cheetahs have always had a problem. All the ones around today are thought to have descended from a single breeding pair around the end of the last ice age, so they were nearly extinct once before. It means very little genetic diversity, so if one dies of a bug, all of them could do so.
Also - they're not a very competent species. They're fast, but that's about all. They have weak jaw muscles so once they catch prey they can only eat the tender bits - usually, after that, some hyena will chase them away. (Unlike leopards, which are tough and smart and keep out of people's way; they survive virtually all the way from Cape Town to Siberia.)
There are people working to protect them, eg
http://www.africat.org/support/adopt-a-carnivore
but they're quite difficult to deal with as they domesticate easily. If you have a baby for 2 weeks, he's yours for life and may never want to hunt again.