The earliest known case of HIV-1 in a human was from a blood sample collected in 1959 from a man in Kinshasa, Democratic Republic of Congo. The virus has existed in the United States since the mid-1970s. Between 1979 and 1981 physicians in New York City and Los Angeles reported treating a number of male patients who had engaged in sex with other men for rare types of pneumonia, cancer, and other illnesses not usually found in individuals with healthy immune systems.