4.3.1.5 - Protist Diseases - Malaria

Malaria is caused by a protist

Malaria is a communicable disease caused by a protist pathogen. Protists are eukaryotic organisms; some protists can cause disease. For this lesson, you only need the example that the pathogens which cause malaria are protists.

The mosquito is not the pathogen. The mosquito is involved in spreading the pathogen from one human host to another. A strong answer separates the cause of the disease from the organism that spreads it: malaria is caused by a protist, and mosquitoes act as vectors.

The mosquito vector

A vector is an organism that carries a pathogen from one host to another. In malaria, the mosquito is the vector because the malarial protist has a life cycle that includes the mosquito.

A simple GCSE pathway is:

1. A mosquito bites a person who has malaria.
2. The mosquito takes in the malarial protist.
3. Later, the mosquito bites another person.
4. The malarial protist is passed into that person, so the disease can spread.

Malaria is therefore not spread like a cold or flu by casual contact or cough droplets. The assessed route here is through a mosquito vector.

[DIAGRAM: asset_name: malaria-vector-lifecycle - diagram 1; asset_slug: 034_4_3_1_5_protist_diseases_diagram1; file: diagram_assets/imagegen_regen_all/034_4_3_1_5_protist_diseases_diagram1_imagegen.png; recommended_method: codex_image_gen; description: Monochrome flow diagram showing the malarial protist moving between an infected human, a mosquito vector and another human, with control points for mosquito nets and preventing mosquito breeding.]

Fever and fatal disease

Malaria causes recurrent episodes of fever. Recurrent means the episodes come back repeatedly rather than happening just once.

The specification also says malaria can be fatal. That means malaria can cause death. At GCSE level, this is enough medical detail for this row: you do not need to learn the detailed organ damage, diagnostic tests or drug treatments for malaria.