Prevalence and drivers of malaria infections among asymptomatic individuals from selected communities in five regions of Mainland Tanzania with varying transmission intensities

Abstract Background: Malaria is still a leading public health problem in Tanzania despite the implementation of effective interventions for the past two decades. Currently, the country experiences heterogeneous transmission and a higher malaria burden in some vulnerable groups, threatening the prospects for elimination by 2030. This study assessed the prevalence and drivers of malaria infections among asymptomatic individuals in selected communities from five districts within five regions with varying endemicity in Mainland Tanzania. Methods: A community cross-sectional survey was conducted in selected communities (covering 15 villages) from five districts, one each from five regions of Kagera, Kigoma, Njombe, Ruvuma, and Tanga from July to August 2023. Asymptomatic participants aged ≥6 months were recruited and tested with rapid diagnostic tests (RDTs) to detect malaria parasites. Demographic, anthropometric, clinical, parasitological, housing type, and socio-economic status (SES) data were captured using questionnaires configured and installed on Open Data Kit (ODK) software run on tablets. The association between parasite prevalence and potential drivers of malaria infections among asymptomatic individuals were determined by univariate and multivariate logistic regression, and the results were presented as crude (cOR) and adjusted odds ratios (aOR), with 95% confidence intervals (CI). Results: Testing involved 10,228 individuals and 3,515 (34.4%) had RDT positive results. The prevalence varied from 21.6% in Tanga to 44.4% in Kagera, and ranged from 14.4% to 68.5% in the different villages, with significant differences among regions and villages (p<0.001). The prevalence and odds of malaria infections were significantly higher in males (aOR =1.32, 95% CI:1.19 – 1.48, p<0.01), under-fives (aOR = 2.02, 95% CI: 1.74 – 2.40, p<0.01), school children [aged 5 – <10 years (aOR = 3.23, 95% CI: 1.19 – 1.48, p<0.01) and 10 – 15 years (aOR = 3.53, 95% CI: 3.03 – 4.11, p<0.01)], and among individuals who were not using bed nets (aOR = 1.49, 95% CI: 1.29 – 1.72, p<0.01). The odds of malaria infections were also higher in individuals from households with low SES (aOR = 1.40, 95% CI:1.16 – 1.69, p<0.001), living in houses with open windows (aOR = 1.24, 95% CI: 1.06 – 1.45, p<0.01) and holes on the wall (aOR = 1.43, 95%CI 1.14 – 1.81, p<0.01). Conclusion: There was a high and varying prevalence of malaria infections in the surveyed regions/villages. The odds of malaria infections were higher in males, school children, individuals who did not use bed nets, and participants with low SES or living in poorly constructed houses (with open windows and holes on walls). These findings provide useful information for identifying high-priority vulnerable groups and areas for implementing targeted malaria control interventions for reducing the burden of asymptomatic infections. Keywords: Malaria, asymptomatic infections, drivers of malaria infections, vulnerable groups, Tanzania ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This work was fully supported by the Bill & Melinda Gates Foundation [grant number 002202]. Under the grant conditions of the Foundation, a Creative Commons Attribution 4.0 Generic License has already been assigned to the Author Accepted Manuscript version that might arise from this submission ### 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 Medical Research Coordinating Committee of the National Institute for Medical Research granted ethical approval for this study. 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 The data used in this paper are available and can be obtained upon request from the corresponding author.