Prevalence of intestinal helminth infection among school children in Maksegnit and Enfranz Towns, northwestern Ethiopia, with emphasis on Schistosoma mansoni infection.

BACKGROUND: Schistosomiasis is endemic in Ethiopia and previously unknown transmission foci have been reported from time to time in different parts of the country. Further surveys are required in areas where endemicity of the disease is not known to cover them with control program if transmission is taking place. This study, therefore, aims to assess the magnitude of schistosomiasis mansoni and soil-transmitted helminthiasis in Maksegnit and Enfranz Towns, northwestern Ethiopia.

METHODS: Cross-sectional parasitological and malacological surveys were conducted in three schools found in Maksegnit and Enfranz Towns. Stool specimens were collected from 550 randomly selected school children (age range 5 to 17 years) and processed for microscopic examination using Kato-Katz method (single smear per stool sample). Malacological survey was conducted in Gumara and Garno Rivers found in the study areas. Biomphalaria pfeifferi snails collected from the two rivers were individually exposed to artificial light in order to induce cercarial shedding. Laboratory-bred Swiss albino mice were exposed to the cercariae and definite identification of the schistosome species was made based on morphology.

RESULTS: The overall prevalence of S. mansoni infection was found to be 49%; however, it varied by schools, with Selam having 60.7%, and Maksegnit Number 1 and 2 having 45.8 and 39.6%, respectively. The respective mean intensity of S. mansoni infection among school children in Selam, Maksegnit Number 1 and Maksegnit Number 2 Schools were 243, 194 and 183 eggs per gram of stool (epg). In all the study areas there was no difference in prevalence of S. mansoni infection in relation to age, however, the prevalence varied by sex, with males having highest prevalence (54.5% vs 44.1%) (p = 0.012). Adult S. mansoni worms were harvested from mice exposed to cercariae shed from B. pfeifferi on the 6(th) week post-exposure. The prevalence of Ascaris lumbricoides single infection was 16.5% while its co-infection with S. mansoni was 18.2%.

CONCLUSION: Infections of young children, findings of schistosome infected snails, establishment of mice infection and harvesting adult worms from the lab-bred mice confirm that autochthonous transmission is taking place in the study areas. Hence, preventive chemotherapy with praziquantel should be put in place, complemented with other measures such as provision of sanitary facilities and health education, to control morbidity and transmission of schistosomiasis and soil-transmitted helminthiasis in the study areas.