13.4 - Bacterial & 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.

Chlamydia

• Chlamydia is caused by a bacterium (Chlamydia trachomatis).
• It's a sexually transmitted disease - passed on during sexual intercourse.
• It often causes no symptoms, so it can go untreated. Left untreated, it can lead to infertility.

Treatment and prevention

• Treatment - Antibiotics.
• Prevention - Using a condom during sex reduces its spread.

Tuberculosis (TB)

• Cause - The bacterium Mycobacterium tuberculosis.
• How it spreads - Through the air, when an infected person coughs.
• Symptoms - Coughing and damage to the lungs.

Infected people can reduce the spread of TB by:

• Avoiding crowded places
• Practising good hygiene
• Sleeping alone
• Keeping their homes well ventilated

A BCG vaccine is also used to help prevent infection.

TB is treated with a long course of antibiotics.

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.

Potato blight

• Potato blight is a fungal disease of potato and similar plants.
• It's spread by spores carried in the air from one plant to another, especially in warm, humid conditions.

Controlling potato blight

• Crop rotation - Growing different crops in a field each year, so the blight pathogen cannot build up and become established.
• Spraying with fungicide - Kills the fungus on the plants.