Prevention of snail miracidia interactions using Phytolacca dodecandra (L'Herit) (endod) as a miracidiacide: an alternative approach to the focal control of schistosomiasis.

The effect of endod berry extract against schistosome miracidia has been tested to determine the sensitivity of these organisms to the molluscicide and to see whether miracidia subjected to sublethal doses of the toxicant will be able to infect their specific host snails. Short contact (30 min) LC50 of endod extract with miracidia of Schistosoma mansoni was 8.2 parts per million (p.p.m.) (95% CL 5-13). However, exposure of S. haematobium to sublethal doses of 3 p.p.m. for 30 min or overnight in open air ponds reduced their infectivity 3.5-5.6-fold when compared with controls. It is suggested that the toxicant could be used in low doses at transmission foci to reduce schistosome infection in snails. This could be done by using a controlled release system to apply the toxicant material at such foci where transmission is likely to occur.