Strongyloides stercoralis infections in the muscles of mice: a model for investigating the systemic phase of strongyloidiasis.

The sequence of events following infection of mice with the intestinal nematode, Strongyloides stercoralis, has been observed. Most infective larvae passed to the muscles where they did not develop further. In mice given primary infections, larvae were found in muscles for the first 9 d or so, then disappeared spontaneously. This was associated with an inflammatory reaction, predominantly eosinophilic and histiocytic in nature, around dying larvae. In mice exposed to the worms previously, both inflammation and worm destruction were hastened indicating the acquisition of resistance. A number of immunological parameters were measured in both primary and challenge infections. Specific antibodies of the IgM and IgG classes appeared, a marked immediate hypersensitivity reaction to injected antigen developed, and a transient blood eosinophilia occurred. No effects on phytohemagglutinin-induced spleen cell transformation were discerned, nor was transformation induced by specific antigen. It is concluded that this system provides a potentially useful model for investigating the systemic phase of strongyloidiasis, particularly with respect to assessing anthelmintic efficacy and the functions of fractionated antigens.