One of the world’s worst plagues is giving ground

THE timing of the pope’s much-discussed change of position on the use of condoms to prevent the spread of HIV (he will now allow prostitutes to use them without fear of hellfire) was surely no coincidence. He made it on November 21st—ten days before World AIDS Day and two before UNAIDS, the United Nations body charged with combating the epidemic, released its latest report on the state of the battle.

That report carries good news. Though some 33m people are infected, the rate of new infections is falling—down from 3.1m a year a decade ago to 2.6m in 2009. Moreover, as the map shows, the figure is falling fastest in many of the most heavily infected countries, especially those of sub-Saharan Africa and South and South-East Asia. …