Schistosomiasis is a parasitic disease which affects more than 200 million people worldwide. Commonly known as ‘snail fever’, it is caused by blood flukes or trematode worms which are released by freshwater snails in tropical and sub-tropical areas. Schistosomiasis is present in 74 countries, but people living in poor communities without access to clean water and adequate sanitation are particularly at risk from these parasites. The play and hygiene habits of children make them especially susceptible and in some areas a large proportion of school-age children can become infected.
The parasites penetrate the skin and the larvae develop into adult schistosomes in the body. Here they can cause an immune reaction or damage to the organs. If the worms become trapped in the urinary system, they damage the bladder, urethra and kidneys. In the intestinal system, progressive enlargement of the liver and spleen can result, as well as damage to the intestines and hypertension. Though mortality is low, the health of those infected can be seriously impaired. In children, the parasites cause malnutrition and growth retardation, as well as short and long-term memory problems and difficulties with mental reasoning and comprehension.
In Cambodia, more than 80,000 residents living along the Mekong River are estimated to be at risk of schistosomiasis. In two remote provinces – Kratie and Stung Treng – the disease was particularly prevalent, with between 30 and 70 per cent of people infected during the 1990s. Now officials at the National Centre for Parasitology, Entomology and Malaria Control are pleased to report a drastic reduction in cases. Since 2002 the government has organised an extensive de-worming programme and in 2004 was the first to reach the World Health Organisation’s goal of covering three-quarters of school-aged children. In the two provinces where the parasite is most prevalent, patients are treated with the drug Praziquantel, which is usually effective with a single dose. Overall, the government’s programme over the last eight years has resulted in prevalence rates of schistosomiasis dropping to less than 5 per cent.
However, officials are still alert to the dangers, particularly in areas where villagers regularly go fishing, bathing or washing clothes in rivers, where they contract the disease from infested water. The parasite’s eggs enter the water through human urine or faeces. Less than a fifth of rural Cambodians have proper sanitation facilities and many people still use rivers as toilets. As well as controlling the number of snails and providing access to drug treatment, it is clear cases of this terrible disease can be reduced with basic improvements to sanitation and better health education.