13.3 - Viral Diseases

HIV and AIDS

• HIV (human immunodeficiency virus) attacks the immune cells - a type of white blood cell.
• There is no cure, but the infection can be controlled with antiretroviral (antiviral) drugs, which stop the virus replicating inside the body.

How HIV is spread

• Through sexual contact.
• Through the exchange of body fluids such as blood - for example when drug users share needles.

Its spread can be reduced by using a condom during sex, and by people who inject drugs not sharing needles.

The stages of infection

1. At first HIV causes a flu-like illness for a few weeks.
2. The person then often feels well for several years while the virus attacks the immune cells.
3. If the immune system becomes so badly damaged that the body can no longer fight off other infections or cancers, the person has late-stage HIV infection, or AIDS (acquired immune deficiency syndrome).
4. With a weakened immune system, a person with AIDS becomes vulnerable to other infections such as tuberculosis and pneumonia.

Influenza and the common cold

• Influenza (flu) is caused by the influenza virus.
• The common cold is also caused by viruses.
• Both are spread in the air, in droplets produced when an infected person coughs or sneezes.

Vaccination against flu

• A flu vaccination is offered to targeted groups, such as:
  • Older people
  • Those with certain health conditions
• These groups are offered it because they are most at risk from complications.

Human papilloma virus (HPV)

• HPV is a virus spread by sexual contact.
• An HPV infection often clears up on its own, but some infections cause changes in cells that can lead to cancer.
• Nearly all cases of cervical cancer are caused by HPV.
• The HPV vaccine protects against the types of the virus most linked to cancer.