High prevalence and risk of malaria among asymptomatic individuals from villages with high rates of artemisinin partial resistance in Kyerwa district, North-western Tanzania

Background Tanzania adopted and has been implementing the World Health Organization (WHO) recommended interventions to control and eventually eliminate malaria. However, malaria is still a leading public health problem and the country experiences heterogeneous transmission; but the drivers of these patterns are not clearly known. This study assessed the prevalence and risk of malaria infections among asymptomatic individuals living in a hyperendemic area which has high prevalence of artemisinin partial resistant parasites in Kyerwa District of Kagera region, North-western Tanzania. Methods This was a community-based cross-sectional survey that recruited participants from five villages of Kyerwa district in Kagera region. Demographic, anthropometric, clinical, parasitological, types of houses inhabited and socio-economic status (SES) data were collected using electronic capture tools running on Open Data Kit (ODK). Risk factors associated with malaria infections were determined by univariate and multivariate logistic regression and the results were presented as crude (cOR) and adjusted Odds Ratio (aOR), with 95% confidence intervals (CI). Results A total of 4,454 individuals were tested using malaria rapid diagnostic tests (RDTs) and 1,979 (44.4%) had a positive test. The prevalence of malaria varied from 14.4% to 68.5% with significant differences among the villages (p<0.001). The prevalence and risk of malaria infections were significantly higher in males (aOR =1.25, 95% CI: 1.06 - 1.48, p=0.04), school children ((aged 5 – 10 years, aOR =4.09, 95% CI: 3.39 – 5.10, p<0.001) and (10-15 years, aOR=4.40, 95% CI: 3.46 – 5.59, p<0.001)) and among individuals who were not using bed nets (aOR =1.29, 95% CI: 1.10 – 1.42, p=0.002). Other risks of malaria infections included lower SES (aOR=1.27, 95% CI:1.04 – 1.55, p<0.001) and living in houses with open windows (aOR=1.26, 95% CI: 1.03 −1.54, p=0.024). Conclusion This study showed high prevalence of malaria infections and high heterogeneity at micro-geographic levels. The risk of malaria infections was higher in school children, males, individuals who did not use bed nets, and among participants with low SES or living in poorly constructed houses. These findings provide important baseline data in an area with a high prevalence of artemisinin partial-resistant parasites and will be utilized in future studies to monitor the trends and potential spread of such parasites. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This work was supported in full 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 gave ethical approval for this work. 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 a request from the corresponding author. * ACT : Artemisinin-based combination therapy ANC : Antenatal care clinic aOR : adjusted odds ratio CI : Confidence interval CSS : Cross-sectional community survey DMFP : District malaria focal person IDs : Identification numbers iMMS : Integrated malaria molecular surveillance IPTp : Intermittent preventive treatment IRS : Indoor residual spraying ITN : Insecticides treated Nets IQR : Interquartile range LSM : Larval source management LLINs : Long-lasting insecticidal nets MMS : Malaria molecular surveillance MRCC : Medical Research Coordinating Committee MSMT : Molecular surveillance of malaria in Tanzania. RDTs : Rapid diagnostic tests for malaria NIMR : National Institute for Medical Research NMCP : National Malaria Control Program NMSP : National malaria strategic plan OR : Odds ratio ODK : Open Data Kit PO-RALG : President’s Office, Regional Administration and Local Government PCA : Principal component analysis SES : Socio-economic status SP : Sulphadoxine-pyrimethamine TMIS Tanzania malaria indicator survey WHO World Health Organization WHO-Afro : WHO Regional office for African