- Weakens the immune system making someone vulnerable to infection.
- Attaches to CD4 receptors on T-helper cells preventing cytokines from being released needed for T-killer cell and B-effector cell activation
- Turns the cell into a 'virus factory' and then destroys it.
- T-killer cells also destroy infected cells lowering the T-helper cell count.
- Spread by bodily fluids: sexual contact, infected blood or breast milk, during birth or in foetus
- Stage 1: Acute HIV. 1st few weeks ill, fever, tired and swollen glands. HIV antigens in blood mean HIV +ve
- Stage 2: Chronic stage. Weeks to years depending on age, health and treatment. No symptoms. Virus replicated and infects.
- May develop secondary infections.
- Stage 3: Symptomatic disease. Immune system starts to fail and T-helper cell levels drop. HIV Symptoms: diarrhoea, fatigue, weight loss and night sweats.
- Stage 4: Advanced AIDS. Major weight loss, dementia as brain cells infected and cancers like Kaposi's sarcoma. Secondary infections like TB and meningitis. Death.
- Mutates rapidly
- Research limited: not a lot of similar viruses in animals
- Antiviral drug therapy and stimulating the immune system expensive.
- Limiting spread through education and better hygiene e.g. safe sex and clean needles.
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