HIV is a sexually transmitted infection (STI). It can also be spread by contact with infected blood or from mother to child during pregnancy.
Many people don't have any symptoms when they first become infected with HIV. Some have a flu-like illness, called HIV sero-conversion syndrome, a month or two after exposure to the virus. For many people, the first signs of infection are large lymph nodes or swollen glands that.
Symptoms of AIDS are caused by the deterioration of the immune system and the decline of CD4+ T cells, which are the immune system's key infection fighters.