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. Author summary: Intestinal worm infections—formally known as soil-transmitted helminth (STH) infections—are a public health problem that can potentially reduce physical growth, cause anemia, and hinder cognitive development. In Uganda, baseline surveys conducted between 1998 and 2005 indicated that STH infection prevalence was over 50% among school-aged children in most surveyed districts. As a result of these findings, in the early 2000s, the Ugandan Ministry of Health began twice-a-year national deworming campaigns and health education among preschool- and school-aged children. In March and May of 2022, we conducted follow-up surveys in five districts to determine how well the deworming campaigns have reduced infection prevalence in these communities. Among surveyed groups (preschool-aged children, school-aged children, and women of reproductive age), we found that in three of the five surveyed districts, STH prevalence had substantially decreased. In these areas, the national deworming program may consider reducing the frequency of the deworming campaigns from its current twice-a-year schedule. The prevalence remained high in the remaining two districts despite several years of deworming. Further investigation is needed to determine why. [ABSTRACT FROM AUTHOR]