The human immunodeficiency virus that causes AIDS appears to have weakened since the start of the pandemic more than two decades ago, according to a Belgian study published today in the journal AIDS. Scientists at Antwerp’s Institute of Tropical Medicine, compared HIV-1 samples from 1986-89 and 2002-03, and found 75 percent of the newer samples were weaker, both in terms of spread within individuals and transmission to others. Of the two types of HIV that infect humans, HIV-1 is more virulent than HIV-2.
