Schistosomiasis is a parasitic disease which infects over 200 million people in 74 countries in the developing world.
Schistosomes are
small flukes which live in the bloodstream of infected people, mainly
children. Parasite eggs, passed in urine or faeces, hatch in contact with
water to release free-swimming larvae which actively seek out and penetrate a
particular kind of freshwater snail. After a period of multiplication
within the snail, the parasites emerge and infect humans or other mammalian
hosts by direct penetration through the skin. Many rural communities, which often lack adequate sanitation facilities and cleran water supplies, have daily contact with natural water bodies that harbour freshwater snails.
In order to understand differences in the distribution, transmission and symptoms of schistosomiasis, we need to be aware of the genetic variability of both the parasites and their snail hosts. Research workers have been using information encoded within the DNA to differentiate forms of the parasite recovered from many parts of Africa, and to assess the relationships between schistosomes from different parts of the world. In collaboration with a research team in Brazil, a new technique for genetic fingerprinting, known as randomly amplified polymorphic DNA (RAPD) analysis has been successfully applied to the identification of schistosomes. The technique shows great promise for the analysis of genetic variation in schistosomes and the snails responsible for transmission. New international research initiatives are now being focused on investigating the genetic make-up of this important parasite.
Illustrations
For further information contact:
Dr. David Rollinson,
The Natural History Museum,
Cromwell Road, London, SW7 5BD, UK
Tel: +44 (0) 171 938 8887 Fax: +44 (0) 171 938 9249
E-mail: David Rollinson dr@nhm.ac.uk
