9700 · 10.1
Infectious diseases flashcards
Revision flashcards for Cambridge 9700 Infectious diseases (syllabus 10.1). Flip, recall, then mark a real past-paper question.
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What is a pathogen?
An organism or biological agent that causes an infectious disease. Examples include viruses, bacteria, fungi, and protoctista.
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Differentiate between an epidemic and a pandemic.
An **epidemic** is a sudden increase in disease cases in a specific population or area. A **pandemic** is an epidemic that has spread across multiple countries or continents, affecting a large number of people globally.
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What is the defining characteristic of a virus as a pathogen?
Viruses are **obligate intracellular parasites**, meaning they can only replicate inside the living cells of a host organism, using the host cell's machinery.
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Name the pathogen and the vector responsible for transmitting malaria.
Pathogen: *Plasmodium* (a protoctistan). Vector: Female *Anopheles* mosquito.
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How does the bacterium *Vibrio cholerae* cause the main symptom of cholera?
It releases a toxin called **choleragen**, which disrupts the function of the small intestine lining, causing a massive loss of water and salts (electrolytes) from the blood, leading to severe diarrhoea.
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What is direct transmission? Give an example.
The transfer of a pathogen from an infected host to a susceptible host without an intermediary. Example: Droplet infection (coughing/sneezing) for influenza.
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What is indirect transmission? Give an example.
The transfer of a pathogen from an infected host to a susceptible host via an intermediary. Example: A vector, like a mosquito transmitting malaria, or contaminated water transmitting cholera.
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What is the purpose of oral rehydration therapy (ORT) in treating cholera?
To replace the water and essential salts (electrolytes) lost through severe diarrhoea, preventing the life-threatening dehydration and electrolyte imbalance that is the primary cause of death from cholera.