Dataset Information

Current status of Schistosoma mansoni infection among previously treated rural communities in the Abbey and Didessa Valleys, Western Ethiopia: Implications for sustainable control.

ABSTRACT:

Background

Schistosoma constitutes a major public health problem and developmental challenges in the majority of developing and subtropical regions. The World Health Organization has set guidelines for the control and elimination of schistosomiasis. Ethiopia is providing school-based Mass Drug Administration (MDA) at the study areas of the Abbey and Didessa Valleys of western Ethiopian since 2015. Moreover, mass treatment was already done in the same villages 30 years ago. However, the current Schistosoma mansoni infection status among humans and snails in the study areas is not known. Hence, the present study aims to determine the current status.

Methods

A community-based cross-sectional study was conducted in the three communities; Chessega, Agallu Metti and Shimala in Schistosoma mansoni endemic areas of the Abbey and Didessa valleys in Western Ethiopia. Using the list of households obtained from the Kebele administration, a systematic sampling technique was used to select households in each village.

Results

Even though the area is under the Ethiopian national Mass Drug Administration campaign, the present study reports prevalence above 50%. Although the majority of the infections were moderate, we found that 13% had heavy infection, above 400 eggs per gram of stool, which is at the same level as before the treatment campaign 30 years ago. The infection was significantly higher among those below 12 years of age, among non-attending school-age children and daily laborers.

Conclusion

Schistosoma mansoni infection is still a public health problem in the study areas, despite control efforts already 30 years ago and present mass treatment in the last years. We suggest making the mass treatment campaign just early after the rainy season, when the snails are washed away. This should be supplemented with provisions of clean water, sanitation, and hygiene (WASH) and reduction of water contact and possible snail control efforts' to prevent reinfection.

SUBMITTER: Assefa A

PROVIDER: S-EPMC7906404 | biostudies-literature | 2021

REPOSITORIES: biostudies-literature

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Publications

Current status of Schistosoma mansoni infection among previously treated rural communities in the Abbey and Didessa Valleys, Western Ethiopia: Implications for sustainable control.

Assefa Alemayehu A Erko Berhanu B Gundersen Svein Gunnar SG Medhin Girmay G Berhe Nega N

PloS one 20210225 2

<h4>Background</h4>Schistosoma constitutes a major public health problem and developmental challenges in the majority of developing and subtropical regions. The World Health Organization has set guidelines for the control and elimination of schistosomiasis. Ethiopia is providing school-based Mass Drug Administration (MDA) at the study areas of the Abbey and Didessa Valleys of western Ethiopian since 2015. Moreover, mass treatment was already done in the same villages 30 years ago. However, the c ...[more]

PMID: 33630891

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Project description:BackgroundPreventive chemotherapy with praziquantel is the cornerstone of schistosomiasis control. However, in some social-ecological settings, the prevalence and/or intensity of Schistosoma infection does not lower meaningfully despite multiple rounds of preventive chemotherapy, a phenomenon termed persistent hotspot (PHS). We assessed the characteristics of PHS in a Schistosoma mansoni-endemic area of Côte d'Ivoire.MethodsIn October 2016, a cross-sectional survey was conducted in 14 schools in the western part of Côte d'Ivoire, one year after multiple rounds of preventive chemotherapy. In each school, 50 children aged 9-12 years provided two stool samples and one urine sample. Stool samples were subjected to triplicate Kato-Katz thick smears for S. mansoni diagnosis. Urine samples were examined by a filtration method for S. haematobium eggs. PHS was defined as failure to achieve a reduction in the prevalence of S. mansoni infection of at least 35% and/or a reduction of infection intensity of at least 50%. Six schools underwent more detailed investigations, including a questionnaire survey for demographic characteristics and a malacological survey.ResultsIn the six schools subjected to detailed investigations, the overall prevalence of S. mansoni and S. haematobium was 9.5% and 2.6%, respectively. Four schools were classified as PHS. The S. mansoni prevalence in the four PHS was 10.9% compared to 6.6% in the remaining two schools. The S. mansoni infection intensity, expressed as arithmetic mean eggs per gram of stool (EPG) among infected children, was 123.8 EPG in PHS and 18.7 EPG in the other two schools. Children bathing in open freshwater bodies were at higher odds of S. mansoni infection (odds ratio: 4.5, 95% confidence interval: 1.6-12.6). A total of 76 human-water contact sites (53 in PHS and 23 in the other schools) were examined and 688 snails were collected, including potential intermediate host snails of Schistosoma (Biomphalaria pfeifferi, Bulinus forskalii, Bu. globosus and Bu. truncatus).ConclusionChildren in PHS schools bathed more frequently in open freshwater bodies, and hence, they are more exposed to Schistosoma transmission. Our findings call for an integrated control approach, complementing preventive chemotherapy with other interventions, particularly in PHS settings.

Project description:BackgroundSchistosoma mansoni, causing intestinal schistosomiasis, is widely distributed in Ethiopia and new transmission foci are continually reported. Here we report new transmission sites and prevalence of S.mansoni infection among school children in Yachi areas, southwestern Ethiopia.MethodsA cross-sectional survey was conducted among school children of Yachi Yisa and Yachi Efo elementary schools, southwestern Ethiopia, from April 2017 to June 2017. Three hundred seventeen school children aged six to 15 years were randomly selected to provide stool specimens for helminth infection examination by Kato-Katz and formol-ether concentration techniques. Snail survey was carried out to assess schistosome infection in Biomphalaria pfeifferi. Laboratory bred mice were also exposed to schistosome cercariae shed by B. pfeifferi en masse for definite identification of Schistosoma species.ResultsFrom the 317 stool specimens examined using double Kato-Katz thick smear and single formol-ether concentration techniques, 224 (70.7%) were found positive for at least one intestinal helminth species. The most prevalent parasite was S. mansoni (42.9%) followed by Trichuris trichiura (34.1%) and Ascaris lumbricoides (14.2%). The prevalence of S. mansoni infection was significantly higher among the children attending Yachi Yisa School (49.4%) than those in Yachi Efo School (35.6%) (P?=?0.002). The study also revealed that there was a significantly higher prevalence of S.mansoni infection among males (51.2%) than females (33.1%) (P?<?0.001). However, the prevalence of S.mansoni infection was not significantly associated with age categories (P?=?0.839). B. pfeifferi snails infected with schistosomes were collected from the water bodies found in the study area. After six weeks post exposure, adult S. mansoni worms were harvested from the mesenteric veins of laboratory bred mice.ConclusionsThe study revealed establishment of new S. mansoni transmission foci and moderate prevalence of schistosomiasis in Yachi areas. Hence, treatment of all school-age children once every two years is recommended. Snail control and non-specific control approaches including provision of clean water supply and health education should also complement mass drug administration of praziquantel.

Project description:BackgroundSocioeconomic inequality including wealth distribution is a barrier to implementation of health policies. Wealth distribution can be measured effectively using household data on durable assets. Compared to other methods of analysing Socio-economic Status (SES) using durable assets, Multiple Correspondence Analysis (MCA) can create more reliable wealth quintiles. We therefore evaluated socioeconomic determinants of Schistosoma mansoni using MCA on household data among adult population in western Kenya. The hypothesis of this study was that MCA would be a useful predictor of S. mansoni prevalence and/or intensity.MethodologyTwelve villages, 6 villages that had showed the greatest decrease in S. mansoni prevalence (Responder villages) and 6 villages that showed relatively lower decrease (Hotspot villages) between the year 2011 and 2015 were randomly selected for this study. This was according to a previous Schistosomiasis Consortium for Operational Research and Elimination (SCORE) report from western Kenya. From each village, convenience sampling was used to identify 50 adults from 50 households for inclusion in this study. An interview with a questionnaire based upon MCA indicators was conducted. One stool sample from each of the 600 adults was examined based on four slides for S. mansoni eggs using Kato Katz technique. Mean Eggs per gram(EPG) was calculated by taking the average of the readings from the four slides. A log binomial regression model was used to identify the influence of the various age-groups(<30 years, 30-60 years and >60 years), household size, wealth class, occupation, education status, main water supply, sex and sub-county of residence on S. mansoni infection. EPG was then compared across variables that were significant based on multivariate log binomial model analysis using a mixed model.Principal findingsOverall prevalence of S. mansoni was 41.3%. Significantly higher prevalence of S. mansoni were associated with males, those aged below 30 years, those who use unsafe water sources (unprotected wells, lakes and rivers), residents of Rachuonyo North, Hotspot villages and those earning livelihood from fishing. Only sex and household size were significant predictors in the multivariate model. Males were associated with significantly higher prevalence compared to the females (aPR = 1.37; 95% CI = 1.14-1.66). In addition, households with at least four persons had higher prevalence compared to those with less than four (aPR = 1.29; 95% CI = 1.03-1.61). However, there was no difference in prevalence between the wealth classes(broadly divided into poor and less poor categories). Intensity of infection (Mean EPG)was also significantly higher among males, younger age group, Rachuonyo North residents and Hotspot Villages.ConclusionSocioeconomic status based on an MCA model was not a contributing factor to S. mansoni prevalence and/or intensity possibly because the study populations were not sufficiently dissimilar. The use of convenience sampling to identify participants could also have contributed to the lack of significant findings.

Project description:BackgroundSchistosoma mansoni is a parasite of major public health importance in developing countries, where it causes a neglected tropical disease known as intestinal schistosomiasis. However, the distribution of the parasite within many endemic regions is currently unknown, which hinders effective control. The purpose of this study was to characterize the prevalence and intensity of infection of S. mansoni in a remote area of western Tanzania.Methodology/principal findingsStool samples were collected from 192 children and 147 adults residing in Gombe National Park and four nearby villages. Children were actively sampled in local schools, and adults were sampled passively by voluntary presentation at the local health clinics. The two datasets were therefore analysed separately. Faecal worm egg count (FWEC) data were analysed using negative binomial and zero-inflated negative binomial (ZINB) models with explanatory variables of site, sex, and age. The ZINB models indicated that a substantial proportion of the observed zero FWEC reflected a failure to detect eggs in truly infected individuals, meaning that the estimated true prevalence was much higher than the apparent prevalence as calculated based on the simple proportion of non-zero FWEC. For the passively sampled data from adults, the data were consistent with close to 100% true prevalence of infection. Both the prevalence and intensity of infection differed significantly between sites, but there were no significant associations with sex or age.Conclusions/significanceOverall, our data suggest a more widespread distribution of S. mansoni in this part of Tanzania than was previously thought. The apparent prevalence estimates substantially under-estimated the true prevalence as determined by the ZINB models, and the two types of sampling strategies also resulted in differing conclusions regarding prevalence of infection. We therefore recommend that future surveillance programmes designed to assess risk factors should use active sampling whenever possible, in order to avoid the self-selection bias associated with passive sampling.

Dataset Information

Current status of Schistosoma mansoni infection among previously treated rural communities in the Abbey and Didessa Valleys, Western Ethiopia: Implications for sustainable control.

Background

Methods

Results

Conclusion

Publications

Current status of Schistosoma mansoni infection among previously treated rural communities in the Abbey and Didessa Valleys, Western Ethiopia: Implications for sustainable control.

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