---

(4) Examples of bacterial pathogen communicable diseases

(4a) Salmonella is a type of bacteria that causes food poisoning e.g. from contaminated food

The symptoms experienced by infected people with salmonella include diarrhoea, fever, stomach cramps and vomiting.

These very unpleasant effects are caused by toxins produced by the salmonella bacteria.

Salmonella food poisoning is often contracted from animals like chickens catching the disease when alive - if 'undercooked' the salmonella bacterium are not killed and the food infected.

Salmonella can also be contracted and spread by eating contaminated food, food prepared in unhygienic conditions and food that has been stored too long at too high a temperature - allowing salmonella bacteria to multiply.

In the UK, to control the spread of the disease, poultry like chickens and turkeys are given a vaccination against salmonella.

In the US chickens are washed with a chlorine solution to kill the salmonella bacterium - a controversial and banned practice in Europe - including the UK - but post-Brexit, who knows!.

Whatever the poultry source, make sure it is well cooked, and wash your hands before and after food preparation.

With salmonella poisoning, you need to minimise food intake and drink lots of water until things in your gut settle down!

---

(4b) Escherichia coli (E. coli) bacterium

E.coli bacteria normally live in the intestines of healthy people and animals and are not usually a problem.

Most varieties of the E. coli bacterium are harmless or cause relatively brief diarrhea.

However, there are a few particularly nasty strains of E.coli bacteria which can cause severe abdominal cramps, bloody diarrhea and vomiting.

E.coli cells can divide every 20 minutes, so their numbers can rapidly increase!

E. coli are found in water polluted by sewage.

If infected with E.coli bacteria you need to minimise food intake and drink lots of water until things in your gut settle down!

---

Key points Source of information is based on textbooks & syllabus-specifications for students taking the AQA GCSE, Edexcel GCSE and OCR GCSE level biology examinations (~US grades 9-10).

Key points about salmonella and E coli infections

Bacterial Pathogen Communicable Diseases: Salmonella and E. coli

1. What Are Bacterial Pathogens?

• Bacteria are prokaryotic microorganisms that can reproduce rapidly inside the body.

• Some bacteria are pathogenic, meaning they cause communicable (infectious) diseases.

• They often cause illness by:

  • Releasing toxins.

  • Damaging tissues.

  • Triggering immune responses.

---

Salmonella

Pathogen Type: Bacterium (Salmonella spp.)

Transmission:

• Foodborne: Eating contaminated or undercooked food (especially poultry, eggs, and unwashed vegetables).

• Poor hygiene: Cross-contamination in kitchens or not washing hands after handling raw meat.

Symptoms:

• Fever

• Abdominal cramps

• Diarrhoea

• Vomiting

Symptoms usually appear 6–72 hours after infection and can last 4–7 days.

Treatment:

• Mild cases: Usually self-limiting — rest and fluids are enough.

• Severe cases: May require oral rehydration therapy or antibiotics (especially in vulnerable individuals).

• Prevention:

  • Cook food thoroughly.

  • Wash hands and surfaces.

  • Vaccinate poultry (in some countries).

---

E. coli (Escherichia coli)

Pathogen Type: Bacterium (E. coli, especially strain O157:H7)

Transmission:

• Contaminated food or water (e.g. undercooked beef, unpasteurised milk).

• Poor hygiene: Especially in food preparation.

• Person-to-person: Via the faecal-oral route.

Symptoms:

• Severe abdominal cramps

• Bloody diarrhoea

• Nausea and vomiting

• In some cases: Hemolytic Uremic Syndrome (HUS) — a serious complication that can cause kidney failure.

Treatment:

• No antibiotics: They can worsen symptoms in some strains.

• Supportive care: Fluids and rest.

• Hospitalisation: In severe cases, especially if HUS develops.

Prevention:

• Cook meat thoroughly (especially minced beef).

• Avoid unpasteurised dairy.

• Wash fruits and vegetables.

• Practice good hand hygiene.

---

Why Is This Important in Human Biology?

• Highlights how bacteria cause disease through toxins and tissue damage.

• Reinforces the importance of hygiene, food safety, and public health.

• Shows how different bacterial strains can vary in severity and treatment.

• Links to immune system responses, antibiotic use, and antibiotic resistance.

• Encourages understanding of epidemics, outbreak control, and preventative medicine.

---

---

Keywords, phrases and learning objectives for this part on the bacterial pathogens salmonella and E. coli

Be able to describe salmonella bacteria and Escherichia coli E. coli poisoning bacterium in terms of communicable diseases.

Be able to describe their characteristic symptoms and how the infections are transmitted.

---

WHAT NEXT?

TOP OF PAGE

INDEX of notes on communicable diseases

INDEX of all my BIOLOGY NOTES

BIG website, try using the [SEARCH BOX], maybe quicker than the many indexes!

Basic Science Quizzes for UK KS3 science students aged ~12-14, ~US grades 6-8

Biology * Chemistry * Physics for UK GCSE level students aged ~14-16, ~US grades 9-10

Advanced Level Chemistry for pre-university age ~16-18 ~US grades 11-12, K12 Honors

Find your GCSE/IGCSE science course for more help links to all science revision notes

email doc brown - comments - query?

---

salmonella & E. coli pathogens communicable diseases described and explained for syllabus-specifications for students taking the IGCSE/GCSE level biology examinations, summary revision notes key points on salmonella & E. coli pathogens communicable diseases described and explained for students studying AQA igcse/gcse biology notes on salmonella & E. coli pathogens communicable diseases described and explained, Edexcel gcse biology notes on salmonella & E. coli pathogens communicable diseases described and explained,  OCR 21st century GCSE biology notes on salmonella & E. coli pathogens communicable diseases described and explained, OCR gateway GCSE biology notes on salmonella & E. coli pathogens communicable diseases described and explained, WJEC gcse biology notes on salmonella & E. coli pathogens communicable diseases described and explained, CCEA gcse biology notes on salmonella & E. coli pathogens communicable diseases described and explained, CIE Cambridge igcse biology, notes on salmonella & E. coli pathogens communicable diseases described and explained useful for US grade 9-10 biology student courses, Explaining importance of symptoms & treatment of salmonella poisoning & E. coli bacteria infection in GCSE level biology, What you need to know about symptoms & treatment of salmonella poisoning & E. coli bacteria infection for GCSE level biology, Explaining use of symptoms & treatment of salmonella poisoning & E. coli bacteria infection knowledge in GCSE level biology, Examples of symptoms & treatment of salmonella poisoning & E. coli bacteria infection explained when studying GCSE level biology, What is the significance of symptoms & treatment of salmonella poisoning & E. coli bacteria infection in GCSE level biology, describing explaining theory of symptoms & treatment of salmonella poisoning & E. coli bacteria infection when studying GCSE level biology, exam revision notes for symptoms & treatment of salmonella poisoning & E. coli bacteria infection, online help for understanding symptoms & treatment of salmonella poisoning & E. coli bacteria infection in GCSE biology, what do I need to learn about symptoms & treatment of salmonella poisoning & E. coli bacteria infection? what do I need to know about symptoms & treatment of salmonella poisoning & E. coli bacteria infection for GCSE biology exams, how to prepare for questions on symptoms & treatment of salmonella poisoning & E. coli bacteria infection in GCSE biology examination?

---