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Human Immunodeficiency Virus (HIV) and AIDS

10 min read

HIV and AIDS

HIV is the Human Immunodeficiency Virus. It attacks the helper T lymphocytes of the immune system, so the body cannot defend itself well. A person infected with HIV gets AIDS (Acquired Immune Deficiency Syndrome) when the immune system is so damaged that it cannot fight infections and certain cancers.

HIV and how it attacksHIV is a virus with a lipid envelope covered with proteins, a protein coat and two strands of RNA with the enzyme reverse transcriptase inside. It attaches to a helper T lymphocyte, enters it, uses reverse transcriptase to make DNA from its RNA, and takes over the cell to make new virus particles. As the helper T cells are destroyed the body loses its defence against infections: AIDS.lipid envelopeprotein coatRNA + reverse transcriptasesurface proteinshelper T cellenters

Transmission and prevention

HIV is spread byHIV is not spread by
Unprotected sexual contactHandshakes, hugs, kisses
Sharing needles or bladesSharing food, cups or toilets
Infected blood transfusionMosquito bites
From mother to child in pregnancy, birth or breastfeedingCoughing or sneezing

It can be prevented by abstinence, being faithful to one uninfected partner, using condoms every time, not sharing sharp instruments, screening blood for transfusion, and giving medicine to infected mothers during pregnancy.

Living with HIV

There is no cure yet, but medicines called antiretrovirals (ARVs) stop the virus from multiplying. A person who takes them every day stays healthy and has a normal life, and the amount of virus can become too small to pass on. A test is the only way to know one’s status. People living with HIV must be treated with care and respect; stigma and discrimination make people afraid to be tested.

How the body fights a pathogenA pathogen enters the body. A white blood cell engulfs and digests it. Other white blood cells make antibodies that stick to the pathogen and mark it for destruction. Memory cells stay in the blood so the next infection is dealt with quickly.pathogenwhite blood cell engulfs itantibodies stick ondestroyedMemory cells remember the pathogen for next time
An illustrative graph of the helper T cell count in an untreated person over the years.
Try itHelper T cells over time

An illustrative model: the number of helper T cells in a person with and without treatment.

Check yourself Which of these can spread HIV?
Check yourself Which cells does HIV attack?
Check yourself What do ARVs do?

Key terms

HIV
The virus that attacks the immune system.
AIDS
The disease stage when the immune system is badly damaged.
ARV
An antiretroviral medicine.
Stigma
Unfair negative attitudes towards a person.

Summary

  • HIV destroys helper T cells; AIDS is the advanced stage.
  • HIV is spread by sex, blood, and from mother to child.
  • It is prevented by abstinence, faithfulness, condoms and safe blood and needles.
  • ARVs allow people to live healthy lives; stigma must be avoided.
Evolution