Diagnosis
In the early stages of infection, HIV often causes no symptoms and the infection can be diagnosed only by testing a person's blood. Two tests are available to diagnose HIV infection - one that looks for the presence of antibodies produced by the body in response to HIV and the other that looks for the virus itself.
The ELISA test
Antibodies are proteins produced by the body whenever a disease threatens it. When the body is infected with HIV, it produces antibodies specific to HIV. The first test, called ELISA (Enzyme Linked Immunosorbent Assay), looks for such antibodies in blood.
In the early stages of infection, HIV often causes no symptoms and the infection can be diagnosed only by testing a person's blood. Two tests are available to diagnose HIV infection - one that looks for the presence of antibodies produced by the body in response to HIV and the other that looks for the virus itself.
The ELISA test
Antibodies are proteins produced by the body whenever a disease threatens it. When the body is infected with HIV, it produces antibodies specific to HIV. The first test, called ELISA (Enzyme Linked Immunosorbent Assay), looks for such antibodies in blood.
If antibodies are present, the test gives a positive result. A positive test has to be confirmed by another test called Western Blot or Immunoflouroscent Assay (IFA). All positive tests by ELISA need not be accurate and hence Western Blot and repeated tests are necessary to confirm a person's HIV status. A person infected with HIV is termed HIV- positive or seropositive.
RAPID TESTS AVAILABLE ON SABA!
As ELISA requires specialized equipment, blood samples need to be sent to a laboratory and the result will be available only after several days or weeks. To cut short this waiting period, RAPID TESTS , that give results in 5 to 30 minutes, are increasingly being used the world over.
As ELISA requires specialized equipment, blood samples need to be sent to a laboratory and the result will be available only after several days or weeks. To cut short this waiting period, RAPID TESTS , that give results in 5 to 30 minutes, are increasingly being used the world over.
The accuracy of rapid tests is stated to be as good as that of ELISA. Though rapid tests are more expensive, researchers have found them to be more cost effective in terms of the number of people covered and the time the tests take.
The HIV- antibodies generally do not reach detectable levels in the blood till about three months after infection. This period, from the time of infection till the blood is tested positive for antibodies, is called the Window Period . Some times, the antibodies might take even six months to show up. Even if the tests are negative, during the Window Period, the amount of virus is very high in an infected person. Hence, if a person is newly infected, the risk of transmission is higher.
If a person is highly likely to be infected with HIV and yet both the tests are negative, a doctor may suggest a repetition of the tests after three months or six months when the antibodies are more likely to have developed.|
PCR tests
The second test is called PCR (Polymerase Chain Reaction), which looks for HIV itself in the blood. This test, which recognizes the presence of the virus' genetic material in the blood, can detect the virus within a few days of infection.
RIPA tests
There are also tests like Radio Immuno Precipitation Assay (RIPA) , a confirmatory blood test that may be used when antibody levels are difficult to detect or when Western Blot test results are uncertain. Other available tests are Rapid Latex Agglutination Assay , a simplified, inexpensive blood test that may prove useful in medically disadvantaged areas where there is a high prevalence of HIV infection.
The HIV- antibodies generally do not reach detectable levels in the blood till about three months after infection. This period, from the time of infection till the blood is tested positive for antibodies, is called the Window Period . Some times, the antibodies might take even six months to show up. Even if the tests are negative, during the Window Period, the amount of virus is very high in an infected person. Hence, if a person is newly infected, the risk of transmission is higher.
If a person is highly likely to be infected with HIV and yet both the tests are negative, a doctor may suggest a repetition of the tests after three months or six months when the antibodies are more likely to have developed.|
PCR tests
The second test is called PCR (Polymerase Chain Reaction), which looks for HIV itself in the blood. This test, which recognizes the presence of the virus' genetic material in the blood, can detect the virus within a few days of infection.
RIPA tests
There are also tests like Radio Immuno Precipitation Assay (RIPA) , a confirmatory blood test that may be used when antibody levels are difficult to detect or when Western Blot test results are uncertain. Other available tests are Rapid Latex Agglutination Assay , a simplified, inexpensive blood test that may prove useful in medically disadvantaged areas where there is a high prevalence of HIV infection.
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