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When it comes to A2/A-level Biology, do you know how does HIV cause AIDS?
Transmission
- HIV can be transmitted via sexual contact.
- Through infected blood.
- Through intravenous drug use.
- From a mother to a foetus, during birth or through breastfeeding.
Symptoms
Stages of Infection
Stage 1: Acute HIV Syndrome
- Experience symptoms in the first few weeks.
- HIV antibodies appear in the blood 3-12 weeks after infection.
Stage 2: Asymptomatic Stage
- All symptoms disappear.
- The virus replicates, infecting CD4 T helper cells.
- Secondary infections develop.
Stage 3: Symptomatic Disease
- Immune system starts to fail.
- T helper cell count falls rapidly.
- Patients suffer HIV-related symptoms.
Stage 4: Advanced AIDS
- Severe symptoms appear (weight loss, dementia, cancers, TB).
Final Stage: Death
Causes of AIDS
- HIV binds to CD4 receptors on the T helper cells and infects them.
- HIV takes over the host DNA and replicates.
- When the new virus leaves the host cell, it is destroyed.
- T killer cells destroy some of the heavily infected T helper cells.
- The number of T helper cells decreases so macrophages and T killer cells are not activated.
- The T helper cells cannot function properly.
- Increased vulnerability to secondary infections.
Controlling Infection
- Education programmes
- Less promiscuous sex
- Use of condoms
- Use of clean needles
That's the end of the topic!
Drafted by Bonnie (Biology)