18.E: Disease and Epidemiology (Exercises)
18.1: How Diseases Spread
Pathogens often have elaborate adaptations to exploit host biology, behavior, and ecology to live in and move between hosts. Hosts have evolved defenses against pathogens, but because their rates of evolution are typically slower than their pathogens (because their generation times are longer), hosts are usually at an evolutionary disadvantage. This section will explore where pathogens survive—both inside and outside hosts—and some of the many ways they move from one host to another.
Multiple Choice
Which is the most common type of biological vector of human disease?
- viruses
- bacteria
- mammals
- arthropods
- Answer
-
D
A mosquito bites a person who subsequently develops a fever and abdominal rash. What type of transmission would this be?
- mechanical vector transmission
- biological vector transmission
- direct contact transmission
- vehicle transmission
- Answer
-
B
Cattle are allowed to pasture in a field that contains the farmhouse well, and the farmer’s family becomes ill with a gastrointestinal pathogen after drinking the water. What type of transmission of infectious agents would this be?
- biological vector transmission
- direct contact transmission
- indirect contact transmission
- vehicle transmission
- Answer
-
D
A blanket from a child with chickenpox is likely to be contaminated with the virus that causes chickenpox (Varicella-zoster virus). What is the blanket called?
- fomite
- host
- pathogen
- vector
- Answer
-
A
Fill in the Blank
A patient in the hospital with a urinary catheter develops a bladder infection. This is an example of a(n) ________ infection.
- Answer
-
nosocomial or healthcare-associated
A ________ is an animal that can transfer infectious pathogens from one host to another.
- Answer
-
vector
Short Answer
Differentiate between droplet vehicle transmission and airborne transmission.
Critical Thinking
Many people find that they become ill with a cold after traveling by airplane. The air circulation systems of commercial aircraft use HEPA filters that should remove any infectious agents that pass through them. What are the possible reasons for increased incidence of colds after flights?