Bacterial, Fungal and Protist Diseases

In this lesson you will learn the specific diseases caused by bacteria, fungi and protists that you need to know for Edexcel GCSE Biology. For each disease, make sure you know the pathogen, how it spreads, the symptoms, and the treatment or prevention.

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Bacterial Diseases

1. Salmonella (Food Poisoning)

Pathogen: Salmonella bacteria (various species, e.g. Salmonella enterica)

How it spreads:

• Eating contaminated food, especially undercooked poultry, eggs, and meat
• Bacteria are ingested and infect the gut

Symptoms:

• Fever
• Abdominal cramps
• Vomiting
• Diarrhoea
• Symptoms usually appear 12–72 hours after infection and last 4–7 days

How Salmonella causes disease:

• The bacteria produce toxins in the gut that cause inflammation, leading to the symptoms above

Prevention and control:

• Proper food hygiene: thorough cooking of poultry and eggs, handwashing, avoiding cross-contamination
• Vaccination of poultry — in the UK, chickens are vaccinated against Salmonella to reduce the presence of the bacteria in eggs and meat
• Food storage: keeping food at correct temperatures (below 5°C for refrigerated foods)