Katayama fever or acute schistosomiasis probably occurs more commonly than is 
recorded. Interviews with a 3-man scuba diving team who had had contact with a 
large dam in an endemic area of the eastern Transvaal Lowveld at the same time 
and contact area on the same day during late summer of 1986 are discussed. Two, 
who had not previously been exposed to infected water, presented with Katayama 
fever, due to Schistosoma mansoni infection, 21 days after contact and it took 
30-36 months for them to recover fully after several treatments. The third 
patient, a keen water-sportsman and resident in the endemic area for a period of 
10 years, presented with a mild infection, probably due to acquired immunity 
initiated during previous contacts with infected water; he took about a year to 
recover. The pathogenesis, clinical features, diagnosis and treatment of the 3 
cases are described in the light of recent observations made elsewhere on 
Katayama fever cases and the effects of chemotherapy on the course of illness. 
The necessity of obtaining basic information on the travel and water-contact 
activities of patients in order to make a diagnosis is emphasised.