In rural Malawi, roughly 10 percent of the adult population has HIV. At the peak of the epidemic, in the 1990s and early 2000s, nearly everyone knew someone infected with or affected by the virus, what demographer Hans-Peter Kohler of the University of Pennsylvania describes as a generalized epidemic.
The problem snowballed to the extent that life expectancy dropped dramatically. In just a short period, the epidemic undid nearly two decades of life-expectancy improvements.
"The probability of surviving from 15 to 50 declined substantially," Kohler said.