Protists Can Be Pathogens
Definition
Protist
A single-celled organism; some protists are pathogens, such as the one that causes malaria.
- Protists are single-celled organisms.
- Most protists are harmless, but a few are pathogens that cause disease.
- The best-known protist disease is malaria.
Key Idea
Diseases caused by protists usually involve a vector that carries the protist to the host.
Malaria and Its Symptoms
Definition
Malaria
A disease caused by a protist that is spread by mosquitoes and causes recurrent episodes of fever.
- Malaria is caused by a protist that is a parasite, living and feeding inside another organism.
- The protist's life cycle includes time in a human and time in a mosquito.
- Inside a person, the protist travels in the blood and damages the red blood cells.
- Malaria causes recurrent episodes of fever and can be fatal.
Note
Malaria weakens a person over time, even when it does not kill them.
The Mosquito Is the Vector
Definition
Vector
An organism that carries a pathogen from one host to another without catching the disease itself, such as a mosquito.
- Malaria is spread by mosquitoes, which act as vectors.
- A vector carries a pathogen from one host to another without catching the disease itself.
- When an infected mosquito bites a person, it passes the protist into their blood.
Example
A female mosquito needs a blood meal before laying eggs, and this is when the protist passes into a person.
Controlling the Spread of Malaria
- Most control methods target the mosquito vector.
- Mosquitoes are stopped from breeding by removing the still water where they lay their eggs.
- Insecticide-treated mosquito nets stop people being bitten while they sleep.
- Insecticides can be used to kill the mosquitoes.
- Travellers can take antimalarial drugs to kill any protists if they are bitten.
Self review
- What type of organism is a protist?
- What causes malaria, and what are its main symptoms?
- What is a vector, and which animal is the vector for malaria?
- How is the malarial protist passed to a person?
- Give two ways the spread of malaria can be controlled.
