Studies of the relationships between Schistosoma and their intermediate hosts. II. The genus Bulinus and Schistosoma haematobium from Sudan, Zaire and Zambia.

The relationship between Schistosoma haematobium from Sudan, Zaire and Zambia and various species and strains of Bulinus, has been investigated. The main emphasis was placed on evaluating the total cercarial production per 100 exposed snails as an index of the compatibility between snail and schistosome. The observations confirmed the results of previous compatibility studies which showed that there were two groups of S. haematobium, truncatus-borne from Sudan and Zaire, and africanus-borne, from Zambia. They also revealed that this division was not absolute, as some overlapping occurred. However, if the cercarial production was taken as an indication of compatibility, instead of the infection rate, there was a more definite division between the two groups. The observation that there is a truncatus-borne strain of S. haematobium present in Zaire extends the area where there is a mixture of truncatus- and africanus-borne strains farther southwards.