Fatal experimental Babesia microti infections in the Norwegian lemming, Lemmus lemmus (L.).

Experimental infections of Babesia microti in laboratory-reared Clethrionomys glareolus revealed that approximately 15% of the erythrocytes were infected with single ring forms during peak parasitemia. Infected erythrocytes could be detected in blood smears up to one month post infection. C. glareolus treated with a single injection of Depo-Medrol i.m. two days prior to infection displayed a four-fold increase in number of infected erythrocytes at peak parasitemia, 35% of which contained more than one Babesia, and a prolongation of the infection. B. microti infections in 35 laboratory--reared Lemmus lemmus were fatal. Multiple invasion of erythrocytes, anemia, icterus, hemoglobinuria, anorexia and weight loss, and adrenal and splenic hypertrophy were characteristic for B. microti infections in Norwegian lemmings.