Where Do Viruses Come From?

Viruses have existed since ancient times, yet their exact origins remain one of biology's open questions. Every virus carries genetic material — RNA or DNA — wrapped in a protein shell, but how that arrangement first arose is still debated. Three leading hypotheses frame the discussion:

  • Progressive (Escape) Hypothesis — viruses descended from genetic elements that learned to move between cells.
  • Regressive (Reduction) Hypothesis — viruses are stripped-down remnants of once-complete cellular organisms.
  • Virus-First Hypothesis — viruses co-evolved alongside their cellular hosts from the very beginning.

HIV and AIDS: The Basics

AIDS (Acquired Immunodeficiency Syndrome) is caused by HIV (Human Immunodeficiency Virus), a retrovirus that targets the immune system's CD4 T-cells. As those cells are destroyed, the body loses its ability to fight off ordinary infections and disease. HIV is present throughout an infected person's body but transmits only through specific bodily fluids — semen, vaginal fluids, blood, and breast milk — via three main routes:

  • Sexual contact — exchange of infected bodily fluids during intercourse.
  • Perinatal transmission — from mother to child during pregnancy, birth or breastfeeding.
  • Blood transmission — through infected blood entering the body by any means.
Close-up scientific illustration of the HIV retrovirus particle structure showing surface glycoproteins
The HIV retrovirus targets and destroys CD4 T-cells, dismantling the body's immune defences over time.

Stages and Symptoms

HIV progresses through three recognisable stages: acute HIV infection, chronic (clinically latent) HIV infection, and AIDS, the most advanced stage.

1Acute stage — flu-like fever, rash, joint pain, sore throat, and fatigue appear weeks after infection
2Asymptomatic stage — no visible symptoms, but the virus continues replicating and damaging the immune system
3Late-stage AIDS — severe immune failure; symptoms include chronic diarrhoea, high fever, blurred vision, and persistent night sweats
Prevention is straightforward: practise safe sex, get tested regularly, and know your partner's status. Early detection and treatment can prevent progression to AIDS entirely.

This article is general information gathered from reputable public sources — not a substitute for advice from a qualified healthcare provider.

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