Viral Diseases: HIV | 9-1 GCSE Biology | OCR, AQA, Edexcel

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Close to unlock the full GCSE Biology & Combined Science videos series for the new 9-1 OCR, AQA and Edexcel specifications.

They key points covered in this video include:
1. Viral Diseases
2. HIV
3. Preventing HIV
4. TMV
5. TMV
6. Measles
7. Ebola
8. Preventing Ebola

Viral Diseases

Viruses are not living cells – they simply use the machinery of host cells to replicate themselves, causing damage to the host cells in the process. Viral diseases can affect both animals and plants. Examples include HIV, measles, tobacco mosaic virus (TMV) and Ebola.


Human Immunodeficiency Virus (HIV) is a viral disease and example of a sexually transmitted disease (STD) or infection (STI). The virus gets into and reproduces inside ‘host’ cells. Specifically, it attacks white blood cells which are a key part of the body’s immune response. Symptoms are initially flu-like, though some may not experience any symptoms at all for several years. However, if the disease is not controlled with antiretroviral drugs (which stop the virus replicating), the body’s immune system gets badly damaged. When the immune system can no longer fight disease, we call it Acquired Immunodeficiency Syndrome (AIDS) or late stage HIV infection.

Preventing HIV

HIV is spread via bodily fluids, e.g. during sexual contact or when needles are shared. Avoiding either will help prevent someone from getting HIV.

Tobacco Mosaic Virus

Tobacco mosaic virus (TMV) is a virus which affects many plants including tomatoes. It causes a mosaic pattern on the leaves which means that the plant cannot photosynthesise as well. As a result, the plant’s growth is stunted

Preventing Tobacco Mosaic Virus

There are several ways people can reduce the spread of TMV. This includes: Removing infected plants and leaves. Sterilising planting equipment. Planting crops which are resistant to TMV around areas which are infected.


Measles is a viral disease which causes fever and a red skin rash. It is spread when someone inhales droplets in the air produced by coughing or sneezing. It may be a fatal because it can lead to other serious diseases, but luckily there is a vaccination for measles.


Ebola is a virus which causes haemorrhagic fever. This is a fever which causes you to bleed internally or from the eyes, nose or mouth.

Preventing Ebola

Ebola can spread via contact with infected bodily fluids (e.g. blood, vomit, saliva). This can be prevented by quarantining infected individuals, and sterilising surfaces they come into contact with. Medical staff must wear protective clothing and regularly wash their hands.


1. Human Immunodeficiency Virus (HIV) leads to Acquired Immunodeficiency Syndrome (AIDS) if left untreated
2. AIDS describes the condition where the body’s immune system can no longer fight disease
3. HIV is spread by sexual contact or by sharing needles
4. Viruses can also affect plants – for example, the Tobacco Mosaic Virus causes leaves to be patchy and stunts growth
5. Measles is a viral disease which causes rashes – it is spread by droplets in the air – there is a vaccination to prevent it being widespread
6. Ebola causes haemorrhagic fever – it is an example of a disease that can spread via infected bodily fluids
7. To prevent the spread of Ebola, contact with an infected individual or infected surface must be avoided at all times


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