3.1.2 - Viral Diseases

How do viruses cause disease?

They invade and reproduce inside living body cells, leading to cell damage

Why is it especially important to prevent the spread of viral disease?

Scientists have not yet developed cures for many viral diseases.

What is measles?

A serious viral disease that can cause blindness and brain damage.

What are the main symptoms of measles?

Fever and a red skin rash

How is measles spread?

By air - through the inhalation of droplets from coughs and sneezes

What is HIV?

A virus that attacks and damages the immune system until it can no longer function properly. There is no cure or vaccine.

What are AIDS?

The condition resulting from a long-term HIV infection. There is no cure or vaccine.

How is HIV spread?

Direct sexual contact and the exchange of bodily fluids e.g. blood, breastmilk

How can the spread of HIV/AIDS be prevented?

• Use of condoms

• Screening of blood for transfusions

• Not sharing needles

• Bottle-feeding by HIV-positive mothers

• Use of antiretroviral drugs to prevent the development of AIDS

What is tobacco mosaic virus?

A plant pathogen that causes leaf discoloration when cells are damaged.

What are the problems with TMV?

Affected areas cannot photosynthesize, reducing the crop yield.

How is the spread of TMV controlled?

As there is no treatment, farmers grow TMV-resistant crop strains to avoid infection.

How is tobacco mosaic virus spread?

Contact between infected and healthy plants. Insects may act as vectors which transfer the virus between different plants.