3.1.2 Viral Diseases

Measles

• Symptoms: Measles causes a high fever and a characteristic red skin rash. It can lead to serious complications such as pneumonia (lung infection), encephalitis (brain infection), and blindness.
• How it is Spread: Measles is highly contagious and spreads through droplet infection when an infected person coughs or sneezes.
• Prevention: Vaccination is the most effective way to prevent measles. Children are routinely vaccinated at a young age to reduce transmission and protect against the disease.

HIV (Human Immunodeficiency Virus)

• Symptoms: Initially, HIV may cause flu-like symptoms. Over time, the virus attacks and weakens the immune system, eventually leading to AIDS (Acquired Immunodeficiency Syndrome), where the body becomes vulnerable to a range of infections and diseases.
• How it is Spread: HIV is transmitted through sexual contact or the exchange of bodily fluids such as blood. Common ways of transmission include unprotected sex, sharing needles, and blood transfusions with contaminated blood.
• Prevention:
  • Preventing Spread: The spread of HIV can be reduced by using condoms, not sharing needles, screening blood before transfusions, and encouraging mothers with HIV to bottle-feed rather than breastfeed their babies.
  • Preventing Progression to AIDS: The use of antiretroviral drugs can significantly slow down the replication of the virus in the body, helping to prevent the progression to AIDS.

Tobacco Mosaic Virus (TMV)

• Symptoms: TMV causes discolouration of the leaves in plants, such as tomatoes. The affected areas of the leaves cannot photosynthesise, leading to a reduction in the plant's yield.
• How it is Spread: TMV spreads through contact between infected and healthy plants. Insects can also act as vectors, carrying the virus from one plant to another.
• Prevention:
  • Maintaining good field hygiene and implementing effective pest control measures can help prevent the spread of TMV.
  • Growing TMV-resistant plant strains is another effective way to protect crops from the virus.