Fight against killer-snails

Press, 26 October 1984, Page 18

Fight against killer-snails

A scientific breakthrough pointing towards the development of human resistance to bilharzia - the debilitating parasitic infection associated with agricultural development, affecting perhaps 250 million people in the poor countries — may well emerge as a focal point of global research co-ordi-nated by the United Nations, writes Thomas Land from Paris. The breakthrough was achieved at the University of Montreal and Institut Pasteur m Lille. It is based on the startling discovery that human blood platelets, which promote clotting and tissue healing at the site of a wound, can be induced to kill the bilharzia parasite. This is vital because |xistmg

medical remedies cure rather than prevent the disease. Moreover, the cures are too expensive for mass application around the hungry belt of the globe, where they are most needed. The parasites take up to 20 years to kill their victims. The carriers are fresh water snails that infest large parts of Africa, the Middle East, Central America, and Asia. Perhaps 600 million people are exposed to the disease worldwide; their number is increasing all the time with the expansion of irrigated agriculture, which encourages the snails. A global programme of research seeking economically attainable solutions has been launched b.v, the

World Health Organisation. It involves many universities and other research institutions in the bilhar-zia-affected countries, as well as Western Europe and North America. The work is co-ordinated on the W.H.O.’s behalf by Eygpt’s Theodore Bilhas Institute in Cairo. It is also in charge of a vast national anti-bilharzia programme aided by a $250 million donation which has just been announced by the United States. More than a quarter of Egypt’s entire population is infected by bilharzia. The high incidence is explained by the growth of the agricultural sector and the numerous desert reclamation projects,

dependent on irrigation. Once the parasite-bearing snails are established in an area, the disease becomes virtually impossible to eradicate. Pesticides released in the canals to kill the snails have proved both expensive and dangerous. The Cairo institute and its collaborators are therefore seeking alternative solutions. They have already identified three kinds of aquatic plant that thrive in the warm canal waters — and kill the snails. They are now looking for rival snails that might conquer the territory of the infested variety without falling Eto the parasite. Copyright — on Observer Service.