Observations on the morphology of adults and larval stages of Oesophagostomum sp. isolated from man in northern Togo and Ghana.

Infection with Oesophagostomum sp. appears to be extremely common in man in northern Togo and Ghana. Adult specimens were recovered from the intestinal lumen by treatment with pyrantel pamoate and the morphological characteristics of oesophagostomes of man could for the first time be compared with information available on the morphology of oesophagostomes of monkeys. The observations and measurements demonstrated that the species involved is Oesophagostomum bifurcum and that the eggs of this species cannot be differentiated from those of Necator americanus. Both infections occur simultaneously in the population involved. The L1 larvae, too, cannot be differentiated from hookworm L1 larvae. The L3 larvae, however, are characteristic. Diagnoses of human Oesophagostomum infections is based on the detection of these larvae in coprocultures. In the present paper, the eggs, the L1 and L3 larval stages and the adults, are carefully described and photos are given.