Pathogens Flashcards
What is a pathogen?
A bacterium, virus or other microorganism that can cause disease
What are the 6 things that makes a succesful pathogen?
- Maintain a reservoir
- Transmission to the new host
- Attch to host cells
- Invading the immune system
- Cause damage to the host
- Leaving and finding a new host
What does it mean to maintain a reservoir?
The infectious agent must primaritly depend on the reservoir for its survival and must be able to multiply there
Where is an infectious agent transmitted to from a reservoir?
To a human
Can the reservoir be biological or environmental?
Both
What does it mean for a reservoir to be biological?
Human - HIV, cold, virus
Animals - rabies, bird fluW
hat does it mean for a reservoir to be enviromental?
Water or soil - anthrax or cholera
What does transmission to a new host mean?
The infectious agent is spread from a reservoir to a human being
What is direct transmission?
Infected host contacts a new host and passes the pathogen to then directly
What is vertical direct transmission?
Mother to baby - HIV, rubella, syphilis
What is horizontal transmission?
Amongst the population
Sexual - Hiv, HPV, herpes, chlamydia
Fluid exchange - kissing, meningitis
Bites - rabies virus
Does the infected need to be present for the pathogen to be passed to the new host?
No
What are the three indirect transmissions?
Vehicel borne transmission
Vector bourne transmission
Airborne transmission
What is vehicle borne transmission?
A material becomes contaminated with the infectious agent
How do vehicle borne transmissions spread?
The vehicle contacts a persons body and is ingested either eaten or drunk, touches the skin or introduced during surgery
What is vector borne transmission?
Transmission from insects or creature that carry infectious disease
How are vector borne transmissions spread?
The infectious agent is transmitted from the vector when it bites or touches a person
What is an airborne transmission?
Infective agents are spread as aerosols
Usually enter a person through the respiratory tract
What is an example of airbrne transmission?
Coughs
Sneezes, items when moved when cleaned or by the wind
Is attaching to the host cell an imporants first step within the infection process?
Yes
Why do infections have to attach to the host cell?
Because they will get cleared away by cilia or th gut
What are attachment proteins?
Surface molecules on apthogens that bind to host receptors
What do antibiotics againts pathogens bind to?
Adhesisns and block the ability of pathogen to bind to host cells and stop the disease
What happens when the host immune system wins when a pathogen is invading the immune system?
The pathogen is eliminated
What happens when the pathogen wins when invading the host immune system?
The infection gets worse
What are the ways that pathogens have evolved to overcome defences from the immune system?
Hide
Disguise
Immunosupression
Interfere with antibody system
How do pathogens ‘hide’?
within cells - viruses
How do pathogens ‘disguise’?
Thy coat themselves in host proteins which hides their own antigenic surface components from the immune system
How do pathogens immunosurpress?
They weaken the immune system
How do pathogens interfere with antibiotic activity?
IgA protease produced by bacteria, inactivate secretory IgA by cleaving the molecule
How do pathogens cause damage to the host?
Pathogens produce enzymes to invade tissues to reach their site of infection
Why do pathogens produce toxins?
To damage host tissues in many ways
How do pathogens leave and find a new host?
Sneezing, Diarrhoea, Behavioural change, Agression. Biting, Vomiting
