Human immunodeficiency virus (HIV) is transmitted when blood or semen from and infected person enters the bloodstream of another person through unprotected fucking of the sharing of needles. Shortly after contact with HIV, a person may (but not always) undergo a sero-conversion illness, a severe flu-like illness that will pass in a matter of weeks. After this time a person becomes HIV-positive as the immune system creates antibodies to fight the infection. There is no cure for HIV and if left untreated the infection can cause serious illness and death. A combination of antiviral drugs can be used to prevent further damage to the immune system. Post-exposure prophylaxis (PEP_ is a course of antiviral drugs the may prevent HIV infection if taken within 72 hours of exposure to the virus.