• Citer

On two schistosomes of wild rodents of the Belgian Congo: Schistosoma rodhaini Brumpt, 1931; and Schistosoma mansoni var. Rodentorum Schwetz, 1953; and their relationship to S. mansoni of man

par Schwetz, Jacques
Référence Transactions of the Royal Society of Tropical Medicine and Hygiene, 48, 1, page (89-92,IN5-IN7,93-100)
Publication Publié, 1954-01

Article révisé par les pairs

• Détails
• Contenu

Résumé :

1. (1) Two schistosomes were discovered in wild rodents in the south-east of the Belgian Congo (Province of Katanga): S. rodhaini Brumpt, 1931; and S. mansoni var. rodentorum Schwetz, 1953. Both belong to the group of S. mansoni, by virtue of their anatomy as well as by the identity of their intermediate hosts (Planorbis). 2. (2) S. rodhaini differs from S. mansoni in the structure of its eggs and in its definitive host. Instead of a lateral spine, the eggs of S. rodhaini have a subterminal spine directed sideways, and a narrow appendix-like opposite extremity, turned in the opposite direction. S. rodhaini has as yet been found only in divers wild rodents, never in human beings. S. rodhaini foci were discovered in Elisabethville, Albertville and Sakania, and it is most likely that it exists elsewhere too. In Elisabethville and Sakania, the transmitters of S. rodhaini were the river Planorbis (P. pfeifferi), while in Albertville the transmission of S. rodhaini was effected by P. tanganikanus.Experimentally, other African (P. boissyi = P. alexandrina) and American (P. glabratus) planorbids were found to be able to transmit this schistosome. In Sakania, the only river present in this locality, was found to contain a mixed focus of S. rodhaini and S. mansoni. Mice infected with the local cercariae were found to pass eggs of S. rodhaini 30 days after their exposure to infection, and after the 50th day eggs of S. mansoni also. In Albertville, on the other hand, the foci of these two schistosomes are as a rule well distinct and separate. 3. (3) While searching for S. rodhaini in the wild rodents, we also found in these animals some very rare eggs with a lateral spine. We found these eggs associated with those of S. rodhaini in Sakania; and alone, in Albertville. Since this was an entirely new discovery, we devoted several months of research to it at the end of 1952, chiefly in Albertville, and, briefly, have arrived at the following conclusions We are dealing with an infection that is both rare and distinct. Out of 480 rodents coming from 15 rivers (rivers containing P. pfeifferi), we found only 18 infected specimens- i.e. an incidence of 4 per cent. As we have already pointed out, this is a very light and inconspicuous infection, usually signified by the finding of several broken or empty eggs in the liver. Only in very few cases did we discover living eggs, and as for the adult worms, they were also a rarity. Although these eggs, too, had a lateral spine, they appeared to us from the very first time we saw them, rather different from the normal eggs of S. mansoni-both in the form of the egg (elongated, with a narrow extremity), and in the form of the spine (a solid spine with a wide insertion, separated from the rest of the egg by a notch). 4. (4) In view of this particular structure and especially of the hitherto unknown definitive host, we have decided to call this schistosome-S. mansoni var. rodentorum. This new schistosome is of great practical interest, especially from the epidemiological and prophylactic viewpoint. Being adapted to definitive hosts which dwell in the same rivers that are frequented by the natives, the question arises whether this is not in reality the same parasite as S. mansoni, modified in its morphology and biology by its adaptation to different hosts-to the wild rodents first, and to human beings thereafter. © 1953.