HIV (human immunodeficiency virus) is a dangerous infection that impairs the immune system and can leave people vulnerable to other infections and diseases. HIV becomes life-threatening once it progresses to its final stage, AIDS (acquired immunodeficiency syndrome).
By the end of 2019, close to 1.2 million people in the United States were living with HIV, according to the Centers for Disease Control and Prevention (CDC). (1)
Alarmingly, about 13 percent of people with HIV were not aware of it, the CDC notes.
This is partly because HIV initially produces symptoms that could easily be confused with other health issues — and some people who are infected go 10 years or more without having any symptoms at all. (2)
Early-Stage Symptoms of HIV Infection
Many people — about two in three — experience flu-like symptoms within two to four weeks of contracting HIV. (2) Known as acute retroviral syndrome (ARS) or primary HIV infection, these symptoms are the immune system’s natural response to the virus.
- Night sweats
- Muscle aches
- Sore throat
- Swollen lymph nodes
- Mouth ulcers (3)
During this very early period, HIV may not be detected by testing. This is because most HIV tests look for antibodies (the proteins the immune system generates in response to the virus) rather than the virus itself, and production of antibodies can take a few weeks. Most rapid tests and home tests are antibody tests. (2,4)
People who have contracted HIV are highly infectious at this early stage, even if they show no symptoms, because virus levels in their blood are extremely high. (3)
Effect on CD4 Cells
HIV infects the immune system’s white blood cells called CD4 cells (also called T-helper cells or T-4 cells), in order to replicate. It destroys those cells and causes CD4 levels to drop precipitously as large amounts of the virus proliferate.
Over time, the immune system will bring the HIV level down to what’s known as a viral set point, where the viral level remains relatively stable and CD4 levels increase. (3)
But your CD4 count may not return to what it was before infection. According to the U.S. Department of Health and Human Services guidelines, anti-retroviral therapy (ART) should be started as soon as possible after diagnosis with HIV. (5)
Testing and Diagnosis
If you think you’ve recently been exposed to the virus and you have flu-like symptoms, it’s important to ask for a test that can diagnose acute HIV.
There are three main tests for HIV: an antigen-antibody test, an antibody test, and a nucleic acid test (NAT).
An antigen-antibody test looks for both HIV antibodies (which are produced by the immune system in response to the virus) and the antigen p24 (small parts of the virus that trigger an immune-system response). After HIV infection, p24 can be detectable in the bloodstream before antibodies develop. An antigen-antibody test, done by a laboratory on blood drawn from a vein, can detect HIV 18 to 45 days after an exposure. It usually takes several days for the lab to produce the result.
A rapid antigen-antibody test uses blood from a finger prick, doesn’t require a lab, and can return results in 30 minutes or less. It can detect infection 18 to 90 days after an exposure.
An antibody test looks for HIV antibodies in the blood (either taken from a vein or from a finger prick) or oral fluid. Also referred to as a rapid HIV test or HIV oral self-test, it works in just 20 or 30 minutes to return a result and can detect infection 23 to 90 days after an exposure.
The NAT test analyzes a blood sample for the presence of HIV virus and can usually detect infection 10 to 33 days after an exposure. It is not routinely used for screening because it’s very expensive and requires several days to process. People may get an NAT test if they have had a high-risk exposure or a possible exposure with early signs of HIV infection. (4)
Clinical Latency Stage of HIV Infection
The symptoms during ARS may last for a few weeks, according to the National Institutes of Health. (6)
After this point, the infection progresses to the clinical latency stage, a period during which the virus reproduces at very low levels, but it is still active.
Also known as asymptomatic HIV infection or chronic HIV infection, the clinical latency stage typically causes no HIV-related symptoms. (3)
For people who are not taking any anti-retroviral medication for their infection, the clinical latency stage lasts for 10 years, on average, but it may progress quicker. (3)
ART, though, can keep the virus from growing and multiplying, prolonging the clinical latency state for several decades.
It's important to note that people living with HIV in the clinical latency stage are contagious and can still transmit the virus to other people. But, as the CDC notes, people who take ART exactly as prescribed and maintain an undetectable viral load have “effectively no risk of transmitting HIV to their HIV negative-partner through sex.” (6)
Late-Stage HIV Infection: AIDS Symptoms
The final stage of an HIV infection is AIDS, which occurs when the immune system is severely damaged.
It's diagnosed when your CD4 cells are very low or when you develop one or more opportunistic illnesses, such as pneumonia or tuberculosis, or specific cancers as a result of an HIV infection. (7)
People with AIDS may experience (2):
- Rapid weight loss
- Recurring fever
- Profuse night sweats
- Pronounced fatigue and weakness
- Prolonged swollen lymph glands
- Chronic diarrhea, which lasts more than a week
- Sores that develop in the mucous membranes of the mouth, anus, or genitals
- Blotches (red, brown, pink, or purplish) on the skin, under the skin, or inside the mouth, nose, or eyelids
- Neurological issues, including memory loss and depression
Many of these symptoms, particularly those that are severe, may be related to other opportunistic infections that develop due to the weakened immune system.
These opportunistic infections can include tuberculosis and pneumonia, as well as candidiasis (fungal infections caused by yeast), when the fungal infection affects the esophagus or lower respiratory tract. (7)
Additional reporting by Deborah Shapiro.
Editorial Sources and Fact-Checking
- HIV/AIDS: Basic Statistics. Centers for Disease Control and Prevention. August 4, 2021.
- Symptoms of HIV. HIV.gov. July 1, 2020.
- What Are HIV and AIDS? HIV.gov. June 5, 2020.
- Types of HIV Tests. Centers for Disease Control and Prevention. May 13, 2021.
- Guidelines for the Use of Antiretroviral Agents in Adults and Adolescents Living With HIV. ClinicalInfo. January 24, 2018.
- The Stages of HIV Infection. National Institutes of Health. June 1, 2021.
- AIDS and Opportunistic Infections. Centers for Disease Control and Prevention. May 20, 2021.