6.14 - Bacterial, Protist & Fungal Diseases

Salmonella food poisoning

• Many bacteria are harmless or helpful, but a few are pathogens that cause disease.
• They often make you ill by producing toxins (poisons) that damage cells and tissues.

How salmonella spreads

• Salmonella is a bacterium that causes food poisoning.
• It is taken in by eating food contaminated with the bacteria, for example:
  • Poultry that carried the disease while alive
  • Food prepared in unhygienic conditions

Symptoms and control

• The toxins the bacteria produce cause fever, stomach cramps, vomiting, and diarrhoea.
• In the UK, most poultry are vaccinated against Salmonella to control its spread.
• Most people recover without treatment, but severe cases can be treated with antibiotics.

Malaria

• Malaria is caused by a protist called Plasmodium - a single-celled parasite.
• It's spread from host to host by mosquitoes acting as vectors (organisms that carry a pathogen from one host to another without getting the disease themselves).

How malaria is spread

1. A mosquito feeds on the blood of an infected animal and picks up the protist.
2. When it next bites, it injects the protist into the blood of a new host.

Effects on the body

• Inside the body, the protist destroys red blood cells.
• In serious cases it also damages the liver.
• This causes recurrent episodes of fever, and malaria can be fatal.

Reducing the spread

• Stopping the mosquitoes breeding.
• Killing them with insecticides.
• Stopping them biting people, using mosquito nets and insect repellent.

Athlete's foot

• Athlete's foot is a fungal disease of humans.
• It makes the skin on the feet itch and flake.

How it spreads and how to prevent it

• Spread - By touching the same surfaces as an infected person, such as shower floors and towels.
• Prevention - Avoid direct contact in places where the spores are likely, for example by wearing flip-flops in changing rooms.
• Treatment - Antifungal creams or sprays.