As if it weren't bad enough that the wildebeest traumatized 90s kids by running down Mufasa in The Lion King, it turns out that they also drag a type of herpes across Africa every spring when they migrate. Ed Yong explains on Not Exactly Rocket Science:
For a few months, 1.3 million wildebeest head north through the Serengetiin search of food and water. There are so many of them that their lines can stretch from one horizon to the next. And almost every one of these animals is infected by a virus called acelaphine herpesvirus 1 (AlHV-1).
Wildebeest calves pick up the virus from their mothers within their first few months of life, and carry the infection until they die. The virus causes no symptoms, and doesn't harm the wildebeest. But domestic cows aren't so fortunate. If they contract the infection, they develop a disease called malignant catarrhal fever (MCF)—a cancer-like illness where white blood cells start dividing out of control. Once a cow shows symptoms, it's almost always dead within a couple of weeks.
MCF is a huge threat to the cattle-farming Maasai people of east Africa—the annual wildebeest migration spells death for their livestock. It's also a problem for any zoos that keep wildebeest, which might infect other hoofed residents. It doesn't help that there is no treatment. The only way of controlling the disease is to corral animals to prevent them from straying near infected wildebeest.