Scanning electron microscope image of a Schistosoma flatworm, the parasite that causes schistosomiasis.
Biomphalaria snails play a key role in the transmission of intestinal schistosomiasis.
The disease is:
The Schistosoma parasite has a very interesting life cycle:
The snails have to be from the genus Biomphalaria and in East Africa B. choanomphala is particularly important. Their necessity for the parasite's life cycle means the distribution of the disease can be very accurately linked to the distribution of these snails.
In certain parts of East Africa, such as Lake Victoria, B. choanomphala snails are known to be the most effective host for the parasite. Habitats where these snails can be found often pose the highest risk for humans to contract the disease.
Due to the lack of facilities, people are often forced to wash clothes, bathe and collect cooking water directly from Lake Victoria. The gentle rocky shore of the lake, interspersed with aquatic plants, is a perfect B. choanomphala habitat and therefore these people are likely to be at very high risk of infection.
Current research, at the Natural History Museum and elsewhere, is looking in more detail at the distribution of B. choanomphala, and seeing whether we can use variables such as water chemistry and temperature to predict their distribution. If so, this will help us provide treatment and education about schistosomiasis to communities that appear to be most at risk.
Learn how thinking has changed since a failed attempt in the 1980s to control schistosomiasis by wiping out host snails, and potential ways the problem could be tackled while still maintaining mollusc diversity.