In 1937, the first instance of West Nile fever was found in Uganda. A woman at Omogo, located in the West Nile district, reported feeling feverish while researchers were investigating the yellow fever virus. In 1939, areas of the Congo, Sudan, and the White Nile region tested positive for West Nile virus.
It was discovered in Egypt in 1942 and India in 1953. A 1950 survey in Egypt found that 90 percent of Egyptians over the age of 40 had West Nile virus antibodies. West Nile virus was noted in horses for the first time in France and Egypt in the 1960s. It was then that it was recognized in Australia, southern Europe, and southwest Asia.