Fatal pulmonary acariasis in an aged indoor rhesus macaque (Macaca mulatta).

Pulmonary acariasis is a sporadic, incidental finding in colony-raised rhesus macaques (Macaca mulatta). Prophylactic treatment in indoor-raised and indoor-housed macaques is not routine due to low prevalence, lack of clinical significance, and potential risk of toxicosis. This case is an unusually severe infestation of Pneumonyssus simicola in an indoor-housed rhesus macaque, which ultimately resulted in this animal's death.