16.E: Disease and Epidemiology (Exercises)
16.1: The Language of Epidemiologists
The field of epidemiology concerns the geographical distribution and timing of infectious disease occurrences and how they are transmitted and maintained in nature, with the goal of recognizing and controlling outbreaks. The science of epidemiology includes etiology (the study of the causes of disease) and investigation of disease transmission (mechanisms by which a disease is spread).
Matching
Match each term with its description.
| ___sporadic disease | A. the number of disease cases per 100,000 individuals |
| ___endemic disease | B. a disease in higher than expected numbers around the world |
| ___pandemic disease | C. the number of deaths from a disease for every 10,000 individuals |
| ___morbidity rate | D. a disease found occasionally in a region with cases occurring mainly in isolation from each other |
| ___mortality rate | E. a disease found regularly in a region |
- Answer
-
D, E, B, A, C
Fill in the Blank
The ________ collects data and conducts epidemiologic studies in the United States.
- Answer
-
Centers for Disease Control and Prevention, or CDC
Short Answer
During an epidemic, why might the prevalence of a disease at a particular time not be equal to the sum of the incidences of the disease?
In what publication would you find data on emerging/reemerging diseases in the United States?
Critical Thinking
Why might an epidemiological population in a state not be the same size as the number of people in a state? Use an example.
16.2: Tracking Infectious Diseases
Some important researchers, such as Florence Nightingale, subscribed to the miasma hypothesis. The transition to acceptance of the germ theory during the 19th century provided a solid mechanistic grounding to the study of disease patterns. The studies of 19th century physicians and researchers such as John Snow, Florence Nightingale, Ignaz Semmelweis, Joseph Lister, Robert Koch, Louis Pasteur, and others sowed the seeds of modern epidemiology.
Matching
Match each type of epidemiology study with its description.
| ___experimental | A. examination of past case histories and medical test results conducted on patients in an outbreak |
| ___analytical | B. examination of current case histories, interviews with patients and their contacts, interpretation of medical test results; frequently conducted while outbreak is still in progress |
| ___prospective | C. use of a set of test subjects (human or animal) and control subjects that are treated the same as the test subjects except for the specific treatment being studied |
| ___descriptive | D. observing groups of individuals to look for associations with disease |
| ___retrospective | E. a comparison of a cohort of individuals through the course of the study |
- Answer
-
C, D, E, B, A
Match each pioneer of epidemiology with his or her contribution.
| ___Florence Nightingale | A. determined the source of a cholera outbreak in London |
| ___Robert Koch | B. showed that surgical wound infection rates could be dramatically reduced by using carbolic acid to disinfect surgical tools, bandages, and surgical sites |
| ___Joseph Lister | C. compiled data on causes of mortality in soldiers, leading to innovations in military medical care |
| ___John Snow | D. developed a methodology for conclusively determining the etiology of disease |
- Answer
-
C, D, B, A
Fill in the Blank
________occurs when an infected individual passes the infection on to other individuals, who pass it on to still others, increasing the penetration of the infection into the susceptible population.
- Answer
-
Propagated spread
A batch of food contaminated with botulism exotoxin, consumed at a family reunion by most of the members of a family, would be an example of a ________ outbreak.
- Answer
-
point source
Short Answer
What activity did John Snow conduct, other than mapping, that contemporary epidemiologists also use when trying to understand how to control a disease?
16.3: 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?
16.4: Global Public Health
A large number of international programs and agencies are involved in efforts to promote global public health. Among their goals are developing infrastructure in health care, public sanitation, and public health capacity; monitoring infectious disease occurrences around the world; coordinating communications between national public health agencies in various countries; and coordinating international responses to major health crises.
Multiple Choice
Which of the following would NOT be considered an emerging disease?
- Ebola hemorrhagic fever
- West Nile virus fever/encephalitis
- Zika virus disease
- Tuberculosis
- Answer
-
D
Which of the following would NOT be considered a reemerging disease?
- Drug-resistant tuberculosis
- Drug-resistant gonorrhea
- Malaria
- West Nile virus fever/encephalitis
- Answer
-
D
Which of the following factors can lead to reemergence of a disease?
- A mutation that allows it to infect humans
- A period of decline in vaccination rates
- A change in disease reporting procedures
- Better education on the signs and symptoms of the disease
- Answer
-
B
Why are emerging diseases with very few cases the focus of intense scrutiny?
- They tend to be more deadly
- They are increasing and therefore not controlled
- They naturally have higher transmission rates
- They occur more in developed countries
- Answer
-
B
Fill in the Blank
The ________ collects data and conducts epidemiologic studies at the global level.
- Answer
-
WHO (World Health Organization)
Critical Thinking
An Atlantic crossing by boat from England to New England took 60–80 days in the 18th century. In the late 19th century the voyage took less than a week. How do you think these time differences for travel might have impacted the spread of infectious diseases from Europe to the Americas, or vice versa?