Schistosomiasis control was impossible without effective
tools. Synthetic molluscicides developed in the 1950s spearheaded
community level control.
Snail eradication proved impossible but repeated
mollusciciding to manage natural snail populations could eliminate
transmission. Escalating costs, logistical complexity, its labour-intensive
nature and possible environmental effects caused some concern. The arrival of
safe, effective, single-dose drugs in the 1970s offered an apparently better
alternative but experience revealed the need for repeated treatments to
minimise reinfection in programmes relying on drugs alone. Combining
treatment with mollusciciding was more successful, but broke down if
mollusciciding was withdrawn to save money.
The provision of sanitation and safe water to prevent transmission is too
expensive in poor rural areas where schistosomiasis is endemic; rendering
ineffective public health education linked to primary health care. In the
tropics, moreover, children (the key group in maintaining transmission) will
always play in water. Large scale destruction of natural snail habitats
remains impossibly expensive (although proper design could render many new
man-made habitats unsuitable for snails). Neither biological control agents
nor plant molluscicides have proved satisfactory alternatives to synthetic
molluscicides. Biologists can develop effective strategies for using
synthetic molluscicides in different epidemiological situations if only,
like drugs, their price can be reduced.