Pathogens
A pathogenMicroorganism that causes disease. is a microorganism that causes a disease. There are four main types of pathogen:
Pathogen | Example in animals | Example in plants |
Viruses | HIV potentially leading to AIDS | Tobacco mosaic virus |
Bacteria | Salmonella | Agrobacterium |
Fungi | Athlete's foot | Black rose spot |
Protists | Malaria | Downy mildew |
Pathogen | Viruses |
---|---|
Example in animals | HIV potentially leading to AIDS |
Example in plants | Tobacco mosaic virus |
Pathogen | Bacteria |
---|---|
Example in animals | Salmonella |
Example in plants | Agrobacterium |
Pathogen | Fungi |
---|---|
Example in animals | Athlete's foot |
Example in plants | Black rose spot |
Pathogen | Protists |
---|---|
Example in animals | Malaria |
Example in plants | Downy mildew |
All types of pathogen have a simple life cycle. They infect a host, reproduce themselves or replicate if it is a virus, spread from their hostThe organism lived on or in by a parasite. and infect other organismLiving entity, eg animals, plants or microorganisms.. They also all have structural adaptationA feature of an organism's body which helps it to survive. that make them successful at completing their life cycles, which enable them to cause further disease.
Diseases caused by pathogens are called communicable diseaseA disease that is caused by a pathogen and so is transmitted rather than inherited or caused by an environmental factor.. This means they can be transferred from one person to another.
All organisms are affected by pathogens. Even bacteria are infected by certain types of virus. Some of these infections can be transferred to organisms of a different species.
Transmission of diseases
transmission The spreading of pathogenic disease, for example by touch, food, water. can occur in a number of important ways, as shown in the table below.
Type | Examples |
Direct contact | This can be sexual contact during intercourse or non-sexual contact, like shaking hands. |
Water | Dirty water can transmit many diseases, such as the cholera bacterium. |
Air | When a person who is infected by the common cold sneezes, they can spray thousands of tiny droplets containing virus particles to infect others. |
Unhygienic food preparation | Undercooked or reheated food can cause bacterial diseases like Escherichia coli which is a cause of food poisoning. |
Vector | Any organism that can spread a disease is called a vector. The mosquito spreads the protist causing malaria. |
Type | Direct contact |
---|---|
Examples | This can be sexual contact during intercourse or non-sexual contact, like shaking hands. |
Type | Water |
---|---|
Examples | Dirty water can transmit many diseases, such as the cholera bacterium. |
Type | Air |
---|---|
Examples | When a person who is infected by the common cold sneezes, they can spray thousands of tiny droplets containing virus particles to infect others. |
Type | Unhygienic food preparation |
---|---|
Examples | Undercooked or reheated food can cause bacterial diseases like Escherichia coli which is a cause of food poisoning. |
Type | Vector |
---|---|
Examples | Any organism that can spread a disease is called a vector. The mosquito spreads the protist causing malaria. |
More guides on this topic
- Field investigations - OCR Gateway
- Monitoring and maintaining the environment - OCR Gateway
- Feeding the human race - OCR Gateway
- Treating, curing and preventing disease - OCR Gateway
- Cancer and cardiovascular disease - non-communicable - OCR Gateway
- Monitoring and maintaining health - non-communicable - OCR Gateway