When Is HIV Most Contagious?

Reviewed on 6/23/2022

Multicolor rendering of the HIV virus
HIV is most contagious in the first stage of HIV, when there is a large amount of HIV in the blood within the first few months of being infected.

HIV (human immunodeficiency virus) is a virus that attacks the body's immune system. People with untreated HIV infection don’t fight off infections or cancer as well as healthy people and can become sick easily. 

If HIV is not treated, it progresses through three stages. 

Stage 1: Acute or primary HIV Infection

  • There is a large amount of HIV in the blood within the first few months of being infected
  • HIV is most contagious at this stage
  • Flu-like symptoms can occur, though not everyone will feel sick and many may not even know they are infected
  • Only antigen/antibody tests or nucleic acid tests (NATs) can diagnose acute infection

Stage 2: Chronic HIV Infection (asymptomatic HIV infection or clinical latency)

  • HIV is active but reproduces at very low levels
  • Symptoms may not occur during this phase
  • Without HIV medication, stage 2 can last a decade or longer in some patients
  • HIV can be transmitted in this phase
  • At the end of stage 2, the amount of HIV in the blood (the viral load) increases and the CD4 cell count decreases
  • Symptoms may occur as virus levels increase in the body, and the person progresses to stage 3
  • If HIV medications are taken as prescribed, patients may not progress to stage 3

Stage 3: Acquired Immunodeficiency Syndrome (AIDS)

  • This is the most severe phase of HIV infection
  • AIDS damages the body’s immune system and patients can develop an increasing number of severe illnesses (called opportunistic infections)
  • AIDS is diagnosed when CD4 cell counts drop below 200 cells/mm or if patients develop certain opportunistic infections
  • People with AIDS may have a high viral load and be highly infectious
  • Without treatment, the life expectancy for AIDS patients is about three years
  • In the U.S., progression to this stage is uncommon because of the availability of antiretroviral therapy (ART) medications

What Are Symptoms of HIV?

The first symptoms of HIV (human immunodeficiency virus) usually occur two to four weeks after a person is infected with the virus and are called acute or primary HIV infection. Acute HIV infection symptoms tend to be mild and last about 2 weeks. People may not even realize they have HIV at this point. 

Early symptoms of HIV may include: 

After several years, if HIV is not treated, other symptoms can develop:

What Is the Treatment for HIV?

HIV (human immunodeficiency virus) is treated with different combinations of antiretroviral medicines to help keep HIV infection controlled.

Early HIV infection is usually treated with an antiretroviral therapy (ART) regimen.


What is HIV? See Answer

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Reviewed on 6/23/2022

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