Japanese Macaques

In the first outbreak to hit the PRI in Inuyama, near Nagoya, between July 2001 and July 2002, seven Japanese macaques (Macaca fuscata) fell ill and six of them died from what the institute scientists provisionally call a 'haemorrhagic syndrome'. Symptoms included anorexia, lethargy, pallor and nasal haemorrhaging.

Autopsies revealed bleeding in the lungs and intestines. Genetic, bacterial and toxicological tests failed to pinpoint a cause, and after the outbreak ran its course, operations at the institute returned to normal. But between March 2008 and April 2010, another 39 cases appeared in the same species. Of those, 25 died of the disease and 13 were humanely killed. Only one monkey survived each outbreak.

On 1 July, an institute committee set up after the second outbreak published its findings in the online version of the Japanese-language journal Primate Research (Kyoto University Primate Research Institute Disease Control Committee Primate Res. 26, 69–71; 2010).

The committee tested blood, faeces and tissues from the diseased monkeys for 6 bacteria and 16 viruses. The tests, which included PCR analysis, turned up nothing that could explain the deaths. François Villinger, director of pathology at the Yerkes National Primate Research Center in Atlanta, Georgia, says that Japanese laboratories tend to have excellent diagnostic capabilities: "Therefore I have confidence in the fact that the illness is probably not due to any of the known agents inducing haemorrhagic fevers."

PRI director Tetsuro Matsuzawa spoke out against suggestions in the local media that the disease could spread to humans or other animals. At the 7 July press conference, he stressed that none of the other primate species at the institute, which houses more than 1,200 animals from 13 species, including chimpanzees, marmosets and crab-eating macaques, has contracted the syndrome.

The humans who handled the monkeys also show no symptoms. "I don't like the headlines in the news media," he says. "We think that the haemorrhagic syndrome is due to a species-specific pathogen of the Japanese monkeys."