Question

What body fluids are used to diagnose HIV?

Answer 1

Human immunodeficiency viruses are two Lentivirus species that infect people. They lead to acquired immunodeficiency syndrome, a disease in which the immune system gradually fails, allowing life-threatening opportunistic infections and malignancies to flourish. AIDS is the most dreadful infectious disease. It can transmit through infected fomites and through unprotected sexual intercourse.

Complete answer:
To solve this question one must know the various diagnostic tests used to screen HIV infection.
The most frequent diagnostic tests are outlined here.
Antibody testing (also known as immunoassay, usually ELISA and rarely RIA) is used to detect antibodies to the HIV virus. These tests can identify antibodies as early as a few weeks after a viral infection. Antibody testing can be performed on a number of bodily fluids, including:
Blood – Blood is drawn from a vein or a finger prick is used for this test. Because blood contains more antibodies than other bodily fluids, a blood test is the most accurate.
Oral fluid – This test examines the cells of the mouth for antibodies. Swabbing the gums and inner cheeks is how it's done. This test is not as precise as a blood test.
Urine – This test looks for antibodies in the urine.
Similarly, Antigen tests can be performed which detect the HIV antigen $p24$.

Blood, Oral fluid and Urine can be used to diagnose the infection of HIV.

Note:
Antibodies against HIV proteins can be identified using a variety of methods; the current gold standards for screening and confirmation are enzyme-linked immunosorbent assays (ELISAs) and Western blot (WB). Particle cell agglutination for screening and immunofluorescence and radio immuno blot test for confirmation are other suitable methods. Nucleic acid based assays are also used in HIV diagnosis.