[Show abstract][Hide abstract] ABSTRACT: This thesis describes aspects of the epidemiology and attempts to control infection and pathology due to the nematode parasite Oesophagostomum bifurcum . In northern Ghana and Togo O. bifurcum is an important parasite of humans; elsewhere it is predominantly seen as a parasite of non-human primates. It is shown that frequency and severity of colonic pathology, measured by ultrasound, is associated with the intensity of infection as measured with coproculture. Females are more infected than males but convincing explanations for the gender-dependent difference of infection rates are not found. Details of the route of transmission remain obscure. Mass treatment with Albendazole resulted in a very important reduction of both prevalence and morbidity of infection. Elimination of human oesophagostomiasis is within reach. The impact on hookworms, also effectively killed by the drug, is considerably smaller. Interruption of Albendazole treatment results of rapidly increasing infection rates in hookworm but not in Oesophagostomum. Integration of control activities in the filariasis elimination programme is likely to result in elimination of human oesophagostomiasis but not of human hookworm infection.