INTERRELATIONSHIP OF AGE OF HOST, IMMUNITY AND PLASMODIUM-BERGHEI INFECTION

Wistar albino rats of age groups varying from 4-18 wk were infected with P. berghei. The course of parasitemia revealed significantly higher (P < 0.05) parasitaemia in younger rats as compared to older ones. Older rats showed an earlier decline of parasitemia as compared to younger rats. The young rats had significantly lower (P < 0.05) T cell counts than the adult rats. There was no significant difference in the B cell counts, hemagglutinin titers and demonstrability of precipitins. The inhibition of leukocyte migration did not differ in young and old rats. The high parasitemia in young rats seems to be due to relatively lower T cell counts and an inadequate T cell mediated protective immune response. The earlier decline of parasitemia in older animals might be due to early onset of protective immune response.