| Seungman Cha | 5 Articles |
Schistosomiasis remains one of the most prevalent neglected tropical diseases in Tanzania. World Vision Tanzania, in collaboration with the Ministry of Health through the National Neglected Tropical Diseases Control Programme, implemented school- and community-based mass drug administrations, community-led total sanitation, and community voice and action from 2020 to 2022. This study assessed changes in the prevalence of schistosomiasis in the Itilima district of northwestern Tanzania following the implementation of these integrated interventions. A total of 1,405 students from 22 schools participated in the baseline survey in August to September 2020, and 1,320 in September 2022. Additionally, 368 adults from 8 villages participated in the baseline survey, and 401 in the endline survey. The prevalence difference was calculated to assess changes before and after the integrated interventions. We also investigated risk factors for Schistosoma haematobium infection using endline data. The prevalence difference between 2020 and 2022 was -20.0% (95% confidence interval (CI)=-22.2%–-17.7%, p<0.001) for students and -19.6% (95% CI=-22.2%–-17.7%, p<0.001) for adults. Individuals without a latrine were more likely to have schistosomiasis (adjusted odds ratio=5.9, 95% CI=1.7–21.5, p=0.01) compared to those who had a latrine. The findings indicate substantial changes in schistosomiasis prevalence in the study area following the implementation of integrated interventions. To sustain these achievements in Itilima, a multi-sectorial approach is highly recommended to integrate additional measures for eliminating schistosomiasis as a public health problem.
In several schistosomiasis-endemic countries, the prevalence has remained high in some areas owing to reinfection despite repeated mass drug administration (MDA) interventions; these areas are referred to as persistent hot spots. Identifying hotspots is critical for interrupting transmission. This study aimed to determine an effective means of identifying persistent hot spots. First, we investigated the differences between Schistosoma haematobium and Schistosoma mansoni prevalence among school-aged children (SAC) estimated by a community-based survey, for which local key informants purposively selected communities, and a randomly sampled school-based survey. A total of 6,225 individuals residing in 60 villages in 8 districts of North Kordofan, Blue Nile, or Sennar States, Sudan participated in a community-based survey in March 2018. Additionally, the data of 3,959 students attending 71 schools in the same 8 districts were extracted from a nationwide school-based survey conducted in January 2017. The community-based survey identified 3 districts wherein the prevalence of S. haematobium or S. mansoni infection among SAC was significantly higher than that determined by the randomly sampled school survey (e.g., S. haematobium in the Sennar district: 10.8% vs. 1.1%, P<0.001). At the state level, the prevalence of schistosomiasis among SAC, as determined by the community-based survey, was consistently significantly higher than that determined by the school-based survey. Purposeful selection of villages or schools based on a history of MDA, latrine coverage, open defecation, and the prevalence of bloody urine improved the ability for identifying persistent hot spots.
Global efforts to identify groups at high risk for schistosomiasis have mainly concentrated on identifying their geographical distribution. Investigations on the socioeconomic characteristics of high-risk groups are relatively scarce. This study aimed to explore the associations between schistosomiasis among students and their parents’ occupations. A nationwide cross-sectional survey was conducted targeting 105,167 students in 1,772 primary schools across Sudan in 2017. From these students, 100,726 urine and 96,634 stool samples were collected to test for Schistosoma haematobium and S. mansoni infection. A multi-level mixed effect analysis was used with age and sex as fixed factors, and school as a random factor. The odd ratios (ORs) of practicing open defecation among farmers’ children were almost 5 times higher than their counterparts whose parents were government officials (OR=4.97, 95% confidence intervals (CIs): 4.57-5.42, P<0.001). The ORs of contacting water bodies for watering livestock among farmers’ children were more than 4 times higher than those of children whose parents were government officials (OR=4.59, 95% CIs: 4.02-5.24, P<0.001). This study shows that schistosomiasis represents a disease of poverty and that farmers’ children constituted a high-risk group.
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We aimed to explore the population dynamics of snail in 3 sites of the White Nile in Sudan. More specifically, we aimed to investigate the annual patterns of snail populations that act as intermediate hosts of schistosomes and monthly snail infection rates and ecological characteristics presumably related to snail populations. We collected snails for 1 year monthly at 3 different shore sites in the vicinity of El Shajara along the White Nile river in Khartoum State, Sudan. In addition, we measured air and water temperatures, water turbidities, vegetation coverages, and water depths and current speeds. Most of the collected snails were Biomphalaria pfeifferi and Bulinus truncatus. The population densities of snails and their infection rates varied across survey sites. The collected snails liberated S. mansoni and S. haematobium cercariae as well as Amphistome and Echinostome cercariae. Infected snails were found during March-June. The ecological characteristics found to be associated with the absence of snails population were: high turbidity, deep water, low vegetation coverage (near absence of vegetation), high water temperature, and high current speed. To our knowledge, this is the first longitudinal study of the snail population and ecological characteristics in the main basin of the White Nile river.
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This study aimed to investigate whether mass drug administration (MDA) intervention has an equivalent effect on reducing the prevalence and intensity of Schistosoma haematobium infection regardless of the baseline values. A repeated cross-sectional survey was performed targeting students of 12 primary schools in Al Jabalain and El Salam districts of White Nile State, Sudan, at both 1 week before and 8 months after the MDA. Prior to the baseline survey, school-aged children in Al Jabalain had received MDA interventions twice in 4 years, while those in El Salam had not. The baseline prevalence was 9.1% in Al Jabalain and 35.2% in El Salam, which were reduced to 1.8% and 5.5% at 8 months after the MDA, respectively. The corresponding reduction rates were 80.3% and 84.4%, not significant difference between both districts. However, changes in the geometric mean intensity (GMI) of egg counts were significantly different between both districts. The baseline GMIs were 14.5 eggs per 10 ml of urine (EP10) in Al Jabalain and 18.5 EP10 in El Salam, which were reduced to 7.1 and 11.2 EP10 after treatment, respectively. The corresponding reduction rates were 51.0% and 39.5%. In conclusion, MDA interventions were found to bring about similar relative reduction in prevalence regardless of the baseline value; however, the relative reduction in infection intensity was more salient in the district with a low baseline value for both prevalence and intensity. This clearly points to the importance of repeated MDA interventions in endemic areas, which will eventually contribute to schistosomiasis elimination.
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