondiba IM, Oyieke FA, Ong’amo GO, Olumula MM, Nyamongo IK, Estambale BBA. Malaria vector abundance is associated with house structures in Baringo County, Kenya. PLoS One 2018; 13:e0198970. [PMID: 29889888 PMCID: PMC5995440 DOI: 10.1371/journal.pone.0198970] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Accepted: 05/28/2018] [Indexed: 12/03/2022] Open
Abstract
Malaria, a major cause of morbidity and mortality, is the most prevalent vector borne disease in Baringo County; a region which has varied house designs in arid and semi-arid areas. This study investigated the association between house structures and indoor-malaria vector abundance in Baringo County. The density of malaria vectors in houses with open eaves was higher than that for houses with closed eaves. Grass thatched roof houses had higher density of malaria vectors than corrugated iron sheet roofs. Similarly, mud walled houses had higher vector density than other wall types. Houses in the riverine zone were significantly associated with malaria vector abundance (p<0.000) possibly due to more varied house structures. In Kamnarok village within riverine zone, a house made of grass thatched roof and mud wall but raised on stilts with domestic animals (sheep/goats) kept at the lower level had lower mosquito density (5.8 per collection) than ordinary houses made of same materials but at ground level (30.5 mosquitoes per collection), suggestive of a change in behavior of mosquito feeding and resting. House modifications such as screening of eaves, improvement of construction material and building stilted houses can be incorporated in the integrated vector management (IVM) strategy to complement insecticide treated bed nets and indoor residual spray to reduce indoor malaria vector density.
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Affiliation(s)
| | | | | | - Macrae M. Olumula
- Division of Research Innovation and Outreach, Jaramogi Oginga Odinga University of Science and Technology, Bondo, Kenya
| | - Isaac K. Nyamongo
- Cooperative Development, Research and Innovation, The Cooperative University of Kenya, Nairobi, Kenya
| | - Benson B. A. Estambale
- Division of Research Innovation and Outreach, Jaramogi Oginga Odinga University of Science and Technology, Bondo, Kenya
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18
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Lippi CA, Stewart-Ibarra AM, Muñoz ÁG, Borbor-Cordova MJ, Mejía R, Rivero K, Castillo K, Cárdenas WB, Ryan SJ. The Social and Spatial Ecology of Dengue Presence and Burden during an Outbreak in Guayaquil, Ecuador, 2012. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2018; 15:ijerph15040827. [PMID: 29690593 PMCID: PMC5923869 DOI: 10.3390/ijerph15040827] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Revised: 04/09/2018] [Accepted: 04/14/2018] [Indexed: 01/19/2023]
Abstract
Dengue fever, a mosquito-borne arbovirus, is a major public health concern in Ecuador. In this study, we aimed to describe the spatial distribution of dengue risk and identify local social-ecological factors associated with an outbreak of dengue fever in the city of Guayaquil, Ecuador. We examined georeferenced dengue cases (n = 4248) and block-level census data variables to identify social-ecological risk factors associated with the presence/absence and burden of dengue in Guayaquil in 2012. Local Indicators of Spatial Association (LISA), specifically Anselin’s Local Moran’s I, and Moran’s I tests were used to locate hotspots of dengue transmission, and multimodel selection was used to identify covariates associated with dengue presence and burden at the census block level. We identified significant dengue transmission hotspots near the North Central and Southern portions of Guayaquil. Significant risk factors for presence of dengue included poor housing conditions, access to paved roads, and receipt of remittances. Counterintuitive positive correlations with dengue presence were observed with several municipal services such as garbage collection and access to piped water. Risk factors for increased burden of dengue included poor housing conditions, garbage collection, receipt of remittances, and sharing a property with more than one household. Social factors such as education and household demographics were negatively correlated with increased dengue burden. These findings elucidate underlying differences with dengue presence versus burden, and suggest that vulnerability and risk maps could be developed to inform dengue prevention and control; this is information that is also relevant for emerging epidemics of chikungunya and Zika viruses.
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Affiliation(s)
- Catherine A Lippi
- Quantitative Disease Ecology and Conservation Lab, Department of Geography, University of Florida, Gainesville, FL 32611 USA.
- Emerging Pathogens Institute, University of Florida, Gainesville, FL 32608, USA.
| | - Anna M Stewart-Ibarra
- Center for Global Health and Translational Science and Department of Medicine, State University of New York Upstate Medical University, Syracuse, NY 13210, USA.
| | - Ángel G Muñoz
- Atmospheric and Oceanic Sciences (AOS), Princeton University, Princeton, NJ 08540, USA.
- International Research Institute for Climate and Society (IRI), Earth Institute, Columbia University, New York, NY 10964, USA.
| | | | - Raúl Mejía
- National Institute of Meteorology and Hydrology (INAMHI), Quito 170135, Ecuador.
| | - Keytia Rivero
- National Institute of Meteorology and Hydrology (INAMHI), Quito 170135, Ecuador.
| | - Katty Castillo
- Institute of Biometrics and Epidemiology, Auf'm Hennekamp 65, 40225 Düsseldorf, Germany.
| | - Washington B Cárdenas
- Laboratorio de Biomedicina, FCV, Escuela Superior Politécnica del Litoral (ESPOL), Guayaquil 09015863, Ecuador.
| | - Sadie J Ryan
- Quantitative Disease Ecology and Conservation Lab, Department of Geography, University of Florida, Gainesville, FL 32611 USA.
- Emerging Pathogens Institute, University of Florida, Gainesville, FL 32608, USA.
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19
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Tangena JAA, Thammavong P, Malaithong N, Inthavong T, Ouanesamon P, Brey PT, Lindsay SW. Diversity of Mosquitoes (Diptera: Culicidae) Attracted to Human Subjects in Rubber Plantations, Secondary Forests, and Villages in Luang Prabang Province, Northern Lao PDR. JOURNAL OF MEDICAL ENTOMOLOGY 2017; 54:1589-1604. [PMID: 28505314 DOI: 10.1093/jme/tjx071] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Indexed: 06/07/2023]
Abstract
The impact of the rapid expansion of rubber plantations in South-East Asia on mosquito populations is uncertain. We compared the abundance and diversity of adult mosquitoes using human-baited traps in four typical rural habitats in northern Lao PDR: secondary forests, immature rubber plantations, mature rubber plantations, and villages. Generalized estimating equations were used to explore differences in mosquito abundance between habitats, and Simpson's diversity index was used to measure species diversity. Over nine months, 24,927 female mosquitoes were collected, including 51 species newly recorded in Lao PDR. A list of the 114 mosquito species identified is included. More mosquitoes, including vector species, were collected in the secondary forest than immature rubber plantations (rainy season, odds ratio [OR] 0.33, 95% confidence interval [CI] 0.31-0.36; dry season, 0.46, 95% CI 0.41-0.51), mature rubber plantations (rainy season, OR 0.25, 95% CI 0.23-0.27; dry season, OR 0.25, 95% CI 0.22-0.28), and villages (rainy season, OR 0.13, 95% CI 0.12-0.14; dry season, 0.20, 95% CI 0.18-0.23). All habitats showed high species diversity (Simpson's indexes between 0.82-0.86) with vectors of dengue, Japanese encephalitis (JE), lymphatic filariasis, and malaria. In the secondary forests and rubber plantations, Aedes albopictus (Skuse), a dengue vector, was the dominant mosquito species, while in the villages, Culex vishnui (Theobald), a JE vector, was most common. This study has increased the overall knowledge of mosquito fauna in Lao PDR. The high abundance of Ae. albopictus in natural and man-made forests warrants concern, with vector control measures currently only implemented in cities and villages.
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Affiliation(s)
- Julie-Anne A Tangena
- Department of Medical Entomology, Institut Pasteur du Laos, Samsenthai Rd, Ban Kao-gnot, PO Box 3560, Vientiane, Lao PDR
- School of Biological and Biomedical Sciences, Durham University, South Road, Durham, DH1 3LE, United Kingdom
| | - Phoutmany Thammavong
- Department of Medical Entomology, Institut Pasteur du Laos, Samsenthai Rd, Ban Kao-gnot, PO Box 3560, Vientiane, Lao PDR
| | - Naritsara Malaithong
- Department of Entomology, Kasetsart University, 50 Ngam Wong Wan Rd., Ladyaow Chatuchak Bangkok 10900, Thailand
| | - Thavone Inthavong
- Agriculture and Forestry Policy Research Center, National Agriculture and Forestry Research Institute, Nongviengkham Village, Vientiane, P.O Box 7170, Lao PDR
| | - Phuthasone Ouanesamon
- Agriculture and Forestry Policy Research Center, National Agriculture and Forestry Research Institute, Nongviengkham Village, Vientiane, P.O Box 7170, Lao PDR
| | - Paul T Brey
- Department of Medical Entomology, Institut Pasteur du Laos, Samsenthai Rd, Ban Kao-gnot, PO Box 3560, Vientiane, Lao PDR
| | - Steve W Lindsay
- School of Biological and Biomedical Sciences, Durham University, South Road, Durham, DH1 3LE, United Kingdom
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20
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Inthavong N, Nonaka D, Kounnavong S, Iwagami M, Phommala S, Kobayashi J, Hongvanthong B, Pongvongsa T, Brey PT, Kano S. Individual and household factors associated with incidences of village malaria in Xepon district, Savannakhet province, Lao PDR. Trop Med Health 2017; 45:36. [PMID: 29151802 PMCID: PMC5678595 DOI: 10.1186/s41182-017-0077-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Accepted: 10/25/2017] [Indexed: 11/18/2022] Open
Abstract
Background In the Lao PDR, the incidence of malaria greatly differs among villages even within a subdistrict, and the reasons for this difference are poorly understood. The objective of this study was to identify differences in villagers’ behavior and the household environment between villages with high incidences and those with low incidences of malaria in a rural district of the Lao PDR. Methods A case-control study was conducted in Xepon district, Savannakhet province. Case villages were defined as those with a high incidence (> 10 cases per 1000 population per year), and control villages were those with a low incidence (0–10 cases per 1000 population per year). Data were collected from 178 households in the six case villages and six control villages between December 2016 and January 2017. The data collection consisted of an interview survey with the heads of households and an observational survey in and around the house. Logistic regression was used to assess the association between the case-control status and individual-level behavioral factors and household-level environmental factors adjusted for socio-demographic and economic factors. Results Compared to the household members in the control villages, household members in the case villages were significantly more likely to work at night in the forest (adjusted odds ratio 1.95; 95% confidence interval 1.28 to 2.98) and more likely to sleep overnight in the forest (adjusted odds ratio 1.94; 95% confidence interval 1.13 to 3.33). Additionally, compared to the households in the control villages, households in the case villages were significantly more likely to have an open space on the house surface (adjusted odds ratio 3.64; 95% confidence interval 1.68 to 7.84). Conclusions There were significant differences in nighttime working and sleeping behaviors in the forest and the presence of an open space on the house surface in the case versus control villages. These differences can partly explain the difference in the incidences of malaria among the villages. The Lao National Malaria Control Program should recommend that villagers use personal protection when working and sleeping in the forest and to reduce any open space on the house surfaces.
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Affiliation(s)
- Nouhak Inthavong
- Department of Global Health, Graduate School of Health Sciences, University of the Ryukyus, Uehara 207, Nishihara-cho, Okinawa, 903-0215 Japan.,SATREPS Project for Parasitic Diseases, Vientiane, Lao People's Democratic Republic.,National Institute of Public Health, Ministry of Health, Ban Kaognot, Samsenthai Road, Sisattanak District, Vientiane, Lao People's Democratic Republic
| | - Daisuke Nonaka
- Department of Global Health, Graduate School of Health Sciences, University of the Ryukyus, Uehara 207, Nishihara-cho, Okinawa, 903-0215 Japan.,SATREPS Project for Parasitic Diseases, Vientiane, Lao People's Democratic Republic
| | - Sengchanh Kounnavong
- National Institute of Public Health, Ministry of Health, Ban Kaognot, Samsenthai Road, Sisattanak District, Vientiane, Lao People's Democratic Republic
| | - Moritoshi Iwagami
- SATREPS Project for Parasitic Diseases, Vientiane, Lao People's Democratic Republic.,Department of Tropical Medicine and Malaria, Research Institute, National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku-ku, Tokyo, 162-8655 Japan.,Institut Pasteur du Laos, Ministry of Health, Sisattanak District, Vientiane, Lao People's Democratic Republic
| | - Souraxay Phommala
- National Institute of Public Health, Ministry of Health, Ban Kaognot, Samsenthai Road, Sisattanak District, Vientiane, Lao People's Democratic Republic
| | - Jun Kobayashi
- Department of Global Health, Graduate School of Health Sciences, University of the Ryukyus, Uehara 207, Nishihara-cho, Okinawa, 903-0215 Japan.,SATREPS Project for Parasitic Diseases, Vientiane, Lao People's Democratic Republic
| | - Bouasy Hongvanthong
- SATREPS Project for Parasitic Diseases, Vientiane, Lao People's Democratic Republic.,Center of Malariology, Parasitology and Entomology, Ministry of Health, Vientiane, Lao People's Democratic Republic
| | - Tiengkham Pongvongsa
- SATREPS Project for Parasitic Diseases, Vientiane, Lao People's Democratic Republic.,Savannakhet Provincial Health Department, Thahea village, Kaysone-Phomvihan District, Savannakhet, Lao People's Democratic Republic
| | - Paul T Brey
- SATREPS Project for Parasitic Diseases, Vientiane, Lao People's Democratic Republic.,Institut Pasteur du Laos, Ministry of Health, Sisattanak District, Vientiane, Lao People's Democratic Republic
| | - Shigeyuki Kano
- SATREPS Project for Parasitic Diseases, Vientiane, Lao People's Democratic Republic.,Department 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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McCann RS, Messina JP, MacFarlane DW, Bayoh MN, Gimnig JE, Giorgi E, Walker ED. Explaining variation in adult Anopheles indoor resting abundance: the relative effects of larval habitat proximity and insecticide-treated bed net use. Malar J 2017; 16:288. [PMID: 28716087 PMCID: PMC5514485 DOI: 10.1186/s12936-017-1938-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 07/13/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Spatial determinants of malaria risk within communities are associated with heterogeneity of exposure to vector mosquitoes. The abundance of adult malaria vectors inside people's houses, where most transmission takes place, should be associated with several factors: proximity of houses to larval habitats, structural characteristics of houses, indoor use of vector control tools containing insecticides, and human behavioural and environmental factors in and near houses. While most previous studies have assessed the association of larval habitat proximity in landscapes with relatively low densities of larval habitats, in this study these relationships were analysed in a region of rural, lowland western Kenya with high larval habitat density. METHODS 525 houses were sampled for indoor-resting mosquitoes across an 8 by 8 km study area using the pyrethrum spray catch method. A predictive model of larval habitat location in this landscape, previously verified, provided derivations of indices of larval habitat proximity to houses. Using geostatistical regression models, the association of larval habitat proximity, long-lasting insecticidal nets (LLIN) use, house structural characteristics (wall type, roof type), and peridomestic variables (cooking in the house, cattle near the house, number of people sleeping in the house) with mosquito abundance in houses was quantified. RESULTS Vector abundance was low (mean, 1.1 adult Anopheles per house). Proximity of larval habitats was a strong predictor of Anopheles abundance. Houses without an LLIN had more female Anopheles gambiae s.s., Anopheles arabiensis and Anopheles funestus than houses where some people used an LLIN (rate ratios, 95% CI 0.87, 0.85-0.89; 0.84, 0.82-0.86; 0.38, 0.37-0.40) and houses where everyone used an LLIN (RR, 95% CI 0.49, 0.48-0.50; 0.39, 0.39-0.40; 0.60, 0.58-0.61). Cooking in the house also reduced Anopheles abundance across all species. The number of people sleeping in the house, presence of cattle near the house, and house structure modulated Anopheles abundance, but the effect varied with Anopheles species and sex. CONCLUSIONS Variation in the abundance of indoor-resting Anopheles in rural houses of western Kenya varies with clearly identifiable factors. Results suggest that LLIN use continues to function in reducing vector abundance, and that larval source management in this region could lead to further reductions in malaria risk by reducing the amount of an obligatory resource for mosquitoes near people's homes.
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Affiliation(s)
- Robert S. McCann
- Department of Entomology, Michigan State University, East Lansing, MI USA
| | - Joseph P. Messina
- Department of Geography, Environment, and Spatial Sciences, Michigan State University, East Lansing, MI USA
| | | | - M. Nabie Bayoh
- Centre for Global Health Research, Kenya Medical Research Institute/Centers for Disease Control and Prevention, Kisumu, Kenya
| | - John E. Gimnig
- Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA USA
| | - Emanuele Giorgi
- Lancaster Medical School, Lancaster University, Lancaster, UK
| | - Edward D. Walker
- Department of Microbiology and Molecular Genetics, Michigan State University, 567 Wilson Road, 2215 Biomedical Physical Sciences Building, East Lansing, MI 48824-4320 USA
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Sperling S, Cordel M, Gordon S, Knols BG, Rose A. Eave tubes for malaria control in Africa: Videographic observations of mosquito behaviour in Tanzania with a simple and rugged video surveillance system. MALARIAWORLD JOURNAL 2017; 8:9. [PMID: 34532232 PMCID: PMC8415065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Eave tubes are novel mosquito control devices that help to protect households against malaria vectors and other mosquitoes. They are installed in the upper walls of human habitations after the eaves have been closed. Mosquitoes trying to enter through these tubes are intercepted by electrostatic netting that can be treated with a variety of insecticides. Using video, mosquito behaviour and duration of contact with netting in eave tubes was recorded and analysed to assess contamination with insecticides under semi-field and field conditions. MATERIALS AND METHODS Off-the-shelf action cameras were used to observe behaviour of mosquitoes in eave tubes near Ifakara, Tanzania. In an experimental hut in a screen house, we observed Anopheles arabiensis females on electrostatic eave tube netting treated with bendiocarb powder or with Beauveria bassiana spores, both in comparison to untreated netting. In village houses that had been equipped with eave tubes we observed the behaviour of wild mosquitoes towards electrostatic netting treated with bendiocarb. Results were evaluated using a short-contact assay (5 second exposure). RESULTS In the semi-field setup, the median contact time of An. arabiensis on bendiocarb-powdered eave tube nets was 276.4 sec (n=56), compared to 26.3 sec on the control (n=59). Of all the mosquitoes observed on the treated net, 94.6% had contact times of more than 5 seconds on the bendiocarb-powdered netting. The median time on nets powdered with B. bassiana spores was 34.4 sec (n=26), compared 37.1 sec in the untreated control (n=22). 88.5% of the mosquitoes spent more than 5 seconds on the treated nets. In the field we recorded 106 individual mosquitoes of unknown species inside tubes. They spent a median time of 70.9 sec on the bendiocarb-treated netting, with 90.6% remaining there for more than 5 seconds. CONCLUSIONS We have found no indication that the behaviour of mosquitoes on electrostatic eave tube netting, treated either with bendiocarb powder or with B. bassiana spores, interferes with successful transfer of lethal doses of these insecticidal actives. The videographic set-up used in this study is simple, sturdy and reliable enough to observe and analyse mosquito behaviour under field conditions.
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Affiliation(s)
| | - Michael Cordel
- Biogents AG, Weißenburgstraße 22, 93055 Regensburg, Germany
| | - Scott Gordon
- Biogents AG, Weißenburgstraße 22, 93055 Regensburg, Germany
| | - Bart G.J. Knols
- Radboud University Nijmegen, Department of Environmental Science, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands
| | - Andreas Rose
- Biogents AG, Weißenburgstraße 22, 93055 Regensburg, Germany,* corresponding author:
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23
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Pongvongsa T, Nonaka D, Iwagami M, Nakatsu M, Phongmany P, Nishimoto F, Kobayashi J, Hongvanthon B, Brey PT, Moji K, Mita T, Kano S. Household clustering of asymptomatic malaria infections in Xepon district, Savannakhet province, Lao PDR. Malar J 2016; 15:508. [PMID: 27756391 PMCID: PMC5069939 DOI: 10.1186/s12936-016-1552-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Accepted: 10/05/2016] [Indexed: 11/10/2022] Open
Abstract
Background In the Lao PDR, malaria morbidity and mortality have remarkably decreased over the past decade. However, asymptomatic infections in rural villages contribute to the on-going local transmission. The primary objective of this study was to explore the characteristics of infections in a malaria-endemic district of the Lao PDR. The specific objectives were to investigate the prevalence and species of malaria parasites using molecular methods and to assess individual and household parasite levels and the characteristics associated with malaria infection. Methods The study population included 870 participants from 236 households in 10 villages of the Xepon district. Interviews, blood examinations and body temperature measurements were conducted between August and September 2013. A multilevel logistic regression model, with adjustment for clustering effects, was used to assess the association between predictor variables and an outcome variable (malaria infection status as principally determined by PCR). The predictive factors included individual-level factors (age, gender, past fever episode, and forest activity during night time) and household-level factors (household member size, household bed net usage/density and a household with one other malaria-infected member). Results Fifty-two participants (including 26 children) tested positive (positive rate: 6.0 %): Plasmodium falciparum mono-infection was the most common infection (n = 41, 78.8 %), followed by P. falciparum and Plasmodium vivax mixed infections (n = 9, 17.3 %). The majority of infected participants (n = 42, 80.8 %) had no fever episodes in the two previous weeks or a measurable fever (>37 °C) at the time of survey. Living in a household with one other malaria-infected member significantly increased the odds of infection (odds ratio 24.33, 95 % confidence interval 10.15–58.32). Among the 40 households that had at least one infected member, nine households were responsible for 40.4 % of the total infections. Conclusions Plasmodium vivax was detected more frequently than it was reported from the district hospital. Most infections were asymptomatic and sub-microscopic and were highly clustered within households. To further eliminate malaria in Xepon and other similar settings in the country, the National Malaria Control Programme should consider household-based strategies, including reactive case detection targeting the household members of index cases. Electronic supplementary material The online version of this article (doi:10.1186/s12936-016-1552-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Tiengkham Pongvongsa
- Savannakhet Provincial Health Department, Phonsavangnuea Village, Kaysone-Phomvihan District, Savannakhet, Lao PDR.,Department of Molecular and Cellular Parasitology, School of Medicine, Juntendo University, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan.,SATREPS Project for Parasitic Diseases, Vientiane, Lao PDR
| | - Daisuke Nonaka
- SATREPS Project for Parasitic Diseases, Vientiane, Lao PDR. .,Department of Global Health, School of Health Sciences, University of the Ryukyus, 207 Uehara, Nishihara-cho, Okinawa, 903-0215, Japan.
| | - Moritoshi Iwagami
- SATREPS Project for Parasitic Diseases, Vientiane, Lao PDR.,Department of Tropical Medicine and Malaria, Research Institute, National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku-ku, Tokyo, 162-8655, Japan.,Institut Pasteur du Laos, Sisattanak District, Vientiane, Lao PDR
| | - Masami Nakatsu
- SATREPS Project for Parasitic Diseases, Vientiane, Lao PDR.,Department of Tropical Medicine and Malaria, Research Institute, National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku-ku, Tokyo, 162-8655, Japan
| | - Panom Phongmany
- Savannakhet Provincial Health Department, Phonsavangnuea Village, Kaysone-Phomvihan District, Savannakhet, Lao PDR
| | - Futoshi Nishimoto
- Graduate School of Tropical Medicine and Global Health, Nagasaki University, 1-12-4 Sakamoto, Nagasaki-shi, Nagasaki, 852-8523, Japan
| | - Jun Kobayashi
- SATREPS Project for Parasitic Diseases, Vientiane, Lao PDR.,Department of Global Health, School of Health Sciences, University of the Ryukyus, 207 Uehara, Nishihara-cho, Okinawa, 903-0215, Japan
| | - Bouasy Hongvanthon
- SATREPS Project for Parasitic Diseases, Vientiane, Lao PDR.,Center of Malariology, Parasitology and Entomology, Ministry of Health, Vientiane, Lao PDR
| | - Paul T Brey
- SATREPS Project for Parasitic Diseases, Vientiane, Lao PDR.,Institut Pasteur du Laos, Sisattanak District, Vientiane, Lao PDR
| | - Kazuhiko Moji
- Graduate School of Tropical Medicine and Global Health, Nagasaki University, 1-12-4 Sakamoto, Nagasaki-shi, Nagasaki, 852-8523, Japan
| | - Toshihiro Mita
- Department of Molecular and Cellular Parasitology, School of Medicine, Juntendo University, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan.,SATREPS Project for Parasitic Diseases, Vientiane, Lao PDR
| | - Shigeyuki Kano
- SATREPS Project for Parasitic Diseases, Vientiane, Lao PDR.,Department of Tropical Medicine and Malaria, Research Institute, National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku-ku, Tokyo, 162-8655, Japan.,Institut Pasteur du Laos, Sisattanak District, Vientiane, Lao PDR
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Donnelly B, Berrang-Ford L, Labbé J, Twesigomwe S, Lwasa S, Namanya DB, Harper SL, Kulkarni M, Ross NA, Michel P. Plasmodium falciparum malaria parasitaemia among indigenous Batwa and non-indigenous communities of Kanungu district, Uganda. Malar J 2016; 15:254. [PMID: 27146298 PMCID: PMC4855715 DOI: 10.1186/s12936-016-1299-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 04/18/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The indigenous Batwa of southwestern Uganda are among the most highly impoverished populations in Uganda, yet there is negligible research on the prevalence of malaria in this population. Plasmodium falciparum malaria parasitaemia prevalence was estimated in an indigenous Batwa and a non-indigenous neighbouring population, and an exploration of modifiable risk factors was carried out to identify potential entry points for intervention. Additionally, evidence of zooprophylaxis was assessed, hypothesizing that livestock ownership may play a role in malaria risk. METHODS Two cross-sectional surveys of Batwa and non-Batwa communities were carried out in Kanungu District, Uganda in July 2013 and April 2014 based on a census of adult Batwa and a two-stage systematic random sample of adult non-Batwa in ten Local Councils where Batwa settlements are located. A community-based questionnaire and antigen rapid diagnostic test for P. falciparum were carried out in the cross-sectional health surveys. A multivariable logistic regression model was built to identify risk factors associated with positive malaria diagnostic test. A subset analysis of livestock owners tested for zooprophylaxis. RESULTS Batwa experienced higher prevalence of malaria parasitaemia than non-Batwa (9.35 versus 4.45 %, respectively) with over twice the odds of infection (OR 2.21, 95 % CI 1.23-3.98). Extreme poverty (OR 1.96, 95 % CI 0.98-3.94) and having an iron sheet roof (OR 2.54, 95 % CI 0.96-6.72) increased the odds of infection in both Batwa and non-Batwa. Controlling for ethnicity, wealth, and bed net ownership, keeping animals inside the home at night decreased the odds of parasitaemia among livestock owners (OR 0.29, 95 % CI 0.09-0.94). CONCLUSION A health disparity exists between indigenous Batwa and non-indigenous community members with Batwa having higher prevalence of malaria relative to non-Batwa. Poverty was associated with increased odds of malaria infection for both groups. Findings suggest that open eaves and gaps in housing materials associated with iron sheet roofing represent a modifiable risk factor for malaria, and may facilitate mosquito house entry; larger sample sizes will be required to confirm this finding. Evidence for possible zooprophylaxis was observed among livestock owners in this population for those who sheltered animals inside the home at night.
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Affiliation(s)
- Blánaid Donnelly
- />Department of Geography, McGill University, Burnside Hall Building, 805 Sherbrooke St West, Montreal, QC H3A 0B9 Canada
| | - Lea Berrang-Ford
- />Department of Geography, McGill University, Burnside Hall Building, 805 Sherbrooke St West, Montreal, QC H3A 0B9 Canada
| | - Jolène Labbé
- />Department of Geography, McGill University, Burnside Hall Building, 805 Sherbrooke St West, Montreal, QC H3A 0B9 Canada
| | | | - Shuaib Lwasa
- />Department of Geography, Geoinformatics and Climatic Sciences, School of Forestry, Environmental and Geographical Sciences, CAES, Makerere University, P.O Box 7062, Kampala, Uganda
| | | | - Sherilee L. Harper
- />Department of Population Medicine, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1 Canada
| | - Manisha Kulkarni
- />School of Epidemiology, Public Health and Preventive Medicine, University of Ottawa, 600 Peter Morand Cres., 301E, Ottawa, ON K1H 8M5 Canada
| | - Nancy A. Ross
- />Department of Geography, McGill University, Burnside Hall Building, 805 Sherbrooke St West, Montreal, QC H3A 0B9 Canada
| | - IHACC Research Team
- />Department of Geography, McGill University, Burnside Hall Building, 805 Sherbrooke St West, Montreal, QC H3A 0B9 Canada
- />Batwa Development Program, Buhoma, Kanungu District, Uganda
- />Department of Geography, Geoinformatics and Climatic Sciences, School of Forestry, Environmental and Geographical Sciences, CAES, Makerere University, P.O Box 7062, Kampala, Uganda
- />Ministry of Health, Plot 6 Lourdel Rd, P.O Box 7272, Kampala, Uganda
- />Department of Population Medicine, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1 Canada
- />School of Epidemiology, Public Health and Preventive Medicine, University of Ottawa, 600 Peter Morand Cres., 301E, Ottawa, ON K1H 8M5 Canada
- />Office of the Chief Science Officer, Public Health Agency of Canada, 130 Colonnade Road, Ottawa, ON K1A 0K9 Canada
| | - Pascal Michel
- />Office of the Chief Science Officer, Public Health Agency of Canada, 130 Colonnade Road, Ottawa, ON K1A 0K9 Canada
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Tangena JAA, Thammavong P, Wilson AL, Brey PT, Lindsay SW. Risk and Control of Mosquito-Borne Diseases in Southeast Asian Rubber Plantations. Trends Parasitol 2016; 32:402-415. [PMID: 26907494 DOI: 10.1016/j.pt.2016.01.009] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Revised: 01/04/2016] [Accepted: 01/19/2016] [Indexed: 11/18/2022]
Abstract
Unprecedented economic growth in Southeast Asia (SEA) has encouraged the expansion of rubber plantations. This land-use transformation is changing the risk of mosquito-borne diseases. Mature plantations provide ideal habitats for the mosquito vectors of malaria, dengue, and chikungunya. Migrant workers may introduce pathogens into plantation areas, most worryingly artemisinin-resistant malaria parasites. The close proximity of rubber plantations to natural forest also increases the threat from zoonoses, where new vector-borne pathogens spill over from wild animals into humans. There is therefore an urgent need to scale up vector control and access to health care for rubber workers. This requires an intersectoral approach with strong collaboration between the health sector, rubber industry, and local communities.
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Affiliation(s)
- Julie-Anne A Tangena
- Laboratory of Vector-Borne Diseases, Institut Pasteur du Laos, Vientiane, Laos; School of Biological and Biomedical Sciences, Durham University, Durham, UK.
| | | | - Anne L Wilson
- School of Biological and Biomedical Sciences, Durham University, Durham, UK
| | - Paul T Brey
- Laboratory of Vector-Borne Diseases, Institut Pasteur du Laos, Vientiane, Laos
| | - Steve W Lindsay
- School of Biological and Biomedical Sciences, Durham University, Durham, UK
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Conlan JV, Vongxay K, Khamlome B, Jarman RG, Gibbons RV, Fenwick SG, Thompson RCA, Blacksell SD. Patterns of Flavivirus Seroprevalence in the Human Population of Northern Laos. Am J Trop Med Hyg 2015; 93:1010-1013. [PMID: 26304925 PMCID: PMC4703266 DOI: 10.4269/ajtmh.15-0072] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Accepted: 06/23/2015] [Indexed: 11/11/2022] Open
Abstract
A total of 1,136 samples from 289 households in four provinces in northern Laos were subjected to Japanese encephalitis virus (JEV) and dengue virus hemagglutination inhibition (DENV HI). Overall, antibodies to JEV were detected by HI in 620 (54.6%) of 1,136 people; of which 217 (19.1%) had HI activity against JEV only. Antibodies to DENV4 were detected by HI in 526 (46.3%) of 1,136 people; of which 124 (10.9%) had HI activity against DENV4 only. Antibodies to DENV1–3 were detected by HI in 296 (26.1%), 274 (24.1%), and 283 (24.9) of 1,136 people, respectively; of which 7, 1, and 0, respectively, had HI activity against DENV1–3 only. JEV was the most prevalent Flavivirus in Oudomxay, Luangprabang, and Huaphan provinces and DENV4 was the most prevalent in Xiengkhouang province. Seroprevalence for JEV increased with increasing age and wealth and was higher in villages where rice was cultivated in paddy fields and highest for people of Lao-Tai ethnicity.
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Affiliation(s)
| | | | | | | | | | | | | | - Stuart D. Blacksell
- *Address correspondence to Stuart D. Blacksell, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, 420/6 Rajvithi Road, Bangkok 10400, Thailand. E-mail:
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27
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Donnelly B, Berrang-Ford L, Ross NA, Michel P. A systematic, realist review of zooprophylaxis for malaria control. Malar J 2015; 14:313. [PMID: 26264913 PMCID: PMC4533963 DOI: 10.1186/s12936-015-0822-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Accepted: 07/28/2015] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Integrated vector management (IVM) is recommended as a sustainable approach to malaria control. IVM consists of combining vector control methods based on scientific evidence to maximize efficacy and cost-effectiveness while minimizing negative impacts, such as insecticide resistance and environmental damage. Zooprophylaxis has been identified as a possible component of IVM as livestock may draw mosquitoes away from humans, decreasing human-vector contact and malaria transmission. It is possible, however, that livestock may actually draw mosquitoes to humans, increasing malaria transmission (zoopotentiation). The goal of this paper is to take a realist approach to a systematic review of peer-reviewed literature to understand the contexts under which zooprophylaxis or zoopotentiation occur. METHODS Three electronic databases were searched using the keywords 'zooprophylaxis' and 'zoopotentiation', and forward and backward citation tracking employed, to identify relevant articles. Only empirical, peer-reviewed articles were included. Critical appraisal was applied to articles retained for full review. RESULTS Twenty empirical studies met inclusion criteria after critical appraisal. A range of experimental and observational study designs were reported. Outcome measures included human malaria infection and mosquito feeding behaviour. Two key factors were consistently associated with zooprophylaxis and zoopotentiation: the characteristics of the local mosquito vector, and the location of livestock relative to human sleeping quarters. These associations were modified by the use of bed nets and socio-economic factors. DISCUSSION This review suggests that malaria risk is reduced (zooprophylaxis) in areas where predominant mosquito species do not prefer human hosts, where livestock are kept at a distance from human sleeping quarters at night, and where mosquito nets or other protective measures are used. Zoopotentiation occurs where livestock are housed within or near human sleeping quarters at night and where mosquito species prefer human hosts. CONCLUSION The evidence suggests that zooprophylaxis could be part of an effective strategy to reduce malaria transmission under specific ecological and geographical conditions. The current scientific evidence base is inconclusive on understanding the role of socio-economic factors, optimal distance between livestock and human sleeping quarters, and the effect of animal species and number on zooprophylaxis.
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Affiliation(s)
- Blánaid Donnelly
- Department of Geography, McGill University, Burnside Hall Building, 805 Sherbrooke St West, Montreal, QC, H3A 0B9, Canada.
| | - Lea Berrang-Ford
- Department of Geography, McGill University, Burnside Hall Building, 805 Sherbrooke St West, Montreal, QC, H3A 0B9, Canada.
| | - Nancy A Ross
- Department of Geography, McGill University, Burnside Hall Building, 805 Sherbrooke St West, Montreal, QC, H3A 0B9, Canada.
| | - Pascal Michel
- Public Health Risk Sciences Division, Public Health Agency of Canada, 3200 Sicotte, PO Box 5000, Saint-Hyacinthe, QC, J2S 7C6, Canada.
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Leandro-Reguillo P, Thomson-Luque R, Monteiro WM, de Lacerda MVG. Urban and architectural risk factors for malaria in indigenous Amazonian settlements in Brazil: a typological analysis. Malar J 2015; 14:284. [PMID: 26194898 PMCID: PMC4509690 DOI: 10.1186/s12936-015-0806-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Accepted: 07/10/2015] [Indexed: 11/10/2022] Open
Abstract
In the Amazon, m alaria is highly endemic in indigenous populations, which are often considered one of the last barriers to malaria elimination due to geographic isolation. Although the improvement of housing conditions is a good strategy towards the control and prevention of vector-borne diseases, such as malaria, this preventive practice has been barely undertaken in Latin America. An analysis of the architectural and urban features of indigenous Amazonian populations is essential to define and adapt these vector control measures. A total of 32 villages of 29 different ethnicities were studied and mapped by reviewing literature and visual information, and using a geographic information system. The most important architectural and urban characteristics influencing malaria were analysed according to the following categories: number of households and dimensions, supporting area, openings, materials, lifespan and location. Housing typologies found were classified within each of these variables. The results of this typological analysis included an easy-to-handle working template and revealing of features that benefit or hamper the presence of malaria vectors in Amerindians communities. Among risk factors, presence of open eaves, permeable walls, open-side constructions, large number of sleepers indoors, temporary-ephemeral houses, linear villages along stream banks, houseboats villages, poor urban drainage and villages surrounded by anthropogenic environments were highlighted. Indigenous settlements very permissive for anophelines were identified in ethnic groups, such as the Yanomami, Palikur, Paumari, Waimiri-Atroari and Wajãpi. Positive features were also recognized, including opaque and closed houses, large radial villages on bare soil, highly elevated stilted houses and the fire indoors, found among the Yawalapiti, Ashaninka, and Gavião-Parkatejê tribes. However, as Amazonian indigenous settlement typologies vary greatly even among villages of the same ethnic group, it is imperative to undertake an individual study for each community. Using the working template in Amazonian settlements it is possible to obtain data that will help researchers not only understand how architectural and urban features affect transmission, but also define vector control measures easily applicable by health authorities and acceptable by these communities.
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Affiliation(s)
| | - Richard Thomson-Luque
- Department of Global Health and Infectious Diseases, College of Public Health, University of South Florida, Tampa, FL, USA.
| | - Wuelton M Monteiro
- Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Av. Pedro Teixeira, 25, Dom Pedro, Manaus, AM, 69040-000, Brazil.
- Universidade do Estado do Amazonas, Av. Pedro Teixeira, 25, Dom Pedro, Manaus, AM, 69040-000, Brazil.
| | - Marcus V G de Lacerda
- Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Av. Pedro Teixeira, 25, Dom Pedro, Manaus, AM, 69040-000, Brazil.
- Universidade do Estado do Amazonas, Av. Pedro Teixeira, 25, Dom Pedro, Manaus, AM, 69040-000, Brazil.
- Instituto de Pesquisas Leônidas and Maria Deane, Fundação Oswaldo Cruz, Rua Terezina, 476, Adrianópolis, Manaus, AM, 69057-070, Brazil.
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Guyant P, Canavati SE, Chea N, Ly P, Whittaker MA, Roca-Feltrer A, Yeung S. Malaria and the mobile and migrant population in Cambodia: a population movement framework to inform strategies for malaria control and elimination. Malar J 2015; 14:252. [PMID: 26088924 PMCID: PMC4474346 DOI: 10.1186/s12936-015-0773-5] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Accepted: 06/09/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The relationships between human population movement (HPM) and health are a concern at global level. In the case of malaria, those links are crucial in relation to the spread of drug resistant parasites and to the elimination of malaria in the Greater Mekong sub-Region (GMS) and beyond. The mobile and migrant populations (MMP) who are involved in forest related activities are both at high risk of being infected with malaria and at risk of receiving late and sub-standard treatment due to poor access to health services. In Cambodia, in 2012, the National Malaria Control Programme (NMCP) identified, as a key objective, the development of a specific strategy for MMPs in order to address these challenges. A population movement framework (PMF) for malaria was developed and operationalized in order to contribute to this strategy. METHODS A review of the published and unpublished literature was conducted. Based on a synthesis of the results, information was presented and discussed with experienced researchers and programme managers in the Cambodian NMCP and led to the development and refinement of a PMF for malaria. The framework was "tested" for face and content validity with national experts through a workshop approach. RESULTS In the literature, HPM has been described using various spatial and temporal dimensions both in the context of the spread of anti-malarial drug resistance, and in the context of malaria elimination and previous classifications have categorized MMPs in Cambodia and the GMS through using a number of different criteria. Building on these previous models, the PMF was developed and then refined and populated with in-depth information relevant to Cambodia collected from social science research and field experiences in Cambodia. The framework comprises of the PMF itself, MMP activity profiles and a Malaria Risk Index which is a summation of three related indices: a vulnerability index, an exposure index and an access index which allow a qualitative ranking of malaria risk in the MMP population. Application of currently available data to the framework illustrates that the highest risk population are those highly mobile populations engaged in forest work. CONCLUSION This paper describes the process of defining MMPs in Cambodia, identifying the different activities and related risks to appropriately target and tailor interventions to the highest risk groups. The framework has been used to develop more targeted behaviour change and outreach interventions for MMPs in Cambodia and its utility and effectiveness will be evaluated as part of those interventions.
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Affiliation(s)
- Philippe Guyant
- Department of Global Health and Development, Malaria Centre, London School of Hygiene and Tropical Medicine, London, UK.
- Partners for Development, Phnom Penh, Cambodia.
| | - Sara E Canavati
- Malaria Consortium, Phnom Penh, Cambodia.
- Department of Clinical Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
| | - Nguon Chea
- National Center for Parasitology, Entomology and Malaria Control, Phnom Penh, Cambodia.
| | - Po Ly
- National Center for Parasitology, Entomology and Malaria Control, Phnom Penh, Cambodia.
| | | | | | - Shunmay Yeung
- Department of Global Health and Development, Malaria Centre, London School of Hygiene and Tropical Medicine, London, UK.
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Tusting LS, Ippolito MM, Willey BA, Kleinschmidt I, Dorsey G, Gosling RD, Lindsay SW. The evidence for improving housing to reduce malaria: a systematic review and meta-analysis. Malar J 2015; 14:209. [PMID: 26055986 PMCID: PMC4460721 DOI: 10.1186/s12936-015-0724-1] [Citation(s) in RCA: 188] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Accepted: 05/06/2015] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND The global malaria burden has fallen since 2000, sometimes before large-scale vector control programmes were initiated. While long-lasting insecticide-treated nets and indoor residual spraying are highly effective interventions, this study tests the hypothesis that improved housing can reduce malaria by decreasing house entry by malaria mosquitoes. METHODS A systematic review and meta-analysis was conducted to assess whether modern housing is associated with a lower risk of malaria than traditional housing, across all age groups and malaria-endemic settings. Six electronic databases were searched to identify intervention and observational studies published from 1 January, 1900 to 13 December, 2013, measuring the association between house design and malaria. The primary outcome measures were parasite prevalence and incidence of clinical malaria. Crude and adjusted effects were combined in fixed- and random-effects meta-analyses, with sub-group analyses for: overall house type (traditional versus modern housing); screening; main wall, roof and floor materials; eave type; ceilings and elevation. RESULTS Of 15,526 studies screened, 90 were included in a qualitative synthesis and 53 reported epidemiological outcomes, included in a meta-analysis. Of these, 39 (74%) showed trends towards a lower risk of epidemiological outcomes associated with improved house features. Of studies assessing the relationship between modern housing and malaria infection (n=11) and clinical malaria (n=5), all were observational, with very low to low quality evidence. Residents of modern houses had 47% lower odds of malaria infection compared to traditional houses (adjusted odds ratio (OR) 0°53, 95% confidence intervals (CI) 0°42-0°67, p< 0°001, five studies) and a 45-65% lower odds of clinical malaria (case-control studies: adjusted OR 0°35, 95 % CI 0°20-0°62, p<0°001, one study; cohort studies: adjusted rate ratio 0°55, 95% CI 0°36-0°84, p=0°005, three studies). Evidence of a high risk of bias was found within studies. CONCLUSIONS Despite low quality evidence, the direction and consistency of effects indicate that housing is an important risk factor for malaria. Future research should evaluate the protective effect of specific house features and incremental housing improvements associated with socio-economic development.
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Affiliation(s)
- Lucy S Tusting
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, WC1E 7HT, UK.
| | - Matthew M Ippolito
- Department of Medicine, Division of Infectious Diseases, Johns Hopkins University School of Medicine, 1830 Building Room 450B, 600 North Wolfe Street, Baltimore, MD, 21287, USA.
| | - Barbara A Willey
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, UK.
| | - Immo Kleinschmidt
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, UK.
| | - Grant Dorsey
- Department of Medicine, University of California, San Francisco, CA, 94143, USA.
| | - Roly D Gosling
- Global Health Group, University of California, San Francisco, CA, 94105, USA.
| | - Steve W Lindsay
- School of Biological and Biomedical Sciences, Durham University, Durham, DH1 3LE, UK.
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Okello AL, Burniston S, Conlan JV, Inthavong P, Khamlome B, Welburn SC, Gilbert J, Allen J, Blacksell SD. Prevalence of Endemic Pig-Associated Zoonoses in Southeast Asia: A Review of Findings from the Lao People's Democratic Republic. Am J Trop Med Hyg 2015; 92:1059-1066. [PMID: 25802431 PMCID: PMC4426289 DOI: 10.4269/ajtmh.14-0551] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Accepted: 01/19/2015] [Indexed: 12/02/2022] Open
Abstract
The increasing intensification of pork production in southeast Asia necessitates an urgent requirement to better understand the dual impact of pig-associated zoonotic disease on both pig production and human health in the region. Sharing porous borders with five countries and representing many regional ethnicities and agricultural practices, the Lao People's Democratic Republic (Lao PDR) appears well placed to gauge the levels of pig-associated zoonoses circulating in the wider region. Despite this, little is known about the true impact of zoonotic pathogens such as leptospirosis, Trichinella, hepatitis E virus (HEV), Japanese encephalitis (JE), and Taenia solium on human health and livestock production in the country. A comprehensive review of the published prevalences of these five pig-associated zoonoses in Lao PDR has demonstrated that although suspicion remains high of their existence in pig reservoirs across the country, epidemiological data are scarce; only 31 epidemiological studies have been undertaken on these diseases in the past 25 years. A greater understanding of the zoonoses prevalence and subsequent risks associated with pork production in the southeast Asian region could help focus public health and food safety interventions at key points along the value chain, benefiting both livestock producers and the broader animal and human health systems in the region.
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Affiliation(s)
- Anna L. Okello
- School of Biomedical Sciences, College of Medicine and Veterinary Medicine, The University of Edinburgh, Edinburgh, United Kingdom; School of Veterinary and Life Sciences, Murdoch University, Murdoch, Western Australia, Australia; National Animal Health Laboratory, Department of Livestock and Fisheries, Ministry of Agriculture, Vientiane, Lao People's Democratic Republic; Department of Hygiene and Prevention, Ministry of Health, Vientiane, Lao People's Democratic Republic; International Livestock Research Institute, Nairobi, Kenya; Australian Animal Health Laboratory (AAHL), CSIRO Animal, Food and Health Sciences, Geelong, Victoria, Australia; Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand; Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, Churchill Hospital, Oxford, United Kingdom
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Sonko ST, Jaiteh M, Jafali J, Jarju LBS, D'Alessandro U, Camara A, Komma-Bah M, Saho A. Does socio-economic status explain the differentials in malaria parasite prevalence? Evidence from The Gambia. Malar J 2014; 13:449. [PMID: 25416303 PMCID: PMC4289203 DOI: 10.1186/1475-2875-13-449] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2014] [Accepted: 09/27/2014] [Indexed: 11/21/2022] Open
Abstract
Background Malaria is commonly associated with poverty. Macro-level estimates show strong links between malaria and poverty, and increasing evidence suggests that the causal link between malaria and poverty runs in both directions. However, micro-level (household and population) analyses on the linkages between malaria and poverty have often produced mixed results. Methods The Gambia Malaria Indicator Survey (MIS) 2010/11 was carried out between November 2010 and January 2011. Laboratory-confirmed malaria and wealth quintiles were used to assess the association of socio-economic status and malaria infection in children and the general population. Simple and multiple logistic regressions and survey data analysis procedures, including linearized standard errors to account for cluster sampling and unequal selection probabilities were applied. Results Children (six to 59 months) from the second, third, fourth and richest quintiles were significantly less likely to have malaria compared to children from the poorest quintiles. Children (five to 14 years) from the fourth and richest quintiles were also significantly less likely to have malaria compared to those from the poorest quintiles. The malaria burden has shifted from the under-five children (six to 59 months) to children aged five to 14 years. Malaria prevalence was significantly higher in the Central River Region compared to the Upper River Region; and males bear the malaria brunt more than females. Children (six to 59 months) and children (five to 14 years) living in houses with poor walls, floors, roofs and windows were significant associated with higher prevalence of malaria. However, in the general population, only poor wall housing materials were associated with higher prevalence of malaria. Conclusions Investments in strategies that address socio-economic disparities and improvements in the quality of housing could, in the long term, significantly reduce the malaria burden in the poorest communities.
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Affiliation(s)
- Sheriff T Sonko
- National Malaria Control Programme, Kanifing Institutional Layout, Plot # 17, Kanifing, The Gambia.
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Mosha JF, Sturrock HJW, Brown JM, Hashim R, Kibiki G, Chandramohan D, Gosling RD. The independent effect of living in malaria hotspots on future malaria infection: an observational study from Misungwi, Tanzania. Malar J 2014; 13:445. [PMID: 25413016 PMCID: PMC4255924 DOI: 10.1186/1475-2875-13-445] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Accepted: 11/10/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND As malaria transmission declines, continued improvements of prevention and control interventions will increasingly rely on accurate knowledge of risk factors and an ability to define high-risk areas and populations at risk for focal targeting of interventions. This paper explores the independent association between living in a hotspot and prospective risk of malaria infection. METHODS Malaria infection status defined by nPCR and AMA-1 status in year 1 were used to define geographic hotspots using two geospatial statistical methods (SaTScan and Kernel density smoothing). Other malaria risk factors for malaria infection were explored by fitting a multivariable model. RESULTS This study demonstrated that residing in infection hotspot of malaria transmission is an independent predictor of malaria infection in the future. CONCLUSION It is likely that targeting such hotspots with better coverage and improved malaria control strategies will result in more cost-efficient uses of resources to move towards malaria elimination.
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Affiliation(s)
- Jacklin F Mosha
- National Institute for Medical Research (NIMR), Mwanza Medical Research Centre, Mwanza, Tanzania.
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Yadav K, Dhiman S, Rabha B, Saikia P, Veer V. Socio-economic determinants for malaria transmission risk in an endemic primary health centre in Assam, India. Infect Dis Poverty 2014; 3:19. [PMID: 24991410 PMCID: PMC4078389 DOI: 10.1186/2049-9957-3-19] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Accepted: 06/17/2014] [Indexed: 11/16/2022] Open
Abstract
Background Malaria is a major cause of morbidity and mortality in Northeast India. As there is limited information available on the potential influence of socio-economic variables on malaria risk, the present study was conducted to assess the influence of demographic factors, the socio-economic status, and knowledge, awareness and education on malaria occurrence. Methods Demographics, malaria knowledge and socio-economic variables were collected in four randomly selected health sub-centres of the Orang primary health centre in the Udalguri district, Assam and the association of malaria occurrence with different variables were analysed. The trend of malaria occurrence for different income groups, proximity to health centres and number of mosquito bites per day was also determined using the chi-square test. Relative risk (RR) for gender, house type, knowledge and use of bed nets was determined using Katz approximation. Results Out of the 71 household heads interviewed, 70.4% (50/71) were males. About half (54.9%, 39/71) of the participants had a history of malaria in the last two years, of which 64.1% (25/39) were males, while 35.9% (14/39) were females (χ2 = 5.13; p = 0.02; RR = 1.79). Of the total population surveyed, 49.3% lived in bamboo houses and 35.2% lived at a distance of >3 km from the nearest health centre. The number of participants who had a history of malaria decreased with an increasing monthly income (p < 0.0001). Malaria occurrence was higher among the households living in bamboo houses (69.2%), as compared to Kucha houses (20.5%) and Pucca houses (10.3%). No significant association was observed between education level and malaria occurrence (p = 0.93). The participants who did not use bed nets regularly reported a high occurrence of malaria infection as compared to those who used bed nets everyday (p < 0.0001). Conclusions Lower income, house type, distance to health sub-centre, knowledge and awareness about malaria, number of mosquito bites per day and use of bed nets were positively associated with malaria occurrence. Increasing the number of health sub-centres close to rural areas, improving the economic status and increasing awareness about malaria prevention measures will thus help to reduce malaria-associated morbidities.
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Affiliation(s)
- Kavita Yadav
- Defence Research Laboratory, Tezpur, Assam 784001, India
| | - Sunil Dhiman
- Defence Research Laboratory, Tezpur, Assam 784001, India
| | - Bipul Rabha
- Defence Research Laboratory, Tezpur, Assam 784001, India
| | - Pk Saikia
- Department of Zoology, Gauhati University, Guwahati, India
| | - Vijay Veer
- Defence Research Laboratory, Tezpur, Assam 784001, India
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Liu JX, Bousema T, Zelman B, Gesase S, Hashim R, Maxwell C, Chandramohan D, Gosling R. Is housing quality associated with malaria incidence among young children and mosquito vector numbers? Evidence from Korogwe, Tanzania. PLoS One 2014; 9:e87358. [PMID: 24505285 PMCID: PMC3914816 DOI: 10.1371/journal.pone.0087358] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Accepted: 12/23/2013] [Indexed: 11/19/2022] Open
Abstract
Background Several studies conducted in Northeast Tanzania have documented declines in malaria transmission even before interventions were scaled up. One explanation for these reductions may be the changes in socio-environmental conditions associated with economic development, and in particular improvements in housing construction. Objective This analysis seeks to identify (1) risk factors for malaria incidence among young children and (2) household and environmental factors associated with mosquito vector numbers collected in the child’s sleeping area. Both analyses focus on housing construction quality as a key determinant. Methodology For 435 children enrolled in a larger trial of intermittent preventive treatment for malaria in infants in the Korogwe District in Tanga, Northeastern Tanzania, detailed information on their dwelling characteristics were collected in the last year of the trial. Principal components analysis was used to construct an index of housing structure quality and converted to quintile units for regression analysis. Univariate and multivariate random effects negative binomial regressions were used to predict risk factors for child malaria incidence and the mean total number of indoor female Anopheles gambiae and funestus mosquitoes collected per household across three occasions. Findings Building materials have substantially improved in Korogwe over time. Multivariate regressions showed that residing in rural areas (versus urban) increased malaria incidence rates by over three-fold and mean indoor female A. gambiae and funestus numbers by nearly two-fold. Compared to those residing in the lowest quality houses, children residing in the highest quality houses had one-third lower malaria incidence rates, even when wealth and rural residence were controlled for. Living in the highest quality houses reduced vector numbers while having cattle near the house significantly increased them. Conclusions Results corroborate findings from other studies that show associations between malaria incidence and housing quality; associations were concentrated amongst the highest quality houses.
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Affiliation(s)
- Jenny X. Liu
- Global Health Group, Global Health Sciences, University of California, San Francisco, San Francisco, California, United States of America
- * E-mail:
| | - Teun Bousema
- Department of Immunology & Infection, London School of Hygiene and Tropical Medicine, London, United Kingdom
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, Netherlands
| | - Brittany Zelman
- Global Health Group, Global Health Sciences, University of California, San Francisco, San Francisco, California, United States of America
| | - Samwel Gesase
- Tanga Research Center, National Institute for Medical Research, Tanga, Tanzania
| | - Ramadhan Hashim
- Mwanza Interventions Trial Unit Center, National Institute for Medical Research, Mwanza, Tanzania
| | - Caroline Maxwell
- Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Daniel Chandramohan
- Department of Immunology & Infection, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Roly Gosling
- Global Health Group, Global Health Sciences, University of California, San Francisco, San Francisco, California, United States of America
- Department of Epidemiology and Biostatistics, University of California, San Francisco, San Francisco, California, United States of America
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