Protist diseases: The malarial protist has a life cycle that includes the mosquito. Malaria causes recurrent episodes of fever and can be fatal. The spread of malaria is controlled by preventing the vectors, mosquitos, from breeding and by using mosquito nets to avoid being bitten.

The idea

Malaria is caused by a protist, a single-celled eukaryotic pathogen. The protist's life cycle requires two hosts: a mosquito, which acts as a vector, and a human. When an infected mosquito bites a person, protists enter the blood and reproduce, eventually destroying red blood cells. This causes recurrent episodes of fever as cells burst in synchrony, and in severe cases the disease can be fatal. Because the mosquito is essential for transmission, control focuses on the vector. Preventing mosquitoes from breeding means removing or covering standing water where larvae develop. Using mosquito nets, especially insecticide-treated nets, creates a physical barrier that stops mosquitoes biting people while they sleep. These measures interrupt the life cycle and reduce the spread of malaria.

What earns the marks

• Malaria is caused by a protist, not by a bacterium or virus.
• The mosquito is a vector that carries the malarial protist between human hosts.
• The protist life cycle includes both the mosquito and a human host.
• Infection leads to recurrent episodes of fever and can be fatal.
• Control methods include preventing mosquitoes from breeding, for example by removing standing water.
• Mosquito nets reduce transmission by preventing bites from infected mosquitoes.

Common mistakes and how to put them right

• Thinking malaria is caused by a virus or bacterium.

  Put it right: The correct cause is a protist.

• Believing the mosquito itself is the pathogen.

  Put it right: The mosquito is the vector that transmits the protist.

• Assuming malaria is spread directly from person to person.

  Put it right: Transmission requires the mosquito vector.

Exam tips

• Name the pathogen group clearly: malaria is caused by a protist.
• Use the term vector when describing the mosquito's role.
• Link each control method to how it breaks the life cycle, such as nets preventing bites or removing water preventing breeding.