Acute HIV Infection

Overview

Acute HIV infection, also called primary or early HIV infection, is the first stage of infection with the human immunodeficiency virus (HIV). It usually develops within two to four weeks after exposure, when the virus is multiplying rapidly and the immune system is just beginning to respond.

During this stage many people develop a flu-like illness, though some have no symptoms at all. Because the amount of virus in the body is very high, this is also a period when HIV can be passed on more easily. Recognizing acute HIV infection matters because early diagnosis allows treatment to begin promptly, which protects health and greatly reduces the risk of transmitting the virus to others.

Symptoms

Symptoms, when present, resemble those of the flu or mononucleosis and usually last from a few days to a few weeks.

• Fever
• Sore throat
• Skin rash
• Swollen lymph nodes
• Muscle and joint aches
• Fatigue
• Headache
• Mouth sores or ulcers
• Night sweats
• Sometimes nausea, diarrhea, or weight loss

Because these symptoms are common to many viral illnesses, acute HIV infection is easy to miss. Anyone with these symptoms and a possible recent exposure should consider HIV testing.

Causes

Acute HIV infection is caused by recent infection with HIV. The virus is spread through specific body fluids of a person who has HIV, including blood, semen, vaginal and rectal fluids, and breast milk. Common ways HIV is transmitted include:

• Sexual contact: Without consistent condom use or preventive medication.
• Sharing needles or syringes: For injecting drugs.
• From parent to child: During pregnancy, birth, or breastfeeding.
• Exposure to infected blood: Such as accidental needlestick injuries.

HIV is not spread through casual contact such as hugging, sharing food, or touching surfaces.

Risk Factors

• Sex without a condom or preventive medication, especially with a partner of unknown HIV status
• Multiple sexual partners
• Sharing needles, syringes, or other injection equipment
• Having another sexually transmitted infection
• A recent known exposure to HIV

Preventive medication (PrEP) can substantially lower the risk for people at higher risk of exposure.

Diagnosis

Acute HIV infection can be missed by older tests that only detect antibodies, because antibodies take time to develop. Newer tests can detect infection earlier.

• Combination antigen/antibody tests: Detect both a viral protein and antibodies, allowing earlier diagnosis.
• HIV RNA (viral load) tests: Detect the virus itself and can identify infection very early.
• Repeat testing: If an early test is negative but exposure is suspected, follow-up testing is recommended.

If you may have been recently exposed, tell the testing provider so the appropriate early-detection test can be used.

Treatment

HIV is treated with antiretroviral therapy (ART), a combination of medicines taken daily that controls the virus. Starting treatment early, including during acute infection, is now standard.

• Antiretroviral therapy: Suppresses the virus, protects the immune system, and improves long-term health.
• Reducing transmission: Effective treatment can lower the virus to undetectable levels, at which point it is not passed on through sex.
• Post-exposure prophylaxis (PEP): If started within 72 hours of a possible exposure, a short course of medicine may prevent infection from taking hold.
• Ongoing care: Regular monitoring and support to maintain treatment.

With consistent treatment, people with HIV can live long, healthy lives.

Prevention

• Use condoms consistently and correctly
• Consider pre-exposure prophylaxis (PrEP) if you are at higher risk
• Seek post-exposure prophylaxis (PEP) within 72 hours of a possible exposure
• Do not share needles, syringes, or other injection equipment
• Get tested regularly and know your and your partner's status
• If you have HIV, taking treatment to reach an undetectable level prevents passing it on through sex

When to See a Doctor

See a healthcare provider promptly if you have a flu-like illness within a few weeks of a possible HIV exposure, or if you have ongoing risk factors and have not been tested. Ask specifically about tests that can detect early infection.

If you think you have been exposed to HIV within the last 72 hours, seek care urgently, as post-exposure medication may prevent infection but must be started as soon as possible. HIV testing and treatment are widely available and confidential.

Related Topics

Frequently Asked Questions

References

1. Centers for Disease Control and Prevention (CDC). About HIV.
2. HIV.gov, U.S. Department of Health and Human Services.
3. National Institute of Allergy and Infectious Diseases (NIAID).
4. MedlinePlus, U.S. National Library of Medicine. HIV/AIDS.