Meet the Pathogens

Learn what pathogens are, how they spread, and how the body and people can stop infection.

About 2 min read
  • Name the four main types of pathogen
  • Describe how pathogens spread
  • Explain how to reduce the spread of disease
Before you start

You know that microorganisms are too small to see without a microscope, and that the body has systems to stay healthy.

What is a pathogen?

Many microorganisms are harmless, but some cause disease. These are called pathogens. Bacteria, viruses, fungi and protists can all be pathogens. A disease that can pass from one person to another is called a transmissible disease. Cholera is caused by a bacterium and influenza by a virus.

Definition: pathogen

A microorganism that causes disease.

Definition: transmissible disease

A disease that can pass from one host to another.

How pathogens spread

Pathogens can spread in air droplets from coughs and sneezes, in contaminated food or water, through direct contact and by vectors such as mosquitoes. Malaria, for example, is spread by mosquitoes. Your body has barriers including skin, stomach acid and mucus, while white blood cells attack pathogens that get inside.

Reduce the spread of cholera

Cholera spreads through water contaminated with sewage. Suggest how a town can reduce its spread.

The pathogen reaches people in dirty water.

Treating sewage and supplying clean water break this route.

Answer: Keep sewage away from drinking water and treat the water supply.

Antibiotics and viruses

Antibiotics kill bacteria. They do not kill viruses, so they cannot cure flu or colds.

Exam focus
Say it like this“Washing hands removes pathogens and reduces transmission.”
Not like this“Washing hands kills illness.” — Name what is removed and how it reduces spread.
Common mistakeSaying that all bacteria are harmful, or that antibiotics treat viral infections.

Practice

Name the four main types of pathogen.
Bacteria, viruses, fungi and protists.
Give one way a disease can spread through the air.
Droplets from coughing or sneezing can carry pathogens.
What is a vector?
An organism that carries a pathogen from one host to another, such as a mosquito.
Going further
Explain why sleeping under a mosquito net helps prevent malaria.
The net stops infected mosquitoes reaching and biting the person, which breaks the route of transmission.

Quick check

Pathogens quick check

Which is a pathogen?

It is a microorganism that invades a host and causes illness.

Which medicine kills bacteria?

This drug damages bacterial cells without harming human cells in the same way.

How does cholera usually reach people?

The bacterium is in sewage and enters the body when people drink polluted supplies.
Key takeaways
  • Pathogens are microorganisms that cause disease.
  • They spread through air, food, water, contact and vectors.
  • Body barriers and white blood cells protect us.
  • Hygiene and clean water reduce transmission.
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