The human immunodeficiency virus (HIV) can be transmitted from one person to another via blood, semen, vaginal and cervical discharge and breast milk. This means an adult can catch the virus during unprotected sex (vaginal or anal intercourse involving contact with the partner's mucosa) or through blood (for instance when sharing needles in connection with drug use). The virus may also pass from the mother to the foetus during pregnancy.

However, there is no evidence of HIV being transmitted via stools, saliva, tears, urine, vomit or sweat. Normal everyday contact, shaking hands, hugging etc. involves no risk of HIV infection. You cannot catch HIV when kissing, either. Oral sex involves a lower risk of HIV infection than vaginal or anal sex or the use of shared needles, but there is always a risk of infection if semen or vaginal discharge enters the mouth. You cannot catch HIV when touching or sucking other parts of the body, such as toes, ears or nipples.

Somewhat less than half of those infected have early symptoms 2 to 6 weeks after the infection. These involve fever, throat pain, rash, muscle pain, joint complaints, headache, swollen lymph nodes, etc. The early symptoms disappear in about one month. When the early symptoms start, the infection may not yet show up in blood tests.

If HIV infection is suspected following unprotected sex or the use of shared injection needles, blood tests can be performed to try and detect the infection. In some cases, the infection can be detected as early as after 3 weeks with antibody tests. You should still bear in mind that a negative test result is only reliable if performed 3 months after infection.

Information sources:

This article was written by
Johanna Castrén, GP
This article was reviewed on 26 Nov. 2012 by SI

Key words: Hiv, Sex, Sexually transmitted diseases