# Malaria is a communicable disease caused by a protist called Plasmodium. It is transmitted to humans through the bite of an infected Anopheles mosquito. Explain how the body's defences may prevent Plasmodium from causing infection, and describe how the spread of malaria between individuals can be reduced.

> Edexcel A-Level Biology A: Salters-Nuffield (9BN0) — 5.2 Pathogens and infection · Explain · 5 marks

> Malaria kills hundreds of thousands of people globally each year. The Plasmodium protist enters the bloodstream when an infected mosquito feeds on a human host. Once inside the body, Plasmodium invades red blood cells and liver cells.

## Mark scheme (5 marks)

1. The skin acts as a physical barrier preventing Plasmodium from entering the body unless the skin is broken (e.g. by a mosquito bite).
2. If Plasmodium enters the blood, white blood cells (phagocytes) can engulf and destroy it by phagocytosis.
3. B-lymphocytes produce antibodies specific to the antigens on the surface of Plasmodium, which trigger an immune response to destroy it.
4. Reducing contact with the mosquito vector prevents transmission, for example by using insecticide-treated bed nets or mosquito repellent.
5. Draining or reducing standing water (mosquito breeding sites) limits the number of mosquitoes and so reduces transmission of malaria.

## Key terms

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

## Related

- [Revision notes for Edexcel A-Level Biology A: Salters-Nuffield (9BN0)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/malaria-is-a-communicable-disease-caused-aa89752b) · Published by Druglandscape Ltd.