AIDS (Acquired Immunodeficiency Syndrome) is a chronic and life-threatening condition caused by the Human Immunodeficiency Virus (HIV). HIV damages the immune system, making the body unable to fight infections and certain cancers. It spreads through unprotected sex, infected blood, shared needles, and from mother to child during pregnancy, childbirth or breastfeeding.
There is no permanent cure for HIV/AIDS. However, modern antiretroviral therapy (ART) helps people live long, healthy lives by controlling the virus.
Symptoms of HIV & AIDS
The symptoms depend on the stage of infection.
1. Acute HIV Infection (Primary Stage)
Occurs 2–6 weeks after exposure and resembles flu. Common symptoms include:
- Fever
- Headache
- Muscle and joint pains
- Sore throat and mouth ulcers
- Rash
- Swollen lymph nodes (mostly in the neck)
During this stage, the viral load is very high, making transmission more likely.
2. Clinical Latent Infection (Chronic HIV)
This stage may last 10 years or more if untreated. Symptoms are usually minimal except for:
- Persistent lymph node swelling
- General tiredness
3. Symptomatic HIV Infection
As CD4 cells decline, mild to moderate infections appear:
- Fever
- Fatigue
- Weight loss
- Diarrhea
- Thrush (oral fungal infection)
- Shingles
4. Progression to AIDS
AIDS occurs when the immune system is severely damaged (very low CD4 count). Opportunistic infections and cancers appear, such as:
- Severe night sweats
- Chronic diarrhea
- Persistent fever
- White patches or unusual mouth lesions
- Rapid weight loss
- Skin rashes or nodules
Pathogenesis (How HIV Damages the Body)
HIV primarily infects and destroys CD4 T cells, the central cells of the immune system. The process occurs in phases:
- Immediately after infection, the virus multiplies rapidly → high viral load
- CD4 count drops sharply due to viral attack and killing by CD8 T cells
- The immune system responds, causing temporary control of virus levels
- During chronic infection, continuous immune activation slowly destroys CD4 cells
Most CD4 cell loss occurs early in the infection, especially in the intestinal mucosa where many CD4 cells possess the CCR5 receptor that HIV uses to enter cells.
Causes & Transmission of HIV
1. Unprotected Sexual Contact
- Virus enters through genital or oral mucosa
- Higher chance if there are mouth sores or genital tears
2. Blood Transfusion
- Rare today due to strict blood screening
3. Sharing Needles
- Common among IV drug users
- Spreads HIV, Hepatitis B and Hepatitis C
4. Mother-to-Child Transmission
- During pregnancy, childbirth or breastfeeding
- Risk is greatly reduced with proper ART during pregnancy
Diagnosis
1. ELISA Test
Common screening method that detects HIV antibodies. Highly sensitive but may show false negatives in early infection.
2. Western Blot
Confirmatory test used after ELISA.
3. Viral Load Testing
- Measures amount of HIV RNA in blood
- Used to monitor treatment progress
4. CD4 Count
Normal: 500–1600 cells/mL A count below 200 cells/mL indicates AIDS.
5. PCR-based Tests
- Reverse transcriptase PCR
- Branched DNA assay
- Nucleic acid sequence–based assay
WHO Disease Staging
- Stage I: Asymptomatic
- Stage II: Minor skin and mucous infections
- Stage III: Chronic diarrhea > 1 month, severe infections, pulmonary TB
- Stage IV: Severe opportunistic infections, Kaposi’s sarcoma, esophageal candidiasis (AIDS-defining)
Treatment
HIV cannot be cured, but antiretroviral therapy (ART) effectively suppresses the virus.
Goals of Therapy
- Reduce viral load
- Increase CD4 count
- Delay progression to AIDS
- Prevent transmission
Classes of Antiretroviral Drugs
1. Non-Nucleoside Reverse Transcriptase Inhibitors (NNRTIs)
- Block reverse transcriptase enzyme
- Examples: Efavirenz, Nevirapine, Etravirine
2. Nucleoside Reverse Transcriptase Inhibitors (NRTIs)
- Faulty DNA building blocks that stop viral replication
- Examples: Abacavir, Emtricitabine, Tenofovir, Lamivudine, Zidovudine
3. Protease Inhibitors (PIs)
- Block viral protease enzyme needed for new virus particles
- Examples: Ritonavir, Darunavir, Atazanavir, Fosamprenavir
4. Entry/Fusion Inhibitors
- Prevent virus from entering CD4 cells
- Examples: Enfuvirtide, Maraviroc
5. Integrase Inhibitors
- Block integrase enzyme that inserts viral DNA into host DNA
- Example: Raltegravir
Prevention
- Practice safe sex — use condoms correctly
- Avoid sharing needles or syringes
- Ensure safe blood transfusion
- Pregnant HIV-positive women must take ART to protect the baby
- Healthcare workers must use gloves, masks and protective equipment
- Clean skin immediately after accidental exposure to blood
- Avoid breastfeeding if mother is HIV-positive (depending on guidelines)
Detailed Notes:
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