Natural progression of Oesophagostomum bifurcum pathology and infection in a rural community of northern Ghana.

An estimated 250,000 people in northern Ghana and Togo are infected with the intestinal helminth parasite Oesophagostomum bifurcum, as detected by stool cultures. Clinical disease caused by O. bifurcum is responsible for about 50 cases per year at the region's central hospital, and presents as painful abdominal masses: inflammatory colonic nodules containing live juvenile stages of the helminth. In individuals living in villages highly endemic with O. bifurcum infection, colonic pathology visible by ultrasound is also highly prevalent. These nodules also contain O. bifurcum juvenile worms but are apparently asymptomatic. Thus, O. bifurcum infection and asymptomatic colonic pathology are highly prevalent within this area, but clinical disease is relatively uncommon. The natural evolution and regression of the colonic pathology in an endemic community in northern Ghana and its distribution within the population is described. Of the 299 individuals in the study group, 28% had colonic pathology at recruitment in the late-rainy season, which decreased with a half-life of 3-4 months during the dry season. Of those negative at recruitment, 28% developed nodules during the year, the majority appearing at the end of the subsequent rainy season. Children tended to have a higher prevalence and intensity of ultrasound-visible pathology compared to adults. Almost half (49%) of the study group had colonic nodules at least once during the year, and 2% of these individuals presented with clinical disease to the local hospital during the mid-rainy season.