- How to understand the result
- HIV blood test
- Rapid HIV test
- What is the viral load test?
- When it can give false negative result
The HIV test is done to detect the presence of the HIV virus in the body and must be done at least 30 days after exposure to risky situations, such as unprotected sex or contact with blood or secretions from people with the virus HIV.
The HIV test is simple and is done mainly by analyzing a blood sample, but saliva can also be used to check for the presence of the virus in the body. All HIV tests screen for two types of existing virus, HIV 1 and HIV 2.
The HIV test must be performed at least 1 month after the risky behavior, since the immunological window, which corresponds to the time between contact with the virus and the possibility of detecting the infection marker, is 30 days, and there may be the release of a false negative result if the test is performed before 30 days.
How to understand the result
In order to understand the result of the HIV test, it is important to check whether it is reactive, non-reactive or indeterminate beyond the indicated values, because normally the higher the value, the more advanced the infection is.
HIV blood test
The blood test for HIV is done with the aim of identifying the presence of the virus and its concentration in the blood, giving information about the stage of the infection. HIV testing can be done using various laboratory diagnostic methods, the most used of which is the ELISA method. Possible results are:
- Reagent: It means that the person was in contact with and became infected with the AIDS virus; Non-reactive: It means that the person is not infected with the AIDS virus; Undetermined: You must repeat the test because the sample was not clear enough. Some situations that lead to this type of result are pregnancy and recent vaccination.
In case of a positive result for HIV, the laboratory itself uses other methods to confirm the presence of the virus in the body, such as Western Blot, Immunoblotting, Indirect immunofluorescence for HIV-1. So, the positive result is really reliable.
In some laboratories, a value is also released, in addition to the indication whether it is reactive, non-reactive or indeterminate. However, this value is not as clinically important as determining the positivity or negativity of the exam, being only interesting for medical monitoring. If the doctor interprets it as an important value from a clinical point of view, more specific tests may be requested, such as the viral load test, in which the number of copies of the virus circulating in the blood is checked.
In the case of an indeterminate result, it is recommended that the test be repeated after 30 to 60 days in order to verify the presence or absence of the virus. In such cases, the test should be repeated even if there are no symptoms, such as rapid weight loss, persistent fever and cough, headache and the appearance of red spots or small skin sores, for example. Know the main symptoms of HIV.
Rapid HIV test
Rapid tests indicate the presence or absence of the virus and are done using a small sample of saliva or a small drop of blood to identify the virus. The result of the rapid test is released between 15 and 30 minutes and is also reliable, with the possible results being:
- Positive: Indicates that the person has the HIV virus but must have an ELISA blood test to confirm the result; Negative: Indicates that the person is not infected with the HIV virus.
Rapid tests are used on the street, in government campaigns at testing and counseling centers (CTA) and in pregnant women who start labor without having performed prenatal care, but these tests can also be purchased over the Internet.
Usually, government campaigns use OraSure tests, which test saliva and the test that can be purchased online at online pharmacies abroad is Home Access Express HIV-1, which is approved by the FDA and uses a drop of blood.
What is the viral load test?
The viral load test is an exam that aims to monitor the evolution of the disease and check if the treatment is being effective by checking the amount of copies of the virus present in the blood at the time of collection.
This test is expensive, since it is done using molecular techniques that require special equipment and reagents, and, therefore, it is not required for diagnostic purposes. Thus, the viral load test is only performed when there is a diagnosis of HIV infection in order to monitor and monitor the patient, being requested by the doctor 2 to 8 weeks after diagnosis or beginning of treatment and repetition every 3 months.
From the result of the test, the doctor can assess the number of copies of the virus in the blood and compare with the previous results, thus verifying the effectiveness of the treatment. When the increase in viral load is noticed, it means that the infection has worsened and, possibly, resistance to treatment, and the doctor must change the therapeutic strategy. When the opposite happens, that is, when the viral load decreases over time, it means that the treatment is being effective, with inhibition of virus replication.
The result of an undetermined viral load does not mean that there is no more infection, but that the virus is found in low concentrations in the blood, indicating that the treatment is being effective. It is a consensus in the scientific community that when the viral load test is undetectable, there is a low risk of transmission of the virus through sex, however it is still important to use condoms during sexual intercourse.
Understand how molecular diagnosis is made.
When it can give false negative result
The false negative result can happen when the person has had the exam within 30 days after the risky behavior that may have been sexual intercourse without a condom, sharing of disposable syringes and needles or piercing with a contaminated cutting object such as knives or scissors, for example. This is because the body is unable to produce enough antibodies for the presence of the virus to be indicated in the test.
However, even if the test was performed 1 month after the risky behavior, it can take up to 3 months for the body to produce enough antibodies against the HIV virus and the result is positive. Thus, it is important that the test is repeated 90 and 180 days after the risk behavior in order to confirm the presence or absence of the HIV virus in the body.
Basically whenever a result is positive, there is no doubt that the person has HIV, while in case of a negative result, it may be necessary to repeat the test due to the false negative. However, an infectious disease specialist can indicate what to do in each case.
