Summary and Conclusions

On the basis of available data in the present study of P. berghei, the following general conclusions seem to be justified:

• 1.  Albino rats are the most satisfactory experimental hosts for high percentages of parasites in intact red cells. The presence of extracellular P. berghei continuously in white mice makes quantitative studies difficult.
• 2.  An inoculum of 60 million parasites per kilogram of body weight gives the most consistent incubation period and course of infection.
• 3.  Differences in age affect the course of P. berghei in white rats. Younger rats under 100 grams develop higher parasitemia rates, while older rats either die with lower parasitemia rates or control infection by acquiring immunity.
• 4.  P. berghei activates latent hemobartonellosis in white rats, causing intense infection with H. muris. The degree of polychromatophilia induced by H. muris results in higher rates of parasitemia with P. berghei, with a peak of 191 per cent being recorded.
• 5.  Infection with P. berghei in Haemobartonella-free rats reveals a shorter incubation period, a lower percentage of polychromatophilic erythrocytes, and the occurrence of death before acute anemia develops.