A factory storekeeper in the Nzara township of Sudan becomes ill on June 27, 1976. Five days later, he dies, and the world’s first recorded Ebola virus epidemic begins making its way through the area. By the time the epidemic is over, 284 cases are reported, with about half of the victims dying from the disease.

Symptoms of Ebola hemorrhagic fever generally begin about four to 15 days after a person is infected with the virus. The average victim will first notice flu-like symptoms, such as a high fever, aching and general weakness. Usually this is followed by diarrhea, vomiting and the eruption of rashes all over the body. Then the person may begin bleeding from any and all body orifices and internal organ damage begins. Within seven to 10 days, exhaustion, dehydration and shock set in.

After the storekeeper in Nzara died, a second man in town died on July 6. His brother became sick soon after, but managed to recover. The brother’s co-worker went to the hospital on July 12 with symptoms and was dead two days later; the co-worker’s wife died five days after that. A week later a male neighbor died. Eventually, another 48 infections and 27 deaths were traced back to the neighbor.

Given this pattern of infection and the fact that hospital workers also started to develop symptoms, doctors realized that transmission of the virus required only close contact. At Maridi Hospital in southern Sudan, 33 of the 61 nurses ended up dead from Ebola fever.

The World Health Organization finally arrived in October and helped to contain the epidemic. Once it became clear that isolating the victims would stop the spread, the epidemic ended almost as quickly as it had appeared. There have been a handful of other Ebola outbreaks in the years since 1976—including one in 2014 that resulted in over 11,000 deaths, mostly in West Africa.