This 1975 image depicted a number of chacma baboons, Papio ursinus, also known as Cape baboons, as well as a number of blue monkeys, also known as diademed monkeys, Cercopithecus mitis, that were located in Victoria Falls. These primates were shown here, riding atop grain cars located on a Victoria Falls railway bridge. Many were trapped, and underwent blood testing as part of the Marburg virus investigation, which moved to the border of Rhodesia, now Zimbabwe, and Zambia. All of the blood tests came back negative. This investigation occurred after two travelers were hospitalized with Marburg disease in Johannesburg. One of the travelers, referred to as Case #1, came into contact with an unknown vector while traveling through Zimbabwe. Case #1 then passed the Marburg virus to his traveling companion, referred to as Case #2, and a treatment nurse, Case #3.