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Communicable diseases - AQA Bacterial diseases

Pathogens are disease-causing viruses, bacteria, fungi or protists, which can infect animals and plants. Humans have an immune system, which can defend them from pathogens.

Part of Biology (Single Science)Infection and response

Bacterial diseases

Not all bacteria are which cause disease. Many , like those found in the intestines, are useful. All bacteria are , and do not have a . Unlike viruses, they are cells and so are larger but cannot be seen without a microscope.

Gonorrhoea

Gonorrhoea is a sexually transmitted disease (STD) caused by a bacterium. It is a common infection, especially amongst people aged 15-24.

Gonorrhoea causes a burning pain when urinating and often forms a thick yellow or green from an infected person's penis or vagina. If untreated it can result in . To prevent infection, people can abstain from having anal, oral or vaginal sex or use a barrier-type of like a condom. Gonorrhoea is treated by . Many of the antibiotics which were effective against bacterial diseases like gonorrhoea are not as effective as they used to be. This is because bacteria are evolving to become resistant to existing antibiotics. Scientists are constantly trying to find new antibiotics to treat these diseases.

Salmonella

An illustration of a salmonella bacterium cell
Figure caption,
Structure of a salmonella bacterium cell

Salmonella is a of bacteria that causes food poisoning. This often means abdominal cramps, vomiting and . It is often found in unhygienic kitchens, undercooked foods such as meat, eggs and poultry, or the same foods that have not been reheated properly. To prevent the spread of salmonella in the UK, all poultry are against it. Cooking food thoroughly, after preparing it in hygienic conditions, is the best way to avoid illness.

Greg James describes the effects of bacterial growth and how to prevent foodborne illness