Some Aspects of Concomitant Infections of Plasmodia and Schistosomes. I. The Effect of Schistosoma Mansoni on the Course of Infection of Plasmodium Berghei in the Field Vole (Microtus Guentheri)

Abstract

Summary The development of S. mansoni from a strain derived from the Yemen (Arabia) has been followed in experimental infection in the field vole (M. guentheri). In this animal all the stages of schistosomal infection were noted and the histopathology of the liver in early and long standing infections observed. The course of infection of Plasmodium berghei was studied in 46 M. guentheri. The mild parasitemias, the low mortality rate (21.7 per cent) and the absence of prolonged chronic infections were noted. The occurrence of spontaneous radical cures observed in earlier work has been confirmed. The course of P. berghei infection in M. guentheri in mixed infections with S. mansoni depends on the stage of the bilharzial infection and probably on the cellular reaction of the host. P. berghei infections which preceded shortly, or followed 1 to 2 weeks after, exposure to S. mansoni showed a high proportion of infections with a chronic course. In a group of voles infected with P. berghei 4 to 7 weeks after S. mansoni, the plasmodial infection was distinguished by its mild course, low parasitemia, no deaths from malaria and absence of parasites from the peripheral blood ab initio in 38.2 per cent. A generalized liver cirrhosis at an early stage of bilharzial infection was observed in one M. guentheri with mixed S. mansoni and P. berghei infections.