Community data on the prevalence of helminth infections is important for guiding health policy, but expensive to collect. As a result most surveys focus on school-aged children, frequently using schools as a sentinel population. Since there already exists a vast amount of data on infection levels in school-aged children, but limited community-based data, we undertook a literature search on age-stratified infection data for intestinal nematode infections and schistosomiasis in Africa, to investigate whether estimates of the prevalence of infection in school-aged children could provide an index for determining community prevalence. The observed data on prevalence of infection in infants, school-aged children and adults were fitted using linear and logistic regression models which take into account variation in sample prevalences. Despite the wide variation in study sites, the observed relationship between community prevalence and school-aged prevalence was remarkably consistent for each parasite species. The prevalence of infection in school-aged children alone was shown to be higher than the predicted prevalence in the community, but the degree of overestimation was dependent on the parasite species and the level of infection. The results suggest that the prevalence of infection in school-aged children could provide a cost-effective predictive tool which can be used at a district/national level to identify target areas for control and to evaluate the numbers at risk of infection.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0031182098003862

Can prevalence of infection in school-aged children be used as an index for assessing community prevalence?

A total of 1535 persons of different age, sex and occupation from 5 villages (Tanan, El-Sad, Sandiun, Kalama and Taha-nob) in Qalyoubia Governorate in Nile Delta were subjected to clinical, stool, urine and intradermal tests accompanied by a questionnaire for 500 of them Snail vectors of Schistosome parasites were collected from 2 villages (El-Sad and Taha-nob) and snail densities in the waterways as well as the prevalence rate of infection with schistosomal cercariae were recorded The results revealed that the average prevalence rate of Schistosoma haematobium in the 5 cillages was 49% (range 23% - 71%) and that of S mansoni was 133% (range 114-144%) The overall prevalence of both types was 182% (range 137-214%) The average density of Biomphalaria alexandrina in the 2 village was 1647% and that of Bulinus truncatus was 75%, the ratio was 2:1 The infectivity with schistosomal cercariae was very low with an average of 25% in B Alexandrina and 15% in B truncatus Factors responsible for the decreased rates of schistosomiasis and snail infectivity were discussed

Abdalla Hf

Papers

Prevalence of Schistosomiasis and dynamics of its distribution in some villages in Qalyoubia Governorate.