A laboratory technician was accidentally infected with the LE strain of Schistosoma mansoni cercariae maintained in our laboratories. After 5 months infection parasitological examination revealed 108 eggs/g faeces. Althrough treated with oxamniquine, the infection still persisted (6 eggs/g of faeces). An isolate (SSF) was obtained from that person and maintained in Biomphalaria glabrata - Swiss mouse by alternate passage. The experimental comparative results between the newly obtained SSF isolate and the original LE strain showed that the differences in pre-patent period, the mice infectivity level and the schistosomicidal response to hycanthone, oxamniquine and praziquantel was not statistically significant. On the other hand the number of miracidia recovered from intestines and livers of equally infected mice was twice as miich in the LE strain than in the SSF isolate. Furthermore, among the LE and SSF infected mice and the non infected control weight gains were different. While the LE infected mice lost weight since the beginning of the infection, the SSF ones initially gained and then lost weight. The conclusion is that only one passage into the human host did not substantially alter the studied strain characteristics.
Schistosoma mansoni; Strain Comparative experimental study