Can the freshwater crayfish eradicate schistosomiasis in Egypt and Africa?

Schistosomiasis is a chronic, parasitic disease, infecting more than 207 million people, mostly from Africa, with an estimated 700 million people at risk in 74 endemic countries. One of strategies to eradicate this disease is biocontrol of its vector snail. Lab experiments and field survey have been carried out to investigate the impact and the relationship between the exotic crayfish; Procambarus clarkii and Schistosoma vector snails in Egypt. In the Lab, several species of freshwater snails, fish and aquatic plants were reported to serve as food for the freshwater crayfish. In the field, a survey for the crayfish and freshwater snails has been conducted at several irrigation channels in Qalyobiya, Ismailia and Behera governorates, which had been previously surveyed during 1990s. The results of the experimental Lab indicated that the vector snails; Biomphalaria alexandrina, Bulinus truncatus and Limnaea natalensis were the preys of first choice for the crayfish. The fields surveys showed high reduction and sometimes complete disappearance of vector snails in irrigation channels, which have been invaded by Procambarus clarkii, while in water courses which do not harbor the crayfish, such as El Manayef drain and Fayed canal (West of Suez Canal), high densities of these vector snails were recorded.The present study is providing encouraging indication of the possible overcoming schistosomiasis and fascioliasis in Egypt and whole Africa by the freshwater crayfish Procombarus clarkii. New estimates of the Egyptian Ministry of Health indicated that the percent of infected people decreased significantly to only 4% comparing to 45% during 1960s. [Magdy T. Khalil & Setaita H. Sleem. Can the freshwater crayfish eradicate schistosomiasis in Egypt and Africa?. Journal of American Science 2011;7(7):457-462]. (ISSN: 1545-1003). http://www.americanscience.org.