Studies on schistosomiasis in Saudi Arabia.

During studies on schistosomiasis in Saudi Arabia, urine and stool samples from inhabitants of various areas (mostly rural) were examined, and 97 aquatic habitats in 46 localities were searched for snails. The results indicate the occurrence of both urinary and intestinal schistosomiasis in most parts of the country, with a patchy distribution and varying infection rates. The snail intermediate host of Schistosoma mansoni was found to be Biomphalaria arabica. For S. haematobium three species of snails, namely, Bulinus truncatus and B. beccarii in the west and B. reticulatus wrighti in the northeast, may transmit the infection; the susceptibility of the two former species has been confirmed in the laboratory. The limitation in the size of snail habitats--which consist of wells, small canals, cisterns, small swamps, interrupted streams, and ponds--creates a special type of transmission which can be defined as "oasis transmission," making control of the disease both simple and practical.