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Ngasala B, Chacky F, Mohamed A, Molteni F, Nyinondi S, Kabula B, Mkali H, Thwai K, Popkin-Hall ZR, Mitchell C, Parr JB, Juliano JJ, Lin JT. Evaluation of Malaria Rapid Diagnostic Test Performance and pfhrp2 Deletion in Tanzania School Surveys, 2017. Am J Trop Med Hyg 2024; 110:887-891. [PMID: 38507797 PMCID: PMC11066367 DOI: 10.4269/ajtmh.23-0771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Accepted: 01/02/2024] [Indexed: 03/22/2024] Open
Abstract
As part of malaria nationwide monitoring and evaluation initiatives, there is an increasing trend of incorporating malaria rapid diagnostic tests (mRDTs) in surveys conducted within primary schools to detect malaria parasites. However, mRDTs based on the detection of histidine-rich protein 2 (HRP2) are known to yield false-positive results due to persistent antigenemia, and false-negative results may result from low parasitemia or Plasmodium falciparum hrp2/3 gene deletion. We evaluated diagnostic performance of an HRP2 and pan-parasite lactate dehydrogenase (HRP2/pLDH) mRDT against polymerase chain reaction (PCR) for detection of P. falciparum among 17,051 primary school-age children from eight regions of Tanzania in 2017. According to PCR, the prevalence of P. falciparum was 19.2% (95% CI: 18.6-19.8). Using PCR as reference, the sensitivity and specificity of mRDT was 76.2% (95% CI: 74.7-77.7) and 93.9% (95% CI: 93.5-94.3), respectively. Test agreement was lowest in low transmission areas, where true-positive mRDTs were outnumbered by false-negatives due to low parasitemia. Discordant samples (mRDT-negative but PCR-positive) were screened for pfhrp2/3 deletion by real-time PCR. Among those with a parasite density sufficient for analysis, pfhrp2 deletion was confirmed in 60 samples, whereas pfhrp3 deletion was confirmed in two samples; one sample had both pfhrp2 and pfhrp3 deletions. The majority of samples with gene deletions were detected in the high-transmission Kagera region. Compared with mRDTs, PCR and other molecular methods offer increased sensitivity and are not affected by pfhrp2/3 deletions, making them a useful supplement to mRDTs in schools and other epidemiological surveys.
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Affiliation(s)
- Billy Ngasala
- Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania
| | - Frank Chacky
- National Malaria Control Programme, Dodoma, Tanzania
| | - Ally Mohamed
- National Malaria Control Programme, Dodoma, Tanzania
| | | | | | | | | | - Kyaw Thwai
- Institute for Global health and Infectious Diseases, University of North Carolina, Chapel Hill, North Carolina
| | - Zachary R. Popkin-Hall
- Institute for Global health and Infectious Diseases, University of North Carolina, Chapel Hill, North Carolina
| | - Cedar Mitchell
- Institute for Global health and Infectious Diseases, University of North Carolina, Chapel Hill, North Carolina
| | - Jonathan B. Parr
- Institute for Global health and Infectious Diseases, University of North Carolina, Chapel Hill, North Carolina
- Division of Infectious Diseases, School of Medicine, University of North Carolina, Chapel Hill, North Carolina
- Curriculum in Genetics and Molecular Biology, School of Medicine, University of North Carolina, Chapel Hill, North Carolina
| | - Jonathan J. Juliano
- Institute for Global health and Infectious Diseases, University of North Carolina, Chapel Hill, North Carolina
- Division of Infectious Diseases, School of Medicine, University of North Carolina, Chapel Hill, North Carolina
- Curriculum in Genetics and Molecular Biology, School of Medicine, University of North Carolina, Chapel Hill, North Carolina
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina
| | - Jessica T. Lin
- Institute for Global health and Infectious Diseases, University of North Carolina, Chapel Hill, North Carolina
- Division of Infectious Diseases, School of Medicine, University of North Carolina, Chapel Hill, North Carolina
- Department of Microbiology and Immunology, School of Medicine, University of North Carolina, Chapel Hill, North Carolina
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Ngasala B, Chiduo MG, Bushukatale S, Mmbando BP, Makene T, Kamugisha E, Ahmed M, Mandara CI, Francis F, Mahende MK, Kavishe RA, Muro F, Ishengoma DS, Mandike R, Molteni F, Chacky F, Kitojo C, Greer G, Bishanga D, Chadewa J, Njau R, Warsame M, Kabula B, Nyinondi SS, Reaves E, Mohamed A. Efficacy and safety of artemether-lumefantrine for the treatment of uncomplicated falciparum malaria in mainland Tanzania, 2018. Malar J 2024; 23:95. [PMID: 38582830 PMCID: PMC10998292 DOI: 10.1186/s12936-024-04926-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Accepted: 04/01/2024] [Indexed: 04/08/2024] Open
Abstract
BACKGROUND The use of artemisinin-based combination therapy (ACT) is recommended by the World Health Organization for the treatment of uncomplicated falciparum malaria. Artemether-lumefantrine (AL) is the most widely adopted first-line ACT for uncomplicated malaria in sub-Saharan Africa (SSA), including mainland Tanzania, where it was introduced in December 2006. The WHO recommends regular assessment to monitor the efficacy of the first-line treatment specifically considering that artemisinin partial resistance was reported in Greater Mekong sub-region and has been confirmed in East Africa (Rwanda and Uganda). The main aim of this study was to assess the efficacy and safety of AL for the treatment of uncomplicated falciparum malaria in mainland Tanzania. METHODS A single-arm prospective anti-malarial drug efficacy trial was conducted in Kibaha, Mlimba, Mkuzi, and Ujiji (in Pwani, Morogoro, Tanga, and Kigoma regions, respectively) in 2018. The sample size of 88 patients per site was determined based on WHO 2009 standard protocol. Participants were febrile patients (documented axillary temperature ≥ 37.5 °C and/or history of fever during the past 24 h) aged 6 months to 10 years. Patients received a 6-dose AL regimen by weight twice a day for 3 days. Clinical and parasitological parameters were monitored during 28 days of follow-up to evaluate the drug efficacy and safety. RESULTS A total of 653 children were screened for uncomplicated malaria and 349 (53.7%) were enrolled between April and August 2018. Of the enrolled children, 345 (98.9%) completed the 28 days of follow-up or attained the treatment outcomes. There were no early treatment failures, but recurrent infections were higher in Mkuzi (35.2%) and Ujiji (23%). By Kaplan-Meier analysis of polymerase chain reaction (PCR) uncorrected adequate clinical and parasitological response (ACPR) ranged from 63.4% in Mkuzi to 85.9% in Mlimba, while PCR-corrected ACPR on day 28 varied from 97.6% in Ujiji to 100% in Mlimba. The drug was well tolerated; the commonly reported adverse events were cough, runny nose, and abdominal pain. No serious adverse event was reported. CONCLUSION This study showed that AL had adequate efficacy and safety for the treatment of uncomplicated falciparum malaria. The high number of recurrent infections were mainly due to new infections, indicating the necessity of utilizing alternative artemisinin-based combinations, such as artesunate amodiaquine, which provide a significantly longer post-treatment prophylactic effect.
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Affiliation(s)
- Billy Ngasala
- Department of Parasitology, Muhimbili University of Health and Allied Sciences, P.O. Box 65011, Dar es Salaam, Tanzania.
| | - Mercy G Chiduo
- Tanga Research Centre, National Institute for Medical Research, P.O Box 5004, Tanga, Tanzania
| | - Samwel Bushukatale
- Department of Parasitology, Muhimbili University of Health and Allied Sciences, P.O. Box 65011, Dar es Salaam, Tanzania
| | - Bruno P Mmbando
- Tanga Research Centre, National Institute for Medical Research, P.O Box 5004, Tanga, Tanzania
| | - Twilumba Makene
- Department of Parasitology, Muhimbili University of Health and Allied Sciences, P.O. Box 65011, Dar es Salaam, Tanzania
| | - Erasmus Kamugisha
- Catholic University of Health and Allied Sciences/Bugando Medical Centre, P. O Box 1464, Mwanza, Tanzania
| | - Maimuna Ahmed
- Catholic University of Health and Allied Sciences/Bugando Medical Centre, P. O Box 1464, Mwanza, Tanzania
| | - Celine I Mandara
- Tanga Research Centre, National Institute for Medical Research, P.O Box 5004, Tanga, Tanzania
- National Institute for Medical Research, Headquarters, P.O. Box 9653, Dar-es-Salaam, Tanzania
| | - Filbert Francis
- Tanga Research Centre, National Institute for Medical Research, P.O Box 5004, Tanga, Tanzania
| | - Muhidin K Mahende
- Ifakara Health Institute Dar es Salaam Office, P. O. Box 78373, Dar es Salaam, Tanzania
| | | | - Florida Muro
- Kilimanjaro Christian Medical Centre, P.O. Box 3010, Moshi, Tanzania
| | - Deus S Ishengoma
- National Institute for Medical Research, Headquarters, P.O. Box 9653, Dar-es-Salaam, Tanzania
| | - Renata Mandike
- National Malaria Control Programme (NMCP), P.O. Box 743, Dodoma, Tanzania
| | - Fabrizio Molteni
- National Malaria Control Programme (NMCP), P.O. Box 743, Dodoma, Tanzania
| | - Frank Chacky
- National Malaria Control Programme (NMCP), P.O. Box 743, Dodoma, Tanzania
| | - Chonge Kitojo
- U.S. President's Malaria Initiative, U.S. Agency for International Development, Dar es Salaam, Tanzania
| | - George Greer
- U.S. President's Malaria Initiative, U.S. Agency for International Development, Dar es Salaam, Tanzania
| | - Dunstan Bishanga
- Department of Community Health, Muhimbili University of Health and Allied Sciences, P.O. Box 65011, Dar es Salaam, Tanzania
| | - Jasmine Chadewa
- Jhpiego, Boresha Afya, P.O. Box 9170, Dar es Salaam, Tanzania
| | - Ritha Njau
- World Health Organization Country Office, P.O Box 9292, Dar es Salaam, Tanzania
| | | | | | | | - Erik Reaves
- U.S. President's Malaria Initiative, U.S. Centers for Disease Control and Prevention, Dar es Salaam, Tanzania
| | - Ally Mohamed
- National Malaria Control Programme (NMCP), P.O. Box 743, Dodoma, Tanzania
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Lucas ER, Nagi SC, Kabula B, Batengana B, Kisinza W, Egyir-Yawson A, Essandoh J, Dadzie S, Chabi J, Van't Hof AE, Rippon EJ, Pipini D, Harding NJ, Dyer NA, Clarkson CS, Miles A, Weetman D, Donnelly MJ. Copy number variants underlie the major selective sweeps in insecticide resistance genes in Anopheles arabiensis from Tanzania. bioRxiv 2024:2024.03.11.583874. [PMID: 38559088 PMCID: PMC10979859 DOI: 10.1101/2024.03.11.583874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
To keep ahead of the evolution of resistance to insecticides in mosquitoes, national malaria control programmes must make use of a range of insecticides, both old and new, while monitoring resistance mechanisms. Knowledge of the mechanisms of resistance remains limited in Anopheles arabiensis, which in many parts of Africa is of increasing importance because it is apparently less susceptible to many indoor control interventions. Furthermore, comparatively little is known in general about resistance to non-pyrethroid insecticides such as pirimiphos-methyl (PM), which are crucial for effective control in the context of resistance to pyrethroids. We performed a genome-wide association study to determine the molecular mechanisms of resistance to deltamethrin (commonly used in bednets) and PM, in An. arabiensis from two regions in Tanzania. Genomic regions of positive selection in these populations were largely driven by copy number variants (CNVs) in gene families involved in resistance to these two insecticides. We found evidence of a new gene cluster involved in resistance to PM, identifying a strong selective sweep tied to a CNV in the Coeae2g-Coeae6g cluster of carboxylesterase genes. Using complementary data from An. coluzzii in Ghana, we show that copy number at this locus is significantly associated with PM resistance. Similarly, for deltamethrin, resistance was strongly associated with a novel CNV allele in the Cyp6aa / Cyp6p cluster. Against this background of metabolic resistance, target site resistance was very rare or absent for both insecticides. Mutations in the pyrethroid target site Vgsc were at very low frequency in Tanzania, yet combining these samples with three An. arabiensis individuals from West Africa revealed a startling diversity of evolutionary origins of target site resistance, with up to 5 independent origins of Vgsc-995 mutations found within just 8 haplotypes. Thus, despite having been first recorded over 10 years ago, Vgsc resistance mutations in Tanzanian An. arabiensis have remained at stable low frequencies. Overall, our results provide a new copy number marker for monitoring resistance to PM in malaria mosquitoes, and reveal the complex picture of resistance patterns in An. arabiensis.
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Affiliation(s)
- Eric R Lucas
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
| | - Sanjay C Nagi
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
| | - Bilali Kabula
- National Institute for Medical Research, Amani Research Centre, P.O. Box 81, Muheza, Tanzania
| | - Bernard Batengana
- National Institute for Medical Research, Amani Research Centre, P.O. Box 81, Muheza, Tanzania
| | - William Kisinza
- National Institute for Medical Research, Amani Research Centre, P.O. Box 81, Muheza, Tanzania
| | | | - John Essandoh
- Department of Biomedical Sciences, University of Cape Coast, Cape Coast, Ghana
| | - Sam Dadzie
- Department of Parasitology, Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana
| | - Joseph Chabi
- Department of Parasitology, Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana
| | - Arjen E Van't Hof
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
- Biology Centre of the Czech Academy of Sciences, Institute of Entomology, Branišovská 31, 370 05 České Budějovice, Czech Republic
| | - Emily J Rippon
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
| | - Dimitra Pipini
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
| | - Nicholas J Harding
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, United Kingdom
| | - Naomi A Dyer
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
| | - Chris S Clarkson
- Wellcome Sanger Institute, Hinxton, Cambridge CB10 1SA, United Kingdom
| | - Alistair Miles
- Wellcome Sanger Institute, Hinxton, Cambridge CB10 1SA, United Kingdom
| | - David Weetman
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
| | - Martin J Donnelly
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
- Wellcome Sanger Institute, Hinxton, Cambridge CB10 1SA, United Kingdom
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Bakari C, Mandara CI, Madebe RA, Seth MD, Ngasala B, Kamugisha E, Ahmed M, Francis F, Bushukatale S, Chiduo M, Makene T, Kabanywanyi AM, Mahende MK, Kavishe RA, Muro F, Mkude S, Mandike R, Molteni F, Chacky F, Bishanga DR, Njau RJA, Warsame M, Kabula B, Nyinondi SS, Lucchi NW, Talundzic E, Venkatesan M, Moriarty LF, Serbantez N, Kitojo C, Reaves EJ, Halsey ES, Mohamed A, Udhayakumar V, Ishengoma DS. Trends of Plasmodium falciparum molecular markers associated with resistance to artemisinins and reduced susceptibility to lumefantrine in Mainland Tanzania from 2016 to 2021. Malar J 2024; 23:71. [PMID: 38461239 PMCID: PMC10924419 DOI: 10.1186/s12936-024-04896-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Accepted: 02/28/2024] [Indexed: 03/11/2024] Open
Abstract
BACKGROUND Therapeutic efficacy studies (TESs) and detection of molecular markers of drug resistance are recommended by the World Health Organization (WHO) to monitor the efficacy of artemisinin-based combination therapy (ACT). This study assessed the trends of molecular markers of artemisinin resistance and/or reduced susceptibility to lumefantrine using samples collected in TES conducted in Mainland Tanzania from 2016 to 2021. METHODS A total of 2,015 samples were collected during TES of artemether-lumefantrine at eight sentinel sites (in Kigoma, Mbeya, Morogoro, Mtwara, Mwanza, Pwani, Tabora, and Tanga regions) between 2016 and 2021. Photo-induced electron transfer polymerase chain reaction (PET-PCR) was used to confirm presence of malaria parasites before capillary sequencing, which targeted two genes: Plasmodium falciparum kelch 13 propeller domain (k13) and P. falciparum multidrug resistance 1 (pfmdr1). RESULTS Sequencing success was ≥ 87.8%, and 1,724/1,769 (97.5%) k13 wild-type samples were detected. Thirty-seven (2.1%) samples had synonymous mutations and only eight (0.4%) had non-synonymous mutations in the k13 gene; seven of these were not validated by the WHO as molecular markers of resistance. One sample from Morogoro in 2020 had a k13 R622I mutation, which is a validated marker of artemisinin partial resistance. For pfmdr1, all except two samples carried N86 (wild-type), while mutations at Y184F increased from 33.9% in 2016 to about 60.5% in 2021, and only four samples (0.2%) had D1246Y mutations. pfmdr1 haplotypes were reported in 1,711 samples, with 985 (57.6%) NYD, 720 (42.1%) NFD, and six (0.4%) carrying minor haplotypes (three with NYY, 0.2%; YFD in two, 0.1%; and NFY in one sample, 0.1%). Between 2016 and 2021, NYD decreased from 66.1% to 45.2%, while NFD increased from 38.5% to 54.7%. CONCLUSION This is the first report of the R622I (k13 validated mutation) in Tanzania. N86 and D1246 were nearly fixed, while increases in Y184F mutations and NFD haplotype were observed between 2016 and 2021. Despite the reports of artemisinin partial resistance in Rwanda and Uganda, this study did not report any other validated mutations in these study sites in Tanzania apart from R622I suggesting that intensified surveillance is urgently needed to monitor trends of drug resistance markers and their impact on the performance of ACT.
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Affiliation(s)
- Catherine Bakari
- National Institute for Medical Research, Dar Es Salaam, Tanzania
- Swiss Tropical and Public Health Institute, Basel, Switzerland
| | - Celine I Mandara
- National Institute for Medical Research, Dar Es Salaam, Tanzania
| | - Rashid A Madebe
- National Institute for Medical Research, Dar Es Salaam, Tanzania
| | - Misago D Seth
- National Institute for Medical Research, Dar Es Salaam, Tanzania
| | - Billy Ngasala
- Department of Parasitology, Muhimbili University of Health and Allied Sciences, Dar Es Salaam, Tanzania
| | - Erasmus Kamugisha
- Catholic University of Health and Allied Sciences, Bugando Medical Centre, Mwanza, Tanzania
| | - Maimuna Ahmed
- Catholic University of Health and Allied Sciences, Bugando Medical Centre, Mwanza, Tanzania
| | - Filbert Francis
- National Institute for Medical Research, Tanga Research Centre, Tanga, Tanzania
| | - Samwel Bushukatale
- Department of Parasitology, Muhimbili University of Health and Allied Sciences, Dar Es Salaam, Tanzania
| | - Mercy Chiduo
- National Institute for Medical Research, Tanga Research Centre, Tanga, Tanzania
| | - Twilumba Makene
- Department of Parasitology, Muhimbili University of Health and Allied Sciences, Dar Es Salaam, Tanzania
| | | | - Muhidin K Mahende
- Ifakara Health Institute, Dar Es Salaam Office, Dar Es Salaam, Tanzania
| | | | - Florida Muro
- Kilimanjaro Christian Medical Centre, Moshi, Tanzania
| | | | | | - Fabrizio Molteni
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- National Malaria Control Program, Dodoma, Tanzania
| | - Frank Chacky
- National Malaria Control Program, Dodoma, Tanzania
| | - Dunstan R Bishanga
- Ifakara Health Institute, Dar Es Salaam Office, Dar Es Salaam, Tanzania
- Maternal and Child Survival Program, Jhpiego, Dar Es Salaam, Tanzania
- School of Public Health and Social Sciences, Muhimbili University of Health and Allied Sciences, Dar Es Salaam, Tanzania
| | - Ritha J A Njau
- Malariologist and Public Health Specialist, Dar Es Salaam, Tanzania
| | | | - Bilali Kabula
- PMI/Okoa Maisha Dhibiti Malaria, RTI International, Dar Es Salaam, Tanzania
- National Institute for Medical Research, Amani Research Centre, Muheza, Tanga, Tanzania
| | - Ssanyu S Nyinondi
- PMI/Okoa Maisha Dhibiti Malaria, RTI International, Dar Es Salaam, Tanzania
| | - Naomi W Lucchi
- Malaria Branch, U.S. Centers for Disease Control and Prevention, Atlanta, GA, USA
- Division of Global Health Protection, U.S. Centers for Disease Control and Prevention, Nairobi, Kenya
| | - Eldin Talundzic
- Malaria Branch, U.S. Centers for Disease Control and Prevention, Atlanta, GA, USA
| | | | - Leah F Moriarty
- Malaria Branch, U.S. President's Malaria Initiative, US Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Naomi Serbantez
- U.S. President's Malaria Initiative, USAID, Dar Es Salaam, Tanzania
| | - Chonge Kitojo
- U.S. President's Malaria Initiative, USAID, Dar Es Salaam, Tanzania
| | - Erik J Reaves
- U.S. President's Malaria Initiative, US Centers for Disease Control and Prevention, Dar Es Salaam, Tanzania
| | - Eric S Halsey
- Malaria Branch, U.S. President's Malaria Initiative, US Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Ally Mohamed
- National Malaria Control Program, Dodoma, Tanzania
| | - Venkatachalam Udhayakumar
- Malaria Branch, U.S. Centers for Disease Control and Prevention, Atlanta, GA, USA
- Independenant Consultant, Decatur, Georgia
| | - Deus S Ishengoma
- National Institute for Medical Research, Dar Es Salaam, Tanzania.
- Faculty of Pharmaceutical Sciences, Monash University, Melbourne, Australia.
- Harvard T.H Chan School of Public Health, Harvard University, Boston, MA, USA.
- Department of Biochemistry, Kampala International University, Dar Es Salaam, Tanzania.
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5
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Mwalimu CD, Kiware S, Nshama R, Derua Y, Machafuko P, Gitanya P, Mwafongo W, Bernard J, Emidi B, Mwingira V, Malima R, Githu V, Masanja B, Mlacha Y, Tungu P, Kabula B, Sambu E, Batengana B, Matowo J, Govella N, Chaki P, Lazaro S, Serbantez N, Kitau J, Magesa SM, Kisinza WN. Dynamics of malaria vector composition and Plasmodium falciparum infection in mainland Tanzania: 2017-2021 data from the national malaria vector entomological surveillance. Malar J 2024; 23:29. [PMID: 38243220 PMCID: PMC10797900 DOI: 10.1186/s12936-024-04849-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Accepted: 01/10/2024] [Indexed: 01/21/2024] Open
Abstract
BACKGROUND In 2015, Tanzania National Malaria Control Programme (NMCP) established a longitudinal malaria vector entomological surveillance (MVES). The MVES is aimed at a periodical assessment of malaria vector composition and abundance, feeding and resting behaviours, and Plasmodium falciparum infection in different malaria epidemiological strata to guide the NMCP on the deployment of appropriate malaria vector interventions. This work details the dynamics of malaria vector composition and transmission in different malaria epidemiological strata. METHODS The MVES was conducted from 32 sentinel district councils across the country. Mosquitoes were collected by the trained community members and supervised by the NMCP and research institutions. Three consecutive night catches (indoor collection with CDC light trap and indoor/outdoor collection using bucket traps) were conducted monthly in three different households selected randomly from two to three wards within each district council. Collected mosquitoes were sorted and morphologically identified in the field. Thereafter, the samples were sent to the laboratory for molecular characterization using qPCR for species identification and detection of P. falciparum infections (sporozoites). ELISA technique was deployed for blood meal analysis from samples of blood-fed mosquitoes to determine the blood meal indices (BMI). RESULTS A total of 63,226 mosquitoes were collected in 32 district councils from January 2017 to December 2021. Out of which, 39,279 (62%), 20,983 (33%) and 2964 (5%) were morphologically identified as Anopheles gambiae sensu lato (s.l.), Anopheles funestus s.l., and as other Anopheles species, respectively. Out of 28,795 laboratory amplified mosquitoes, 13,645 (47%) were confirmed to be Anopheles arabiensis, 9904 (34%) as An. funestus sensu stricto (s.s.), and 5193 (19%) as An. gambiae s.s. The combined average entomological inoculation rates (EIR) were 0.46 (95% CI 0.028-0.928) for An. gambiae s.s., 0.836 (95% CI 0.138-1.559) for An. arabiensis, and 0.58 (95% CI 0.165-0.971) for An. funestus s.s. with variations across different malaria transmission strata. Anopheles funestus s.s. and An. arabiensis were predominant in the Lake and South-Eastern zones, respectively, mostly in high malaria transmission areas. Monthly mosquito densities displayed seasonal patterns, with two peaks following the rainy seasons, varying slightly across species and district councils. CONCLUSION Anopheles arabiensis remains the predominant vector species followed by An. funestus s.s. in the country. Therefore, strengthening integrated vector management including larval source management is recommended to address outdoor transmission by An. arabiensis to interrupt transmission particularly where EIR is greater than the required elimination threshold of less than one (< 1) to substantially reduce the prevalence of malaria infection.
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Affiliation(s)
- Charles D Mwalimu
- National Malaria Control Programme (NMCP), Dodoma, United Republic of Tanzania
| | - Samson Kiware
- Ifakara Health Institute (IHI), Dar es Salaam, Tanzania.
- Pan African Mosquito Control Association (PAMCA), Dar es Salaam, Tanzania.
| | - Rosemary Nshama
- National Malaria Control Programme (NMCP), Dodoma, United Republic of Tanzania
| | - Yahya Derua
- National Institute for Medical Research (NIMR), Amani Centre, Muheza, Tanzania
| | - Pendael Machafuko
- National Institute for Medical Research (NIMR), Amani Centre, Muheza, Tanzania
| | - Peter Gitanya
- National Malaria Control Programme (NMCP), Dodoma, United Republic of Tanzania
| | - Winfred Mwafongo
- National Malaria Control Programme (NMCP), Dodoma, United Republic of Tanzania
| | - Jubilate Bernard
- National Malaria Control Programme (NMCP), Dodoma, United Republic of Tanzania
| | - Basiliana Emidi
- National Institute for Medical Research (NIMR), Mwanza, Tanzania
| | - Victor Mwingira
- National Institute for Medical Research (NIMR), Amani Centre, Muheza, Tanzania
| | - Robert Malima
- National Institute for Medical Research (NIMR), Amani Centre, Muheza, Tanzania
- University of Dar es Salaam, Mbeya College of Health and Allied Sciences, Mbeya, Tanzania
| | | | - Brian Masanja
- Ifakara Health Institute (IHI), Dar es Salaam, Tanzania
| | - Yeromin Mlacha
- Ifakara Health Institute (IHI), Dar es Salaam, Tanzania
- Pan African Mosquito Control Association (PAMCA), Dar es Salaam, Tanzania
| | - Patrick Tungu
- National Institute for Medical Research (NIMR), Amani Centre, Muheza, Tanzania
| | - Bilali Kabula
- National Institute for Medical Research (NIMR), Amani Centre, Muheza, Tanzania
| | - Edward Sambu
- National Institute for Medical Research (NIMR), Amani Centre, Muheza, Tanzania
| | - Bernard Batengana
- National Institute for Medical Research (NIMR), Amani Centre, Muheza, Tanzania
| | - Johnson Matowo
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College, Moshi, Tanzania
| | - Nicodem Govella
- Ifakara Health Institute (IHI), Dar es Salaam, Tanzania
- Population Services International (PSI), Dar es Salaam, Tanzania
| | - Prosper Chaki
- Ifakara Health Institute (IHI), Dar es Salaam, Tanzania
- Pan African Mosquito Control Association (PAMCA), Dar es Salaam, Tanzania
| | - Samwel Lazaro
- National Malaria Control Programme (NMCP), Dodoma, United Republic of Tanzania
| | - Naomi Serbantez
- U.S. President's Malaria Initiative, Dar es Salaam, Tanzania
| | - Jovin Kitau
- World Health Organization, Country Office, Dar es Salaam, Tanzania
| | - Stephen M Magesa
- Pan African Mosquito Control Association (PAMCA), Dar es Salaam, Tanzania
- National Institute for Medical Research (NIMR), Amani Centre, Muheza, Tanzania
| | - William N Kisinza
- National Institute for Medical Research (NIMR), Amani Centre, Muheza, Tanzania
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Sendor R, Mitchell CL, Chacky F, Mohamed A, Mhamilawa LE, Molteni F, Nyinondi S, Kabula B, Mkali H, Reaves EJ, Serbantez N, Kitojo C, Makene T, Kyaw T, Muller M, Mwanza A, Eckert EL, Parr JB, Lin JT, Juliano JJ, Ngasala B. Similar Prevalence of Plasmodium falciparum and Non-P. falciparum Malaria Infections among Schoolchildren, Tanzania 1. Emerg Infect Dis 2023; 29:1143-1153. [PMID: 37209670 DOI: 10.3201/eid2906.221016] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2023] Open
Abstract
Achieving malaria elimination requires considering both Plasmodium falciparum and non-P. falciparum infections. We determined prevalence and geographic distribution of 4 Plasmodium spp. by performing PCR on dried blood spots collected within 8 regions of Tanzania during 2017. Among 3,456 schoolchildren, 22% had P. falciparum, 24% had P. ovale spp., 4% had P. malariae, and 0.3% had P. vivax infections. Most (91%) schoolchildren with P. ovale infections had low parasite densities; 64% of P. ovale infections were single-species infections, and 35% of those were detected in low malaria endemic regions. P. malariae infections were predominantly (73%) co-infections with P. falciparum. P. vivax was detected mostly in northern and eastern regions. Co-infections with >1 non-P. falciparum species occurred in 43% of P. falciparum infections. A high prevalence of P. ovale infections exists among schoolchildren in Tanzania, underscoring the need for detection and treatment strategies that target non-P. falciparum species.
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7
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Tungu P, Kabula B, Nkya T, Machafuko P, Sambu E, Batengana B, Sudi W, Derua YA, Mwingira V, Masue D, Malima R, Kitojo C, Serbantez N, Reaves EJ, Mwalimu C, Nhiga SL, Ally M, Mkali HR, Joseph JJ, Chan A, Ngondi J, Lalji S, Nyinondi S, Eckert E, Reithinger R, Magesa S, Kisinza WN. Trends of insecticide resistance monitoring in mainland Tanzania, 2004-2020. Malar J 2023; 22:100. [PMID: 36932400 PMCID: PMC10024418 DOI: 10.1186/s12936-023-04508-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Accepted: 02/20/2023] [Indexed: 03/19/2023] Open
Abstract
BACKGROUND Insecticide resistance is a serious threat to the continued effectiveness of insecticide-based malaria vector control measures, such as long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS). This paper describes trends and dynamics of insecticide resistance and its underlying mechanisms from annual resistance monitoring surveys on Anopheles gambiae sensu lato (s.l.) populations conducted across mainland Tanzania from 2004 to 2020. METHODS The World Health Organization (WHO) standard protocols were used to assess susceptibility of the wild female An. gambiae s.l. mosquitoes to insecticides, with mosquitoes exposed to diagnostic concentrations of permethrin, deltamethrin, lambdacyhalothrin, bendiocarb, and pirimiphos-methyl. WHO test papers at 5× and 10× the diagnostic concentrations were used to assess the intensity of resistance to pyrethroids; synergist tests using piperonyl butoxide (PBO) were carried out in sites where mosquitoes were found to be resistant to pyrethroids. To estimate insecticide resistance trends from 2004 to 2020, percentage mortalities from each site and time point were aggregated and regression analysis of mortality versus the Julian dates of bioassays was performed. RESULTS Percentage of sites with pyrethroid resistance increased from 0% in 2004 to more than 80% in the 2020, suggesting resistance has been spreading geographically. Results indicate a strong negative association (p = 0.0001) between pyrethroids susceptibility status and survey year. The regression model shows that by 2020 over 40% of An. gambiae mosquitoes survived exposure to pyrethroids at their respective diagnostic doses. A decreasing trend of An. gambiae susceptibility to bendiocarb was observed over time, but this was not statistically significant (p = 0.8413). Anopheles gambiae exhibited high level of susceptibility to the pirimiphos-methyl in sampled sites. CONCLUSIONS Anopheles gambiae Tanzania's major malaria vector, is now resistant to pyrethroids across the country with resistance increasing in prevalence and intensity and has been spreading geographically. This calls for urgent action for efficient malaria vector control tools to sustain the gains obtained in malaria control. Strengthening insecticide resistance monitoring is important for its management through evidence generation for effective malaria vector control decision.
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Affiliation(s)
- Patrick Tungu
- National Institute for Medical Research, Amani Medical Research Centre, Muheza, Tanzania.
| | - Bilali Kabula
- National Institute for Medical Research, Amani Medical Research Centre, Muheza, Tanzania
- USAID-Okoa Maisha Dhibiti Malaria Project, RTI International, Dar es Salaam, Tanzania
| | - Theresia Nkya
- University of Dar es Salaam, Dar es Salaam, Tanzania
| | - Pendael Machafuko
- National Institute for Medical Research, Amani Medical Research Centre, Muheza, Tanzania
| | - Edward Sambu
- National Institute for Medical Research, Amani Medical Research Centre, Muheza, Tanzania
| | - Bernard Batengana
- National Institute for Medical Research, Amani Medical Research Centre, Muheza, Tanzania
| | - Wema Sudi
- National Institute for Medical Research, Amani Medical Research Centre, Muheza, Tanzania
| | - Yahaya A Derua
- National Institute for Medical Research, Amani Medical Research Centre, Muheza, Tanzania
| | - Victor Mwingira
- National Institute for Medical Research, Amani Medical Research Centre, Muheza, Tanzania
| | - Denis Masue
- University of Dar es Salaam, Dar es Salaam, Tanzania
| | - Robert Malima
- University of Dar es Salaam, Dar es Salaam, Tanzania
| | - Chonge Kitojo
- U.S. President's Malaria Initiative, U.S. Agency for International Development, Dar es Salaam, Tanzania
| | - Naomi Serbantez
- U.S. President's Malaria Initiative, U.S. Agency for International Development, Dar es Salaam, Tanzania
| | - Erik J Reaves
- U.S. President's Malaria Initiative, U.S. Centers for Disease Control and Prevention, Dar es Salaam, Tanzania
| | - Charles Mwalimu
- National Malaria Control Programme, Ministry of Health, Community Development, Gender, Elderly and Children, Dodoma, Tanzania
| | - Samwel L Nhiga
- National Malaria Control Programme, Ministry of Health, Community Development, Gender, Elderly and Children, Dodoma, Tanzania
| | - Mohamed Ally
- National Malaria Control Programme, Ministry of Health, Community Development, Gender, Elderly and Children, Dodoma, Tanzania
| | - Humphrey R Mkali
- USAID-Okoa Maisha Dhibiti Malaria Project, RTI International, Dar es Salaam, Tanzania
| | - Joseph J Joseph
- USAID-Okoa Maisha Dhibiti Malaria Project, RTI International, Dar es Salaam, Tanzania
| | - Adeline Chan
- U.S. President's Malaria Initiative, U.S. Centers for Disease Control and Prevention, Atlanta, USA
| | | | - Shabbir Lalji
- USAID-Okoa Maisha Dhibiti Malaria Project, RTI International, Dar es Salaam, Tanzania
| | - Ssanyu Nyinondi
- USAID-Okoa Maisha Dhibiti Malaria Project, RTI International, Dar es Salaam, Tanzania
| | | | | | - Stephen Magesa
- National Institute for Medical Research, Amani Medical Research Centre, Muheza, Tanzania
| | - William N Kisinza
- National Institute for Medical Research, Amani Medical Research Centre, Muheza, Tanzania
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Njoroge H, van't Hof A, Oruni A, Pipini D, Nagi S, Lynd A, Lucas ER, Tomlinson S, Grau‐Bove X, McDermott D, Wat'senga FT, Manzambi EZ, Agossa FR, Mokuba A, Irish S, Kabula B, Mbogo C, Bargul J, Paine MJI, Weetman D, Donnelly MJ. Identification of a rapidly-spreading triple mutant for high-level metabolic insecticide resistance in Anopheles gambiae provides a real-time molecular diagnostic for antimalarial intervention deployment. Mol Ecol 2022; 31:4307-4318. [PMID: 35775282 PMCID: PMC9424592 DOI: 10.1111/mec.16591] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 06/07/2022] [Accepted: 06/27/2022] [Indexed: 12/01/2022]
Abstract
Studies of insecticide resistance provide insights into the capacity of populations to show rapid evolutionary responses to contemporary selection. Malaria control remains heavily dependent on pyrethroid insecticides, primarily in long lasting insecticidal nets (LLINs). Resistance in the major malaria vectors has increased in concert with the expansion of LLIN distributions. Identifying genetic mechanisms underlying high-level resistance is crucial for the development and deployment of resistance-breaking tools. Using the Anopheles gambiae 1000 genomes (Ag1000g) data we identified a very recent selective sweep in mosquitoes from Uganda which localized to a cluster of cytochrome P450 genes. Further interrogation revealed a haplotype involving a trio of mutations, a nonsynonymous point mutation in Cyp6p4 (I236M), an upstream insertion of a partial Zanzibar-like transposable element (TE) and a duplication of the Cyp6aa1 gene. The mutations appear to have originated recently in An. gambiae from the Kenya-Uganda border, with stepwise replacement of the double-mutant (Zanzibar-like TE and Cyp6p4-236 M) with the triple-mutant haplotype (including Cyp6aa1 duplication), which has spread into the Democratic Republic of Congo and Tanzania. The triple-mutant haplotype is strongly associated with increased expression of genes able to metabolize pyrethroids and is strongly predictive of resistance to pyrethroids most notably deltamethrin. Importantly, there was increased mortality in mosquitoes carrying the triple-mutation when exposed to nets cotreated with the synergist piperonyl butoxide (PBO). Frequencies of the triple-mutant haplotype remain spatially variable within countries, suggesting an effective marker system to guide deployment decisions for limited supplies of PBO-pyrethroid cotreated LLINs across African countries.
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Affiliation(s)
- Harun Njoroge
- Department of Vector BiologyLiverpool School of Tropical MedicineLiverpoolUK
- Kenya Medical Research Institute (KEMRI) Centre for Geographic Medicine CoastKEMRI‐Wellcome Trust Research ProgrammeKilifiKenya
| | - Arjen van't Hof
- Department of Vector BiologyLiverpool School of Tropical MedicineLiverpoolUK
| | - Ambrose Oruni
- Department of Vector BiologyLiverpool School of Tropical MedicineLiverpoolUK
- College of Veterinary MedicineAnimal Resources and Bio‐securityMakerere UniversityKampalaUganda
| | - Dimitra Pipini
- Department of Vector BiologyLiverpool School of Tropical MedicineLiverpoolUK
| | - Sanjay C. Nagi
- Department of Vector BiologyLiverpool School of Tropical MedicineLiverpoolUK
| | - Amy Lynd
- Department of Vector BiologyLiverpool School of Tropical MedicineLiverpoolUK
| | - Eric R. Lucas
- Department of Vector BiologyLiverpool School of Tropical MedicineLiverpoolUK
| | - Sean Tomlinson
- Department of Vector BiologyLiverpool School of Tropical MedicineLiverpoolUK
| | - Xavi Grau‐Bove
- Department of Vector BiologyLiverpool School of Tropical MedicineLiverpoolUK
| | - Daniel McDermott
- Department of Vector BiologyLiverpool School of Tropical MedicineLiverpoolUK
| | | | - Emile Z. Manzambi
- Institut National de Recherche BiomédicaleKinshasaDemocratic Republic of Congo
| | - Fiacre R. Agossa
- USAID President's Malaria Initiative, VectorLink Project, Abt AssociatesRockvilleMarylandUSA
| | - Arlette Mokuba
- USAID President's Malaria Initiative, VectorLink Project, Abt AssociatesRockvilleMarylandUSA
| | - Seth Irish
- U.S. President's Malaria Initiative and Centers for Disease Control and PreventionAtlantaGeorgiaUSA
| | - Bilali Kabula
- Amani Research CentreNational Institute for Medical ResearchTanzania
| | - Charles Mbogo
- Population Health UnitKEMRI‐Wellcome Trust Research ProgrammeNairobiKenya
- KEMRI‐Centre for Geographic Medicine Research CoastKilifiKenya
| | - Joel Bargul
- Department of BiochemistryJomo Kenyatta University of Agriculture and TechnologyJujaKenya
- The Animal Health DepartmentInternational Centre of Insect Physiology and EcologyNairobiKenya
| | - Mark J. I. Paine
- Department of Vector BiologyLiverpool School of Tropical MedicineLiverpoolUK
| | - David Weetman
- Department of Vector BiologyLiverpool School of Tropical MedicineLiverpoolUK
| | - Martin J. Donnelly
- Department of Vector BiologyLiverpool School of Tropical MedicineLiverpoolUK
- Parasites and Microbes ProgrammeWellcome Sanger InstituteCambridgeUK
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9
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Mitchell CL, Ngasala B, Janko MM, Chacky F, Edwards JK, Pence BW, Mohamed A, Mhamilawa LE, Makene T, Kyaw T, Molteni F, Mkali H, Nyinondi S, Kabula B, Serbantez N, Eckert EL, Kitojo C, Reaves E, Emch M, Juliano JJ. Evaluating malaria prevalence and land cover across varying transmission intensity in Tanzania using a cross-sectional survey of school-aged children. Malar J 2022; 21:80. [PMID: 35264152 PMCID: PMC8905829 DOI: 10.1186/s12936-022-04107-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 02/24/2022] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Transmission of malaria in sub-Saharan Africa has become increasingly stratified following decades of malaria control interventions. The extent to which environmental and land cover risk factors for malaria may differ across distinct strata of transmission intensity is not well known and could provide actionable targets to maximize the success of malaria control efforts. METHODS This study used cross-sectional malaria survey data from a nationally representative cohort of school-aged children in Tanzania, and satellite-derived measures for environmental features and land cover. Hierarchical logistic regression models were applied to evaluate associations between land cover and malaria prevalence within three distinct strata of transmission intensity: low and unstable, moderate and seasonal, and high and perennial. RESULTS In areas with low malaria transmission, each 10-percentage point increase in cropland cover was associated with an increase in malaria prevalence odds of 2.44 (95% UI: 1.27, 5.11). However, at moderate and higher levels of transmission intensity, no association between cropland cover and malaria prevalence was detected. Small associations were observed between greater grassland cover and greater malaria prevalence in high intensity settings (prevalence odds ratio (POR): 1.10, 95% UI: 1.00, 1.21), and between greater forest cover and reduced malaria prevalence in low transmission areas (POR: 0.74, 95% UI: 0.51, 1.03), however the uncertainty intervals of both estimates included the null. CONCLUSIONS The intensity of malaria transmission appears to modify relationships between land cover and malaria prevalence among school-aged children in Tanzania. In particular, greater cropland cover was positively associated with increased malaria prevalence in areas with low transmission intensity and presents an actionable target for environmental vector control interventions to complement current malaria control activities. As areas are nearing malaria elimination, it is important to re-evaluate environmental risk factors and employ appropriate interventions to effectively address low-level malaria transmission.
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Affiliation(s)
- Cedar L. Mitchell
- grid.410711.20000 0001 1034 1720Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC USA
| | - Billy Ngasala
- grid.25867.3e0000 0001 1481 7466Muhimbili University of Health and Allied Sciences, Dar es Salam, Tanzania
| | - Mark M. Janko
- grid.34477.330000000122986657Institute for Health Metrics and Evaluation, University of Washington, Washington, USA
| | - Frank Chacky
- grid.490706.cGender, Elderly and Children, Ministry of Health, Community Development, Dodoma, Tanzania ,grid.415734.00000 0001 2185 2147National Malaria Control Programme, Dodoma, Tanzania
| | - Jessie K. Edwards
- grid.410711.20000 0001 1034 1720Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC USA
| | - Brian W. Pence
- grid.410711.20000 0001 1034 1720Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC USA
| | - Ally Mohamed
- grid.490706.cGender, Elderly and Children, Ministry of Health, Community Development, Dodoma, Tanzania ,grid.415734.00000 0001 2185 2147National Malaria Control Programme, Dodoma, Tanzania
| | - Lwidiko E. Mhamilawa
- grid.25867.3e0000 0001 1481 7466Muhimbili University of Health and Allied Sciences, Dar es Salam, Tanzania
| | - Twilumba Makene
- grid.25867.3e0000 0001 1481 7466Muhimbili University of Health and Allied Sciences, Dar es Salam, Tanzania
| | - Thwai Kyaw
- grid.10698.360000000122483208Division of Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, NC USA
| | - Fabrizio Molteni
- grid.490706.cGender, Elderly and Children, Ministry of Health, Community Development, Dodoma, Tanzania ,Tropical and Public Health Institute, Basel, Switzerland
| | | | | | | | - Naomi Serbantez
- US President’s Malaria Initiative (PMI), United States Agency for International Development, Dar es Salaam, Tanzania
| | - Erin L. Eckert
- grid.62562.350000000100301493RTI International, Washington, DC USA
| | - Chonge Kitojo
- US President’s Malaria Initiative (PMI), United States Agency for International Development, Dar es Salaam, Tanzania
| | - Erik Reaves
- President’s Malaria Initiative, U.S. Centers for Disease Control and Prevention, Dar es Salaam, Tanzania
| | - Michael Emch
- grid.410711.20000 0001 1034 1720Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC USA ,grid.410711.20000 0001 1034 1720Department of Geography, University of North Carolina, Chapel Hill, NC USA
| | - Jonathan J. Juliano
- grid.10698.360000000122483208Division of Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, NC USA
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10
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Mutalemwa P, Massue D, Kisoka W, Munga M, Kabula B, Kisinza W. "Should We Take Them or Leave Them?" A Qualitative Study to Understand the Social, Cultural, and Ethical Issues Associated With the Lifecycle Management of Insecticide-Treated Nets in Tanzania. East Afr Health Res J 2018. [DOI: 10.24248/eahrj.v2i2.587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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11
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Mutalemwa PP, Massue DJ, Kisoka WJ, Munga MA, Kabula B, Kisinza WN. "Should We Take Them or Leave Them?" A Qualitative Study to Understand the Social, Cultural, and Ethical Issues Associated With the Lifecycle Management of Insecticide-Treated Nets in Tanzania. East Afr Health Res J 2018; 2:135-141. [PMID: 34308184 PMCID: PMC8279212 DOI: 10.24248/eahrj-d-18-00016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Accepted: 09/13/2018] [Indexed: 11/20/2022] Open
Abstract
Background: Insecticide-treated nets (ITNs) are highly effective in reducing morbidity and mortality from malaria. However, it is widely accepted that ITNs – if not re-treated – lose their effectiveness with time and eventually need to be replaced. This study sought to determine the social, ethical, and cultural issues related to the lifecycle of ITNs, which includes net ownership, usage, maintenance, reuse, recycling, disposal, and replacement. Methods: In this qualitative study, conducted in the districts of Mtwara Rural, Kilombero, and Muheza, Tanzania, we collected information about bed nets, including usage habits, types, treatment status, materials used, brands, acquisition sources, and perceptions thereof. We conducted 23 key informant interviews and 20 focus group discussions with village leaders, other influential people in the community, and district health-care personnel. Results: ITNs were deemed acceptable and used by most community members in the participating communities. Alternative uses and disposal practices of used bed nets were also common among community members; however, participants had limited knowledge regarding the health and environmental risks associated with these practices. Most participants did not perceive bed net recycling as a sustainable option. Recycling was considered feasible, however, if effective infrastructure for collection and disposal could be established. Poverty was identified as a major driving force towards alternative uses of bed nets. Financial constraints also meant that not all household members were able to sleep under bed nets; pregnant mothers, children under 5 years old, and the elderly were prioritised. Conclusion: Our findings may inform the National Malaria Control Programme and other stakeholders as they develop country-specific and environmentally friendly bed net replacement strategies. Appropriate strategies will help ensure sustained protection of vulnerable populations against malaria, while considering local social, ethical, and cultural issues related to the recovery of bed nets.
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Affiliation(s)
| | - Dennis J Massue
- Amani Research Centre, National Institute for Medical Research, Tanga, Tanzania
| | - William J Kisoka
- National Institute for Medical Research, Dar es Salaam, Tanzania
| | - Michael A Munga
- National Institute for Medical Research, Dar es Salaam, Tanzania
| | - Bilali Kabula
- Amani Research Centre, National Institute for Medical Research, Tanga, Tanzania
| | - William N Kisinza
- Amani Research Centre, National Institute for Medical Research, Tanga, Tanzania
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12
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Kisinza WN, Nkya TE, Kabula B, Overgaard HJ, Massue DJ, Mageni Z, Greer G, Kaspar N, Mohamed M, Reithinger R, Moore S, Lorenz LM, Magesa S. Multiple insecticide resistance in Anopheles gambiae from Tanzania: a major concern for malaria vector control. Malar J 2017; 16:439. [PMID: 29084560 PMCID: PMC5663032 DOI: 10.1186/s12936-017-2087-2] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Accepted: 10/24/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Malaria vector control in Tanzania is based on use of long-lasting insecticide treated nets (LLINs) and indoor residual spraying (IRS), which both rely on the use of chemical insecticides. The effectiveness of these control tools is endangered by the development of insecticide resistance in the major malaria vectors. This study was carried out to monitor the susceptibility status of major malaria vectors to insecticides used for IRS and LLINs in mainland Tanzania. METHODS Mosquito larvae were collected in 20 sites of Tanzania mainland in 2015. Phenotypic resistance was determined using standard WHO susceptibility tests. Molecular assay were used to determine distribution of Anopheles gambiae sub-species. A microplate assay approach was used for identifying enzyme levels on single mosquitoes from each sites compared with a susceptible reference strain, An. gambiae sensu stricto (s.s.) Kisumu strain. RESULTS Anopheles arabiensis was the dominant malaria specie in the country, accounting for 52% of the sibling species identified, while An. gambiae s.s. represented 48%. In Arumeru site, the dominant species was An. arabiensis, which was resistant to both pyrethroids (permethrin and deltamethrin), and pirimiphos-methyl, and had significant elevated levels of GSTs, non-specific esterases, and oxidase enzymes. An. arabiensis was also a dominant species in Kilombero and Kondoa sites, both were resistant to permethrin and deltamethrin with significant activity levels of oxidase enzymes. Resistance to bendiocarb was recorded in Ngara site where specie composition is evenly distributed between An. gambiae s.s. and An.arabiensis. Also bendiocarb resistance was recorded in Mbozi site, where An. gambiae s.s. is the dominant species. CONCLUSIONS Overall, this study confirmed resistance to all four insecticide classes in An. gambiae sensu lato in selected locations in Tanzania. Results are discussed in relation to resistance mechanisms and the optimization of resistance management strategies.
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Affiliation(s)
- William N Kisinza
- National Institute for Medical Research (NIMR), Amani Research Center, Muheza, Tanzania
| | - Theresia E Nkya
- National Institute for Medical Research (NIMR), Amani Research Center, Muheza, Tanzania.
| | - Bilali Kabula
- National Institute for Medical Research (NIMR), Amani Research Center, Muheza, Tanzania
| | - Hans J Overgaard
- Department of Mathematical Sciences and Technology, Norwegian University of Life Sciences, Akershus, Norway.,Institut de Recherche pour le Développement, Maladies Infectieuses et Vecteurs, Ecologie, Génétique, Evolution et Contrôle, Montpellier, France
| | - Dennis J Massue
- National Institute for Medical Research (NIMR), Amani Research Center, Muheza, Tanzania.,Epidemiology and Public Health Department, Swiss Institute of Tropical and Public Health, Soccinstrase 57, 4002, Basel, Switzerland.,University of Basel, Petersplatz 1, 4003, Basel, Switzerland
| | | | - George Greer
- U.S. President's Malaria Initiative/U.S. Agency for International Development, Dar es Salaam, Tanzania
| | - Naomi Kaspar
- U.S. President's Malaria Initiative/U.S. Agency for International Development, Dar es Salaam, Tanzania
| | | | - Richard Reithinger
- RTI International, Washington, DC, USA.,London School of Hygiene & Tropical Medicine, Keppel Street, London, UK
| | - Sarah Moore
- Epidemiology and Public Health Department, Swiss Institute of Tropical and Public Health, Soccinstrase 57, 4002, Basel, Switzerland.,University of Basel, Petersplatz 1, 4003, Basel, Switzerland.,Ifakara Health Institute (IHI), Bagamoyo, Tanzania
| | - Lena M Lorenz
- London School of Hygiene & Tropical Medicine, Keppel Street, London, UK
| | - Stephen Magesa
- National Institute for Medical Research (NIMR), Amani Research Center, Muheza, Tanzania.,RTI International, Dar es Salaam, Tanzania
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13
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Kabula B, Tungu P, Rippon EJ, Steen K, Kisinza W, Magesa S, Mosha F, Donnelly MJ. A significant association between deltamethrin resistance, Plasmodium falciparum infection and the Vgsc-1014S resistance mutation in Anopheles gambiae highlights the epidemiological importance of resistance markers. Malar J 2016; 15:289. [PMID: 27216484 PMCID: PMC4877992 DOI: 10.1186/s12936-016-1331-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 05/06/2016] [Indexed: 11/16/2022] Open
Abstract
Background The success of malaria vector control is threatened by widespread pyrethroid insecticide resistance. However, the extent to which insecticide resistance impacts transmission is unclear. The objective of this study was to examine the association between the DDT/pyrethroid knockdown resistance mutation Vgsc-1014S, commonly termed kdr, and infection with Plasmodium falciparum sporozoites in Anopheles gambiae. Methods WHO standard methods were used to characterize susceptibility of wild female mosquitoes to 0.05 % deltamethrin. PCR-based molecular diagnostics were used to identify mosquitoes to species and to genotype at the Vgsc-L1014S locus. ELISAs were used to detect the presence of P.falciparum sporozoites and for blood meal identification. Results Anopheles mosquitoes were resistant to deltamethrin with mortality rates of 77.7 % [95 % CI 74.9–80.3 %]. Of 545 mosquitoes genotyped 96.5 % were A. gambiaes.s. and 3.5 % were Anopheles arabiensis. The Vgsc-1014S mutation was detected in both species. Both species were predominantly anthropophagic. In A. gambiaes.s., Vgsc-L1014S genotype was significantly associated with deltamethrin resistance (χ2 = 11.2; p < 0.001). The P. falciparum sporozoite infection rate was 4.2 %. There was a significant association between the presence of sporozoites and Vgsc-L1014S genotype in A. gambiaes.s. (χ2 = 4.94; p = 0.026). Conclusions One marker, Vgsc-1014S, was associated with insecticide resistance and P. falciparum infection in wild-caught mixed aged populations of A. gambiaes.s. thereby showing how resistance may directly impact transmission.
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Affiliation(s)
- Bilali Kabula
- Kilimanjaro Christian Medical University College (KCMUCo), Moshi, Tanzania.,Amani Research Centre, National Institute for Medical Research, Muheza, Tanzania.,Tukuyu Research Centre, National Institute for Medical Research, Tukuyu, Tanzania
| | - Patrick Tungu
- Amani Research Centre, National Institute for Medical Research, Muheza, Tanzania
| | - Emily J Rippon
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Keith Steen
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - William Kisinza
- Amani Research Centre, National Institute for Medical Research, Muheza, Tanzania
| | - Stephen Magesa
- Amani Research Centre, National Institute for Medical Research, Muheza, Tanzania.,Global Health Division, RTI International, Dar es Salaam, Tanzania
| | - Franklin Mosha
- Kilimanjaro Christian Medical University College (KCMUCo), Moshi, Tanzania
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Kabula B, Tungu P, Malima R, Rowland M, Minja J, Wililo R, Ramsan M, McElroy PD, Kafuko J, Kulkarni M, Protopopoff N, Magesa S, Mosha F, Kisinza W. Distribution and spread of pyrethroid and DDT resistance among the Anopheles gambiae complex in Tanzania. Med Vet Entomol 2014; 28:244-52. [PMID: 24192019 PMCID: PMC10884793 DOI: 10.1111/mve.12036] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2013] [Revised: 09/10/2013] [Accepted: 09/19/2013] [Indexed: 06/02/2023]
Abstract
The development of insecticide resistance is a threat to the control of malaria in Africa. We report the findings of a national survey carried out in Tanzania in 2011 to monitor the susceptibility of malaria vectors to pyrethroid, organophosphate, carbamate and DDT insecticides, and compare these findings with those identified in 2004 and 2010. Standard World Health Organization (WHO) methods were used to detect knock-down and mortality rates in wild female Anopheles gambiae s.l. (Diptera: Culicidae) collected from 14 sentinel districts. Diagnostic doses of the pyrethroids deltamethrin, lambdacyhalothrin and permethrin, the carbamate propoxur, the organophosphate fenitrothion and the organochlorine DDT were used. Anopheles gambiae s.l. was resistant to permethrin in Muleba, where a mortality rate of 11% [95% confidence interval (CI) 6-19%] was recorded, Muheza (mortality rate of 75%, 95% CI 66-83%), Moshi and Arumeru (mortality rates of 74% in both). Similarly, resistance was reported to lambdacyhalothrin in Muleba, Muheza, Moshi and Arumeru (mortality rates of 31-82%), and to deltamethrin in Muleba, Moshi and Muheza (mortality rates of 28-75%). Resistance to DDT was reported in Muleba. No resistance to the carbamate propoxur or the organophosphate fenitrothion was observed. Anopheles gambiae s.l. is becoming resistant to pyrethoids and DDT in several parts of Tanzania. This has coincided with the scaling up of vector control measures. Resistance may impair the effectiveness of these interventions and therefore demands close monitoring and the adoption of a resistance management strategy.
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Affiliation(s)
- B Kabula
- Amani Research Centre, National Institute for Medical Research, Ubwari, Muheza, Tanzania; Department of Parasitology and Entomology, Kilimanjaro Christian Medical University College, Tumaini University, Moshi, Tanzania
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15
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Matowo J, Jones CM, Kabula B, Ranson H, Steen K, Mosha F, Rowland M, Weetman D. Genetic basis of pyrethroid resistance in a population of Anopheles arabiensis, the primary malaria vector in Lower Moshi, north-eastern Tanzania. Parasit Vectors 2014; 7:274. [PMID: 24946780 PMCID: PMC4082164 DOI: 10.1186/1756-3305-7-274] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Accepted: 06/15/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Pyrethroid resistance has been slower to emerge in Anopheles arabiensis than in An. gambiae s.s and An. funestus and, consequently, studies are only just beginning to unravel the genes involved. Permethrin resistance in An. arabiensis in Lower Moshi, Tanzania has been linked to elevated levels of both P450 monooxygenases and β-esterases. We have conducted a gene expression study to identify specific genes linked with metabolic resistance in the Lower Moshi An. arabiensis population. METHODS Microarray experiments employing an An. gambiae whole genome expression chip were performed on An. arabiensis, using interwoven loop designs. Permethrin-exposed survivors were compared to three separate unexposed mosquitoes from the same or a nearby population. A subsection of detoxification genes were chosen for subsequent quantitative real-time PCR (qRT-PCR). RESULTS Microarray analysis revealed significant over expression of 87 probes and under expression of 85 probes (in pairwise comparisons between permethrin survivors and unexposed sympatric and allopatric samples from Dar es Salaam (controls). For qRT-PCR we targeted over expressed ABC transporter genes (ABC '2060'), a glutathione-S-transferase, P450s and esterases. Design of efficient, specific primers was successful for ABC '2060'and two P450s (CYP6P3, CYP6M2). For the CYP4G16 gene, we used the primers that were previously used in a microarray study of An. arabiensis from Zanzibar islands. Over expression of CYP4G16 and ABC '2060' was detected though with contrasting patterns in pairwise comparisons between survivors and controls. CYP4G16 was only up regulated in survivors, whereas ABC '2060' was similar in survivors and controls but over expressed in Lower Moshi samples compared to the Dar es Salaam samples. Increased transcription of CYP4G16 and ABC '2060' are linked directly and indirectly respectively, with permethrin resistance in Lower Moshi An. arabiensis. CONCLUSIONS Increased transcription of a P450 (CYP4G16) and an ABC transporter (ABC 2060) are linked directly and indirectly respectively, with permethrin resistance in Lower Moshi An. arabiensis. Our study provides replication of CYP4G16 as a candidate gene for pyrethroid resistance in An. arabiensis, although its role may not be in detoxification, and requires further investigation.
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Affiliation(s)
- Johnson Matowo
- Kilimanjaro Christian Medical University College (KCMUCo), Moshi, Tanzania.
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16
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Kabula B, Kisinza W, Tungu P, Ndege C, Batengana B, Kollo D, Malima R, Kafuko J, Mohamed M, Magesa S. Co-occurrence and distribution of East (L1014S) and West (L1014F) African knock-down resistance in Anopheles gambiae sensu lato population of Tanzania. Trop Med Int Health 2014; 19:331-341. [PMID: 24386946 PMCID: PMC4190685 DOI: 10.1111/tmi.12248] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Objective Insecticide resistance molecular markers can provide sensitive indicators of resistance development in Anopheles vector populations. Assaying these makers is of paramount importance in the resistance monitoring programme. We investigated the presence and distribution of knock-down resistance (kdr) mutations in Anopheles gambiae s.l. in Tanzania. Methods Indoor-resting Anopheles mosquitoes were collected from 10 sites and tested for insecticide resistance using the standard WHO protocol. Polymerase chain reaction-based molecular diagnostics were used to genotype mosquitoes and detect kdr mutations. Results The An. gambiae tested were resistance to lambdacyhalothrin in Muheza, Arumeru and Muleba. Out of 350 An. gambiae s.l. genotyped, 35% were An. gambiae s.s. and 65% An. arabiensis. L1014S and L1014F mutations were detected in both An. gambiae s.s. and An. arabiensis. L1014S point mutation was found at the allelic frequency of 4–33%, while L1014F was at the allelic frequency 6–41%. The L1014S mutation was much associated with An. gambiae s.s. (χ2 = 23.41; P < 0.0001) and L1014F associated with An. arabiensis (χ2 = 11.21; P = 0.0008). The occurrence of the L1014S allele was significantly associated with lambdacyhalothrin resistance mosquitoes (Fisher exact P < 0.001). Conclusion The observed co-occurrence of L1014S and L1014F mutations coupled with reports of insecticide resistance in the country suggest that pyrethroid resistance is becoming a widespread phenomenon among our malaria vector populations. The presence of L1014F mutation in this East African mosquito population indicates the spreading of this gene across Africa. The potential operational implications of these findings on malaria control need further exploration. Objectif Les marqueurs moléculaires de la résistance aux insecticides peuvent fournir des indicateurs sensibles du développement de la résistance dans les populations de vecteurs Anopheles. Le test de ces indicateurs est d'une importance énorme dans le programme de surveillance de la résistance. Nous avons étudié la présence et la répartition des mutations de résistance knockdown (kdr) chez Anopheles gambiae s.l. en Tanzanie. Méthodes Des anophèles d'intérieur, au repos ont été collectées dans 10 sites et testées pour la résistance aux insecticides en utilisant le protocole standard de l'OMS. Les diagnostics moléculaires basés sur la PCR ont été utilisés pour le génotypage des moustiques et la détection des génotypes kdr. Résultats Les An. gambiae testées étaient résistantes à la lambdacyhalothrine à Muheza, Arumeru et Muleba. Sur 350 An. gambiae s.l. génotypées, 35% étaient An. gambiae s.s. et 65% étaient An. arabiensis. Les mutations L1014S et L1014F ont été détectées à la fois chez An. gambiae s.s. et An. arabiensis. La mutation ponctuelle L1014S a été trouvée à la fréquence allélique de 4 à 33%, tandis que L1014F était à la fréquence allélique de 6 à 14%. La mutation L1014S a été fortement associée à An. gambiae s.s. (Chi carré = 23,41; P<0,0001) et L1014F était associée à An. arabiensis (chi carré = 11,21; P = 0,0008). L'allèle L1014S était significativement associé aux moustiques résistants à la lambdacyhalothrine (Fisher P exact <0,001). Conclusion La cooccurrence des mutations L1014S et L1014F couplées à des rapports sur la résistance aux insecticides suggèrent que la résistance aux pyréthrinoïdes est en train de devenir un phénomène répandu dans les populations de vecteurs du paludisme en Tanzanie. La présence de la mutation L1014F dans cette population de moustiques en Afrique de l'Est indique la propagation de ce gène à travers l'Afrique. L'investigation des implications opérationnelles potentielles de ces résultats sur le contrôle du paludisme devraient être approfondie. Objetivo Los marcadores moleculares de resistencia a insecticidas pueden ser indicadores sensibles del desarrollo de resistencias en las poblaciones de los vectores Anopheles. Evaluar dichos marcadores es crucial para los programas de monitorización de resistencias. Hemos investigado la presencia y la distribución de las mutaciones de resistencia knockdown (kdr) en Anopheles gambiae s.l. en Tanzania. Métodos Se recolectaron mosquitos Anopheles intradomiciliarios de 10 lugares diferentes y se evaluaron en busca de resistencia a insecticidas utilizando el protocolo estándar de la OMS. Mediante un diagnóstico molecular basado en la PCR se genotiparon los mosquitos y se detectaron los genotipos kdr. Resultados Los An. gambiae evaluados eran resistentes a lambdacialotrina en Muheza, Arumeru y Muleba. De 350 An. gambiae s.l. genotipados, 35% eran An. gambiae s.s. y 65% eran An. arabiensis. Se detectaron mutaciones L1014S y L1014F tanto en An. gambiae s.s. como en An. arabiensis. La mutación puntual L1014S se encontró con una frecuencia alélica de 4-33%, mientras que L1014F tenía una frecuencia alélica de 6-14%. La mutación L1014S estaba ampliamente asociada a An. gambiae s.s. (Chi-Cuadrado = 23.41; P < 0.0001) y la L1014F estaba asociada con An. arabiensis (Chi-Square = 11.21; P = 0.0008). El alelo L1014S estaba significativamente asociado con mosquitos resistentes a la lambdacialotrina (P < 0.001). Conclusión La simultaneidad de mutaciones de L1014S y L1014F junto con informes de resistencia a los insecticidas sugiere que la resistencia a piretroides se está convirtiendo en un fenómeno común entre las poblaciones del vector de la malaria en Tanzania. La presencia de la mutación L1014F en estas poblaciones del Este de África indican la diseminación del gen a lo largo del continente africano. Determinar las implicaciones potenciales a nivel operativo de estos hallazgos sobre el control de la malaria requiere de más estudios.
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Affiliation(s)
- Bilali Kabula
- National Institute for Medical Research, Amani Research Centre, Muheza, Tanzania.,Kilimanjaro Christian Medical University College, Tumaini University, Moshi, Tanzania
| | - William Kisinza
- National Institute for Medical Research, Amani Research Centre, Muheza, Tanzania
| | - Patrick Tungu
- National Institute for Medical Research, Amani Research Centre, Muheza, Tanzania
| | - Chacha Ndege
- National Institute for Medical Research, Mwanza Research Centre, Mwanza, Tanzania
| | - Benard Batengana
- National Institute for Medical Research, Amani Research Centre, Muheza, Tanzania
| | - Douglas Kollo
- National Institute for Medical Research, Mwanza Research Centre, Mwanza, Tanzania
| | - Robert Malima
- National Institute for Medical Research, Amani Research Centre, Muheza, Tanzania
| | - Jessica Kafuko
- The Presidents' Malaria Initiative, PMI/USAID Office, Dar es Salaam, Tanzania
| | - Mahdi Mohamed
- Global Health Division, RTI International, Dar es Salaam, Tanzania
| | - Stephen Magesa
- National Institute for Medical Research, Amani Research Centre, Muheza, Tanzania.,Global Health Division, RTI International, Nairobi, Kenya
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Jones CM, Haji KA, Khatib BO, Bagi J, Mcha J, Devine GJ, Daley M, Kabula B, Ali AS, Majambere S, Ranson H. The dynamics of pyrethroid resistance in Anopheles arabiensis from Zanzibar and an assessment of the underlying genetic basis. Parasit Vectors 2013; 6:343. [PMID: 24314005 PMCID: PMC3895773 DOI: 10.1186/1756-3305-6-343] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Accepted: 11/28/2013] [Indexed: 12/02/2022] Open
Abstract
Background The emergence of pyrethroid resistance in the malaria vector, Anopheles arabiensis, threatens to undermine the considerable gains made towards eliminating malaria on Zanzibar. Previously, resistance was restricted to the island of Pemba while mosquitoes from Unguja, the larger of the two islands of Zanzibar, were susceptible. Here, we characterised the mechanism(s) responsible for resistance on Zanzibar using a combination of gene expression and target-site mutation assays. Methods WHO resistance bioassays were conducted using 1-5d old adult Anopheles gambiae s.l. collected between 2011 and 2013 across the archipelago. Synergist assays with the P450 inhibitor piperonyl-butoxide were performed in 2013. Members of the An. gambiae complex were PCR-identified and screened for target-site mutations (kdr and Ace-1). Gene expression in pyrethroid resistant An. arabiensis from Pemba was analysed using whole-genome microarrays. Results Pyrethroid resistance is now present across the entire Zanzibar archipelago. Survival to the pyrethroid lambda-cyhalothrin in bioassays conducted in 2013 was 23.5-54.3% on Unguja and 32.9-81.7% on Pemba. We present evidence that resistance is mediated, in part at least, by elevated P450 monoxygenases. Whole-genome microarray scans showed that the most enriched gene terms in resistant An. arabiensis from Pemba were associated with P450 activity and synergist assays with PBO completely restored susceptibility to pyrethroids in both islands. CYP4G16 was the most consistently over-expressed gene in resistant mosquitoes compared with two susceptible strains from Unguja and Dar es Salaam. Expression of this P450 is enriched in the abdomen and it is thought to play a role in hydrocarbon synthesis. Microarray and qPCR detected several additional genes putatively involved in this pathway enriched in the Pemba pyrethroid resistant population and we hypothesise that resistance may be, in part, related to alterations in the structure of the mosquito cuticle. None of the kdr target-site mutations, associated with pyrethroid/DDT resistance in An. gambiae elsewhere in Africa, were found on the islands. Conclusion The consequences of this resistance phenotype are discussed in relation to future vector control strategies on Zanzibar to support the ongoing malaria elimination efforts on the islands.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | - Hilary Ranson
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK.
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Kabula B, Tungu P, Matowo J, Kitau J, Mweya C, Emidi B, Masue D, Sindato C, Malima R, Minja J, Msangi S, Njau R, Mosha F, Magesa S, Kisinza W. Susceptibility status of malaria vectors to insecticides commonly used for malaria control in Tanzania. Trop Med Int Health 2012; 17:742-50. [PMID: 22519840 DOI: 10.1111/j.1365-3156.2012.02986.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE The aim of the study was to monitor the insecticide susceptibility status of malaria vectors in 12 sentinel districts of Tanzania. METHODS WHO standard methods were used to detect knock-down and mortality in the wild female Anopheles mosquitoes collected in sentinel districts. The WHO diagnostic doses of 0.05% deltamethrin, 0.05% lambdacyhalothrin, 0.75% permethrin and 4% DDT were used. RESULTS The major malaria vectors in Tanzania, Anopheles gambiae s.l., were susceptible (mortality rate of 98-100%) to permethrin, deltamethrin, lambdacyhalothrin and DDT in most of the surveyed sites. However, some sites recorded marginal susceptibility (mortality rate of 80-97%); Ilala showed resistance to DDT (mortality rate of 65% [95% CI, 54-74]), and Moshi showed resistance to lambdacyhalothrin (mortality rate of 73% [95% CI, 69-76]) and permethrin (mortality rate of 77% [95% CI, 73-80]). CONCLUSIONS The sustained susceptibility of malaria vectors to pyrethroid in Tanzania is encouraging for successful malaria control with Insecticide-treated nets and IRS. However, the emergency of focal points with insecticide resistance is alarming. Continued monitoring is essential to ensure early containment of resistance, particularly in areas that recorded resistance or marginal susceptibility and those with heavy agricultural and public health use of insecticides.
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Affiliation(s)
- Bilali Kabula
- National Institute for Medical Research, Amani Research Centre, Muheza, Tanzania.
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Kabula B, Derua YA, Tungui P, Massue DJ, Sambu E, Stanley G, Mosha FW, Kisinza WN. Malaria entomological profile in Tanzania from 1950 to 2010: a review of mosquito distribution, vectorial capacity and insecticide resistance. Tanzan J Health Res 2011; 13:319-331. [PMID: 26591987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
In Sub Saharan Africa where most of the malaria cases and deaths occur, members of the Anopheles gambiae species complex and Anophelesfunestus species group are the important malaria vectors. Control efforts against these vectors in Tanzania like in most other Sub Saharan countries have failed to achieve the set objectives of eliminating transmission due to scarcity of information about the enormous diversity of Anopheles mosquito species and their susceptibility status to insecticides used for malaria vector control. Understanding the diversity and insecticide susceptibility status of these vectors and other factors relating to their importance as vectors (such as malaria transmission dynamics, vector biology, ecology, behaviour and population genetics) is crucial to developing a better and sound intervention strategies that will reduce man-vector contact and also manage the emergency of insecticide resistance early and hence .a success in malaria control. The objective of this review was therefore to obtain the information from published and unpublished documents on spatial distribution and composition of malaria vectors, key features of their behaviour, transmission indices and susceptibility status to insecticides in Tanzania. All data available were collated into a database. Details recorded for each data source were the locality, latitude/longitude, time/period of study, species, abundance, sampling/collection methods, species identification methods, insecticide resistance status, including evidence of the kdr allele, and Plasmodium falciparum sporozoite rate. This collation resulted in a total of 368 publications, encompassing 806,273 Anopheles mosquitoes from 157 georeferenced locations being collected and identified across Tanzania from 1950s to 2010. Overall, the vector species most often reported included An. gambiae complex (66.8%), An. funestus complex (21.8%), An. gambiae s.s. (2.1%) and An. arabiensis (9%). A variety of sampling/ collection and species identification methods were used with an increase in molecular techniques in recent decades. Only 32.2% and 8.4% of the data sets reported on sporozoite analysis and entomological inoculation rate (EIR), respectively which highlights the paucity of such important information in the country. Studies demonstrated efficacy of all four major classes of insecticides against malaria vectors in Tanzania with focal points showing phenotypic resistance. About 95% of malaria entomological data was obtained from northeastern Tanzania. This shows the disproportionate nature of the available information with the western part of the country having none. Therefore it is important for the country to establish entomological surveillance system with state of the art to capture all vitally important entomological indices including vector bionomics in areas of Tanzania where very few or no studies have been done. This is vital in planning and implementing evidence based malaria vector control programmes as well as in monitoring the current malaria control interventions.
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Affiliation(s)
- Bilali Kabula
- National-Institute for Medical Research, Amani Research Centre, Muheza, Tanzania
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Sindato C, Kabula B, Mbilu TJNK, Manga C, Tungu P, Kazimoto JP, Kibonai SN, Kisinza WN, Magesa SM. Resting behaviour of Anopheles gambiae s.l. and its implication on malaria transmission in Uyui District, western Tanzania. ACTA ACUST UNITED AC 2011; 13:122-5. [PMID: 26592058 DOI: 10.4314/thrb.v13i4.70200] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
An entomological survey to determine resting behaviour and species composition of malaria vectors was carried out in Uyui District in western Tanzania in May 2009. Mosquitoes were collected using indoor resting catch, window exit trap and outdoor "bed-net" techniques. The mosquitoes were identified using morphological key and polymerase chain reaction (PCR). A total of 672 Anopheles gambiae sensu lato were collected. Of these, 661 (98.4%) were collected outdoor whereas few (1.6%) were collected indoor. The exit trap catch: mechanical aspirator catch ratio was 1:1.75. The overall indoor resting density of An. gambiae s.l. as determined by mechanical aspirator and exit trap was 0.7 and 0.5 mosquitoes per room, respectively. The overall density of the host-seeking as determined by bed net trap outdoor was 44.1 mosquitoes per person. A sample of 44 specimens taken randomly from morphologically identified An.gambiae s.l. population was further analyzed to species level using PCR techniques. Of these 44 specimens 26 (59%) and 18 (41%) were Anopheles arabiensis and Anopheles gambiae sensu stricto respectively. This study contributes to the understanding of the distribution of malaria vectors with respect to species composition and their resting behaviour that could contribute to vector control operations in western Tanzania. A longitudinal study considering dry and wet seasons is recommended to provide more information on the seasonal distribution, abundance and biting behaviour of malaria vectors in the study area.
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Affiliation(s)
- Calvin Sindato
- National Institute for Medical Research, Tabora Research Centre, PO Box 482 Tabora, Tanzania.
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Maegga BTA, Kalinga AK, Kabula B, Post RJ, Krueger A. Investigations into the isolation of the Tukuyu focus of onchocerciasis (Tanzania) from S. damnosum s.l. vector re-invasion. Acta Trop 2011; 117:86-96. [PMID: 21029718 DOI: 10.1016/j.actatropica.2010.10.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2010] [Revised: 10/07/2010] [Accepted: 10/07/2010] [Indexed: 11/29/2022]
Abstract
As part of the feasibility study for an onchocerciasis vector elimination project we investigated the isolation of the Tukuyu focus in Tanzania from possible vector re-invasion. This was achieved by examining the distribution of the Simulium damnosum complex vector cytospecies outside the focus to look for potential sources of re-invasion. Besides cytotaxonomic identifications of the aquatic stages, we applied morphotaxonomic and molecular techniques to identify S. thyolense and confirm it as the anthropophilic species in both the Tukuyu and the neighbouring Ruvuma foci. We detected significant differences in chromosome inversion frequencies between the Tukuyu populations and those breeding to the southwest in the adjacent Songwe river basin and in northern Malawi (where there is no man-biting and no onchocerciasis), suggesting that there is not normally a great deal of migration in either direction. By contrast, populations of S. thyolense from the Tukuyu and Ruvuma foci (150km southeast of Tukuyu) were much more similar in terms of their chromosomal polymorphisms, indicating a higher possibility of re-invasion, although migration is still restricted to some extent, as indicated by some differences in chromosome polymorphisms between the two foci. Future migratory events which might be associated with vector control operations can be monitored by vector cytospecies identification, the frequency of polymorphic inversions which characterise the different vector populations, and the identification of accompanying non-vector cytospecies (e.g. S. plumbeum and cytotype Kasyabone occur exclusively in the two foci, and hence their re-appearance in Tukuyu could have only one outside source). The morphology of the scutal pattern of neonate males may act as a quick test for vector species identification where chromosome squashes are unavailable.
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Affiliation(s)
- B T A Maegga
- National Institute for Medical Research, PO Box 9653, Dar es Salaam, Tanzania
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Mweya CN, Kalinga AK, Kabula B, Malley KD, Ruhiso MH, Maegga BTA. Onchocerciasis situation in the Tukuyu focus of southwest Tanzania after ten years of ivermectin mass treatment. Tanzan Health Res Bull 2007; 9:174-9. [PMID: 18087895 DOI: 10.4314/thrb.v9i3.14325] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
A purposive cross-sectional epidemiological study was conducted in the Tukuyu Onchocerciasis focus in south-western Tanzania in 2004, ten years after launching the ivermectin mass treatment programme, and 23 years after establishing focal parasite prevalence. The objective was to assess contemporary Onchocerciasis clinical and parasitological situation and assess community knowledge about the disease and its control. From historical data, five villages with high parasite prevalence were selected, two each on the Lufilyo and Kiwira Rivers and one on lower Lumbira River. Skin biopsies were taken from the iliac crest on the left and right buttocks, for examination of Onchocerca volvulus microfilariae. Onchocercal skin lesions were checked using natural light, while nodules were palpated from head to ankles and scored. A structured questionnaire was administered to participants. A total of 438 persons (age=16-99 years) were examined. No skin microfilariae (mf) were detected. Onchocercal skin symptoms were found in 170 (38.8%), of which 30 (6.9%) had nodules, 48 (11.0%) chronic onchodermatitis and 92 (21%) itching. One-third (34.5%) had correct knowledge that black flies ("tusunya") are vectors of onchocerciasis. Half of the respondents (n=217) confirmed taking ivermectin for onchocerciasis treatment, and 428 (97.7%) were willing to continue for any duration. It is concluded that the undetectable skin microfilariae in the study sample was partly attributable to the consequences of ongoing ivermectin mass treatment. It is recommended that the control efforts, as well as monitoring and evaluation be sustained to determine its long term impact, and that a more sensitive technique be used to check O. volvulus skin mf prevalence.
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Affiliation(s)
- C N Mweya
- National Institute for Medical Research, Tukuyu Station, P.O. Box 538, Tukuyu, Tanzania
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Kulkarni MA, Malima R, Mosha FW, Msangi S, Mrema E, Kabula B, Lawrence B, Kinung'hi S, Swilla J, Kisinza W, Rau ME, Miller JE, Schellenberg JA, Maxwell C, Rowland M, Magesa S, Drakeley C. Efficacy of pyrethroid-treated nets against malaria vectors and nuisance-biting mosquitoes in Tanzania in areas with long-term insecticide-treated net use. Trop Med Int Health 2007; 12:1061-73. [PMID: 17875017 DOI: 10.1111/j.1365-3156.2007.01883.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVE To measure pyrethroid susceptibility in populations of malaria vectors and nuisance-biting mosquitoes in Tanzania and to test the biological efficacy of current insecticide formulations used for net treatment. METHODS Anopheles gambiae Giles s.l., An. funestus Giles s.l. and Culex quinquefasciatus Say were collected during three national surveys and two insecticide-treated net (ITN) studies in Tanzania. Knockdown effect and mortality were measured in standard WHO susceptibility tests and ball-frame bio-efficacy tests. Test results from 1999 to 2004 were compared to determine trends in resistance development. RESULTS Anopheles gambiae s.l. and An. funestus s.l. were highly susceptible to permethrin (range 87-100%) and deltamethrin (consistently 100%) in WHO tests in 1999 and 2004, while Culex quinquefasciatus susceptibility to these pyrethroids was much lower (range 7-100% and 0-84% respectively). Efficacy of pyrethroid-treated nets was similarly high against An. gambiae s.l. and An. funestus s.l. (range 82-100%) while efficacy against Cx. quinquefasciatus was considerably lower (range 2-100%). There was no indication of development of resistance in populations of An. gambiae s.l. or An. funestus s.l. where ITNs have been extensively used; however, susceptibility of nuisance-biting Cx. quinquefasciatus mosquitoes declined in some areas between 1999 and 2004. CONCLUSION The sustained pyrethroid susceptibility of malaria vectors in Tanzania is encouraging for successful malaria control with ITNs. Continued monitoring is essential to ensure early resistance detection, particularly in areas with heavy agricultural or public health use of insecticides where resistance is likely to develop. Widespread low susceptibility of nuisance-biting Culex mosquitoes to ITNs raises concern for user acceptance of nets.
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Affiliation(s)
- Manisha A Kulkarni
- Department of Natural Resource Sciences, McGill University, Ste Anne de Bellevue, QC, Canada.
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Mdegela RH, Kusiluka LJM, Kapaga AM, Karimuribo ED, Turuka FM, Bundala A, Kivaria F, Kabula B, Manjurano A, Loken T, Kambarage DM. Prevalence and Determinants of Mastitis and Milk-borne Zoonoses in Smallholder Dairy Farming Sector in Kibaha and Morogoro Districts in Eastern Tanzania. ACTA ACUST UNITED AC 2004; 51:123-8. [PMID: 15107038 DOI: 10.1111/j.1439-0450.2004.00735.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- R H Mdegela
- Department of Veterinary Medicine and Public Health, Sokoine University of Agriculture, PO Box 3021, Morogoro, Tanzania.
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