Abstract:
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 6th 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.
Keywords: Schistosoma mansoni, Biomphalaria pfeifferi, Maksegnit, Enfranz, Transmission foci, Ethiopia
