The potential role of various species of intermediate hosts of Schistosoma haematobium in Saudi Arabia.

The potential role of 3 species of Bulinus in the transmission of Schistosoma haematobium in Saudi Arabia was assessed on the basis of their susceptibility to experimental infection, their geographical distribution and numbers, and the type of habitats in which they were found. B. truncatus, distributed mainly in the mid- and south-western regions, showed extremely low susceptibility to strains of S. haematobium from Yemen, Egypt and Sudan. The same species from one area in the north-west was refractory to a strain of the parasite from Yemen. In contrast, B. wrighti was very susceptible to infection but is found only in a few habitats far from human settlements, thus probably playing little part in the transmission of the disease. As B. beccarii is highly susceptible to the infection and is distributed widely, this snail is probably the main intermediate host of schistosomiasis in Saudi Arabia.