The effect of BCG-vaccine upon experimental visceral leishmaniasis in hamsters

Stimulation with Bacillus Calmette-Guerin (BCG) vaccine has been reported to enhance resistance of mice against Leishmania donovani infection. Such infection is usually lethal in hamsters, thus providing a more stringent animal model to assess the effect of BCG upon visceral leishmaniasis. Animals receive two IP injections (2-8 X 10(7) BCG) pre or post IC challenge with 4 X 10(6) amastigotes. Controls received BCG alone (with no infection) or were untreated (NT). Pretreated animals exhibited significantly fewer (P less than 0.05) hepatic or splenic amastigotes than NT animals at days 7, 14, and 28 post challenge, but most BCG treated hamsters died earlier than NT. Post treated hamsters showed no significant reduction in parasite burdens, or in median time to death as compared to NT group. Hamsters which received BCG but were not infected appeared healthy during the study. The reason for increased susceptibility of BCG-treated hamsters to disease is not clear, but observed pathologic complications of L. donovani infected hamsters appear to be exacerbated by BCG stimulation.