HIV and AIDS
HIV (human immunodeficiency virus) attacks the body's immune system. With modern treatment, people with HIV can live long, healthy lives and prevent transmission to others. Without treatment, HIV progresses to AIDS over time.
Table of Contents
Quick Facts
- Type: Chronic viral infection
- ICD-10: B20–B24
- Transmission: Blood, sex, mother-to-child
- Treatment: Antiretroviral therapy (ART)
Overview
HIV (human immunodeficiency virus) infects CD4 cells, a critical part of the immune system. Over time, untreated HIV reduces immune function, allowing infections and cancers that the body would normally control. AIDS (acquired immunodeficiency syndrome) is the most advanced stage, defined by a CD4 count below 200 or specific opportunistic illnesses.
With antiretroviral therapy (ART), the virus can be suppressed to undetectable levels. People with an undetectable viral load do not sexually transmit HIV — a concept known as U=U (undetectable = untransmittable).
Symptoms
Acute HIV infection (2–4 weeks after exposure)
- Flu-like illness: fever, fatigue, sore throat, body aches
- Swollen lymph nodes
- Rash
- Headache, nausea
Some people have no symptoms at this stage.
Chronic infection
Many people feel well for years. Without treatment, immune decline eventually leads to opportunistic infections, weight loss, persistent diarrhea, and other illnesses.
Transmission
HIV is transmitted through:
- Vaginal, anal, or oral sex without protection
- Sharing needles or syringes
- Mother to child during pregnancy, birth, or breastfeeding
- Occupational exposure (rare with proper precautions)
HIV is not transmitted through saliva, sweat, tears, casual contact, sharing food, or insect bites.
Diagnosis
- Fourth-generation antibody/antigen tests — detect HIV within ~2–4 weeks of exposure
- HIV RNA (viral load) testing — detects infection earlier
- Rapid in-home tests
- CD4 count and viral load to guide treatment
Routine HIV testing is recommended for all adults at least once in a lifetime, more often for those at higher risk.
Treatment
The cornerstone of HIV treatment is antiretroviral therapy — combinations of medications taken daily that prevent viral replication.
- Most regimens use 2–3 medications in one daily pill
- Long-acting injectable options now available every 1–2 months
- Treatment is recommended for everyone with HIV, regardless of CD4 count
- Vaccinations and prevention of opportunistic infections are part of comprehensive care
Prevention
- Pre-exposure prophylaxis (PrEP) — daily pill or injection that reduces sexual HIV risk by ~99%
- Post-exposure prophylaxis (PEP) — 28-day course started within 72 hours of exposure
- Consistent condom use
- Treatment as prevention (U=U)
- Sterile needle programs and harm-reduction services
- Antenatal HIV testing and treatment to prevent mother-to-child transmission
When to See a Doctor
Get tested if you may have been exposed, or if you have not had an HIV test in adulthood. If you may have had a recent high-risk exposure (within 72 hours), seek immediate care to discuss PEP.
Frequently Asked Questions
There is no broadly available cure, but treatment can fully suppress the virus. A small number of people have been functionally cured through stem cell transplants for unrelated cancers; this is not a standard treatment due to its risks.
Undetectable = Untransmittable. People taking effective HIV treatment with a consistently undetectable viral load do not sexually transmit HIV.
Daily oral PrEP reduces sexual HIV acquisition by about 99% when taken as prescribed. It is also highly effective for people who inject drugs.
HIV is the virus; AIDS is the most advanced stage of infection, defined by a CD4 count below 200 or by specific opportunistic illnesses. With modern treatment, very few people in countries with widespread ART access ever progress to AIDS.
References
- Centers for Disease Control and Prevention. HIV Basics.
- World Health Organization. HIV/AIDS Fact Sheet.