Dr. Robert Jean Ngola says a deluge of harassment and racist taunts followed him, both online and in-person.

Genes taken from archived blood samples show the U.S. AIDS epidemic started in New York in the early 1970s, definitively debunking the long-held belief that the virus was spread in the early 1980s by a flight attendant who became vilified as "Patient Zero" for seeding the U.S. outbreak.

Canadian infectious disease experts explain why health officials are working to identify "patient zero" in the world’s longest and largest Ebola epidemic.