HIV test

From ArticleWorld

HIV is a retrovirus based on RNA which affects the immune system and can develop into AIDS. HIV tests are carried out on both blood and body fluids such as saliva in an effort to detect antibodies, antigens or RNA associated with the disease. One test alone does not provide indisputable evidence of the absence or presence of HIV and a combination of antibody, antigen and nucleic tests are used in Western countries; and even then accuracy is not 100% guaranteed. Indeed, the World Health Organization estimates that one million new cases of HIV infections were the result of inadequate screening in the year 2000.

Antibody tests

Antibodies are proteins which are produced by the immune system to defend against antigens, or foreign substances, entering the body such as viruses. Someone who has been in contact with HIV will produce antibodies specific to the disease. One problem with antibody tests is that a person may be HIV positive but antibody tests are only able to detect the virus about 22 days after infection. This means the virus may be passed on before the patient is aware they have the disease. Another problem is that some infections such as the flu, malaria or herpes may have similar antigens to HIV and so may be diagnosed as having the virus when, in fact, they do not.

Antigen tests

Antigen tests are not used for general diagnostic purposes as they only work for a certain period after infection. They are used to detect the p24 protein which is a major component of the HIV virus.

Nucleic acid tests

In this category of tests, blood plasma is examined in such a way as to detect the presence of the RNA in the virus. As it is quite an expensive process, it is only carried out when a positive result has been detected by the use of other tests. It is also used to monitor the progress of patients on antiretroviral drugs.

Anyone undergoing a HIV test must be assured of confidentiality, must have access to counseling and must have knowingly consented to the test according to World Health Organization stipulations. Unfortunately, in many areas of the world these criteria are not adhered to and because of the stigma attached to the process, many of those most at risk do not dare to take the test.