She had helped devise a computer program to predict the spread of HIV in a given population based on such factors as the number of sexual partners people had and the duration of those relationships.
Outside of sub-Saharan Africa, many HIV-positive people are injecting drug users, prostitutes, and highly promiscuous homosexual men who may have hundreds of different sexual partners every year.
The high rates come despite efforts in many communities to stem the HIV epidemic through educational programs, condom distribution, and treatment for such sexually transmitted diseases as gonorrhea and syphilis, which create genital sores and ulcers that make it easier for the virus to spread.
In most cases these programs have had little effect.
The picture in the rest of sub-Saharan Africa is nearly as dire.
AIDS has killed Zulu nurses in South Africa, Masai teachers in Tanzania, Kikuyu housewives in Kenya, Pygmy elders in Uganda.