The Role of Anopheles Arabiensis and Anopheles Funestus in Malaria Transmission Within Houses with Different Characteristics in South-eastern Tanzania

Background Malaria vectors persist predominantly in houses lacking screened windows, doors, and eave space, leading to ongoing transmission. Some other vectors adapt their feeding behavior to sustain reproduction. This study evaluates the role of primary malaria vectors on malaria transmission in relation to house characteristics in Kilombero Valley. Methods Mosquito data collection was done using three methods: a CDC light trap, a miniaturized double net trap (DN-Mini trap), and a Prokopack aspirator through 222 households that were randomly selected in the three villages, namely Ebuyu, Chirombora, and Mzelezi. The houses are characterized during mosquito collections, and the Geographical Position System (GPS) was used to geolocate the sampled houses. Morphological identification was done on the collected sample (i.e., fed, part-fed, gravid, and unfed), and a sub-sample was sent to the laboratory to assess the sibling species, blood meal, and sporozoite. Results A total of 1542 Anopheline mosquitoes were collected, of which 79.1% (n= 1219) were An. funestus and 20.3% (n= 313) were An. arabiensis as primary malaria vectors, while the secondary malaria vector was 0.6% (n = 10). Out of 487 anopheline mosquitoes assayed for plasmodium falciparum sporozoite, 92.8% (n = 13) of An. funestus was reported to be dominant while An. arabiensis was dominant by 7.2% (n = 1). While An. funestus was the only species that had a blood meal and was found to feed on humans (88.16%, n = 134), dogs (11.18% n = 17), and a mixture of both human and chicken blood meal. In addition to that, the house with screened eave space had fewer An. funestus compared to the house with open eave space (RR = 0.978, p =0.864), while the house with a brick wall had a higher An. funestus compared with the house with a mud wall (RR = 0.690, p =0.107). Conclusion Anopheles funestus remained the dominant malaria vector responsible for all transmissions in the villages. The human population is at risk due to their preference for An. funestus , which contributes about 92.8% of infections in the village. Additionally, the house design appears to play a significant role in facilitating malaria vectors to continue transmitting malaria. ### Competing Interest Statement The authors have declared no competing interest. ### Clinical Trial "N/A" ### Funding Statement The author(s) received no specific funding for this work. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The study was conducted following the principles of the Declaration of Helsinki. Ethical approval for conducting this study was obtained from the Muhimbili University of Health and Allied Sciences Review Board (MUHAS-REC-12-2021-910), while the permission to publish the work was approved by NIMR (Ref: NIMR/HQ/P.12VOL.XXXVI/27). Permission to conduct this study was secured through the approval of the District Medical Officer of Ulanga district and the cooperation of local government authorities in the chosen villages. Prior to commencing the study, comprehensive meetings were convened with local government leaders to elucidate the study's objectives and methodologies. Informed consent, both verbal and written, was diligently obtained from all individual residents of the households and the human volunteers engaged in mosquito collection. Participants were provided with detailed information regarding the potential benefits and risks associated with their participation, and their voluntary involvement was emphasized and respected. Participants were also assured of their right to withdraw from the study at any point without facing any adverse consequences, and strict measures were in place to maintain confidentiality, ensuring the anonymity of all participants. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All relevant data are within the manuscript and its Supporting Information file * DN : Double Net CDC : Centre for Disease Control LLINs : Long Lasting Insecticides Nets IRS : Indoor Residual Spray GLMM : Generalized Linear mixed model EMM : Estimated Marginal Means ELISA : Enzyme linked immunosorbent assays PCR : Polymerase Chain Reaction GPS : Geographic Position System