Human immunodeficiency virus (HIV) is the two types of Lentivirus (the retrovirus sub-group) that infects humans. In the long run, they cause them to acquire immunodeficiency syndrome (AIDS), a condition in which the ongoing failure of the immune system allows life-threatening diseases and cancers to develop. Without treatment, the average survival time after HIV infection is from 9 to 11 years, depending on the HIV subtype. In many cases, HIV is a sexually transmitted disease and occurs through contact or transmission of blood, pre-ejaculate, sperm, and vaginal secretions. Studies have shown (in both sexes) that HIV cannot be explained by sexual intercourse without condoms if an HIV-positive partner has an undetectable viral load. Non-sexual transmission can occur from an infected mother to her baby during pregnancy, during labor by exposure to her blood or to the vagina, and through breast milk. In the body fluids, HIV exists as both germs and viruses inside infected cells.