Macaque the other monkey's mouth. Several species of macaque are used extensively in animal testing, particularly in the neuroscience of visual perception and the visual system. Nearly all (73–100%) pet and captive rhesus macaques are carriers of the herpes B virus. This virus is harmless to macaques, but infections of humans, while rare, are potentially fatal, a risk that makes macaques unsuitable as pets. Urban performing macaques also carried simian foamy virus, suggesting they could be involved in the species-to-species jump of similar retroviruses to humans. In Vietnam, macaque is eaten by some people as bushmeat. In January 2018, scientists in
Crab-eating macaque of populations due to increased wild trade and rising levels of human-macaque conflict, which are reducing overall population levels despite the species being widely distributed. Each subspecies faces differing levels of threats, and too little information is available on some subspecies to assess their conditions. The "M. f. umbrosa" subspecies is likely of important biological significance and has been recommended as a candidate for protection in the Nicobar Islands, where its small, native population has been seriously fragmented, and is listed as vulnerable on the IUCN Red List. The Philippine long-tailed macaque ("M. f. philippensis") is listed as near threatened,