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Omoke D, Impoinvil LM, Derilus D, Okeyo S, Saizonou H, Mulder N, Dada N, Lenhart A, Djogbénou L, Ochomo E. Whole transcriptomic analysis reveals overexpression of salivary gland and cuticular proteins genes in insecticide-resistant Anopheles arabiensis from Western Kenya. BMC Genomics 2024; 25:313. [PMID: 38532318 DOI: 10.1186/s12864-024-10182-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Accepted: 03/04/2024] [Indexed: 03/28/2024] Open
Abstract
BACKGROUND Effective vector control is key to malaria prevention. However, this is now compromised by increased insecticide resistance due to continued reliance on insecticide-based control interventions. In Kenya, we have observed heterogenous resistance to pyrethroids and organophosphates in Anopheles arabiensis which is one of the most widespread malaria vectors in the country. We investigated the gene expression profiles of insecticide resistant An. arabiensis populations from Migori and Siaya counties in Western Kenya using RNA-Sequencing. Centers for Disease Control and Prevention (CDC) bottle assays were conducted using deltamethrin (DELTA), alphacypermethrin (ACYP) and pirimiphos-methyl (PMM) to determine the resistance status in both sites. RESULTS Mosquitoes from Migori had average mortalities of 91%, 92% and 58% while those from Siaya had 85%, 86%, and 30% when exposed to DELTA, ACYP and PMM, respectively. RNA-Seq analysis was done on pools of mosquitoes which survived exposure ('resistant'), mosquitoes that were not exposed, and the insecticide-susceptible An. arabiensis Dongola strain. Gene expression profiles of resistant mosquitoes from both Migori and Siaya showed an overexpression mainly of salivary gland proteins belonging to both the short and long form D7 genes, and cuticular proteins (including CPR9, CPR10, CPR15, CPR16). Additionally, the overexpression of detoxification genes including cytochrome P450s (CYP9M1, CYP325H1, CYP4C27, CYP9L1 and CYP307A1), 2 carboxylesterases and a glutathione-S-transferase (GSTE4) were also shared between DELTA, ACYP, and PMM survivors, pointing to potential contribution to cross resistance to both pyrethroid and organophosphate insecticides. CONCLUSION This study provides novel insights into the molecular basis of insecticide resistance in An. arabiensis in Western Kenya and suggests that salivary gland proteins and cuticular proteins are associated with resistance to multiple classes of insecticides.
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Affiliation(s)
- Diana Omoke
- Kenya Medical Research Institute (KEMRI), Centre for Global Health Research (CGHR), Kisumu, Kenya.
| | - Lucy Mackenzie Impoinvil
- Entomology Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, USA
| | - Dieunel Derilus
- Entomology Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, USA
| | - Stephen Okeyo
- Kenya Medical Research Institute (KEMRI), Centre for Global Health Research (CGHR), Kisumu, Kenya
| | | | | | - Nsa Dada
- School of Life Sciences, Arizona State University, Tempe, AZ, USA
- Tropical Infectious Disease Research Center, University of Abomey- Calavi, Abomey Calavi, Benin
| | - Audrey Lenhart
- Entomology Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, USA
| | - Luc Djogbénou
- Entomology Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, USA
- Tropical Infectious Disease Research Center, University of Abomey- Calavi, Abomey Calavi, Benin
| | - Eric Ochomo
- Kenya Medical Research Institute (KEMRI), Centre for Global Health Research (CGHR), Kisumu, Kenya.
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Tarimo FS, Dillip A, Kosia EM, Lwetoijera DW. Community perception of the autodissemination of pyriproxyfen for controlling malaria vectors in south-eastern Tanzania. Malar J 2023; 22:333. [PMID: 37924148 PMCID: PMC10625276 DOI: 10.1186/s12936-023-04773-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 10/26/2023] [Indexed: 11/06/2023] Open
Abstract
BACKGROUND The efficacy of the autodissemination of pyriproxyfen to control malaria vectors has been demonstrated under semi field environment in Tanzania. However, the information on how best communities should be engaged for its routine and large-scale adoption are lacking. This study assessed the community's level of knowledge, perceptions, acceptability of the autodissemination of pyriproxyfen, and the perceived risks on the safety of pyriproxyfen on the environment. METHODS This was a concurrent mixed methods study, comprised of a community-based survey of 400 household representatives and eight focus group discussions (FGDs). The study was conducted in two villages in Mlimba district in south-eastern Tanzania between June and August 2022. For the quantitative data analysis, descriptive statistics were applied using R software, while inductive approach was used for qualitative data analysis, using NVivo software. RESULTS Knowledge on autodissemination of pyriproxyfen approach was found to be relatively low among both the FGD respondents and surveyed community members (36%, n = 144). Nevertheless, when it was explained to them, the envisioned community support for the autodissemination approach was relatively high (97%, n = 388). One of the major perceived benefits of the autodissemination of pyriproxyfen was the reduction of malaria-transmitting mosquitoes and associated malaria transmission. Environmental impact of pyriproxyfen on non-target organisms and health risk to children were among the major concerns. When provided with information on the safety and its utilization particularly through autodissemination approach, 93.5% (n = 374) of the survey respondents said that they would allow the PPF-contaminated pots to be placed around their homes. Similarly, FGD respondents were receptive towards the autodissemination of pyriproxyfen, but emphasized on the need for raising awareness among community members before related field trials. CONCLUSION This study indicates a low knowledge but high support for scaling up of the autodissemination of pyriproxyfen as a complementary tool for malaria control in rural Tanzania. The Findings of this study suggest that community sensitization activities are required to improve the community's acceptability and trust of the approach before respective field trials.
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Affiliation(s)
- Felista S Tarimo
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P. O. Box 53, Ifakara, United Republic of Tanzania.
- School of Life Sciences and Bio Engineering, The Nelson Mandela, African Institution of Science and Technology, P. O. Box 4447, Tengeru, Arusha, United Republic of Tanzania.
| | - Angel Dillip
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P. O. Box 53, Ifakara, United Republic of Tanzania
- School of Life Sciences and Bio Engineering, The Nelson Mandela, African Institution of Science and Technology, P. O. Box 4447, Tengeru, Arusha, United Republic of Tanzania
- Apotheker Health Access Initiative, P. O. Box 70022, Dar es Salaam, United Republic of Tanzania
| | - Efraim M Kosia
- School of Life Sciences and Bio Engineering, The Nelson Mandela, African Institution of Science and Technology, P. O. Box 4447, Tengeru, Arusha, United Republic of Tanzania
| | - Dickson W Lwetoijera
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P. O. Box 53, Ifakara, United Republic of Tanzania.
- School of Life Sciences and Bio Engineering, The Nelson Mandela, African Institution of Science and Technology, P. O. Box 4447, Tengeru, Arusha, United Republic of Tanzania.
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Nzioki I, Machani MG, Onyango SA, Kabui KK, Githeko AK, Ochomo E, Yan G, Afrane YA. Differences in malaria vector biting behavior and changing vulnerability to malaria transmission in contrasting ecosystems of western Kenya. Parasit Vectors 2023; 16:376. [PMID: 37864217 PMCID: PMC10590029 DOI: 10.1186/s13071-023-05944-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Accepted: 08/24/2023] [Indexed: 10/22/2023] Open
Abstract
BACKGROUND Designing, implementing, and upscaling of effective malaria vector control strategies necessitates an understanding of when and where transmission occurs. This study assessed the biting patterns of potentially infectious malaria vectors at various hours, locations, and associated human behaviors in different ecological settings in western Kenya. METHODS Hourly indoor and outdoor catches of human-biting mosquitoes were sampled from 19:00 to 07:00 for four consecutive nights in four houses per village. The human behavior study was conducted via questionnaire surveys and observations. Species within the Anopheles gambiae complex and Anopheles funestus group were distinguished by polymerase chain reaction (PCR) and the presence of Plasmodium falciparum circumsporozoite proteins (CSP) determined by enzyme-linked immunosorbent assay (ELISA). RESULTS Altogether, 2037 adult female anophelines were collected comprising the An. funestus group (76.7%), An. gambiae sensu lato (22.8%), and Anopheles coustani (0.5%). PCR results revealed that Anopheles arabiensis constituted 80.5% and 79% of the An. gambiae s.l. samples analyzed from the lowland sites (Ahero and Kisian, respectively). Anopheles gambiae sensu stricto (hereafter An. gambiae) (98.1%) was the dominant species in the highland site (Kimaeti). All the An. funestus s.l. analyzed belonged to An. funestus s.s. (hereafter An. funestus). Indoor biting densities of An. gambiae s.l. and An. funestus exceeded the outdoor biting densities in all sites. The peak biting occurred in early morning between 04:30 and 06:30 in the lowlands for An. funestus both indoors and outdoors. In the highlands, the peak biting of An. gambiae occurred between 01:00 and 02:00 indoors. Over 50% of the study population stayed outdoors from 18:00 to 22:00 and woke up at 05:00, coinciding with the times when the highest numbers of vectors were collected. The sporozoite rate was higher in vectors collected outdoors, with An. funestus being the main malaria vector in the lowlands and An. gambiae in the highlands. CONCLUSION This study shows heterogeneity of anopheline distribution, high outdoor malaria transmission, and early morning peak biting activity of An. funestus when humans are not protected by bednets in the lowland sites. Additional vector control efforts targeting the behaviors of these vectors, such as the use of non-pyrethroids for indoor residual spraying and spatial repellents outdoors, are needed.
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Affiliation(s)
- Irene Nzioki
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
- School of Zoological Sciences, Kenyatta University, Nairobi, Kenya
| | - Maxwell G Machani
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya.
| | | | - Kevin K Kabui
- School of Zoological Sciences, Kenyatta University, Nairobi, Kenya
| | - Andrew K Githeko
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Eric Ochomo
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Guiyun Yan
- Program in Public Health, College of Health Sciences, University of California, Irvine, CA, 92697, USA
| | - Yaw A Afrane
- Department of Medical Microbiology, University of Ghana Medical School, College of Health Sciences, University of Ghana, Accra, Ghana.
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Nzioki I, Machani MG, Onyango SA, Kabui KK, Githeko AK, Ochomo E, Yan G, Afrane YA. Current observations on shifts in malaria vector biting behavior and changing vulnerability to malaria transmission in contrasting ecosystems in Western Kenya. RESEARCH SQUARE 2023:rs.3.rs-2772202. [PMID: 37090522 PMCID: PMC10120786 DOI: 10.21203/rs.3.rs-2772202/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
Background Designing, implementing, and upscaling effective malaria vector control strategies necessitates understanding of when and where transmission occurs. This study assessed the biting patterns of potentially infectious malaria vectors at various hours, locations, and human behavior in different ecological settings in western Kenya. Methods Hourly indoor and outdoor catches of human-biting mosquitoes were sampled from 1900 to 0700 hours for four consecutive nights in four houses per village using human landing collection method. The nocturnal biting activities of each Anopheles species were expressed as the mean number of mosquitoes landing per person per hour. The human behavior study was conducted via observations and questionnaire surveys. Species within Anopheles gambiae and Anopheles funestus complexes were differentiated by polymerase chain reaction (PCR) and the presence of Plasmodium falciparumcircumsporozoite proteins (CSP) determined by enzyme-linked immunosorbent assay (ELISA). Results Altogether, a total of 2,037 adult female Anophelines were collected comprising of An. funestus s.l. (76.7%), An.gambiae s.l.(22.8%) and Anopheles coustani (0.5%). Overall, Anopheles funestus was the predominant species collected in Ahero (96.7%) while An. gambiae s.l was dominant in Kisian (86.6%) and Kimaeti (100%) collections. PCR results revealed that An. arabiensis constituted 80.5% and 79% of the An.gambiae s.l samples analysed from Ahero and Kisian respectively. An. gambiae s.s (hereafter An.gambiae) (98.1%) was the dominant species collected in Kimaeti. All the An. funestus s.l samples analysed belonged to An. funestus s.s (hereafter An. funestus). Indoor biting densities of Anopheles gambiae and An. funestus exceeded the outdoor biting densities in all sites. The peak biting occurred early morning between 0430-0630 hours in the lowlands for An. funestus both indoors and outdoors. In the highlands (Kimaeti), the peak biting of An.gambiae occurred between 0100-0200 hours indoors. Over 50% of the study population stayed outdoors from 1800 to 2200 hours and woke up at 0500 hours coinciding with the times highest numbers of vectors were collected. The sporozoite rate was higher in vectors collected outdoors, with An. funestus being the main malaria vector in the lowlands and An. gambiaein the highland. Conclusion The study shows heterogeneity of Anophelines distribution, high outdoor malaria transmission, and peak biting activity by An. funestus (early morning) when humans are not protected by bed nets in the lowland sites. Additional vector control efforts targeting the behaviors of these vectors i.e using non-pyrethroids-based indoor residual spraying and spatial repellents outdoors are needed.
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Affiliation(s)
| | | | | | | | | | | | | | - Yaw A Afrane
- University of Ghana Medical School, University of Ghana
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Wilfred G, Songoro EK, Gathirwa JW, Kimani F, Kariuki HN. In vivo antiplasmodial activities of stem bark extracts of Avicennia marina in Plasmodium berghei-infected mice. Pan Afr Med J 2023; 44:93. [PMID: 37229304 PMCID: PMC10204109 DOI: 10.11604/pamj.2023.44.93.38448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Accepted: 01/13/2023] [Indexed: 05/27/2023] Open
Abstract
Introduction malaria remains the leading cause of morbidity and mortality in developing tropical and subtropical nations. Due to the emergence and spread of drug resistance to currently available drugs, there is a need for the search of novel, safe, and reasonably affordable anti-malarial medications. The objective of this study was to assess the in vivoanti-malarial effectiveness of Avicennia marina stem bark extracts in a mice model. Methods guidelines 425 of the Organization for Economic Cooperation and Development were used to determine the extracts' acute toxicity. Mice infected with chloroquine-sensitive Plasmodium berghei (ANKA strain) were tested for in vivoanti-plasmodial activity, and by giving oral doses of 100 mg/kg, 250 mg/kg, and 500 mg/kg body weight of extracts, the plant's suppressive, curative, and preventive effects were assessed. Results mice treated with dosages of up to 5000 mg/kg showed no evidence of acute toxicity or mortality. Consequently, it was determined that the acute lethal dosage of Avicennia marina extracts in swiss albino mice was greater than 5000 mg/kg. All doses of the extracts exhibited significant (p<0.05) dose-dependent suppression of P. berghei in the suppressive tests compared to the control group. At the highest dose (500 mg/kg), Methanolic crude extracts exerted the highest (93%) parasitemia suppression during the 4-day suppressive test. The extracts also displayed significant (p<0.001) prophylactic and curative activities at all doses compared to the control. Conclusion results from this study ascertained the safety and promising curative, prophylactic and suppressive anti-plasmodial capabilities of the stem bark extracts of Avicennia marina in mice model.
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Affiliation(s)
- Gitau Wilfred
- Department of Medical Microbiology, Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya
| | - Edinah Kwamboka Songoro
- Department of Medical Microbiology, Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya
| | - Jeremiah Waweru Gathirwa
- Centre for Traditional Medicine, Drugs and Research, Kenya Medical Research Institute, Nairobi, Kenya
| | - Francis Kimani
- Centre for Biotechnology, Research Development, Kenya Medical Research Institute, Nairobi, Kenya
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Omotayo AI, Ande AT, Oduola AO, Adelaja OJ, Adesalu O, Jimoh TR, Ghazali AI, Awolola ST. Multiple insecticide resistance mechanisms in urban population of Anopheles coluzzii (Diptera: culicidae) from Lagos, South-West Nigeria. Acta Trop 2022; 227:106291. [PMID: 34958768 DOI: 10.1016/j.actatropica.2021.106291] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 12/18/2021] [Accepted: 12/21/2021] [Indexed: 11/01/2022]
Abstract
Malaria is a major public health challenge in Africa with Nigeria accounting for the highest burden of the disease in the world. Vector control has proved to be a highly effective component of malaria control, however, the development and spread of insecticide resistance in major vectors of malaria have been a major challenge. This study assessed resistance mechanisms in Anopheles coluzzii populations from Kosofe, Lagos mainland and Ojo Local Government Areas in Lagos, Nigeria where An. gambiae s.l is resistant to DDT and Permethrin. WHO susceptibility bioassay test was used in determining resistance status of An. coluzzii to discriminating doses of DDT and Permethrin while synergist assay was used to assess the involvement of monooxygenases in resistance development. Sub-species of An. gambiae s.l (An. gambiae and An. coluzzii) were identified using polymerase chain reaction (PCR) and Restriction Fragment Length Polymorphism (PCR-RFLP) while Allele-Specific Polymerase Chain Reaction (AS-PCR) assay was used to detect knockdown mutation (kdr-West; L1014F). Biochemical assays were used in determining the activities of metabolic enzymes. High DDT resistance was recorded in An. coluzzii populations from the three sites. Mortality rate of mosquitoes exposed confirmed Permethrin resistance in Kosofe (50%) and Lagos mainland (48%) but resistance was suspected in Ojo (96%). All specimens tested were confirmed as An. coluzzii with low kdr frequency; 11.6%, 16.4% and 6.7% in Kosofe, Lagos mainland and Ojo respectively. Pre-exposure to synergist (PBO) before exposure to Permethrin led to increased mortality in all populations. Esterase activity was insignificantly overexpressed in Kosofe (p = 0.849) and Lagos mainland (p = 0.229) populations. In contrast, GST activity was significantly lower in populations from Lagos mainland (63.650 ± 9.861; p = 0.007) and Ojo (91.765 ± 4.959; p = 0.042) than Kisumu susceptible strains (120.250 ± 13.972). Monooxygenase activity was higher in Lagos mainland (2.371 ± 0.261) and Ojo (1.361 ± 0.067) populations, albeit significantly in Lagos mainland (p = 0.007) only. Presence of target-site mutation in all populations, increased mortality with pre-exposure to PBO and elevated monooxygenase in Lagos mainland population were confirmed. Multiple resistance mechanisms in some urban populations of An. coluzzii from Lagos, Nigeria calls for appropriate resistance management strategies.
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Demissew A, Animut A, Kibret S, Tsegaye A, Hawaria D, Degefa T, Getachew H, Lee MC, Yan G, Yewhalaw D. Evidence of pyrethroid resistance in Anopheles amharicus and Anopheles arabiensis from Arjo-Didessa irrigation scheme, Ethiopia. PLoS One 2022; 17:e0261713. [PMID: 35030201 PMCID: PMC8759678 DOI: 10.1371/journal.pone.0261713] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 12/08/2021] [Indexed: 11/18/2022] Open
Abstract
Background Indoor residual spraying and insecticide-treated nets are among the key malaria control intervention tools. However, their efficacy is declining due to the development and spread of insecticide resistant vectors. In Ethiopia, several studies reported resistance of An. arabiensis to multiple insecticide classes. However, such data is scarce in irrigated areas of the country where insecticides, pesticides and herbicides are intensively used. Susceptibility of An. gambiae s.l. to existing and new insecticides and resistance mechanisms were assessed in Arjo-Didessa sugarcane plantation area, southwestern Ethiopia. Methods Adult An. gambiae s.l. reared from larval/pupal collections of Arjo-Didessa sugarcane irrigation area and its surrounding were tested for their susceptibility to selected insecticides. Randomly selected An. gambiae s.l. (dead and survived) samples were identified to species using species-specific polymerase chain reaction (PCR) and were further analyzed for the presence of knockdown resistance (kdr) alleles using allele-specific PCR. Results Among the 214 An. gambiae s.l. samples analyzed by PCR, 89% (n = 190) were An. amharicus and 9% (n = 20) were An. arabiensis. Mortality rates of the An. gambiae s.l. exposed to deltamethrin and alphacypermethrin were 85% and 86.8%, respectively. On the other hand, mortalities against pirmiphos-methyl, bendiocarb, propoxur and clothianidin were 100%, 99%, 100% and 100%, respectively. Of those sub-samples (An. amharicus and An. arabiensis) examined for presence of kdr gene, none of them were found to carry the L1014F (West African) allelic mutation. Conclusion Anopheles amharicus and An. arabiensis from Arjo-Didessa sugarcane irrigation area were resistant to pyrethroids which might be synergized by extensive use of agricultural chemicals. Occurrence of pyrethroid resistant malaria vectors could challenge the ongoing malaria control and elimination program in the area unless resistance management strategies are implemented. Given the resistance of An. amharicus to pyrethroids, its behavior and vectorial capacity should be further investigated.
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Affiliation(s)
- Assalif Demissew
- Department of Medical Laboratory Sciences, College of Medicine and Health Sciences, Ambo University, Ambo, Ethiopia
- Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia
- * E-mail: ,
| | - Abebe Animut
- Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia
| | - Solomon Kibret
- Program in Public Health, University of California at Irvine, Irvine, California, United States of America
| | - Arega Tsegaye
- Department of Biology, College of Natural Science, Jimma University, Jimma, Ethiopia
- Tropical and Infectious Diseases Research Center (TIDRC), Jimma University, Jimma, Ethiopia
| | - Dawit Hawaria
- Tropical and Infectious Diseases Research Center (TIDRC), Jimma University, Jimma, Ethiopia
- Yirgalem Hospital Medical College, Yirgalem, Ethiopia
- School of Medical Laboratory Sciences, Faculty of Health Sciences, Jimma University, Jimma, Ethiopia
| | - Teshome Degefa
- Tropical and Infectious Diseases Research Center (TIDRC), Jimma University, Jimma, Ethiopia
- School of Medical Laboratory Sciences, Faculty of Health Sciences, Jimma University, Jimma, Ethiopia
| | - Hallelujah Getachew
- Tropical and Infectious Diseases Research Center (TIDRC), Jimma University, Jimma, Ethiopia
- School of Medical Laboratory Sciences, Faculty of Health Sciences, Jimma University, Jimma, Ethiopia
- Department of Medical Laboratory Sciences, Arbaminch College of Health Sciences, Arba Minch, Ethiopia
| | - Ming-Chieh Lee
- Program in Public Health, University of California at Irvine, Irvine, California, United States of America
| | - Guiyun Yan
- Program in Public Health, University of California at Irvine, Irvine, California, United States of America
| | - Delenasaw Yewhalaw
- Tropical and Infectious Diseases Research Center (TIDRC), Jimma University, Jimma, Ethiopia
- School of Medical Laboratory Sciences, Faculty of Health Sciences, Jimma University, Jimma, Ethiopia
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Mwagira-Maina S, Runo S, Wachira L, Kitur S, Nyasende S, Kemei B, Ochomo E, Matoke-Muhia D, Mbogo C, Kamau L. Genetic markers associated with insecticide resistance and resting behaviour in Anopheles gambiae mosquitoes in selected sites in Kenya. Malar J 2021; 20:461. [PMID: 34903240 PMCID: PMC8670025 DOI: 10.1186/s12936-021-03997-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Accepted: 11/28/2021] [Indexed: 11/16/2022] Open
Abstract
Background Molecular diagnostic tools have been incorporated in insecticide resistance monitoring programmes to identify underlying genetic basis of resistance and develop early warning systems of vector control failure. Identifying genetic markers of insecticide resistance is crucial in enhancing the ability to mitigate potential effects of resistance. The knockdown resistance (kdr) mutation associated with resistance to DDT and pyrethroids, the acetylcholinesterase-1 (ace-1R) mutation associated with resistance to organophosphates and carbamates and 2La chromosomal inversion associated with indoor resting behaviour, were investigated in the present study. Methods Anopheles mosquitoes sampled from different sites in Kenya and collected within the context of malaria vector surveillance were analysed. Mosquitoes were collected indoors using light traps, pyrethrum spray and hand catches between August 2016 and November 2017. Mosquitoes were identified using morphological keys and Anopheles gambiae sensu lato (s.l.) mosquitoes further identified into sibling species by the polymerase chain reaction method following DNA extraction by alcohol precipitation. Anopheles gambiae and Anopheles arabiensis were analysed for the presence of the kdr and ace-1R mutations, while 2La inversion was only screened for in An. gambiae where it is polymorphic. Chi-square statistics were used to determine correlation between the 2La inversion karyotype and kdr-east mutation. Results The kdr-east mutation occurred at frequencies ranging from 0.5 to 65.6% between sites. The kdr-west mutation was only found in Migori at a total frequency of 5.3% (n = 124). No kdr mutants were detected in Tana River. The ace-1R mutation was absent in all populations. The 2La chromosomal inversion screened in An. gambiae occurred at frequencies of 87% (n = 30), 80% (n = 10) and 52% (n = 50) in Baringo, Tana River and Migori, respectively. A significant association between the 2La chromosomal inversion and the kdr-east mutation was found. Conclusion The significant association between the 2La inversion karyotype and kdr-east mutation suggests that pyrethroid resistant An. gambiae continue to rest indoors regardless of the presence of treated bed nets and residual sprays, a persistence further substantiated by studies documenting continued mosquito abundance indoors. Behavioural resistance by which Anopheles vectors prefer not to rest indoors may, therefore, not be a factor of concern in this study’s malaria vector populations.
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Affiliation(s)
- Sharon Mwagira-Maina
- Department of Biochemistry and Biotechnology, Kenyatta University, P.O Box 43844-00100, Nairobi, Kenya.
| | - Steven Runo
- Department of Biochemistry and Biotechnology, Kenyatta University, P.O Box 43844-00100, Nairobi, Kenya
| | - Lucy Wachira
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute (KEMRI), P.O Box 54840-00200, Nairobi, Kenya
| | - Stanley Kitur
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute (KEMRI), P.O Box 54840-00200, Nairobi, Kenya
| | - Sarah Nyasende
- Institute of Tropical Medicine and Infectious Diseases (ITROMID), P.O. Box 54840-00200, Nairobi, Kenya
| | - Brigid Kemei
- Centre for Global Health Research, KEMRI_CDC, P.O Box 1578-40100, Kisumu, Kenya
| | - Eric Ochomo
- Centre for Global Health Research, KEMRI_CDC, P.O Box 1578-40100, Kisumu, Kenya
| | - Damaris Matoke-Muhia
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute (KEMRI), P.O Box 54840-00200, Nairobi, Kenya
| | - Charles Mbogo
- KEMRI -Wellcome Trust Research Programme, Public Health Unit, P.O. Box 43640-00100, Nairobi, Kenya
| | - Luna Kamau
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute (KEMRI), P.O Box 54840-00200, Nairobi, Kenya
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Orondo PW, Nyanjom SG, Atieli H, Githure J, Ondeto BM, Ochwedo KO, Omondi CJ, Kazura JW, Lee MC, Zhou G, Zhong D, Githeko AK, Yan G. Insecticide resistance status of Anopheles arabiensis in irrigated and non-irrigated areas in western Kenya. Parasit Vectors 2021; 14:335. [PMID: 34174946 PMCID: PMC8235622 DOI: 10.1186/s13071-021-04833-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Accepted: 06/09/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Malaria control in Kenya is based on case management and vector control using long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS). However, the development of insecticide resistance compromises the effectiveness of insecticide-based vector control programs. The use of pesticides for agricultural purposes has been implicated as one of the sources driving the selection of resistance. The current study was undertaken to assess the status and mechanism of insecticide resistance in malaria vectors in irrigated and non-irrigated areas with varying agrochemical use in western Kenya. METHODS The study was carried out in 2018-2019 in Homa Bay County, western Kenya. The bioassay was performed on adults reared from larvae collected from irrigated and non-irrigated fields in order to assess the susceptibility of malaria vectors to different classes of insecticides following the standard WHO guidelines. Characterization of knockdown resistance (kdr) and acetylcholinesterase-inhibiting enzyme/angiotensin-converting enzyme (Ace-1) mutations within Anopheles gambiae s.l. species was performed using the polymerase chain reaction (PCR) method. To determine the agricultural and public health insecticide usage pattern, a questionnaire was administered to farmers, households, and veterinary officers in the study area. RESULTS Anopheles arabiensis was the predominant species in the irrigated (100%, n = 154) area and the dominant species in the non-irrigated areas (97.5%, n = 162), the rest being An. gambiae sensu stricto. In 2018, Anopheles arabiensis in the irrigated region were susceptible to all insecticides tested, while in the non-irrigated region reduced mortality was observed (84%) against deltamethrin. In 2019, phenotypic mortality was decreased (97.8-84% to 83.3-78.2%). In contrast, high mortality from malathion (100%), DDT (98.98%), and piperonyl butoxide (PBO)-deltamethrin (100%) was observed. Molecular analysis of the vectors from the irrigated and non-irrigated areas revealed low levels of leucine-serine/phenylalanine substitution at position 1014 (L1014S/L1014F), with mutation frequencies of 1-16%, and low-frequency mutation in the Ace-1R gene (0.7%). In addition to very high coverage of LLINs impregnated with pyrethroids and IRS with organophosphate insecticides, pyrethroids were the predominant chemical class of pesticides used for crop and animal protection. CONCLUSION Anopheles arabiensis from irrigated areas showed increased phenotypic resistance, and the intensive use of pesticides for crop protection in this region may have contributed to the selection of resistance genes observed. The susceptibility of these malaria vectors to organophosphates and PBO synergists in pyrethroids offers a promising future for IRS and insecticide-treated net-based vector control interventions. These findings emphasize the need for integrated vector control strategies, with particular attention to agricultural practices to mitigate mosquito resistance to insecticides.
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Affiliation(s)
- Pauline Winnie Orondo
- Department of Biochemistry, Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya. .,International Center of Excellence for Malaria Research, Tom Mboya University College of Maseno University, Homa Bay, Kenya.
| | - Steven G Nyanjom
- Department of Biochemistry, Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya
| | - Harrysone Atieli
- International Center of Excellence for Malaria Research, Tom Mboya University College of Maseno University, Homa Bay, Kenya.,School of Public Health and Community Development, Maseno University, Kisumu, Kenya
| | - John Githure
- International Center of Excellence for Malaria Research, Tom Mboya University College of Maseno University, Homa Bay, Kenya
| | - Benyl M Ondeto
- International Center of Excellence for Malaria Research, Tom Mboya University College of Maseno University, Homa Bay, Kenya
| | - Kevin O Ochwedo
- International Center of Excellence for Malaria Research, Tom Mboya University College of Maseno University, Homa Bay, Kenya
| | - Collince J Omondi
- International Center of Excellence for Malaria Research, Tom Mboya University College of Maseno University, Homa Bay, Kenya
| | - James W Kazura
- Center for Global Health & Diseases, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Ming-Chieh Lee
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA, USA
| | - Guofa Zhou
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA, USA
| | - Daibin Zhong
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA, USA
| | - Andrew K Githeko
- International Center of Excellence for Malaria Research, Tom Mboya University College of Maseno University, Homa Bay, Kenya. .,Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya.
| | - Guiyun Yan
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA, USA.
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10
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Mustapha AM, Musembi S, Nyamache AK, Machani MG, Kosgei J, Wamuyu L, Ochomo E, Lobo NF. Secondary malaria vectors in western Kenya include novel species with unexpectedly high densities and parasite infection rates. Parasit Vectors 2021; 14:252. [PMID: 33980273 PMCID: PMC8117294 DOI: 10.1186/s13071-021-04748-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 04/26/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Malaria vector control has been implemented chiefly through indoor interventions targeting primary vectors resulting in population declines-pointing to a possible greater proportional contribution to transmission by secondary malaria vectors with their predominant exophagic and exophilic traits. With a historical focus on primary vectors, there is paucity of data on secondary malaria vectors in many countries in Africa. This study sought to determine the species compositions and bionomic traits, including proportions infected with Plasmodium falciparum and phenotypic insecticide resistance, of secondary vectors in three sites with high malaria transmission in Kisumu County, western Kenya. METHODS Cross-sectional sampling of adult Anopheles was conducted using indoor and outdoor CDC light traps (CDC-LT) and animal-baited traps (ABTs) in Kakola-Ombaka and Kisian, while larvae were sampled in Ahero. Secondary vectors captured were exposed to permethrin using WHO bioassays and then analyzed by ELISA to test for proportions infected with P. falciparum sporozoites. All Anopheles were identified to species using morphological keys with a subset being molecularly identified using ITS2 and CO1 sequencing for species identification. RESULTS Two morphologically identified secondary vectors captured-An. coustani and An. pharoensis-were determined to consist of four species molecularly. These included An. christyi, An. sp. 15 BSL-2014, an unidentified member of the An. coustani complex (An. cf. coustani) and a species similar to that of An. pharoensis and An. squamosus (An. cf. pharoensis). Standardized (Anopheles per trap per night) capture rates demonstrate higher proportions of secondary vectors across most trapping methods-with overall indoor and outdoor CDC-LTs and ABT captures composed of 52.2% (n = 93), 78.9% (n = 221) and 58.1% (n = 573) secondary vectors respectively. Secondary vectors were primarily caught outdoors. The overall proportion of secondary vectors with P. falciparum sporozoite was 0.63% (n = 5), with the unidentified species An. cf. pharoensis, determined to carry Plasmodium. Overall secondary vectors were susceptible to permethrin with a > 99% mortality rate. CONCLUSIONS Given their high densities, endophily equivalent to primary vectors, higher exophily and Plasmodium-positive proportions, secondary vectors may contribute substantially to malaria transmission. Unidentified species demonstrate the need for further morphological and molecular identification studies towards further characterization. Continued monitoring is essential for understanding their temporal contributions to transmission, the possible elevation of some to primary vectors and the development of insecticide resistance.
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Affiliation(s)
- Amine M Mustapha
- Department of Biochemistry and Biotechnology, Kenyatta University, P.O. Box 43844, Nairobi, Kenya.
- Entomology Section, Centre for Global Health Research, KEMRI_KISUMU, P.O. Box 1578-40100, Kisumu, Kenya.
| | - Susan Musembi
- Department of Biochemistry and Biotechnology, Kenyatta University, P.O. Box 43844, Nairobi, Kenya
| | - Anthony K Nyamache
- Department of Biochemistry and Biotechnology, Kenyatta University, P.O. Box 43844, Nairobi, Kenya
| | - Maxwell G Machani
- Entomology Section, Centre for Global Health Research, KEMRI_KISUMU, P.O. Box 1578-40100, Kisumu, Kenya
| | - Jackline Kosgei
- Entomology Section, Centre for Global Health Research, KEMRI_KISUMU, P.O. Box 1578-40100, Kisumu, Kenya
| | - Lucy Wamuyu
- Institute of Biotechnology Research (IBR), Jomo Kenyatta University of Agriculture and Technology (JKUAT), P.O. Box 62000-00200, Nairobi, Kenya
| | - Eric Ochomo
- Entomology Section, Centre for Global Health Research, KEMRI_KISUMU, P.O. Box 1578-40100, Kisumu, Kenya
| | - Neil F Lobo
- Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, 46556, USA
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11
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Munywoki DN, Kokwaro ED, Mwangangi JM, Muturi EJ, Mbogo CM. Insecticide resistance status in Anopheles gambiae (s.l.) in coastal Kenya. Parasit Vectors 2021; 14:207. [PMID: 33879244 PMCID: PMC8056612 DOI: 10.1186/s13071-021-04706-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 03/31/2021] [Indexed: 11/12/2022] Open
Abstract
Background The rapid and widespread evolution of insecticide resistance has emerged as one of the major challenges facing malaria control programs in sub-Saharan Africa. Understanding the insecticide resistance status of mosquito populations and the underlying mechanisms of insecticide resistance can inform the development of effective and site-specific strategies for resistance prevention and management. The aim of this study was to investigate the insecticide resistance status of Anopheles gambiae (s.l.) mosquitoes from coastal Kenya. Methods Anopheles gambiae (s.l.) larvae sampled from eight study sites were reared to adulthood in the insectary, and 3- to 5-day-old non-blood-fed females were tested for susceptibility to permethrin, deltamethrin, dichlorodiphenyltrichloroethane (DDT), fenitrothion and bendiocarb using the standard World Health Organization protocol. PCR amplification of rDNA intergenic spacers was used to identify sibling species of the An. gambiae complex. The An. gambiae (s.l.) females were further genotyped for the presence of the L1014S and L1014F knockdown resistance (kdr) mutations by real-time PCR. Results Anopheles arabiensis was the dominant species, accounting for 95.2% of the total collection, followed by An. gambiae (s.s.), accounting for 4.8%. Anopheles gambiae (s.l.) mosquitoes were resistant to deltamethrin, permethrin and fenitrothion but not to bendiocarb and DDT. The L1014S kdr point mutation was detected only in An. gambiae (s.s.), at a low allelic frequency of 3.33%, and the 1014F kdr mutation was not detected in either An. gambiae (s.s.) or An. arabiensis. Conclusion The findings of this study demonstrate phenotypic resistance to pyrethroids and organophosphates and a low level of the L1014S kdr point mutation that may partly be responsible for resistance to pyrethroids. This knowledge may inform the development of insecticide resistance management strategies along the Kenyan Coast. ![]()
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Affiliation(s)
- Daniel N Munywoki
- Center for Geographic Medicine Research, Coast, Kenya Medical Research Institute, P.O Box 230-80108, Kilifi, Kenya. .,Department of Zoological Sciences, Kenyatta University, P.O Box 43844-00100, Nairobi, Kenya.
| | - Elizabeth D Kokwaro
- Department of Zoological Sciences, Kenyatta University, P.O Box 43844-00100, Nairobi, Kenya
| | - Joseph M Mwangangi
- Center for Geographic Medicine Research, Coast, Kenya Medical Research Institute, P.O Box 230-80108, Kilifi, Kenya
| | - Ephantus J Muturi
- Crop Bioprotection Research Unit, National Center for Agricultural Utilization Research, Agricultural Research Service, US Department of Agriculture, 1815 N. University, St. Peoria, IL, 61604, USA
| | - Charles M Mbogo
- Center for Geographic Medicine Research, Coast, Kenya Medical Research Institute, P.O Box 230-80108, Kilifi, Kenya.,Population Health Unit, KEMRI-Wellcome Trust Research Programme, Lenana Road, 197 Lenana Place, P.O Box 43640-00100, Nairobi, Kenya
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12
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Omoke D, Kipsum M, Otieno S, Esalimba E, Sheth M, Lenhart A, Njeru EM, Ochomo E, Dada N. Western Kenyan Anopheles gambiae showing intense permethrin resistance harbour distinct microbiota. Malar J 2021; 20:77. [PMID: 33557825 PMCID: PMC7869237 DOI: 10.1186/s12936-021-03606-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 01/22/2021] [Indexed: 12/11/2022] Open
Abstract
Background Insecticide resistance poses a growing challenge to malaria vector control in Kenya and around the world. Following evidence of associations between the mosquito microbiota and insecticide resistance, the microbiota of Anopheles gambiae sensu stricto (s.s.) from Tulukuyi village, Bungoma, Kenya, with differing permethrin resistance profiles were comparatively characterized. Methods Using the CDC bottle bioassay, 133 2–3 day-old, virgin, non-blood fed female F1 progeny of field-caught An. gambiae s.s. were exposed to five times (107.5 µg/ml) the discriminating dose of permethrin. Post bioassay, 50 resistant and 50 susceptible mosquitoes were subsequently screened for kdr East and West mutations, and individually processed for microbial analysis using high throughput sequencing targeting the universal bacterial and archaeal 16S rRNA gene. Results 47 % of the samples tested (n = 133) were resistant, and of the 100 selected for further processing, 99 % were positive for kdr East and 1 % for kdr West. Overall, 84 bacterial taxa were detected across all mosquito samples, with 36 of these shared between resistant and susceptible mosquitoes. A total of 20 bacterial taxa were unique to the resistant mosquitoes and 28 were unique to the susceptible mosquitoes. There were significant differences in bacterial composition between resistant and susceptible individuals (PERMANOVA, pseudo-F = 2.33, P = 0.001), with presence of Sphingobacterium, Lysinibacillus and Streptococcus (all known pyrethroid-degrading taxa), and the radiotolerant Rubrobacter, being significantly associated with resistant mosquitoes. On the other hand, the presence of Myxococcus, was significantly associated with susceptible mosquitoes. Conclusions This is the first report of distinct microbiota in An. gambiae s.s. associated with intense pyrethroid resistance. The findings highlight differentially abundant bacterial taxa between resistant and susceptible mosquitoes, and further suggest a microbe-mediated mechanism of insecticide resistance in mosquitoes. These results also indicate fixation of the kdr East mutation in this mosquito population, precluding further analysis of its associations with the mosquito microbiota, but presenting the hypothesis that any microbe-mediated mechanism of insecticide resistance would be likely of a metabolic nature. Overall, this study lays initial groundwork for understanding microbe-mediated mechanisms of insecticide resistance in African mosquito vectors of malaria, and potentially identifying novel microbial markers of insecticide resistance that could supplement existing vector surveillance tools.
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Affiliation(s)
- Diana Omoke
- Department of Biochemistry, Microbiology and Biotechnology, Kenyatta University, Nairobi, Kenya.,Entomology Section, Center for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Mathew Kipsum
- Entomology Section, Center for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Samson Otieno
- Entomology Section, Center for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Edward Esalimba
- Entomology Section, Center for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Mili Sheth
- Biotechnology Core Facility Branch, Division of Scientific Resources, National Center for Emerging & Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Audrey Lenhart
- Entomology Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Diseases Control and Prevention, Atlanta, GA, USA
| | - Ezekiel Mugendi Njeru
- Department of Biochemistry, Microbiology and Biotechnology, Kenyatta University, Nairobi, Kenya
| | - Eric Ochomo
- Entomology Section, Center for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Nsa Dada
- Faculty of Science and Technology, Norwegian University of Life Science, Aas, Norway. .,Public Health and Epidemiology Department, Nigerian Institute of Medical Research, Lagos, Nigeria.
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13
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Influence of a Major Mountainous Landscape Barrier (Mount Cameroon) on the Spread of Metabolic ( GSTe2) and Target-Site ( Rdl) Resistance Alleles in the African Malaria Vector Anopheles funestus. Genes (Basel) 2020; 11:genes11121492. [PMID: 33322524 PMCID: PMC7764057 DOI: 10.3390/genes11121492] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 12/05/2020] [Accepted: 12/08/2020] [Indexed: 12/03/2022] Open
Abstract
Increased levels of insecticide resistance in major malaria vectors such as Anopheles funestus threaten the effectiveness of insecticide-based control programmes. Understanding the landscape features impacting the spread of resistance makers is necessary to design suitable resistance management strategies. Here, we examined the influence of the highest mountain in West Africa (Mount Cameroon; 4095 m elevation) on the spread of metabolic and target-site resistance alleles in An. funestus populations. Vector composition varied across the four localities surveyed along the altitudinal cline with major vectors exhibiting high parity rate (80.5%). Plasmodium infection rates ranged from 0.79% (An. melas) to 4.67% (An. funestus). High frequencies of GSTe2R (67–81%) and RdlR (49–90%) resistance alleles were observed in An. funestus throughout the study area, with GSTe2R frequency increasing with altitude, whereas the opposite is observed for RdlR. Patterns of genetic diversity and population structure analyses revealed high levels of polymorphisms with 12 and 16 haplotypes respectively for GSTe2 and Rdl. However, the reduced diversity patterns of resistance allele carriers revealed signatures of positive selection on the two genes across the study area irrespective of the altitude. Despite slight variations associated with the altitude, the spread of resistance alleles suggest that control strategies could be implemented against malaria vectors across mountainous landscapes.
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14
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The Impact of Insecticide Pre-Exposure on Longevity, Feeding Succession, and Egg Batch Size of Wild Anopheles gambiae s.l. J Trop Med 2020; 2020:8017187. [PMID: 33061994 PMCID: PMC7539113 DOI: 10.1155/2020/8017187] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 09/11/2020] [Accepted: 09/19/2020] [Indexed: 11/18/2022] Open
Abstract
Background Insecticide resistance among the vector population is the main threat to existing control tools available. The current vector control management options rely on applications of recommended public health insecticides, mainly pyrethroids through long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS). Regular monitoring of insecticide resistance does not provide information on important factors that affect parasite transmission. Such factors include vector longevity, vector competence, feeding success, and fecundity. This study investigated the impacts of insecticide resistance on longevity, feeding behaviour, and egg batch size of Anopheles gambiae s.l. Method The larval sampling was conducted in rice fields using a standard dipper (350 ml) and reared to adults in field insectary. A WHO susceptibility test was conducted using standard treated permethrin (0.75%) and deltamethrin (0.05%) papers. The susceptible Kisumu strain was used for reference. Feeding succession and egg batch size were monitored for all survivors and control. Results The results revealed that mortality rates declined by 52.5 and 59.5% for permethrin and deltamethrin, respectively. The mortality rate for the Kisumu susceptible strain was 100%. The survival rates of wild An. gambiae s.l. was between 24 and 27 days. However, the Kisumu susceptible strain blood meal feeding was significantly higher than resistant colony (t = 2.789, df = 21, P=0.011). Additionally, the susceptible An. gambiae s.s. laid more eggs than the resistant An.gambiae s.l. colony (Χ2 = 1366, df = 1, P ≤ 0.05). Conclusion It can, therefore, be concluded that the wild An. gambiae s.l. had increased longevity, blood feeding, and small egg batch size compared to Kisumu susceptible colonies.
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15
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Kweka EJ, Mazigo HD, Lyaruu LJ, Mausa EA, Venter N, Mahande AM, Coetzee M. Anopheline Mosquito Species Composition, Kdr Mutation Frequency, and Parasite Infectivity Status in Northern Tanzania. JOURNAL OF MEDICAL ENTOMOLOGY 2020; 57:933-938. [PMID: 31923308 DOI: 10.1093/jme/tjz245] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Indexed: 06/10/2023]
Abstract
The scaling-up of malaria control interventions in northern Tanzania has resulted in a decline in malaria prevalence and vector species composition. Despite this achievement, residual malaria transmission remains a concern in the area. The main aim of this study was to investigate malaria vector species composition, parasite infectivity rates, and the presence of insecticide knockdown resistance (kdr) mutations in three sites that have experienced a significant decline in malaria in northern Tanzania. Adult mosquitoes were sampled using light traps in houses and hand-aspirators in cowsheds, whereas the standard dipping method was used for sampling mosquito larvae. Adult mosquitoes identified as Anopheles gambiae s.l. and An. funestus s.l. and larval stages III and IV of An. gambiae s.l. were stored in absolute ethanol for further laboratory molecular identification. The identified species in the An. gambiae complex were An. gambiae s.s., An. merus, An. quadriannulatus, and An. arabiensis, whereas the An. funestus group comprised An. funestus s.s., An. rivulorum, and An. leesoni. For An. gambiae s.s. analyzed from Zeneth, 47.6% were kdr-East homozygous susceptible, 35.7% kdr-East heterozygous resistant, 9.6% kdr-East homozygous resistant, and 7.1% undefined, whereas specimens from Kwakibuyu were 45.5% kdr-East homozygous susceptible, 32.7% kdr-East heterozygous resistant, 16.3% kdr-East homozygous resistant, and 5.5% undefined. There were no kdr-West alleles identified from any specimen. The overall malaria parasite infectivity rate was 0.75%. No infections were found in Moshi. The findings indicate that populations of the major malaria vector mosquitoes are still present in the study area, with An. funestus taking a lead in malaria transmission.
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Affiliation(s)
- Eliningaya J Kweka
- Division of Livestock and Human Diseases Vector Control, Tropical Pesticides Research Institute, Arusha, Tanzania
- Department of Medical Parasitology and Entomology, Catholic University of Health and Allied Sciences, Mwanza, Tanzania
| | - Humphrey D Mazigo
- Department of Medical Parasitology and Entomology, Catholic University of Health and Allied Sciences, Mwanza, Tanzania
| | - Lucile J Lyaruu
- Division of Livestock and Human Diseases Vector Control, Tropical Pesticides Research Institute, Arusha, Tanzania
| | - Emmanuel A Mausa
- National Plant Genetic Resource Centre, Tropical Pesticides Research Institute, Arusha, Tanzania
| | - Nelius Venter
- Wits Research Institute for Malaria and Wits/MRC Collaborating Centre for Multi-disciplinary Research on Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- Centre for Emerging, Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases, Johannesburg, South Africa
| | - Aneth M Mahande
- Mabogini Field Station, Tropical Pesticides Research Institute, Moshi, Tanzania
| | - Maureen Coetzee
- Wits Research Institute for Malaria and Wits/MRC Collaborating Centre for Multi-disciplinary Research on Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- Centre for Emerging, Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases, Johannesburg, South Africa
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16
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Staedke SG, Gonahasa S, Dorsey G, Kamya MR, Maiteki-Sebuguzi C, Lynd A, Katureebe A, Kyohere M, Mutungi P, Kigozi SP, Opigo J, Hemingway J, Donnelly MJ. Effect of long-lasting insecticidal nets with and without piperonyl butoxide on malaria indicators in Uganda (LLINEUP): a pragmatic, cluster-randomised trial embedded in a national LLIN distribution campaign. Lancet 2020; 395:1292-1303. [PMID: 32305094 PMCID: PMC7181182 DOI: 10.1016/s0140-6736(20)30214-2] [Citation(s) in RCA: 87] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Revised: 01/16/2020] [Accepted: 01/24/2020] [Indexed: 12/13/2022]
Abstract
BACKGROUND Long-lasting insecticidal nets (LLINs) are the primary malaria prevention tool, but their effectiveness is threatened by pyrethroid resistance. We embedded a pragmatic cluster-randomised trial into Uganda's national LLIN campaign to compare conventional LLINs with those containing piperonyl butoxide (PBO), a synergist that can partially restore pyrethroid susceptibility in mosquito vectors. METHODS 104 health sub-districts, from 48 districts in Uganda, were randomly assigned to LLINs with PBO (PermaNet 3.0 and Olyset Plus) and conventional LLINs (PermaNet 2.0 and Olyset Net) by proportionate randomisation using an iterative process. At baseline 6, 12, and 18 months after LLIN distribution, cross-sectional surveys were done in 50 randomly selected households per cluster (5200 per survey); a subset of ten households per cluster (1040 per survey) were randomly selected for entomological surveys. The primary outcome was parasite prevalence by microscopy in children aged 2-10 years, assessed in the as-treated population at 6, 12, and 18 months. This trial is registered with ISRCTN, ISRCTN17516395. FINDINGS LLINs were delivered to households from March 25, 2017, to March 18, 2018, 32 clusters were randomly assigned to PermaNet 3.0, 20 to Olyset Plus, 37 to PermaNet 2.0, and 15 to Olyset Net. In the as-treated analysis, three clusters were excluded because no dominant LLIN was received, and four clusters were reassigned, resulting in 49 PBO LLIN clusters (31 received PermaNet 3.0 and 18 received Olyset Plus) and 52 non-PBO LLIN clusters (39 received PermaNet 2.0 and 13 received Olyset Net). At 6 months, parasite prevalence was 11% (386/3614) in the PBO group compared with 15% (556/3844) in the non-PBO group (prevalence ratio [PR] adjusted for baseline values 0·74, 95% CI 0·62-0·87; p=0·0003). Parasite prevalence was similar at month 12 (11% vs 13%; PR 0·73, 95% CI 0·63-0·85; p=0·0001) and month 18 (12% vs 14%; PR 0·84, 95% CI 0·72-0·98; p=0·029). INTERPRETATION In Uganda, where pyrethroid resistance is high, PBO LLINs reduced parasite prevalence more effectively than did conventional LLINs for up to 18 months. This study provides evidence needed to support WHO's final recommendation on use of PBO LLINs. FUNDING The Against Malaria Foundation, UK Department for International Development, Innovative Vector Control Consortium, and Bill and Melinda Gates Foundation.
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Affiliation(s)
- Sarah G Staedke
- Department of Clinical Research, London School of Hygiene & Tropical Medicine, London, UK; Infectious Diseases Research Collaboration, Kampala, Uganda.
| | | | - Grant Dorsey
- Department of Medicine, University of California, San Francisco, CA, USA
| | - Moses R Kamya
- Infectious Diseases Research Collaboration, Kampala, Uganda; Department of Medicine, Makerere University, Kampala, Uganda
| | | | - Amy Lynd
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | | | - Mary Kyohere
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Peter Mutungi
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Simon P Kigozi
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Jimmy Opigo
- National Malaria Control Division, Ministry of Health, Kampala, Uganda
| | - Janet Hemingway
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Martin J Donnelly
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK; Wellcome Sanger Institute, Hinxton, UK
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17
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Karungu S, Atoni E, Ogalo J, Mwaliko C, Agwanda B, Yuan Z, Hu X. Mosquitoes of Etiological Concern in Kenya and Possible Control Strategies. INSECTS 2019; 10:E173. [PMID: 31208124 PMCID: PMC6627689 DOI: 10.3390/insects10060173] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/12/2019] [Revised: 06/11/2019] [Accepted: 06/12/2019] [Indexed: 12/21/2022]
Abstract
Kenya is among the most affected tropical countries with pathogen transmitting Culicidae vectors. For decades, insect vectors have contributed to the emergence and distribution of viral and parasitic pathogens. Outbreaks and diseases have a great impact on a country's economy, as resources that would otherwise be used for developmental projects are redirected to curb hospitalization cases and manage outbreaks. Infected invasive mosquito species have been shown to increasingly cross both local and global boarders due to the presence of increased environmental changes, trade, and tourism. In Kenya, there have been several mosquito-borne disease outbreaks such as the recent outbreaks along the coast of Kenya, involving chikungunya and dengue. This certainly calls for the implementation of strategies aimed at strengthening integrated vector management programs. In this review, we look at mosquitoes of public health concern in Kenya, while highlighting the pathogens they have been linked with over the years and across various regions. In addition, the major strategies that have previously been used in mosquito control and what more could be done to reduce or combat the menace caused by these hematophagous vectors are presented.
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Affiliation(s)
- Samuel Karungu
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China.
- University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Evans Atoni
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China.
- University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Joseph Ogalo
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China.
- University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Caroline Mwaliko
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China.
- University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Bernard Agwanda
- Mammalogy Section, National Museum of Kenya, P.O. Box 40658, Nairobi 00100, Kenya.
| | - Zhiming Yuan
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China.
| | - Xiaomin Hu
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China.
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Amoudji AD, Ahadji-Dabla KM, Hien AS, Apétogbo YG, Yaméogo B, Soma DD, Bamogo R, Atcha-Oubou RT, Dabiré RK, Ketoh GK. Insecticide resistance profiles of Anopheles gambiae s.l. in Togo and genetic mechanisms involved, during 3-year survey: is there any need for resistance management? Malar J 2019; 18:177. [PMID: 31118032 PMCID: PMC6530008 DOI: 10.1186/s12936-019-2813-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Accepted: 05/15/2019] [Indexed: 11/11/2022] Open
Abstract
Background Malaria, one of the world’s greatest public health challenges, is an endemic disease with stable transmission in Togo. Combating malaria requires an effective vector control. This study provides temporal data on insecticide resistance status in the major malaria vector Anopheles gambiae sensu lato (s.l.) from Togo. Methods Two to 5 days old females of An. gambiae s.l., originating from three localities (Baguida, Kovié, Kolokopé) were subjected to insecticide-impregnated papers during 3 years (2012, 2013, 2016) as follows: organochlorides (4% DDT), pyrethroids (0.05% deltamethrin, 0.75% permethrin, 0.05% lambdacyhalothrin), carbamates (0.4% bendiocarb and 0.1% propoxur), and organophosphates (5% malathion, 0.4% chlorpyrifos methyl, 1% fenitrothion) following the WHO standard protocol. Dead and surviving mosquitoes were stored separately in Eppendorf tubes containing silica gel for DNA extraction, species identification, and kdr and ace-1 genotyping. Results Knockdown times (KDT50 and KDT95) were high in An. gambiae s.l. The lowest KDTs were recorded at Baguida in 2013 for deltamethrin (KDT50 = 24.7, CI [22.4–27.12] and KDT95 = 90.78, CI [76.35–113.49]). No KDTs were recorded for DDT and in some instances for permethrin. In general, An. gambiae s.l. was resistant to most of the four classes of insecticides during the survey periods regardless of locality and year, except to chlorpyrifos methyl. In some instances, mosquitoes were fully susceptible to fenitrothion (Kolokopé: 100% and Kovié: 98.05%, CI [95.82–100.26]) and malathion (100% at both Kolokopé and Kovié) in 2013, and malathion only (Kolokopé; 100%) in 2016. Anopheles coluzzii, An. gambiae and Anopheles arabiensis were the three sibling species identified at the three localities with some hybrids at Baguida (2013), and Kovié (2012 and 2016), respectively. Anopheles gambiae was relatively dominant (61.6%). The kdr 1014F allele frequency was > 0.9 in most of the cases, except at Kolokopé (f (1014F) = 0.63, CI [0.55–0.71]) in 2013. The kdr 1014S allele frequency was below 0.02. The highest ace-1 frequencies were identified in An. gambiae at Baguida (2012: 0.52, CI [0.34–0.69] and 2013: 0.66, CI [0.46–0.86]). Conclusion The resistance status is worrying in Togo and should be considered in future malaria vector resistance management programmes by decision-makers. Electronic supplementary material The online version of this article (10.1186/s12936-019-2813-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Adjovi D Amoudji
- Department of Zoology and Animal Biology, Faculty of Sciences, University of Lomé, 01 B.P. 1515, Lomé 01, Togo.
| | - Koffi M Ahadji-Dabla
- Department of Zoology and Animal Biology, Faculty of Sciences, University of Lomé, 01 B.P. 1515, Lomé 01, Togo. .,Biodiversity Institute & Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS, 66045, USA.
| | - Aristide Sawdetuo Hien
- Institut de Recherche en Sciences de la Santé/Centre Muraz, 01 BP 545, Bobo-Dioulasso 01, Burkina Faso
| | - Yawo Georges Apétogbo
- Department of Zoology and Animal Biology, Faculty of Sciences, University of Lomé, 01 B.P. 1515, Lomé 01, Togo
| | - Bienvenu Yaméogo
- Institut de Recherche en Sciences de la Santé/Centre Muraz, 01 BP 545, Bobo-Dioulasso 01, Burkina Faso
| | - Diloma Dieudonné Soma
- Institut de Recherche en Sciences de la Santé/Centre Muraz, 01 BP 545, Bobo-Dioulasso 01, Burkina Faso
| | - Rabila Bamogo
- Institut de Recherche en Sciences de la Santé/Centre Muraz, 01 BP 545, Bobo-Dioulasso 01, Burkina Faso
| | | | - Roch Kounbobr Dabiré
- Institut de Recherche en Sciences de la Santé/Centre Muraz, 01 BP 545, Bobo-Dioulasso 01, Burkina Faso
| | - Guillaume Koffivi Ketoh
- Department of Zoology and Animal Biology, Faculty of Sciences, University of Lomé, 01 B.P. 1515, Lomé 01, Togo
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Nderu D, Kimani F, Karanja E, Thiong'o K, Akinyi M, Too E, Chege W, Nambati E, Wangai LN, Meyer CG, Velavan TP. Genetic diversity and population structure of Plasmodium falciparum in Kenyan-Ugandan border areas. Trop Med Int Health 2019; 24:647-656. [PMID: 30816614 DOI: 10.1111/tmi.13223] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Kenya has, in the last decade, made tremendous progress in the fight against malaria. Nevertheless, continued surveillance of the genetic diversity and population structure of Plasmodium falciparum is required to refine malaria control and to adapt and improve elimination strategies. Twelve neutral microsatellite loci were genotyped in 201 P. falciparum isolates obtained from the Kenyan-Ugandan border (Busia) and from two inland malaria-endemic sites situated in western (Nyando) and coastal (Msambweni) Kenya. Analyses were done to assess the genetic diversity (allelic richness and expected heterozygosity, [He ]), multilocus linkage disequilibrium ( I S A ) and population structure. A similarly high degree of genetic diversity was observed among the three parasite populations surveyed (mean He = 0.76; P > 0.05). Except in Msambweni, random association of microsatellite loci was observed, indicating high parasite out-breeding. Low to moderate genetic structure (FST = 0.022-0.076; P < 0.0001) was observed with only 5% variance in allele frequencies observed among the populations. This study shows that the genetic diversity of P. falciparum populations at the Kenyan-Ugandan border is comparable to the parasite populations from inland Kenya. In addition, high genetic diversity, panmixia and weak population structure in this study highlight the fitness of Kenyan P. falciparum populations to successfully withstand malaria control interventions.
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Affiliation(s)
- David Nderu
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany.,School of Health Sciences, Kirinyaga University, Kerugoya, Kenya
| | - Francis Kimani
- Center for Biotechnology Research and Development, Kenya Medical Research Institute, Nairobi, Kenya
| | - Evaline Karanja
- Department of Biochemistry and Biotechnology, School of Biological and Life Sciences, Technical University of Kenya, Nairobi, Kenya
| | - Kelvin Thiong'o
- Center for Biotechnology Research and Development, Kenya Medical Research Institute, Nairobi, Kenya
| | - Maureen Akinyi
- Center for Biotechnology Research and Development, Kenya Medical Research Institute, Nairobi, Kenya
| | - Edwin Too
- Center for Biotechnology Research and Development, Kenya Medical Research Institute, Nairobi, Kenya
| | - William Chege
- Center for Biotechnology Research and Development, Kenya Medical Research Institute, Nairobi, Kenya
| | - Eva Nambati
- Center for Biotechnology Research and Development, Kenya Medical Research Institute, Nairobi, Kenya
| | - Laura N Wangai
- School of Health Sciences, Kirinyaga University, Kerugoya, Kenya
| | - Christian G Meyer
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany.,Vietnamese-German Centre for Medical Research, Hanoi, Vietnam.,Faculty of Medicine, Duy Tan University, Da Nang, Vietnam
| | - Thirumalaisamy P Velavan
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany.,Vietnamese-German Centre for Medical Research, Hanoi, Vietnam.,Faculty of Medicine, Duy Tan University, Da Nang, Vietnam.,Fondation Congolaise pour la Recherche Médicale, Brazzaville, Republic of Congo
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Mahande AM, Msangi S, Lyaruu LJ, Kweka EJ. Bio-efficacy of DuraNet® long-lasting insecticidal nets against wild populations of Anopheles arabiensis in experimental huts. Trop Med Health 2018; 46:36. [PMID: 30410416 PMCID: PMC6219078 DOI: 10.1186/s41182-018-0118-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 10/23/2018] [Indexed: 11/21/2022] Open
Abstract
Background Mosquitoes have developed resistance to multiple classes of insecticides for malaria vector control. A new generation of long-lasting insecticidal bed nets (LLINs) has been developed with increased efficacy against these resistant mosquitoes. The present study therefore evaluated the efficacy of the pyrethroid-based LLINs, DuraNet versus PermaNet 3.0, in an Eastern Africa hut design in Magugu in northern Tanzania where mosquitoes’ population higher proportion (69.3%) has been identified as Anopheles gambiae s.l. Methods Standard World Health Organization bioefficacy evaluations were conducted in both laboratory and experimental huts. Experimental hut evaluations were conducted in an area with high populations of Anopheles arabiensis. All nets used were subjected to laboratory cone bioassays and then to experimental hut trials. Mosquito mortality, blood-feeding inhibition, and personal protection rate were compared between untreated nets, unwashed LN, and LN that were washed 20 times. Results Standard WHO laboratory bioefficacy evaluations of DuraNet and PermaNet® 3.0 which were untreated, washed, or 20 times washed showed optimal knockdown and mortality for both net types against a susceptible strain of An. arabiensis. In standard experimental hut evaluations, the blood feeding inhibition for PermaNet® 3.0 unwashed and washed was 82.4% (76.3–88.6%) to 91.5% (84.1–98.8%) while for DuraNet was 98.3% (97.0–99.5%) to 96.0% (94.1–88.2%) respectively. The DuraNet LLINs showed a significantly higher killing effect than the other treatment of 90.0% (86.1–94.2%) and 94.0% (90.2–97.9%) for unwashed and washed nets respectively. No significant difference in deterrence or induced exophily was detected between the treatment arms. There were no adverse effects reported among sleepers in the experimental huts. Conclusion The findings of this study indicate that the pyrethroid-based net DuraNet LLINs attained required efficacy when evaluated against wild population of An. arabiensis from Northern Tanzania. This adds value to the existing vector control tool box which gives community wider choice for vector control.
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Affiliation(s)
- Aneth M Mahande
- 1Division of Livestock and Human Diseases Vector Control, Tropical Pesticides Research Institute, Mabogini Field Station, Moshi, Tanzania
| | - Shandala Msangi
- 2Division of Livestock and Human Diseases Vector Control, Mosquito Section, Tropical Pesticides Research Institute, P.O. Box 3024, Arusha, Tanzania
| | - Lucile J Lyaruu
- 2Division of Livestock and Human Diseases Vector Control, Mosquito Section, Tropical Pesticides Research Institute, P.O. Box 3024, Arusha, Tanzania
| | - Eliningaya J Kweka
- 2Division of Livestock and Human Diseases Vector Control, Mosquito Section, Tropical Pesticides Research Institute, P.O. Box 3024, Arusha, Tanzania.,3Department of Medical Parasitology and Entomology, School of Medicine, Catholic University of Health and Allied Sciences, P.O. Box 1464, Mwanza, Tanzania
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Kapesa A, Kweka EJ, Atieli H, Afrane YA, Kamugisha E, Lee MC, Zhou G, Githeko AK, Yan G. The current malaria morbidity and mortality in different transmission settings in Western Kenya. PLoS One 2018; 13:e0202031. [PMID: 30092043 PMCID: PMC6084967 DOI: 10.1371/journal.pone.0202031] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2018] [Accepted: 07/26/2018] [Indexed: 01/17/2023] Open
Abstract
Background Passive surveillance of malaria in health facilities remains vital for implementation of control and elimination programs. It is therefore essential understanding current age profile of clinical malaria morbidity, mortality and presentations in areas with variant infection susceptibility. This study aimed at understanding the current malaria morbidity and mortality in Western Kenya. Methods Surveillance of clinical and asymptomatic parasitological positivity rates of all malaria suspected patients and school children were respectively determined from June 2015 to August 2016. From 2014 to 2016, register books in hospitals were referred and the confirmed malaria cases in conjunction with total number of monthly outpatient visits (OPD) counted. All registered malaria admissions were counted together with other causes of admissions. Moreover, outcome of malaria admissions in terms of discharge or death was recorded using inpatient charts within the same time frame. Prospective surveillance of severe malaria collected information on clinical features of the disease. Giemsa stained blood slides confirmed existence of malaria parasitemia. Chi-square and analysis of variance tests were used, respectively, to compute proportions and means; then a comparison was made between different age groups, periods, and study areas. Results During the survey of asymptomatic infections among school children, overall blood slide positivity ranged from 6.4% at the epidemic prone site to 38.3% at the hyperendemic site. During the clinical malaria survey, school age children (5–14) presented with overall the highest (45%) blood slide positivity rate among those suspected to have the infection at the epidemic prone study site. The survey of all malaria confirmed and registered cases at OPD found 17% to 27% of all consultations among <5 children and 9.9% to 20.7% of all OPD visits among the ≥5 patients were due to malaria. Moreover, survey of all registered causes of admission in hospitals found 47% of admissions were due to malaria. The disease was a major cause of admission in epidemic prone setting where 63.4% of the <5 children and 62.8% of the ≥5 patients were admitted due to malaria (p>0.05) and 40% of all malaria admissions were school age children. Malaria related death rate was highest among <5 years at the hyperendemic site, that is 60.9 death per 1000 malaria <5 admissions. Conversely, the epidemic prone setting experienced highest malaria related death among ≥15 years (18.6 death per 1000 admissions) than the < 15 years (5.7 death per 1000 admissions of the <15 years) (p< 0.001). Surveillance of severe form of the disease found that hyperpyrexia, hyperparastemia, prostration and convulsions as common presentations of severe disease. Conclusion Malaria is still the major cause of hospital consultations in Western Kenya with an alarming number of severe forms of the disease among the school aged children at the epidemic prone setting. Mortalities were higher among <5 children years in high infection transmission setting and among ≥15 years in low and moderate transmission settings. Surveillance of asymptomatic and symptomatic malaria along with evaluation of current interventions in different age groups should be implemented in Kenya.
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Affiliation(s)
- Anthony Kapesa
- Climate and Health Laboratory, Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
- Department of Community Medicine, School of Public Health, Catholic University of Health and Allied Sciences, Mwanza, Tanzania
- * E-mail: (AK); (GY)
| | - Eliningaya J. Kweka
- Department of Medical Parasitology and Entomology, School of Medicine, Catholic University of Health and Allied Sciences, Mwanza, Tanzania
- Division of Livestock and Human Health Disease Vector Control, Tropical Pesticides Research Institute, Arusha, Tanzania
| | - Harrysone Atieli
- Climate and Health Laboratory, Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Yaw A. Afrane
- Climate and Health Laboratory, Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
- Department of Medical Microbiology, College of Health Sciences, University of Ghana, Accra, Ghana
| | - Erasmus Kamugisha
- Department of Biochemistry and Molecular Biology, School of Medicine, Catholic University of Health and Allied Sciences, Mwanza, Tanzania
| | - Ming-Chieh Lee
- Program in Public Health, University of California, Irvine, CA, United States of America
| | - Guofa Zhou
- Program in Public Health, University of California, Irvine, CA, United States of America
| | - Andrew K. Githeko
- Climate and Health Laboratory, Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Guiyun Yan
- Program in Public Health, University of California, Irvine, CA, United States of America
- * E-mail: (AK); (GY)
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