Measles

Measles is a viral disease that can cause fever and a red skin rash. It can be serious, and complications can sometimes be fatal.

An infected person releases droplets when they cough or sneeze. Another person can inhale these droplets, allowing the virus to enter their body and potentially cause infection.

Young children are commonly vaccinated against measles to protect them from the disease.

Tobacco mosaic virus

Tobacco mosaic virus (TMV) is a widespread plant pathogen: a virus that causes disease in plants. It infects many plant species, including tomato plants.

Infected leaves develop a distinctive mosaic pattern of discolouration. The affected leaves carry out less photosynthesis, so the plant makes less glucose for growth. As a result, the plant grows less.

HIV transmission and control

HIV is a virus that attacks cells of the immune system, weakening the body’s ability to defend itself. It can be transmitted through sexual contact or through the exchange of certain body fluids. For example, sharing needles can transfer infected blood from one person to another.

After infection, HIV can initially cause a flu-like illness. The virus then continues to damage immune cells. If the immune system becomes severely damaged, the infection can progress to AIDS. At this stage, the body cannot deal effectively with other infections or some cancers.

Antiretroviral drugs control HIV by reducing the amount of virus in the body. This reduces damage to immune cells and helps prevent progression to AIDS.