HIV 

HIV

Consultant Microbiologist, Telemedicine Department

The human immunodeficiency viruses (HIV) are two unique species of viruses that infect humans. The viruses cause a disease known as Acquired Immunodeficiency Syndrome (AIDS), a life-threatening condition where the natural ability to resist common infections is lost. 

How does HIV Spread?

In the majority of patients, HIV is a sexually transmitted infection. It occurs due to unprotected sexual contact with or transfer of semen or vaginal fluids from an infected person to a non-infected person. However, in some individuals, the non-sexual transmission may take place from an infected mother to her baby during pregnancy, during childbirth or through breast milk.

Less commonly, injury from an HIV-contaminated needle or similar sharp instruments results in transmission of the virus, which is a risk for health care workers.

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The spread of the virus through blood transfusions, blood products, or organ transplants is very remote, owing to rigorous testing of potential donors.

When to see a doctor?

If an individual suspects exposure to the virus either by sexual contact or other routes. It is always good to seek medical help or visit a dedicated HIV counselling centre at the earliest. The advantage of early counselling is that the individual can receive a medication called post-exposure prophylaxis (PEP) to prevent a possible infection. It is highly essential to start post-exposure prophylaxis within 24 hrs of suspected exposure to the virus. The earlier PEP is initiated, the better it is for the individual.

An individual must consult a doctor if there are flu-like symptoms lasting for several days associated with rapid weight loss, swollen lymph nodes and white patches in the oral cavity called thrush.

Testing for HIV

There are three types of tests used for the detection of the HIV virus. The various tests are nucleic acid tests (NAT), antigen-antibody tests and antibody tests. The above-mentioned tests are performed on blood or oral fluid. It is mandatory to emphasize that all tests performed for HIV require informed written consent from the individual subjected to these tests. Absolute confidentiality has to be enforced.

1. Nucleic Acid Tests (NAT)

A NAT can confirm if an individual has HIV or determine the quantity of HIV present in the blood, which is called the HIV viral load. The NAT is the earliest test that can detect HIV as compared with the other types of tests. The NAT can detect HIV infection from 10 to 33 days following exposure to the virus.

NAT is used for screening individuals with possible exposure or who have early symptoms of HIV infection.

2. Antigen-Antibody tests

The antigen-antibody test detects both HIV antigens like the P24 antigen and HIV antibodies. The HIV antibodies are produced by the immune system of the individual who is exposed to the HIV or the P24 antigen. The Antigen-Antibody tests detect HIV infection in approximately 18 to 45 days following exposure to the virus. 

3. Antibody tests

      The antibody tests detect only the antibodies to HIV in the blood or serum. The Antibody tests for HIV detect HIV infection in about 23 to 90 days following exposure. Most currently available rapid tests for HIV belong to the category of antibody tests.

What will be the window period for an HIV test?

The window period is defined as the time between HIV infection and the time when an HIV test will be positive. 

It is very important to note that during the window period, a person can have HIV and be very infectious, but still, the HIV test will be negative.

Different types of tests will have different window periods.

  • 4th generation antibody/antigen (Ab/Ag) tests: 45 days
  • 3rd generation antibody only tests: 60 days
  • Point of care tests (self-sampling, self-testing and rapid tests): 90 days

During the window period, a person can have HIV and are very infectious but still test HIV negative.

Tests done after Diagnosing HIV

After testing positive for HIV by the above-mentioned test, an individual will be overwhelmed with disbelief and denial. The individuals exhibit a lot of concerns for themselves and their families. Therefore, it is imperative to emphasize to HIV-positive individuals that HIV can be treated effectively with medication.

The following lab tests are undertaken to implement treatment for the HIV-positive individual.

  • CD4 T lymphocyte cell count (CD4 count) 
  • Plasma HIV RNA (viral load) measures how much virus is in the blood as HIV progresses to Acquired Immunodeficiency Syndrome (AIDS), a person’s viral load increases.
  • Complete blood count, transaminase levels, blood urea nitrogen (BUN) and creatinine, urinalysis and serologies for Hepatitis A, B and C viruses.
  • Fasting blood glucose and serum lipids (AIII); and
  • Genotypic resistance testing 
  • Drug-resistance testing helps to identify the anti-retroviral drug that may not be effective against a specific strain of HIV virus in a particular individual

In addition, tests include screening tests for sexually transmitted infections and tests for determining the risk of opportunistic infections like TB, Toxoplasmosis, Cytomegalovirus, fungal infections and others.

Tests done for staging HIV

 The WHO has staged HIV into four stages based on CD4 counts and viral load testing. The WHO classification ranges from stage 1 (asymptomatic) to stage 4 (AIDS).

Cancers in HIV Patients

Three kinds of cancer, called AIDS-defining cancers, are remarkably very common in advanced HIV patients. They are Kaposi sarcoma, certain types of non-Hodgkin lymphoma, and invasive cervical cancer. It should be noted that HAART (highly active anti-retroviral therapy) may significantly reduce the incidence of these cancers but however may not eliminate the risk.

Conclusion

HIV is by far and large the deadliest epidemic known to mankind. More than twenty-two million people have died, and more than forty-two million are infected with the virus. The final impact of this infection will greatly depend on how individuals, communities and the world respond to this threat, today and tomorrow. 

FAQs

Can stress cause HIV?

Research into the various comorbid conditions that can accelerate the disease process in HIV/AIDS has demonstrated that by an indirect mechanism, conditions like chronic stress, traumatic events and depression can lead to an increased viral load and decreased CD4 counts. Therefore, the disease process is accelerated.

How often are HIV tests false positive?

The tests that are undertaken for the detection of HIV are highly accurate. The Centre for Disease Control (CDC) Atlanta, USA, states that HIV tests have 99.6% trusted source specificity. This implies that for every 1,000 people without HIV who take the test, 996 will receive true negative results, and four may receive a false positive. 

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