Named diseases

Measles (virus)

: virus.
Symptoms: fever and a red skin rash. Measles is a serious illness and can be fatal if complications arise.
Spread: by inhaling droplets from the sneezes and coughs of an infected person.
Control: most young children are vaccinated against measles. There is no specific treatment, so infected people are isolated.

: virus (human immunodeficiency virus).
Symptoms: at first a flu-like illness. The virus then attacks the body's immune cells. If untreated, the immune system becomes so badly damaged that it can no longer deal with other infections or cancers — this is late-stage HIV, or .
Spread: by sexual contact or exchange of body fluids such as blood, e.g. when drug users share needles.
Control: stop the virus multiplying. Spread is reduced by using condoms and not sharing needles.

: virus that infects many plants, including tomatoes and tobacco.
Symptoms: a distinctive 'mosaic' pattern of discolouration on the leaves. The discoloured parts can't photosynthesise, so the plant's growth is reduced.
Spread: by contact between infected and healthy plants, or on hands and tools.
Control: remove and destroy infected plants, wash hands and tools, and grow resistant varieties. There is no treatment.

: bacterium.
Symptoms: fever, abdominal cramps, vomiting and diarrhoea, caused by the the bacteria secrete.
Spread: in food — e.g. undercooked meat or eggs, or food prepared in unhygienic conditions.
Control: in the UK, poultry are vaccinated against salmonella. Cook food thoroughly and prepare it hygienically.

: bacterium; a .
Symptoms: a thick yellow or green discharge from the vagina or penis, and pain on urinating.
Spread: by sexual contact.
Control: treated with antibiotics — originally penicillin, but many resistant strains have now appeared. Spread is reduced by using condoms and by treating infected people (and their partners).

: fungus that infects rose plants.
Symptoms: purple or black spots on the leaves. The leaves often turn yellow and drop early, so less photosynthesis happens and the plant doesn't grow well.
Spread: spores are carried in the environment by water or wind.
Control: spray with , and remove and destroy affected leaves.

: protist.
Life cycle: part of the protist's life cycle takes place inside a mosquito, which acts as the vector. When an infected mosquito bites a person, the protist enters their blood.
Symptoms: recurrent episodes of fever. Malaria can be fatal.
Control: stop mosquitoes breeding (e.g. drain standing water, use insecticides), use mosquito nets to avoid being bitten, and take antimalarial drugs.