Human Immunodeficiency Virus, or HIV, is a virus that targets the body’s immune system. Specifically, it infects and destroys a type of white blood cell called the CD4 cell, also known as a T cell. These cells are a fundamental component of the immune system. By weakening this defense system, HIV makes the body more susceptible to other illnesses.
The virus achieves this by inserting its own genetic material into the DNA of the CD4 cells, a process that defines it as a retrovirus. This action turns the body’s own immune cells into factories for producing more of the virus. Over time, as more CD4 cells are destroyed, the immune system’s ability to fight off pathogens diminishes significantly.
How HIV Spreads
HIV is transmitted through specific bodily fluids, and for transmission to occur, these fluids must come into direct contact with a mucous membrane, damaged tissue, or be introduced directly into the bloodstream. The fluids capable of carrying and transmitting the virus include blood, semen, pre-seminal fluid, rectal fluids, vaginal fluids, and breast milk. The most common ways this happens are through unprotected sexual contact and the sharing of needles or other equipment used for injecting drugs.
It is also possible for the virus to be passed from a mother to her child during pregnancy, childbirth, or breastfeeding, although medical interventions have greatly reduced this risk. The concentration of the virus in these fluids is a factor in the likelihood of transmission. The highest concentrations are found in blood and semen, which is why activities involving potential exposure to these fluids carry a higher risk.
A significant amount of misinformation surrounds HIV transmission, leading to unnecessary stigma. It is important to understand that HIV is not spread through casual contact. The virus cannot be transmitted through saliva, tears, or sweat, meaning activities like hugging, shaking hands, sharing food, or using the same toilet facilities pose no risk. HIV is also not transmitted by insects such as mosquitoes or ticks.
Stages of Infection
Stage 1: Acute HIV Infection
The initial stage of HIV infection, known as acute HIV infection, develops within two to four weeks after the virus enters the body. During this period, the virus multiplies rapidly, leading to a very high level of HIV in the blood, referred to as the viral load. This high viral load makes the risk of transmitting the virus to others particularly elevated as the body’s immune system begins to respond.
Many people in this stage experience flu-like symptoms, which can include fever, headache, muscle and joint pain, rash, or a sore throat. These symptoms are the body’s natural reaction to the infection and can last for a few weeks. However, some individuals may not experience any symptoms at all. Because the symptoms are non-specific, many people may not realize they have been infected with HIV.
Stage 2: Chronic HIV Infection
Following the acute phase, the infection moves into the chronic stage, also referred to as clinical latency. During this period, the virus continues to reproduce at much lower levels than in the acute stage. People in the chronic stage may not have any symptoms, and without medical intervention, this stage can last for a decade or longer, though the progression rate can vary.
Even though a person may feel well, the virus is still active and can be transmitted to others. The immune system is in a prolonged battle with the virus, and over time, the CD4 cell count gradually declines. For individuals who begin treatment, they can remain in this stage for several decades, managing the infection and preventing its advancement.
Stage 3: Acquired Immunodeficiency Syndrome (AIDS)
If left untreated, chronic HIV infection will progress to the final and most severe stage, Acquired Immunodeficiency Syndrome (AIDS). AIDS is not a separate virus but a condition that results from the severe damage HIV has caused to the immune system. A person is diagnosed with AIDS when their CD4 cell count drops below 200 cells per cubic millimeter of blood or if they develop certain opportunistic infections.
Opportunistic infections are illnesses caused by pathogens that a healthy immune system would be able to fight off. These can include severe forms of pneumonia, tuberculosis, and certain types of cancer. At this stage, the body is highly vulnerable to a wide range of infections. Without treatment, the prognosis for individuals who have progressed to AIDS is poor.
Testing and Diagnosis
The only definitive way to know if you have HIV is to get tested. Several types of tests are used to diagnose HIV, each with a “window period,” which is the time between potential exposure and when the test can accurately detect the virus. The three primary types are nucleic acid tests (NATs), antigen/antibody tests, and antibody-only tests.
A Nucleic Acid Test (NAT) looks for the actual virus in the blood. This test can detect HIV infection sooner than other types, within 10 to 33 days after an exposure. Because of its cost, it is not commonly used for routine screening but may be ordered for someone who has had a recent high-risk exposure and is showing early symptoms.
The most common type of lab test is the antigen/antibody test. This test looks for both HIV antigens and antibodies produced by the immune system. A lab-based antigen/antibody test using blood from a vein can detect HIV infection 18 to 45 days after exposure. Rapid antigen/antibody tests, using a finger prick blood sample, can detect infection 18 to 90 days after exposure.
Antibody-only tests look for the presence of antibodies to HIV in blood or oral fluid. Most rapid self-tests are antibody tests. It can take 23 to 90 days for the body to develop enough antibodies to be detected by this type of test. If an initial test result is positive, a follow-up confirmatory test is always performed to ensure the diagnosis is accurate.
Treatment and Long-Term Outlook
While there is no cure for HIV, the infection can be effectively managed with medical treatment. The standard of care for HIV is Antiretroviral Therapy (ART), which involves taking a combination of medicines every day. These medications work by preventing the virus from replicating, which reduces the amount of HIV in the body, known as the viral load.
The primary goal of ART is to reduce the viral load to an undetectable level. An undetectable viral load means the amount of HIV in the blood is so low that a standard lab test cannot measure it. Reaching and maintaining an undetectable viral load is the best way a person with HIV can stay healthy and live a long life.
A person with an undetectable viral load has effectively no risk of transmitting HIV to a sexual partner. This concept is known as Undetectable = Untransmittable (U=U). This scientific consensus has transformed the lives of people with HIV, allowing them to have sexual relationships without fear of passing on the virus. Consistent adherence to the prescribed ART regimen is necessary to maintain an undetectable status.
Thanks to the effectiveness of ART, HIV has become a manageable chronic health condition. People with HIV who are diagnosed early, start treatment promptly, and take their medication as prescribed can expect to live long, healthy lives. Their life expectancy is similar to that of someone without HIV.