Detecting the infection is possible if we do tests for the present of antibodies to HIV. The test must be done about three months after the time when the infection was supposed to take place (it is called “serological window” – carrier is infected but the HIV tests are negative) because it is the length of the time when antibodies appears in the number that can be detected in tests. Nowadays there are some tests, mostly ELISA III and HIV-DUO are used. The positive result (HIV+) of the first test must be confirmed by the test Western Blot. It is the most important test – confirming test and only on the basic of this test the diagnosis of HIV infection can be verified with absolute certainty.