Prevalence and drivers of malaria infection among asymptomatic and symptomatic community members in five regions with varying transmission intensity in mainland Tanzania.

Background: Despite implementation of effective interventions in the past two decades, malaria is still a major public health problem in Tanzania. This study assessed the prevalence and drivers of malaria infections among symptomatic and asymptomatic members of selected communities from five regions with varying endemicity in mainland Tanzania.

Methods: A cross-sectional community survey was conducted in five districts, including one district/region in Kagera, Kigoma, Njombe, Ruvuma and Tanga from July to August 2023. Participants aged ≥ 6 months were recruited and tested using rapid diagnostic tests (RDTs). Demographic, anthropometric, clinical, parasitological, type of house, and socio-economic status (SES) data were captured using structured questionnaires. Associations between parasite prevalence and potential drivers were determined by logistic regression, and the results were presented as crude (cOR) and adjusted odds ratios (aOR), with 95% confidence intervals (CIs).

Results: Among 10,228 individuals tested, 3515 (34.4%) had positive results by RDTs. The prevalence of malaria varied from 21.6% in Tanga to 44.4% in Kagera, and from 14.4% to 68.5% among the different villages (P < 0.001). The odds of malaria infections were higher in males (aOR = 1.32, 95% CI 1.19-1.48, P < 0.001), under-fives (aOR = 2.02, 95% CI 1.74-2.40, P < 0.001), schoolchildren [aged 5-9 years (aOR = 3.23, 95% CI 1.19-1.48, P < 0.001) and 10-14 years (aOR = 3.53, 95% CI 3.03-4.11, P < 0.001)], and non-bednet users (aOR = 1.49, 95% CI 1.29-1.72, P < 0.001). Individuals from households with low SES (aOR = 1.40, 95% CI 1.16-1.69, P < 0.001), or living in houses with open windows (aOR = 1.24, 95% CI 1.06-1.45, P < 0.001) and/or holes on the walls (aOR = 1.43, 95% CI 1.14-1.81, P < 0.001) also had higher odds.

Conclusions: Malaria prevalence varied widely across regions and villages, and the odds of infections were higher in males, schoolchildren, non-bednet users, and individuals with low SES or living in houses with open windows and/or holes on the walls. The identified vulnerable groups and hotspots should be targeted with specific interventions to reduce the disease burden and support the ongoing malaria elimination efforts in Tanzania.