Prevalence and intensity of soil-transmitted helminth infections in Uganda: Results from population-based prevalence surveys in five districts.

BACKGROUND: Soil-transmitted helminth (STH) infections are caused by roundworms (Ascaris lumbricoides), whipworms (Trichuris trichiura), and hookworms (Necator americanus and Ancylostoma duodenale). In Uganda, baseline surveys conducted during the late 1990s and early 2000s suggested STH infections were common, with prevalence >50% among surveyed schoolchildren. In 2003, a national program was launched with mass preventative chemotherapy (PC) and health education for children 1-14 years old. Little evidence is available to show the impact of national deworming. METHODS: We conducted population-based, cross-sectional household surveys in five districts (Buikwe, Kassanda, Kiryandongo, Kisoro, and Rubanda) in March and May 2022. Our primary objective was to estimate STH prevalence by species due to infections of any intensity and infections of moderate-to-heavy intensity among preschool-aged children (PSAC, 1-4 years old), school-aged children (SAC, 5-14 years old), and women of reproductive age (WRA, 15-49 years old). Laboratory technicians used duplicate Kato-Katz microscopy to determine fecal egg count. RESULTS: Overall, 3,352 PSAC; 3,884 SAC; and 1,226 WRA provided stool samples. The prevalence of any infection remained high in Kisoro at or above ~50% within all risk groups. In other districts, the prevalence of any infection ranged from approximately 5 to 16% among PSAC, 6 to 23% among SAC, and 12 to 19% among WRA. Moderate-to-heavy intensity infection prevalence was highest in Kisoro (~15-26%), followed by Rubanda (<5%), and was ≤1% in other districts. A. lumbricoides and T. trichiura infections were largely confined to Kisoro and Rubanda, whereas hookworm was most common in other districts. CONCLUSIONS: The STH prevalence has decreased markedly in three districts in Uganda. Based on our findings, the national deworming program should consider decreasing PC distribution frequency in these districts per the World Health Organization guidelines. Efforts are needed to understand why the Kisoro and Rubanda districts did not demonstrate similar gains.

Towards malaria microscopy at the point-of-contact: an assessment of the diagnostic performance of the Newton Nm1 microscope in Uganda.

Malaria microscopy in sub-Saharan Africa is often restricted by access to light microscopes. To address this gap, a novel portable inverted monocular microscope, the Newton Nm1, was designed and is now commercially available. Its diagnostic performance was assessed in a blinded-slide trial at ×1000 (oil) of Giemsa-stained thick blood films against a conventional microscope as undertaken by four Ugandan Ministry of Health technicians. With the Newton Nm1, diagnostic performance was: sensitivity 93.5% (95% confidence interval (CI) 78.6-99.2%), specificity 100.0% (95% CI 82.4-100.0%), positive predictive value 100.0% (95% CI 88.1-100.0%) and negative predictive value 90.5% (95% CI 69.6-98.8%). Discordance was due to a systematic error underestimating parasitaemia by ~45%; when counting Plasmodium parasites against 200 white blood cells, blood films with low parasitaemia (i.e. <100 µL(-1) of blood) could be overlooked and misclassified. By contrast, specificity was excellent with no false positives encountered. Whilst proven useful, especially in resource-poor environments, it is still unclear how we can ensure the uptake of the Newton Nm1 within sub-Saharan Africa.