A Common Infection of Man Ln Northern Togo and Ghana

Infection with Oesophagostomum sp. is normally considered a rare zoonosis and up to this time its diagnosis has been based on the demonstration of larvae and young adults in the typical nodules formed in the intestinal wall. Only in Dapaong, in North Togo, and Bawku, North Ghana, have larger series of clinical cases been described. In the rural areas around these towns, a survey was made in which stool samples were collected and cultured. Third-stage larvae of Oesophagostomum sp. could be found after 5-7 days of incubation at room temperature, and the prevalence of infection with this parasite was often high but varied from one village to another. It was over 30% in seven villages out of the 15 villages surveyed. Anthelmintic treatment resulted in the evacuation of adult males and females of O. bifurcum. It is concluded that O. bifurcum is a locally common parasite of humans, not requiring an animal reservoir for completion of its lifecycle. Oesophagostomiasis, a locally common infection 15 Introduction and history In 1911, four years before his famous articles on schistosomiasis in Egypt appeared, Leiper wrote a short article which started as follows "Andrew Foy, of West African medical staff, was good enough whilst on home leave to present to the London School of Tropical Medicine a tube containing a considerable number of species of Necator americanus, passed by a patient at Ibi, Northern Nigeria. In the course of routine examination of individual specimens, I have been able to single out six examples of Oesophagostomum apiostomum " [1]. And further: "The specimens resemble N. americanus very closely and would probably have been overlooked had they not been scrutinized with a hand lense". The first report on oesophagostomiasis in humans dates from 1905 when Railliet and Henry described the parasites obtained by Brumpt from tumors of caecum and colon of "a native on the river Omo" in Southern Ethiopia [2] A very careful description of the macroscopical and microscopical pathology was given in 1910 by Wolferstan Thomas on material from a similar case observed during the Amazon expedition of 1905-1909 [3]. The adult worms described by Leiper were not only the first adult oesophagostomes described in humans, they were almost the last ones as well. On 3 April 1913 Dr. W.B. Johnson, Medical Officer in Zunguru, Nigeria, and a colleague of Dr. Foy, sent a report to London on the "Entozoal Infection Amongst Prisoners" : upon stool examination of 200 prisoners eight appeared to be infected with oesophagostomes [4]. Johnson administered thymol and eucalyptus to his patients to remove hookworms; apparently, he found oesophagostomes as well. Thereafter, in 1920, Henry and Joyeux briefly mention that in 1910 or 1911 they once found adult specimens of Oesophagostomum brumpti in a stool specimen obtained after anthelminthic treatment for hookworm infection in French Guinea [5]. No other reports of adult worms in man could be found. Immature worms, on the other hand, have been found in humans from time to time and have been attributed to a variety of species (O. brumpti, O. stephanostomum var thomasi, O. apiostomum, O. aculeatum and O. bifurcum). The immature worms are found in nodules and tumours in surgical material from clinical cases. In total some 15 original and reliable publications on human infections are known to us. Clearly, these cases are also fairly rare and by most authors humans are believed to be an abnormal host. Elmes and McAdam, for instance, in 1954 and Chabaud and Larivière in 1958 stress the point: young adult worms which should have entered the intestinal lumen were still found in the