Observations on "lung shift" after chemotherapy in mice infected with Schistosoma mansoni.

It is known from work with Puerto Rican strains of Schistosoma mansoni that in experimental bilharziasis in laboratory animals there may be a shift of flukes from the mesenteric vessels to the lungs, and that this occurs both in untreated animals and in those given chemotherapy. The work reported in this paper was undertaken to study this phenomenon with an Egyptian strain of S. mansoni.With but one exception, no schistosomes were found in groups of untreated mice autopsied 6-12 weeks after infection. Some were found in the lungs of a few mice treated 6 weeks after infection and more in the lungs of those treated 10 weeks after infection.A shift of flukes to the lungs appears to be dependent upon a number of linked factors. In the study reported, the important factor was the effect of an active compound which resulted in a passive shift of flukes from their normal sites in the mesenteric vessels. Possible routes by which schistosomes may reach the lungs are discussed.