# Cholera is a communicable disease caused by the bacterium Vibrio cholerae. Explain how Vibrio cholerae spreads between individuals and describe TWO ways in which the human body can defend itself against this pathogen before it enters the bloodstream.

> Pearson Edexcel A-Level Biology A (9BI0) — 5.2 Pathogens and infection · Explain · 5 marks

> Cholera outbreaks are most common in areas where clean drinking water and adequate sanitation are not available. The bacterium Vibrio cholerae produces toxins that cause severe diarrhoea, leading to dehydration.

## Mark scheme (5 marks)

1. Vibrio cholerae is spread through contaminated water (water-borne transmission) / ingestion of food or water contaminated with the bacterium
2. Mucus in the trachea / airways traps pathogens / bacteria before they can enter the body further
3. Cilia waft / sweep the mucus (and trapped bacteria) away from the lungs / up towards the throat so it can be swallowed or expelled
4. Hydrochloric acid in the stomach kills / destroys many pathogens / bacteria that are swallowed
5. The skin / cell wall acts as a physical barrier preventing the pathogen from entering the bloodstream

## Key terms

- [communicable disease](https://www.gradenine.co.uk/glossary/communicable-disease)
- [pathogen](https://www.gradenine.co.uk/glossary/pathogen)
- [Vibrio cholerae](https://www.gradenine.co.uk/glossary/vibrio-cholerae)

## Related

- [Revision notes for Pearson Edexcel A-Level Biology A (9BI0)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/cholera-is-a-communicable-disease-caused-ed80529d) · Published by Druglandscape Ltd.