Science Series #4: Human Immunodeficiency Virus (HIV)
What is HIV?
The human immunodeficiency virus (HIV) can lead to acquired immunodeficiency syndrome or AIDS if not treated. Unlike some other viruses, the human body can’t get rid of HIV completely, even with treatment. So once you get HIV, you have it for life.
(Source: Centers for Disease Control and Prevention)
HIV is a type of virus that uses RNA as its genetic material. After infecting a cell, a retrovirus uses an enzyme called reverse transcriptase to convert its RNA into DNA. The retrovirus then integrates its viral DNA into the DNA of the host cell, which allows the retrovirus to replicate.
There are two major types of the human immunodeficiency virus. HIV-1, which was discovered first, is the most widespread type worldwide. HIV-2 is more than 55% genetically different from HIV-1. HIV-2 is most common in western Africa and is becoming more common in India, although numbers there are still relatively small. Small numbers of cases have also been seen in Portugal, France, other European countries including the UK and the Americas, largely in individuals of west African origin or their sexual partners.
(Source: NAM aidsmap)
Transmission
The HIV is transmitted through:
- Sexual contact – HIV is spread most commonly by sexual contact with an infected partner. The virus enters the body through the lining of the vagina, vulva, penis, rectum, or mouth during sexual activity.
- Blood contamination – HIV may also be spread through contact with infected blood. However, due to the screening of blood for evidence of HIV infection, the risk of acquiring HIV from blood transfusions is extremely low.
- Needles – HIV is frequently spread by sharing needles, syringes, or drug use equipment with someone who is infected with the virus. Transmission from patient to healthcare worker, or vice-versa through accidental sticks with contaminated needles or other medical instruments, is rare.
- Mother-infant – HIV also can be spread to babies born to or breastfed by mothers infected with the virus. The exact mechanism of mother-to-child transmission of HIV remains unknown. Transmission may occur during intrauterine life, delivery or breastfeeding. The greatest risk factor for vertical transmission exists with advanced disease in the mother due to high HIV viral loads. Unfortunately, 30% of women during pregnancy do not get tested for HIV, and another 15-20% receive none or minimal prenatal care, increasing the chance of possible transmission to the newborn.
(Source: Medscape and Department of Health & Human Services)
What are the stages of HIV?
There are several symptoms of HIV. Not everyone will have the same symptoms. It depends on the person and what stage of the disease they are in.
Below are the three stages of HIV and some of the symptoms people may experience.
Within 2 to 4 weeks after infection with HIV, about two-thirds of people will have a flu-like illness. This is the body’s natural response to HIV infection.
Flu-like symptoms can include:
- Fever
- Chills
- Rash
- Night sweats
- Muscle aches
- Sore throat
- Fatigue
- Swollen lymph nodes
- Mouth ulcers
These symptoms can last anywhere from a few days to several weeks. But some people do not have any symptoms at all during this early stage of HIV.
In this stage, the virus still multiplies but at very low levels. People in this stage may not feel sick or have any symptoms. Without HIV treatment, people can stay in this stage for 10 or 15 years but some move through this stage faster.
If you take HIV medicine every day, exactly as prescribed and maintain an undetectable viral load have effectively no risk of transmitting HIV to your sexual partner(s).
However, if your viral load is detectable, you can transmit HIV during that stage, even without showing any symptoms. Therefore, it is important to visit your health care provider regularly to have your viral load checked.
If you have HIV and you are not on HIV treatment, eventually the virus will weaken your body’s immune system and you will progress to AIDS. This is the late stage of HIV infection.
Symptoms of AIDS can include:
- Rapid weight loss
- Recurring fever or profuse night sweats
- Extreme and unexplained tiredness
- Prolonged swelling of the lymph glands in the armpits, groin, or neck
- Diarrhea that lasts for more than a week
- Sores of the mouth, anus, or genitals
- Pneumonia
- Red, brown, pink, or purplish blotches on or under the skin or inside the mouth, nose, or eyelids
- Memory loss, depression, and other neurologic disorders
Each of these symptoms can also be related to other illnesses. The only way to know for sure if you have HIV is to get tested. If you are HIV-positive, a health care provider will diagnose if your HIV has progressed to stage 3 (AIDS) based on certain medical criteria.
(Source: HIV.GOV)
How do I know if I have HIV?
HIV tests are very accurate but none can immediately detect the virus after it has been infected. How fast they work depends on many factors, including the type of test used.
Types of HIV diagnostic and monitoring tests:
Look for the actual virus in the blood. This test is very expensive and is not routinely used for HIV screening unless the person recently had a high-risk exposure or a possible exposure with early symptoms of HIV infection. There are several ways of amplification, including polymerase chain reaction (PCR), strand displacement assay (SDA), or transcription mediated assay. A NAT can usually detect HIV infection 10 to 33 days after an exposure.
Look for both HIV antibodies and antigens. Antibodies are produced by your immune system when you’re exposed to viruses like HIV. Antigens are foreign substances that cause your immune system to activate. If you have HIV, an antigen called p24 is produced even before antibodies develop.
Antigen/antibody tests are recommended for testing done in labs and are now common in the United States. An antigen/antibody test performed by a laboratory on blood from a vein can usually detect HIV infection 18 to 45 days after an exposure. There is also a rapid antigen/antibody test available that is done with a finger prick. Antigen/antibody tests done with blood from a finger prick can take longer to detect HIV (18 to 90 days after an exposure).
Look for antibodies to HIV in your blood or oral fluid. Antibody tests can take 23 to 90 days to detect HIV infection after an exposure. Most rapid tests and the only FDA-approved HIV self-test are antibody tests. In general, antibody tests that use blood from a vein can detect HIV sooner after infection than tests done with blood from a finger prick or with oral fluid.
Such as PCR or NASBA (nucleic acid sequence based amplification), are used to measure viral loads for people who are HIV-positive. It is important to regularly monitor viral loads to ensure effective antiretroviral treatment.
(Source: Canada’s source for HIV and hepatitis C information and Centers for Disease Control and Prevention)
Is there a cure for HIV?
HIV is treated with antiretroviral medications, which work by stopping the virus replicating in the body. This allows the immune system to repair itself and prevent further damage. A combination of HIV drugs is used because HIV can quickly adapt and become resistant. Some HIV treatments have been combined into a single pill, known as a fixed dose combination, although these often cost more to prescribe. Usually, people who have just been diagnosed with HIV take between 1 and 4 pills a day.
Different combinations of HIV medicines work for different people, so the medicine you take will be individual to you. The amount of HIV virus in your blood (viral load) is measured to see how well treatment is working. Once it can no longer be measured it’s known as undetectable. Most people taking daily HIV treatment reach an undetectable viral load within 6 months of starting treatment.
(Source: The National Health Service)
Doing Our Part
The Jacinto Convit World Organization supports a free of cost molecular diagnostics program for the control and survival of pediatric patients affected by HIV, in poor developing countries. Through a strategic partnership with local NGOs, specialized tests are performed to detect through PCR, viral proteins in the peripheral blood of the patient like envelope (ENV) and structural (GAG) proteins.
To date, 2 genetic sequences based on these diagnostics are published in GenBank, a world reference sequence database of the National Center for Biotechnology Information (NIH); contributing to scientific advances in infectious diseases.
