more on HIV, not on the spec (2.4 extra)

how is HIV transmitted?

• direct sexual contact with an infected person, without the use of a condom.

• exchange of bodily fluids, via:

  • blood transfusion.

  • sharing infected needles and syringes.

  • breastmilk from HIV positive mothers.

how can we prevent the spread of HIV?

• abstain from sex.

• use condoms.

• don’t share needles and syringes.

• screen blood for transfusion.

• antiretroviral drugs.

what does SIV stand for?

what is SIV?

• Simian Immunodeficieny Virus.

• it is a HIV-like virus that infects monkeys and apes and can cause a disease similar to AIDS.

• SIV cannot infect humans and HIV cannot infect monkeys.

where did HIV originate from?

when did HIV come about?

western central Africa the early 20th century

how is HIV believed to have started?

• it is commonly accepted that SIV was transmitted from African monkeys to humans.

• this is possibly due to humans in Africa eating/slaughtering mangabeys and chimpanzees.

• once SIV was in humans it evolved into HIV-1 and HIV-2 via random mutation.

what are the 3 phases of HIV infection?

• acute HIV infection

• chronic HIV infection

• progression to AIDS

what is acute HIV also known as?

primary infection

what is chronic HIV also known as?

clinic latent infection

explain acute HIV infection

• flu-like symptoms within 2 - 4 weeks after the virus enters the body.

• can last 3 - 12 weeks after infection.

• rapid viral multiplication → loss of helper T-cells.

• increase in HIV antibodies, now HIV positive.

• cytotoxic T-cells (T-killer cells) destroy infected helper T-cells, thus reducing the rate of viral multiplication.

explain the symptoms of acute HIV infection

flu-like symptoms:

• fever

• headache

• sore throat

• swollen lymph glands (nodes)

• rash

• sweats

explain chronic HIV infection

• rapid viral multiplication continues; 109 new viruses produced every day.

• continued loss of helper T-cells.

• active virus so the HIV positive person is infectious.

• can last for up to 20 years.

• around 1 mutation every replication cycle, which may cause antibodies to no longer recognise the virus if the mutation means that structure of the antigens changes.

• reduced immune system efficiency so minor infections like colds become harder to combat.

what are the symptoms of chronic HIV?

• oral yeast infection (thrush)

• shingles (herpes zoster)

• pneumonia

• tuberculosis

• swollen lymph glands (nodes)

• diarrhoea

• weight loss

• fatigue

explain the progession to AIDS

• an increase in the number of viruses and an ever declining number of helper T-cells which weakens the immune system.

• leads to opportunistic infections.

what are the symptoms of progession to AIDS?

• opportunistic diseases:

  • tuberculosis

  • pneumonia

• persistent diarrhoea.

• vomitting.

• weight loss.