The best therapeutic approach to acute schistosomiasis (Katayama fever) is still 
unsettled. In this paper we report a synergistic effect between schistosomicides 
and steroids in the treatment of the early stages of Schistosoma mansoni 
infection in the mouse. CBA mice infected with 150 S. mansoni cercariae were 
treated with oxamniquine or praziquantel and dexamethasone or prednisolone. The 
rate of parasite egg excretion by treated mice and appropriate controls was 
monitored, and the mice were perfused 43 d after infection for estimation of 
worm burdens and tissue egg densities. Mice treated with schistosomicides alone 
or with schistosomicides plus steroids had worm burdens of similar size. 
Significant reductions in egg counts were, however, recorded in faeces, and in 
the intestines and livers (with consequent reduction in liver pathology), of 
mice treated with schistosomicide and steroid, when compared to mice treated 
with schistosomicide alone or steroid alone. The apparent inhibition of 
fecundity of S. mansoni by combining these drugs has clear implications for 
treatment of the Katayama syndrome.