HIV is a virus that damages the immune system. The immune system helps the body fight off infections. Untreated HIV infects and kills CD4 cells, which are a type of immune cell called T cells. Over time, as HIV kills more CD4 cells, the body is more likely to get various types of infections and cancers.
HIV is transmitted through bodily fluids that include:
- vaginal and rectal fluids
- breast milk
The virus doesn’t spread in air or water, or through casual contact.