GCSE-readyCommon infections: symptoms, spread and prevention
You need to know a set of named diseases: the pathogen, the symptoms, how each spreads and how the spread is reduced.
The named diseases
| Disease | Pathogen | Main effect | Spread by |
|---|---|---|---|
| Cholera | Bacterium | Watery diarrhoea | Water contaminated with faeces |
| Tuberculosis (TB) | Bacterium | Lung damage | Airborne droplets from coughs and sneezes |
| Stomach ulcers | Bacterium (Helicobacter) | Ulcers in the stomach lining | Oral transmission (contaminated food and water) |
| Malaria | Protist | Damage to blood and liver; repeated fevers | Mosquitoes (a vector) |
| HIV | Virus | Destroys white blood cells, leading to AIDS | Body fluids: unprotected sex, shared needles, mother to baby |
| Ebola | Virus | Haemorrhagic fever (internal bleeding) | Body fluids |
| Chalara ash dieback | Fungus | Leaf loss and bark lesions on ash trees | Airborne spores; moving infected young trees |
Reducing the spread
TB: isolating infected people, vaccination, completing antibiotic courses, good ventilation.
Malaria: mosquito nets, insect repellent and insecticides; draining standing water where mosquitoes breed.
Ebola: isolating patients, protective clothing for health workers, safe burial.
Chalara: removing infected trees and controlling the movement of young ash trees.
Sexually transmitted infections and susceptibility
The spread is reduced by condoms, screening (testing) and treating infected people, and needle exchange schemes.
Having one disease can make you more likely to catch others. HIV destroys white blood cells, so people with HIV are much more likely to develop diseases such as TB.
Explain why people with untreated HIV are more likely to develop TB.
- HIV destroys white blood cells.
- The immune system becomes weaker.
- The body cannot fight off other pathogens, such as the TB bacterium, as well.
Answer: HIV destroys white blood cells, weakening the immune system, so other pathogens such as TB are not destroyed.
Cholera (water), TB (droplets), Helicobacter (stomach ulcers), malaria (mosquitoes), HIV and Ebola (body fluids), Chalara (spores) and Chlamydia (unprotected sex). One disease, such as HIV, can make a person more likely to catch another.
- Pathogen
- A microorganism that causes disease, such as a bacterium, virus, fungus or protist.
- Vaccination
- Giving a dead, weakened or harmless form of a pathogen (or its antigens) so the body makes memory cells without becoming ill.
- Antibiotic
- A medicine that kills bacteria or stops them growing. Antibiotics do not work on viruses.
- Virus
- A non-living particle made of genetic material in a protein coat. It can only reproduce inside a host cell.
All GCSE and International GCSE Biology key terms and definitions →
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2 more questions
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Which type of pathogen causes malaria?
- A bacterium
- A protist
- A virus
- A fungus
Show the answer
Answer: A protist
Plasmodium is a protist.
What type of organism is Helicobacter?
- A fungus
- A bacterium
- A protist
- A virus
Show the answer
Answer: A bacterium
Helicobacter pylori causes stomach ulcers.
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- Pearson Edexcel GCSE Biology (1BI0) specification, topic 5.3, 5.5, 5.6, 5.8
- Pearson Edexcel GCSE (9-1) Biology specification
- WHO fact sheet: Cholera
- WHO fact sheet: Malaria
Checked by the GCSE-ready editorial team, 17 October 2026. Last updated 2 October 2026. Spotted a mistake? Tell us and we will fix it.
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