Gorillas are able to get infected with almost all of the diseases that humans can get. This is one of the reasons why tourists should stay away from animals.
Most gorillas that live in the world have parasites and these are mainly internal in the form of worms and protozoans. There are some of these parasites which can equally affect humans and gorillas. When their bodies were examined, traces of the human metapneumovirus were found in their tissues. Among humans, this virus can cause severe respiratory infections and it has infected and killed gorillas.
There are some severe dangers that can affect a whole population of gorillas and these are epidemics such as Ebola. Viruses such as Ebola can be transferred from humans to gorillas and this, of course, is vice-versa. Another example is HIV, originally SIV evolved from chimps and other primates.