Fatal measles virus infection in Japanese macaques (Macaca fuscata)

An outbreak of natural measles virus infection occurred in a group of Japan ese macaques (Macaca fuscata). Over a period of 4 months, 12 of 53 Japanese macaques died following a 2-23-day history of anorexia, diarrhea, and derm atitis. The monkeys were kept in outdoor exhibits but had been moved tempor arily into indoor caging and then transferred to new outdoor exhibits. Ten monkeys died while they were in temporary caging, and two monkeys died afte r they were moved to new outdoor exhibits. The diagnoses were made based on the results of histopathology, immunohistochemistry (IHC), in situ hybridi zation (ISH), and electron microscopy. Measles virus antigens were detected in the lung, stomach, skin, salivary gland, spleen, and lymph nodes. Tangl ed, tubular nucleocapsids compatible with paramyxovirus were noted in the l ung tissue. As a result of immunosuppression following measles virus infect ion, various secondary infections including disseminated cytomegalovirus in fection, adenoviral and bacterial pneumonia, and Candida albicans-associate d gingivitis and esophagitis were noted. The primary infective source or th e mode of infection could not be determined in this outbreak but measles vi rus may have been transmitted to the monkeys from human visitors while the monkeys were on exhibit.