SUMMARY. Owls are frequent carriers of blood parasites but clinical malaria infections are rare. Various stages of Plasmodium
subpraecox were seen in 90% of the erythrocytes of an Eastern screech owl (Otus asio) showing symptoms consistent with malaria 1
wk after admission for traumatic injuries. An additional unidentified blood parasite, either a Plasmodium or a Haemoproteus spp.
was found in small numbers of red blood cells on blood films examined at admission and at day 7 postadmission. Combined
infestation, trauma-induced stress, and iatrogenic corticosteroid administration are possible factors that could have induced disease.
Oral treatment with mefloquine at 30 mg/kg, repeated after 12, 24, and 48 hr, proved successful in eliminating both organisms and
signs of clinical disease.