Since the first case of the human immunodeficiency virus (HIV) infection was identified, the number of children infected with HIV has risen dramatically in developing countries, the result of an increased number of HIV-infected women of childbearing age in these areas. HIV is a retrovirus and can be transmitted vertically, sexually, or via contaminated blood products or IV drug abuse. The number of kids who get infected with HIV each year is going down. At the end of 2015, 2.6 million children throughout the world ages 15 and younger were living with the virus, but only about one-third of them were getting treatment. Children get pretty much the same treatment as adults: a combination of medications called ART (antiretroviral therapy). But it isn't that simple, because some HIV drugs don't come in a liquid form that babies and small children can swallow. And some drugs cause serious side effects for kids.