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Monitoring & maintaining health - Communicable diseases - OCR Gateway Pathogens

Health is the state of physical and mental well-being. Factors can work together to both physical and mental health. A disease is a disorder that affects an organism鈥檚 body, organs, tissues or cells.

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Pathogens

A is a microorganism that causes a disease. There are four main types of pathogen:

PathogenExample in animalsExample in plants
VirusesHIV potentially leading to AIDSTobacco mosaic virus
BacteriaSalmonellaAgrobacterium
FungiAthlete's footBlack rose spot
ProtistsMalariaDowny mildew
PathogenViruses
Example in animalsHIV potentially leading to AIDS
Example in plantsTobacco mosaic virus
PathogenBacteria
Example in animalsSalmonella
Example in plantsAgrobacterium
PathogenFungi
Example in animalsAthlete's foot
Example in plantsBlack rose spot
PathogenProtists
Example in animalsMalaria
Example in plantsDowny 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 and infect other . They also all have structural that make them successful at completing their life cycles, which enable them to cause further disease.

Diseases caused by pathogens are called . 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

can occur in a number of important ways, as shown in the table below.

TypeExamples
Direct contactThis can be sexual contact during intercourse or non-sexual contact, like shaking hands.
WaterDirty water can transmit many diseases, such as the cholera bacterium.
AirWhen 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 preparationUndercooked or reheated food can cause bacterial diseases like Escherichia coli which is a cause of food poisoning.
VectorAny organism that can spread a disease is called a vector. The mosquito spreads the protist causing malaria.
TypeDirect contact
ExamplesThis can be sexual contact during intercourse or non-sexual contact, like shaking hands.
TypeWater
ExamplesDirty water can transmit many diseases, such as the cholera bacterium.
TypeAir
ExamplesWhen a person who is infected by the common cold sneezes, they can spray thousands of tiny droplets containing virus particles to infect others.
TypeUnhygienic food preparation
ExamplesUndercooked or reheated food can cause bacterial diseases like Escherichia coli which is a cause of food poisoning.
TypeVector
ExamplesAny organism that can spread a disease is called a vector. The mosquito spreads the protist causing malaria.
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Interactions between different types of diseases

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