Exposure, infection and immune responses to Schistosoma haematobium in young children

M. E. J. WOOLHOUSE a1c1, F. MUTAPI a2, P. D. NDHLOVU a3, S. K. CHANDIWANA a3 and P. HAGAN a4
a1 Centre for Veterinary Tropical Medicine, University of Edinburgh, Scotland
a2 Prince Leopold Institute of Tropical Medicine, Antwerp, Belgium
a3 Blair Research Laboratory, Harare, Zimbabwe
a4 Division of Infection and Immunity, Institute of Biomedical and Life Sciences, University of Glasgow, Scotland


Behavioural, parasitological and immunological data were obtained from 48 children up to 6 years old, resident in a Schistosoma haematobium endemic area in Zimbabwe. The children averaged more than 1 contact with infective water bodies every 3 days and all showed immunological evidence of exposure (an anti-cercarial and/or anti-egg antibody response). IgM was the dominant isotype and appeared in the youngest children, followed by IgA, IgE and IgG3. However, only 38 children showed evidence of infection (an anti-egg response or eggs in urine) and only 14 were excreting eggs. The best estimates from these data are that less than 1 in 100 contacts result in infection and less than 1 in 1000 result in egg output. This suggests that there may be substantial attrition of invading cercaria even in naïve individuals.

(Received May 8 1999)
(Revised July 1 1999)
(Accepted July 15 1999)

Key Words: antibody; cercaria; epidemiology; schistosomiasis; water contact; Zimbabwe.

c1 Corresponding author: Centre for Veterinary Tropical Medicine, University of Edinburgh, Easter Bush Veterinary Centre, Roslin, Midlothian EH25 9RG, Scotland. Tel/Fax: +0131 6506264. E-mail: