Prevalence and drivers of malaria infections among asymptomatic individuals from selected communities in five regions of Mainland Tanzania with varying transmission intensities
Authors: Chacha Gervas A. , Francis Filbert , Mandai Salehe S. , Seth Misago D. , Madebe Rashid A. , Challe Daniel P. , Petro Daniel A. , Pereus Dativa , Moshi Ramadhani , Budodo Rule , Kisambale Angelina J. , Mbwambo Ruth B. , Bakari Catherine , Aaron Sijenunu , Mbwambo Daniel , Lazaro Samuel , Mandara Celine I. , Ishengoma Deus S. 
Published: June 2024

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.