How common was asymptomatic malaria among children surveyed in northern Uganda?

Details

Asymptomatic malaria infections are important parasite reservoirs that could sustain transmission in a population, but they often go unreported. Researchers conducted a community-based survey in a historically high-transmission setting in northern Uganda to investigate their prevalence and associated factors.

In a cross-sectional study, 288 children aged 2–15 years were enrolled and tested for malaria parasites using rapid diagnostic tests (RDTs) and blood smear microscopy between January and May 2022. Statistical analysis used the exact binomial and Fisher's exact tests, with p ≤ 0.05 indicating significance. Logistic regression was used to explore factors associated with asymptomatic infection.

Overall prevalence of asymptomatic infection was 34.7% (95% CI 29.2–40.5), with the highest prevalence observed among children aged 5–10 years: 45.9% (95% CI 35.0–57.0). Gweri village accounted for 39.1% (95% CI 27.6–51.6) of malaria infections. Median parasite density was 1,500 parasites/µl of blood. Plasmodium falciparum was the dominant species (86%), followed by Plasmodium malariae (5%).

Sleeping under a mosquito net was associated with asymptomatic infection (adjusted odds ratio [aOR] 0.27; 95% CI 0.13–0.56; p = 0.001), as was the presence of village health teams (VHTs) (aOR 0.02; 95% CI 0.01–0.45; p = 0.001). Compared with HRP2-only RDTs, P. falciparum/pLDH RDTs had higher sensitivity and specificity, respectively 90% (95% CI 86.5–93.5) and 95.2% (95% CI 92.8–97.7), p = 0.001.

The researchers concluded that asymptomatic infections were present in the study population and varied by place and person across age groups. P. falciparum was dominant, but P. malariae and Plasmodium ovale were also observed, which may have implications for choosing and deploying diagnostic tools. People who slept under a mosquito net or had functional VHTs present were less likely to have asymptomatic malaria infection. P.f/pLDH RDTs performed better than routinely used HRP2 RDTs. The researchers recommended investigating and reporting asymptomatic malaria reservoirs through community surveys to estimate disease burden accurately and better target control.