01 Disease Reservoirs and Transmission

Question 1

Disease transmission is a result of

Answer 1

interaction between the host, agent, and environment

Question 2

John Snow

Answer 2

1841 published evidence that cholera is transmitted by the fecal-oral route and by the water supply

Question 3

Robert Koch

Answer 3

1876 first isolated the bacterium –and used experimental infection of naïve animals to prove that B. anthraciscauses anthrax

Question 4

Pasteur

Answer 4

1881 developed and tested an early vaccine in sheep, goats, and cattle

Question 5

Typhoid Mary

Answer 5

Asymptomatic Carrier, Caused several outbreaks of typhoid fever (SalmonellaTyphi = anthroponotic) between 1900-1915

Question 6

Ronald Ross

Answer 6

1897 malaria is transmitted by mosquitoes; some credit the discovery to the Italian scientist, Grassi

Question 7

Walter Reed

Answer 7

1900 yellow fever is transmitted by mosquitoes

Question 8

In disease prevention, knowing the _____ is generally more important than ______

Answer 8

mode of transmission, identifying the specific agent

Question 9

“Chain” of Infection

Answer 9

host susceptability-pathogenic microorganism-reservior-means of escape-mode of transmission-means of entry

Question 10

Reservoir definition

Answer 10

habitat in which an infectious agent normally lives, grows, and multiplies (humans, animals, or the environment)

Question 11

Reservoirs do this

Answer 11

maintain pathogens over time, from year to year or generation to generation

Question 12

3 questions to define a reservior

Answer 12

1. Is it naturally infected with the pathogen?
2. Can that species of animal (etc.) maintain the pathogen over time?
3. Can this source transmit the disease to a new, susceptible host?

Question 13

Two questions concerning reservoirs in practical disease control

Answer 13

1) Can an acceptable level of control be accomplished without consideration of a reservoir?
2) If not, what populations constitute the reservoir?

Question 14

Clinically ill animals that are reservoir competent are probably infectious (T/F)

Answer 14

True

Question 15

Asymptomatic animals can be infectious = carrier (T/F)

Answer 15

True

Question 16

All sick animals are reservoirs (T/F)

Answer 16

False

Question 17

Verticle transmission includes

Answer 17

• Congenital: some pathogens can cross the placenta, infect eggs, etc.
• Perinatal: during parturition, via colostrum

Question 18

Horizontal transmission includes

Answer 18

• Direct: directly from the reservoir to a susceptible host

- Indirect: via any sort of intermediary, animate or inanimate

Question 19

Direct contact

Answer 19

Skin-skin contact, mucous membrane contact (including sexual transmission), direct contact with a soil reservoir, bite, scratch, etc

Question 20

Direct projection

Answer 20

-aka droplet spread

–Wet, large, and short range aerosols (sneezing, coughing or talking)

Question 21

Airborne*

Answer 21

Considered to be a form of direct transmission because disease agents do not generally survive for extended periods within aerosolized particles

Question 22

Vehicle

Answer 22

An inanimate object which serves to communicate disease.

Question 23

Vector

Answer 23

A living organism that serves to communicate disease.

Question 24

Common vehicles

Answer 24

–Food, water

–Contaminated IV drugs

Question 25

Fomites

Answer 25

Object that can be contaminated and transmit disease on a limited scale

Question 26

Mechanical vector

Answer 26

the agent DOES NOT multiply or undergo part of its life cycle while in/on the arthropod

Question 27

Biological vector

Answer 27

the agent undergoes changes or multiples while in the vector; these activities are required for transmission