Protist diseases: The pathogens that cause malaria are protists.

The idea

Malaria is caused by protist pathogens, not by a virus or bacterium. The protists are transmitted to humans by the bite of an infected mosquito, which acts as a vector. The mosquito takes blood containing the protists from an infected person and later injects them into another person when it feeds again. Inside the human body the protists reproduce and damage red blood cells, causing symptoms such as fever and fatigue. Because the pathogen is a protist, antibiotics that target bacteria are not effective against it. Control measures therefore target the vector, for example using mosquito nets and insecticides, rather than relying on antibacterial drugs.

What earns the marks

• Malaria is caused by protist pathogens, so the pathogen group is protists.
• The protists are transmitted to humans by mosquitoes, which act as vectors.
• A vector is an organism that carries a pathogen from one host to another without being infected itself in the same way.
• The mosquito bites an infected person, takes up protists with blood, then injects them into another person when it feeds.
• The protists reproduce in the human body and damage red blood cells, producing symptoms such as fever.
• Control targets the mosquito vector, for example mosquito nets and insecticides, because the pathogen is a protist.

Common mistakes and how to put them right

• Saying malaria is caused by a virus or bacterium.

  Put it right by stating that the pathogen is a protist.

• Calling the mosquito the pathogen.

  Put it right by describing the mosquito as the vector that transmits the protist.

• Suggesting antibiotics cure malaria.

  Put it right by explaining that antibiotics act on bacteria, not protists.

Exam tips

• Use the word protist when naming the pathogen, and keep the mosquito described as the vector.
• Explain transmission as a sequence: infected person, mosquito bite, protists transferred, new person infected.
• If asked about prevention, link each method to interrupting the vector, such as nets or insecticides.