Age-related susceptibility of the gerbil, Meriones unguiculatus, to the bovine parasite, Babesia divergens.

Immature gerbils (4 weeks of age or less) proved to be more resistant to Babesia divergens infections than did mature animals (greater than 8 weeks old). Nutritional studies showed that a milk diet contributes little to this innate resistance. Similarly, the apparent predilection of B. divergens for mature erythrocytes, and also in vitro serum incubation studies, suggested that blood factors do not contribute to any major degree. Splenectomy of immature gerbils abolished their nonspecific resistance and studies with splenocyte incubations with the piroplasm imply that splenic integrity is necessary for the maintenance of this, apparently antibody-independent, resistance to infection with B. divergens.