Human immune-deficiency virus, the virus that causes acquired immune deficiency syndrome, or AIDS. Type 1 and type 2 viruses are recognised, and both are usually tested for in serum HIV antibodies.

A test for HIV, the virus that causes AIDS, and which comes in two strains, type 1 and type 2. They need separate tests, but mostly both are done as a routine. The test looks for the development of an immune reaction against the virus, it does not look for the virus itself, so it's possible, for a few weeks, to have been infected (and to be infective to others) with the test itself still a negative test, that is, apparently (but falsely) clear.

In medicine generally it may be best for tests to be negative (like tests for brain tumors or tests for sexually transmitted diseases such as HIV -- as for 'histories', compare negative history), but this is not always so in infertility. Infertility tests are generally better if they're positive, like the postcoital test, tests for ovulation, tests for tubal patency, and (not least) a pregnancy test.

In medicine, it might generally be best for tests to be negative (like tests for brain tumors or tests for sexually transmitted diseases, such as HIV -- as for medical histories, compare positive history) -- but not so in infertility. Infertility tests, such as the postcoital test, tests for ovulation, tests for tubal patency, and (not least) a pregnancy test, are generally better if they're positive.

Sexually transmitted diseases, such as gonorrhea, chlamydia and HIV.