Every day more than 1,000 infants worldwide are infected with HIV during gestation, delivery or breast-feeding, according to U.N. estimates. But the United Nations Children's Fund (UNICEF) says it will eliminate the transmission of HIV from mothers to their babies in just four years. It's an ambitious goal that the fund is unlikely to meet without major changes, but it's not impossible.

"What it doesn't require is a new scientific breakthrough," says Jimmy Kolker, chief of UNICEF's HIV/AIDS Programme. Mother-to-child HIV transmission virtually never happens in developed nations, where babies and moms have easier access to a prophylactic regimen of antiretroviral drugs. Medically, protecting infants from HIV infection means "just doing what we're already doing" in developed nations, such as giving moms a combination antiretroviral drug treatment during pregnancy and babies a dose of the drug nevirapine immediately after birth. For women who do not have access to clean, safe water to mix infant formula, it also means continuing antiretroviral treatments for moms and babies during breast-feeding.

The challenge now is to bring these drugs, which have been available since the late 1990s and have since undergone several revisions and improvements, to middle- and low-income countries. "The problems are logistical," says Laurie Garrett, a global health researcher at the Council on Foreign Relations.

This slide show explores what is needed to stop mother-to-child HIV transmission by 2015, following Inonge Siamalambo and her baby Elson of Lusaka, Zambia, through their 18-month commitment to a transmission prevention program.

View a slide show of Siamalambo and Elson