Browsing by Author "Njalambaha, Rukiyah"

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Characterization of a new laboratory colony of Anopheles funestus mosquitoes established in Ifakara, Tanzania
(bioRxiv, 2025-11-24) Hape, Emmanuel; Njalambaha, Rukiyah; Muyaga, Letus; Nambunga, Ismail; Mgando, Joseph; Mwasheshi, Dickson; Nombo, Neema; Mabula, Daniel; Zengenene, Munyaradzi; Kahamba, Najat; Odero, Joel; Ngowo, Halfan; Mapua, Salum; Chaki, Prosper; Govella, Nicodem; Lyimo, Issa; Kiware, Samson; Lwetoijera, Dickson; Tarimo, Brian; Kaindoa, Emmanuel; Selvaraj, Prashanth; Tripet, Frederic; Wondji, Charles; Baldini, Francesco; Koekemoer, Lizette; Ferguson, Heather; Okumu, Fredros O.
Background: Anopheles funestus, a major vector of malaria in Africa, has proven difficult to colonize in laboratory settings, impeding research on its biology and control. After several attempts, our team recently succeeded in colonizing a strain of An. funestus from Tanzania (FUTAZ). The objective of this study was to analyse the key fitness and genotypic characteristics of these mosquitoes during multiple filial generations of laboratory adaptation and compare them to wild An. funestus from Tanzania and a pre-existing colony of An. funestus from Mozambique (FUMOZ). Methods: Measures of mating success (percentage of female mosquitoes inseminated), body size (wing length), fecundity (number of eggs laid per female), and insecticide susceptibility (percentage of 24-hour mortality after exposure to insecticides) were compared between the newly established colonies of Tanzanian An. funestus (FUTAZ colonies), the long-established FUMOZ colonies, and a colony of Anopheles arabiensis maintained in the same laboratory. The maternal lineages of the An. funestus mosquitoes were investigated through a hydrolysis probe analysis of their mitochondrial DNA to identify distinct clades, I and II. Additionally, other intragenomic variations were examined through a PCR analysis of restriction fragment length polymorphisms (RFLP) on the third domain of 28S ribosomal DNA. These molecular markers were used to compare the FUTAZ colonies, FUMOZ colonies in Tanzania and South Africa, and the wild-collected An. funestus from Tanzania. Result: The mating success and body size of FUTAZ females declined significantly from filial generations F1 to F6 relative to the founder population (F0), but then increased from F7 onwards eventually matching FUMOZ by F9. Fecundity was similar across all colonies tested. However, it took significantly longer for 50% of the females in the FUTAZ and FUMOZ colonies (over 10 days) to mate compared to females in the An. arabiensis colony (approximately 5 days). Insecticide resistance appeared to be lost during colonization, but this varied with insecticide classes. Majority of mosquitoes in the FUTAZ colony, as well as the wild-caught Tanzanian An. funestus belonged to Clade I (80.4-89.4%) and RFLP type “Y” (90.5-91.4%), while the FUMOZ colonies were mostly Clade II (65.5-88.5%) and RFLP type “MW” (90.5-91.5%). Conclusion: This study suggests that the mating success and body size of An. funestus decreases significantly during the early stages of colonization, then increase as the mosquitoes adapt to laboratory conditions. It is therefore crucial to have a large enough founder population to persist through these early generations in order to achieve stable colonization of An. funestus. The Clade and RFLP genotyping demonstrated the genetic similarities between the FUTAZ mosquitoes and wild- caught Tanzanian An. funestus, but also showed that the new colony can be distinguished from the FUMOZ colony.
The needs and opportunities for housing improvement for malaria control in southern Tanzania
(BMC, 2023-02-27) Bofu, Ramadhani; Santos, Ellen; Msugupakulya, Betwel; Kahamba, Najat; Swilla, Joseph; Njalambaha, Rukiyah; Kelly, Ann; Lezaun, Javier; Christofides, Nicola; Okumu, Fredros; Finda, Marceline;
Background Malaria disproportionately afects low-income households in rural communities where poor housing is common. Despite evidence that well-constructed and mosquito-proofed houses can reduce malaria risk, housing improvement is rarely included in malaria control toolboxes. This study assessed the need, magnitude, and opportuni ties for housing improvement to control malaria in rural Tanzania. Methods A mixed-methods study was conducted in 19 villages across four district councils in southern Tanzania. A structured survey was administered to 1292 community members to assess need, perceptions, and opportunities for housing improvement for malaria control. Direct observations of 802 houses and surrounding environments were done to identify the actual needs and opportunities, and to validate the survey fndings. A market survey was done to assess availability and cost of resources and services necessary for mosquito-proofng homes. Focus group discussions were conducted with key stakeholders to explore insights on the potential and challenges of housing improvement as a malaria intervention. Results Compared to other methods for malaria control, housing improvement was among the best understood and most preferred by community members. Of the 735 survey respondents who needed housing improvements, a majority needed window screening (91.1%), repairs of holes in walls (79.4%), door covers (41.6%), closing of eave spaces (31.2%) and better roofs (19.0%). Community members invested signifcant eforts to improve their own homes against malaria and other dangers, but these eforts were often slow and delayed due to high costs and limited household incomes. Study participants suggested several mechanisms of support to improve their homes, including government loans and subsidies. Conclusion Addressing the need for housing improvement is a critical component of malaria control eforts in southern Tanzania. In this study, a majority of the community members surveyed needed modest modifcations and had plans to work on those modifcations. Without additional support, their eforts were however generally slow; households would take years to sufciently mosquito-proof their houses. It is, therefore, crucial to bring together the key players across sectors to reduce barriers in malaria-proofng housing in endemic settings. These may include government subsidies or partnerships with businesses to make housing improvement more accessible and afordable to residents.
Risk of Aedes-borne diseases in and around the Tanzanian seaport of Tanga despite community members being more concerned about malaria
(BioMed Central, 2024-12-18) Abas, Amri; Simfukwe, Alfred; Masalu, John; Kahamba, Najat; Nambunga, Ismail; Msaky, Dickson; Limwagu, Alex; Kipekepeke, Abdallah; Wergin, Carsten; Njalambaha, Rukiyah; Kemibala, Elison; Seleman, Amour; Mlacha, Yeromin; Finda, Marceline; Beisel, Uli; Kimaro, Esther; Ngowo, Halfan; Okumu, Fredros
Background Increased global trade, while beneficial economically, can also increase the spread of vector-borne diseases, particularly those transmitted by Aedes mosquitoes spreading via trade routes. Given the heightened trade- induced activity at ports of entry, it is particularly crucial to assess the risk of mosquito-borne diseases in these set- tings. This study compared the risks of Aedes-borne disease in and around the eastern Tanzanian seaport of Tanga. Methods A 200 m × 200 m grid-based system was used to sample mosquitoes within the port area, and in surround- ing areas at 2 km, 2.5 km, and 5 km away, between June and December 2023. We characterized mosquito breeding habitats, collected mosquito larvae using standard dippers and tested susceptibility of raised adult Aedes aegypti populations to different insecticides. Adult mosquitoes were collected using BG sentinel traps (daytime) and Centers for Disease Control (CDC) light traps (night-time). Additionally, more than 200 port users and neighboring residents were surveyed to assess their experiences with and perceptions of mosquito biting and disease risks. Results There were 2931 breeding sites, with (60.8%, n = 1782) positive for Aedes larvae. The percentage of water- holding containers infested with Aedes immatures, i.e., the container index (CI), was highest in the port area (66.2%), and lowest 5 km away (44.6%). The port area also had a greater proportion of temporary breeding sites (64.9%) than did the surrounding areas. The adult mosquito surveys revealed 20,449 mosquito species including: Culex quinquefasciatus (56.2%), Mansonia uniformis (38.6%), Ae. aegypti (5.1%), Anopheles gambiae (0.1%), and Anoph- eles funestus. Ae. aegypti were more abundant in the port area than in the surrounding areas (P < 0.001), whereas Culex sp., and Mansonia sp., were significantly outside (P < 0.001). Adult Anopheles sp., were found only in the port area, but Anopheles larvae were found both within and outside the port areas. Tests on Ae. aegypti sp., revealed susceptibility to bendiocarb and DDT, and resistance to permethrin. Awareness of mosquito-borne diseases among respondents was high for malaria (64.8%), but low for dengue (26.3%) and Chikungunya (1.7%). Most respond- ents reported being bothered by mosquitoes mostly at night (53.4%) or in the evening (40.7%). In addition to insecti- cidal bednets, which are used primarily against malaria, preventive measures for Aedes-borne diseases are limited. Conclusions This study identified significant potential risk of Aedes species, specifically Ae. aegypti sp., and associated diseases, but low perception of risk and inadequate personal protection measures in the study area. This low percep- tion of risk highlights the need to improve public knowledge of the transmission and control of Aedes-borne diseases.