The prognosis of HIV infection is dramatic for children living in poor countries. Over 50% die within two years. The World Health Organization has estimated that 1500 children will be infected daily until large-scale national programs for prevention of mother-to-child transmission are implemented. A better understanding of the causes underlying early morbidity could lead to a substantial reduction in mortality pending use of antiretroviral drugs which have demonstrated promising results in preliminary tests on children in poor countries.