While disease is a natural component of wildlife ecology, evidence suggests that in western equatorial Africa, endemic disease is having a catastrophic effect on great apes.

The Ebola virus has had a devastating impact and may be responsible for a 50–90% decline in western gorilla populations in many parts of Gabon and Congo over recent years. Disease risks posed by humans pose an additional danger. Western gorillas have already been shown to be vulnerable to human pathogens, mainly those associated with respiratory, intestinal and skin diseases.

Only one remaining gorilla stronghold (Loango/Moukalaba-Doudou/Gamba in Gabon) is remote from current or recent Ebola epidemics. The additional threat posed by the commercial trade in bushmeat means that small post-Ebola populations of great apes, are at high risk of being extirpated before their numbers are able to recover.