I’ve posted before about the serious threat to conservation posed by emerging infectious diseases. Disease-induced declines are a particular problem for amphibians, but other species are vulnerable as well. An article in this week’s issue of Science reports that Ebola is wiping out thousands of gorillas. A story like this makes it into Science because gorillas are charismatic megafauna, and because Ebola is a clear danger to humans. But as far as loss of biodiversity is concerned, gorillas are just one of many, many species endangered by infectious disease.
It’s still not clear how easy it is for a disease to drive a species extinct. Once the host becomes rare enough, transmission slows down or stops. The disease often evolves to be less virulent, so it doesn’t kill off a host before it can jump to another one. But diseases can and do cause extinctions. Especially when combined with other risk factors like habitat loss, hunting, pollution, or climate change, diseases can be deadly not just to individuals, but to whole species.