- Viral Diseases (126.96.36.199)
- HIV infection initially causes flu-like illness and the virus attacks the body's immune cells (white blood cells) if it is not successfully controlled with antiretroviral drugs.
- AIDS occurs when the body's immune system becomes so badly damaged it can no longer deal with other infections or cancers.
- Explain how HIV is spread (by sexual contact or exchange of body fluids such as blood which occurs when drug users share needles)
- TMV is a widespread plant pathogen affecting many species of plants including tomatoes and that it gives a distinctive 'mosaic' pattern of discoloration on the leaves which affects the growth of the plant due to lack of photosynthesis.
- Measles is a viral disease showing symptoms of fever and a red skin rash and that it is a serious illness that can be fatal if complications arise (which is why most young children are vaccinated against measles).
- Describe how: the measles virus is spread by air (by inhalation of droplets from sneezes and coughs).