A rat model for combined Trypanosoma cruzi and Pneumocystis carinii infection

Dexamethasone treated rats inoculated with Trypanosoma cruzi developed acut e parasitemia. In addition, these animals concomitantly developed severe Pn eumocystis carinii pneumonia (PCP) and died after 4 weeks of immunosuppress ion (100%). However, immunocompetent (untreated) rats inoculated with T. cr uzi did not acquire P. carinii and recovered from T. cruzi infection. Rats immunosuppressed, but not inoculated with T. cruzi, developed only PCP and died 5-6 weeks later (93%). In contrast, immunocompetent or immunocompromiz ed IRC mice infected with T. cruzi all died of acute parasitemia in only 8- 12 days with no detectable PCP infection. In conclusion, rats immunosuppres sed and T. cruzi inoculated can serve as a MOPPS model for a single drug ev aluation. In addition, T. cruzi infection independently does not provoke P. carinii pneumonia in this model. Finally, patients with Chagas' disease tr eated with corticosteroids may be at risk for PCP and should be considered for chemoprophylaxis. (C) 2000 Academic Press.