evaluation of mollusiciding in the control of bilharziasis and problems impeding complete control of the disease in iran

the effect of the mollusciciding of 364 different snail habitat with bayer 73 (bayluscide), undertaken during the period january 1968 to january 1973, for the control of urinary bilharziasis bas been evaluated in khuzestan, southwest iran. the criteria for assessment were as follows:1. complete kill was obtained when no live b.truncatus was found in monthly surveys for one entire year after mollusciciding; 2. failure occurred when all or more live snails were found by monthly surveys during one year. complete kill ranged from 53.7% in 1969 to 59.7% in 1968, and the difference in the percentage of complete kill observed in various years was not significant. the highest percentage of complete kill was achieved in ponds. the results obtained from this evaluation indicate that 1) there is no possibility of bulinus truncatus snails building up a resistance to the molluscicide used in this study; 2) by the increase in the number of snail habitats with running water in the endemic area of khuzestan, as the result of a huge program of extension of irrigation networks already underway, the destruction of the snail intermediate host will become increasingly difficult in the future.