This news from Nigeria, on the verge of an AIDS explosion that could kill millions and wreak untold economic damage, a new report says today. It is released to coincide with World AIDS Day yesterday, showing overall HIV infection rates in Africa’s most populous nation of 5.4%, climbing as high as 21% in the worst affected areas. Like other West African countries, Nigeria has been less severely affected by the epidemic than eastern and southern Africa, but its population of more than 108 million means that it already has more people infected with HIV, which possibly leads to AIDS, than many other African countries.