Successful control of schistosomiasis in large sugar irrigation estates of Zimbabwe

To assess the impact of schistosomiasis control activities in Hippo Valley Sugar Estates.

A situation analysis of schistosomiasis control activities in Hippo Valley Estates was made. Snail and parasitology data collected over 13 and 21 years respectively was analysed to determine the impact of control activities.

Only data collected in Hippo Valley Sugar Estates was analysed.

Reduction in prevalence of schistosomiasis and snail population densities.

Prevalence of Schistosoma haematobium reduced from over 50% in 1980 to below 10% in 2000. Similarly, prevalence of S. mansoni reduced from 25% in 1980 to below 10% in 2000. Over the years, prevalences for both S. haematobium and S. mansoni fluctuated but showed a general decline. Snail numbers in water bodies within the estates fluctuated over the years, dropping from over 100,000 snails in 1986 to about 10,000 snails in 1998. The amount of niclosamid used to control snails varied over the years with less than 10 kg per year being used between 1995 and 1998. A marked improvement in safe water and sanitation facilities was noted.

The significant reduction in prevalence and snail numbers suggests that the Hippo Valley Estates control programme has been successful. The success is attributed to chemotherapy and snail control supported by general improvement in safe water and sanitation facilities and health education.