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Passage 7 HIVAIDS AIDS has now surpassed the Black Death on its course to become the worst pandemic in human history. At the end of 2004. 20 million people had been killed by it, and twice that number are currently infected with HIV. Barring a medical breakthrough, it could claim the lives of some 60 million people by 2015. AIDS exerts a terrible toll on societies, crippling their economies, decimating their labor forces and orphaning their children. Nine out of 10 people living with HIV are in the developing world; 60 to 70% of those are in Sub-Saharan Africa. But the disease is spreading in every region, with fierce epidemics threatening to tear through countries such as India, Russia and the islands of the Caribbean. The statistics are sobering in some Southern African towns 44% of pregnant women are HIV positive, in Botswana 37% of people carry the virus. Immune Assassin The human immunodeficiency virus is a retrovirusa virus built of RNA instead of more typical DNA. It attacks the very cells of the immune system that should be protecting the body against itT lymphocytes and other white blood cells with CD4 receptors on their surfaces. The virus uses the CD4 receptor to bind with and thereby enter the lymphocyte. HIV then integrates itself into the cell sown DNA, turning the cell into a virus-generating factory. The new viruses break free, destroying the cell, then move on to attack other lymphocytes. | 
