Half of all new HIV infections in the United States occur in people under 25 years of age, and thousands of U.S. teens become infected with HIV each year. HIV stands for human immunodeficiency virus . The medical community has made great progress in AIDS research since the disease was first recognized. If a woman with HIV is pregnant, her newborn baby can catch the virus from her before he is born, during the birthing process, or from breast-feeding. In the United States and many other countries, donated blood is tested for HIV before it is used so that HIV is not spread through blood transfusions.
Helper cells help the immune system to function normally and fight off certain kinds of infections.
They do this by acting as messengers to other types of immune system cells, telling them to become active and fight against an invading infection. The HIV virus attaches to these CD4 cells, infects them, and uses them to replicate. In doing so, the virus destroys the ability of the infected cells to do the job of helping transmit messages to other cells of the immune system. The body then loses the ability to fully fight many infections. Because their immune systems are compromised, people who have AIDS are unable to fight off many infections, such as meningitis and certain types of pneumonia .