Different appearance of parasitized erythrocytes in blood between normal and toxoplasma-infected rats after infection of Plasmodium berghei.

When normal rats were infected with Plasmodium berghei (Pb), both IgG and IgM immunofluorescent antibody titers were found to rise in the 1st week with increase of parasitaemia. After reinoculation of P. berghei into Pb-immune rats, IgG titer was further increased remarkably, although no parasitaemia was observed.