Disease Reservoirs & Transmission Flashcards
Who was responsible for the beginning of the modern “germ theory”?
Which bacteria did he work with?
- Robert Koch
- B. anthracis
In 1900, Walter Reed discovered that mosquitoes transmitted what disease?
Yellow fever
T/F: In disease prevention, knowing the mode of transmission is generally more important than identifying the specific agent.
True
T/F: Disease transmission can be represented as a chain of events.
True
What are 6 possible links in a chain of infection?
- Pathogen/microorganism
- Reservoir
- Means of escape/portal of exit
- Mode of transmission
- Means of entry/exposure
- Host susceptibility
What is a reservoir?
What are some examples of reservoirs?
- A habitat in which an infectious agent normally lives, grows and multiplies.
- Humans, animals, environment
What is one way pathogens are maintained over time, from year to year or generation to generation?
Reservoirs
Answering yes to which three questions will help to determine if something is a reservoir?
- Is it naturally infected with the pathogen?
- Can that species of animals (human, soil) maintain the pathogen over time?
- Can this source transmit the disease to a new, susceptible host?
Name 4 diseases/pathogens that humans are a reservoir for.
- Smallpox
- Measles
- Mumps
- Taenia solium
Name 4 disease/pathogens that animals are a reservoir for.
- Salmonella spp.
- Toxoplasma gondii
- Feline leukemia virus
- Foot and Mouth disease virus
Name 2 diseases/pathogens for which the reservoir is in the environment.
- Legionella
- Coccidioides
T/F: Pathogens use the same strategy to survive, over time, in the reservoir as a population.
False - They used different strategies to survive.
What are 3 examples of survival strategies used by pathogens?
- Mutate to escape immunity, so that animals become susceptible again over time.
- Evade immunity, allowing reinfection to occur after a short period of time.
- Cause chronic infections with minimal symptoms (balanced pathogenicity).
Does infection = disease = infectivity?
No
T/F: Clinically ill animals that are reservoir competent are probably infectious.
True
Can asymptomatic animals be carriers?
Yes
Are all sick animals reservoirs?
No
What are 2 examples of direct horizontal transmission?
Projection and contact
What are 2 examples of indirect horizontal transmission?
What are 2 examples of both of these?
- Vehicle: common vehicle and fomite
- Vector: biological vector and mechanical vector
What is vertical transmission?
From a reservoir host to its offspring.
What is congenital transmission?
When pathogen can cross the placenta, infect eggs, etc.
What is perinatal transmission?
When transmission occurs during parturition or via the colostrum.
What is horizontal transmission?
From the reservoir to a new host.
What is direct horizontal transmission?
Direct from the reservoir to a susceptible host.
