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Yared S, Gebresilassie A, Aklilu E, Abdulahi E, Kirstein OD, Gonzalez-Olvera G, Che-Mendoza A, Bibiano-Marin W, Waymire E, Lines J, Lenhart A, Kitron U, Carter T, Manrique-Saide P, Vazquez-Prokopec GM. Building the vector in: construction practices and the invasion and persistence of Anopheles stephensi in Jigjiga, Ethiopia. Lancet Planet Health 2023; 7:e999-e1005. [PMID: 38056970 DOI: 10.1016/s2542-5196(23)00250-4] [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: 05/22/2023] [Revised: 10/26/2023] [Accepted: 10/30/2023] [Indexed: 12/08/2023]
Abstract
Anopheles stephensi is a major vector of malaria in Asia and the Arabian Peninsula, and its recent invasion into Africa poses a major threat to malaria control and elimination efforts on the continent. The mosquito is well adapted to urban environments, and its presence in Africa could potentially lead to an increase in malaria transmission in cities. Most of the knowledge about An stephensi ecology in Africa has been generated from studies conducted during the rainy season, when vectors are most abundant. Here, we provide evidence from the peak of the dry season in the city of Jigjiga in Ethiopia, and report An stephensi immature stages infesting predominantly in water reservoirs made to support construction operations (ie, in construction sites or associated with brick-manufacturing businesses). Political and economic changes in Ethiopia (particularly the Somali Region) have fuelled an unprecedented construction boom since 2018 that, in our opinion, has been instrumental in the establishment, persistence, and propagation of An stephensi via the year-round availability of perennial larval habitats associated with construction. We argue that larval source management during the dry season might provide a unique opportunity for focused control of An stephensi in Jigjiga and similar areas.
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Affiliation(s)
- Solomon Yared
- Department of Biology, Jigjiga University, Jigjiga, Ethiopia
| | - Araya Gebresilassie
- Department of Zoological Sciences, Addis Ababa University, Addis Ababa, Ethiopia
| | - Esayas Aklilu
- Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia
| | - Elyas Abdulahi
- Population, Resources and Environmental Economics, Jigjiga University, Jigjiga, Ethiopia
| | | | - Gabriela Gonzalez-Olvera
- Collaborative Unit for Entomological Bioassays, Autonomous University of Yucatan, Mérida, Mexico
| | - Azael Che-Mendoza
- Collaborative Unit for Entomological Bioassays, Autonomous University of Yucatan, Mérida, Mexico
| | - Wilbert Bibiano-Marin
- Collaborative Unit for Entomological Bioassays, Autonomous University of Yucatan, Mérida, Mexico
| | | | - Jo Lines
- London School of Public Health, London, UK
| | - Audrey Lenhart
- Entomology Branch, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Uriel Kitron
- Department of Environmental Sciences, Emory University, Atlanta, GA, USA
| | - Tamar Carter
- Department of Biology, Baylor University, Wako, TX, USA
| | - Pablo Manrique-Saide
- Collaborative Unit for Entomological Bioassays, Autonomous University of Yucatan, Mérida, Mexico
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Khan A, Bisanzio D, Mutuku F, Ndenga B, Grossi-Soyster EN, Jembe Z, Maina PW, Chebii PK, Ronga CO, Okuta V, LaBeaud AD. Spatiotemporal overlapping of dengue, chikungunya, and malaria infections in children in Kenya. BMC Infect Dis 2023; 23:183. [PMID: 36991340 PMCID: PMC10053720 DOI: 10.1186/s12879-023-08157-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 03/14/2023] [Indexed: 03/31/2023] Open
Abstract
Malaria, chikungunya virus (CHIKV), and dengue virus (DENV) are endemic causes of fever among children in Kenya. The risks of infection are multifactorial and may be influenced by built and social environments. The high resolution overlapping of these diseases and factors affecting their spatial heterogeneity has not been investigated in Kenya. From 2014-2018, we prospectively followed a cohort of children from four communities in both coastal and western Kenya. Overall, 9.8% were CHIKV seropositive, 5.5% were DENV seropositive, and 39.1% were malaria positive (3521 children tested). The spatial analysis identified hot-spots for all three diseases in each site and in multiple years. The results of the model showed that the risk of exposure was linked to demographics with common factors for the three diseases including the presence of litter, crowded households, and higher wealth in these communities. These insights are of high importance to improve surveillance and targeted control of mosquito-borne diseases in Kenya.
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Affiliation(s)
- Aslam Khan
- Stanford University School of Medicine, Stanford, CA, USA.
- Center for Academic Medicine, 453 Quarry Road, Palo Alto, CA, 94304, USA.
| | | | | | | | | | - Zainab Jembe
- Msambweni County Referral hospital, Msambweni, Kenya
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Burton TA, Kabinga LH, Simubali L, Hayre Q, Moore SJ, Stevenson JC, Lobo NF. Semi-field evaluation of a volatile transfluthrin-based intervention reveals efficacy as a spatial repellent and evidence of other modes of action. PLoS One 2023; 18:e0285501. [PMID: 37167335 PMCID: PMC10174509 DOI: 10.1371/journal.pone.0285501] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Accepted: 04/25/2023] [Indexed: 05/13/2023] Open
Abstract
Presently, the most common malaria control tools-i.e., long lasting insecticide-treated nets (LLINs) and indoor residual spraying (IRS)-are limited to targeting indoor biting and resting behaviors of Anopheles mosquito species. Few interventions are targeted towards malaria control in areas where transmission is driven or persists due to outdoor biting behaviors. This study investigated a volatile pyrethroid-based spatial repellent (VPSR) designed to bridge this gap and provide protection from mosquito bites in outdoor spaces. Southern Province, Zambia, is one such environment where outdoor biting is suspected to contribute to malaria transmission, where people are active in the evening in open-walled outdoor kitchens. This study assessed the VPSR in replica kitchens within a controlled semi-field environment. Endpoints included effects on mosquito host seeking, immediate and delayed mortality, deterrence, blood feeding inhibition, and fertility. Host-seeking was reduced by approximately 40% over the course of nightly releases in chambers containing VPSR devices. Mosquito behavior was not uniform throughout the night, and the modeled effect of the intervention was considerably higher when hourly catch rates were considered. These two observations highlight a limitation of this overnight semi-field design and consideration of mosquito circadian rhythms is recommended for future semi-field studies. Additionally, deterrence and immediate mortality were both observed in treatment chambers, with evidence of delayed mortality and a dose related response. These results demonstrate a primarily personal protective mode of action with possible positive and negative community effects. Further investigation into this primary mode of action will be conducted through a field trial of the same product in nearby communities.
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Affiliation(s)
- Timothy A Burton
- Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, United States of America
| | | | | | - Quinton Hayre
- Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, United States of America
| | - Sarah J Moore
- Vector Control Product Testing Unit (VCPTU), Ifakara Health Institute, Environmental Health, and Ecological Sciences, Bagamoyo, Tanzania
- Vector Biology Unit, Department of Epidemiology and Public Health, Swiss Tropical & Public Health Institute, Basel, Switzerland
- Faculty of Science, University of Basel, Basel, Switzerland
- The Nelson Mandela African Institution of Science and Technology (NM-AIST), Tengeru, Arusha, Tanzania
| | - Jennifer C Stevenson
- Macha Research Trust, Choma, Choma District, Zambia
- Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, United States of America
| | - Neil F Lobo
- Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, United States of America
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Msoffe R, Hewitt M, Masalu JP, Finda M, Kavishe DR, Okumu FO, Mpolya EA, Kaindoa EW, Killeen GF. Participatory development of practical, affordable, insecticide-treated mosquito proofing for a range of housing designs in rural southern Tanzania. Malar J 2022; 21:318. [PMCID: PMC9636681 DOI: 10.1186/s12936-022-04333-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2022] [Accepted: 10/18/2022] [Indexed: 11/08/2022] Open
Abstract
Abstract
Background
Insecticidal mosquito-proof netting screens could combine the best features of insecticide-treated nets (ITNs) and indoor residual spraying (IRS), the two most important front line vector control interventions in Africa today, and also overcome the most important limitations of these methods. This study engaged members of a rural Tanzanian community in developing and evaluating simple, affordable and scalable procedures for installing readily available screening materials on eave gaps and windows of their own houses, and then treating those screens with a widely used IRS formulation of the organophosphate insecticide pirimiphos-methyl (PM).
Methods
A cohort of 54 households recruited upon consent, following which the structural features and occupant demographics of their houses were surveyed. Indoor mosquito densities were surveyed longitudinally, for approximately 3 months before and over 5 months after participatory house modification and screening using locally available materials. Each house was randomly assigned to one of three study arms: (1) No screens installed until the end of the study (negative control), (2) untreated screens installed, and (3) screened installed and then treated with PM, the insecticidal activity of which was subsequently assessed using standard cone assays.
Results
Almost all (52) recruited households participated until the end, at which point all houses had been successfully screened. In most cases, screening was only installed after making enabling structural modifications that were accepted by the enrolled households. Compared to unscreened houses, houses with either treated or untreated screens both almost entirely excluded Anopheles arabiensis (Relative reduction (RR) ≥ 98%, P < < 0.0001), the most abundant local malaria vector. However, screens were far less effective against Culex quinquefasciatus (RR ≤ 46%, P < < 0.0001), a non-malaria vector causing considerable biting nuisance, regardless of their treatment status. While PM did not augment household level protection by screens against either mosquito species (P = 0.676 and 0.831, respectively), 8 months after treatment it still caused 73% and 89% mortality among susceptible insectary-reared Anopheles gambiae following exposures of 3 and 30 min, respectively.
Conclusions
Participatory approaches to mosquito proofing houses may be acceptable and effective, and installed screens may be suitable targets for residual insecticide treatments.
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