One of the world's worst plagues is giving ground

ON NOVEMBER 23rd UNAIDS, the UN body charged with combatting the AIDS epidemic, released its latest report. This 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. The reason is a combination of behavioural change (people are losing their virginity later, are being less promiscuous and are using condoms more), a big reduction in mother-to-child transmission at birth and through breast-feeding, and the roll-out of drug treatment for those already infected. Besides prolonging life, antiretroviral drugs make those taking them less likely to pass the virus on. More than 5m people in poor and middle-income countries are now on these drugs, though another 10m could benefit. (The remainder of those infected are not yet ill enough for the drugs to do do them good.) The problem, as always, is money. UNAIDS reckons the fight needs about $25 billion a year to be fully effective. At the moment, the sum spent is around $17 billion. Not a bad fraction of what is needed, but one that it will be difficult to sustain in the face of the world's current economic difficulties.