Hiv symptoms and causes
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HIV symptoms acute chronic infection stages
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HIV causes transmission pathophysiology risk factors
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HIV: Symptoms and Causes
What is HIV?
HIV (Human Immunodeficiency Virus) is a retrovirus that attacks the immune system, specifically CD4⁺ T lymphocytes, which are essential for maintaining effective immune function. Without treatment, HIV progressively depletes these cells, ultimately leading to AIDS (Acquired Immunodeficiency Syndrome) — a state of life-threatening immunodeficiency (Sexually Transmitted Infections Guidelines, p. 26).
Causes & Transmission
HIV is caused by infection with HIV-1 or HIV-2 virus. It is transmitted through specific routes:
1. Sexual Transmission
- Unprotected vaginal, anal, or oral sex with an infected person
- Anal intercourse carries the highest risk
- Risk is amplified when the infected partner has a high viral load (untreated infection)
2. Blood-to-Blood Contact
- Sharing needles, syringes, or drug injection equipment
- Needlestick injuries in healthcare settings — risk increases with:
- Device visibly contaminated with blood
- Hollow-bore needle placed directly in a vein or artery
- Deep injury
- High viral load in the source patient (Harrison's, p. 5776)
- Blood transfusions (rare in countries with screening programs)
3. Mother-to-Child (Vertical) Transmission
- During pregnancy, childbirth, or breastfeeding
HIV is NOT transmitted through:
- Casual contact (hugging, handshakes, sharing utensils)
- Air, water, or saliva
- Mosquitoes or insects
Symptoms by Stage
HIV infection progresses through three main stages:
Stage 1 — Acute HIV Infection (2–4 weeks after exposure)
This is the most infectious period. Symptoms resemble a flu-like or mononucleosis-like illness and may include (Sexually Transmitted Infections Guidelines, p. 26):
| Symptom | Details |
|---|---|
| Fever | Most common symptom |
| Malaise / Fatigue | Profound tiredness |
| Lymphadenopathy | Swollen lymph nodes |
| Pharyngitis | Sore throat |
| Skin rash | Maculopapular, often on trunk |
| Arthralgia / Myalgia | Joint and muscle pain |
| Headache | Common |
| Mouth ulcers | Painful sores |
Most people experience at least one symptom; however, some may be asymptomatic and not recognize they are ill. This stage is frequently missed or misdiagnosed as a common viral illness.
Stage 2 — Chronic (Clinical Latency) Stage
- Can last 10+ years without treatment
- The virus continues to replicate at low levels
- The person may be largely asymptomatic but can still transmit HIV
- CD4⁺ T-cell count gradually declines
- Late in this stage, symptoms like persistent swollen lymph nodes, weight loss, fatigue, and recurrent infections may appear
Stage 3 — AIDS
Defined by a CD4⁺ T-cell count < 200 cells/mm³ (normal: 500–1,500) or the presence of AIDS-defining conditions, including:
- Opportunistic infections: Pneumocystis jirovecii pneumonia (PCP), Toxoplasmosis, Cryptococcal meningitis, CMV retinitis, TB
- Cancers: Kaposi's sarcoma, Non-Hodgkin's lymphoma, cervical cancer
- Severe wasting syndrome
- AIDS dementia complex
Key Risk Factors
- Multiple sexual partners or unprotected sex
- Men who have sex with men (MSM)
- Injection drug use
- Pre-existing sexually transmitted infections (increase mucosal vulnerability)
- Born to an HIV-positive mother
- Healthcare workers with occupational exposure
Important Note
HIV is a manageable chronic condition with modern antiretroviral therapy (ART). People on effective ART can achieve an undetectable viral load, live a near-normal lifespan, and cannot sexually transmit the virus (U=U: Undetectable = Untransmittable). Early testing and treatment are critical.
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