Deck 12: Epidemiology of Infectious Diseases

Question 1

If a disease is fatal, virulence can be measured by the case fatality rate.

Answer 1

True

Question 2

Antigenicity of an infectious agent is measured by the secondary attack rate.

Answer 2

False

Question 3

The presence of an infectious agent is a sufficient cause for outbreaks of infectious disease to occur.

Answer 3

False

Question 4

Administration of immune globulin confers passive immunity.

Question 5

Diseases that have only human reservoirs and are transmitted from person to person are the zoonoses.

Question 6

Eradication of smallpox was successful because of a program to immunize its primary reservoir, the green monkey in central Africa.

Question 7

Physical environmental factors in the natural history of disease include weather, temperature, and biologic components.

Question 8

The social environment refers to the totality of behavioral, personality, attitudinal, and cultural characteristics of a group of people.

Question 9

Sexually transmitted diseases, influenza, and acute respiratory infections are examples of conditions transmitted directly (person-to-person).

Question 10

When an individual comes into contact with a piece of clothing that subsequently infects him or her, that piece of clothing is a fomite, and the infection is direct.

Question 11

Vectors can be considered as one way in which infectious diseases can be transmitted.

Question 12

The term generation time relates to the time interval between lodgment of an infectious agent in a host and the maximal communicability of the host.

Question 13

Herd immunity refers to protection of a population against an infectious disease when a large proportion of individuals are immune through either vaccinations or past infections.

Question 14

Incubation period refers to the time between exposure to an infectious agent and the first signs and symptoms of disease.

Question 15

Herd immunity must be 100% to confer protection to a group.

Question 16

Colonization refers to the spread of plague to the Americas by settlers from Europe.

Question 17

A secondary attack rate is used to show the spread of disease in a household.

Question 18

The case fatality rate is the same thing as the cause-specific mortality rate for a disease.

Question 19

The case fatality rate of a disease is defined as the number of deaths due to the disease divided by the number of cases of the disease during a specified time period times 100.

Question 20

Home-canned foods would be a likely source for an outbreak of salmonellosis.

Question 21

Vaccine-preventable diseases include Haemophilus influenzae type b (Hib).

Question 22

A major resurgence of measles occurred during the period 1989 to 1990.

Question 23

Reasons for the resurgence of tuberculosis include the increasing prevalence of HIV infection.

Question 24

In 2017, the groups in the United States most affected by tuberculosis were foreign-born individuals and racial and ethnic minorities.

Question 25

An enzootic disease among animals is similar to an endemic disease among humans.

Question 26

The reservoir for Q fever is infected livestock, such as cattle, sheep, or goats.

Question 27

Lyme disease is an example of a disease transmitted by arthropod vectors.

Question 28

A person with an inapparent infection:

A) can transmit the infection to others.
B) is a danger to family members but not to others in the community.
C) never develops antibodies.
D) is of no epidemiologic importance.

Question 29

You have just finished administering a food/drink questionnaire to ill and non-ill participants in a Minnesota summer picnic party. The ill individuals developed moderate to severe diarrhea 16 to 46 hours after the picnic. Six persons experienced vomiting. The following data were collected:
Which food item appears to be the most probable vehicle for the salmonella (agent) infection associated with the illness?

A) Hot dogs
B) Hamburgers
C) Potato salad
D) Ice cream
E) Lemonade

Question 30

In two communities of similar size and age structure (A and B), there were outbreaks of viral illnesses (virus A in community A, and virus B in community B), both of which were traced back to a single source. Exposure to these viruses in each community confers permanent immunity. In community A, 200 susceptible people were exposed to an index case, 150 people were infected (not including the index case), 75 people became ill, and 40 people died. In community B, pathogenicity was 40%, infectivity was 90%, and virulence was 60%. Which virus had the greatest infectivity?

A) Virus A
B) Virus B
C) Both A and B were equal in infectivity.

Question 31

In two communities of similar size and age structure (A and B), there were outbreaks of viral illnesses (virus A in community A, and virus B in community B), both of which were traced back to a single source. Exposure to these viruses in each community confers permanent immunity. In community A, 200 susceptible people were exposed to an index case, 150 people were infected (not including the index case), 75 people became ill, and 40 people died. In community B, pathogenicity was 40%, infectivity was 90%, and virulence was 60%. Which virus was most pathogenic?

A) Virus A
B) Virus B
C) Both A and B were equally pathogenic.

Question 32

In two communities of similar size and age structure (A and B), there were outbreaks of viral illnesses (virus A in community A, and virus B in community B), both of which were traced back to a single source. Exposure to these viruses in each community confers permanent immunity. In community A, 200 susceptible people were exposed to an index case, 150 people were infected (not including the index case), 75 people became ill, and 40 people died. In community B, pathogenicity was 40%, infectivity was 90%, and virulence was 60%. Which virus was most virulent?

A) Virus A
B) Virus B
C) Both A and B were equally virulent.

Question 33

Community A receives its water from several sources. The water source responsible for causing an outbreak of disease X is unknown. The best evidence to determine which suspected water supply is responsible would be:

A) the identity of the water supply providing water to the largest proportion of cases.
B) the relationship between quantity of water consumed and the severity of attack for each individual.
C) the identity of the water supply that has the greatest opportunity for contamination during the epidemic.
D) the attack rates for disease X in those who did and did not drink from each water supply.

Question 34

The Centers for Disease Control and Prevention published an article concerning the high rate of foot fungal disease in New Orleans. The article explains that there has been a high rate of foot fungal disease in New Orleans for decades. Foot fungal disease in New Orleans is best described as:

A) epidemic.
B) endemic.
C) incident.
D) pathogenic.

Question 35

An attack rate is an alternative incidence rate that is used:

A) when describing the occurrence of foodborne illness or infectious diseases.
B) when the occurrence of disease among a population at risk increases greatly over a short period of time.
C) for acute health-related events, such as acute exposures of large groups to toxic agents.
D) All are correct.

Question 36

An important point about the agent-host-environment model (the epidemiologic triangle) of epidemiologic investigation is that:

A) the agent is not as important a factor in disease causality as the host or the environment.
B) the etiology of infectious disease involves more complex multivariate causality as well.
C) it is necessary that the agent be linked to both the host and the environment and that the agent is present in every case of the disease.
D) in order to prove causality, which is a difficult task, the researcher must prove that the agent, host, and environmental factors under investigation are both necessary and sufficient to cause the disease being studied.

Question 37

The following table shows the mumps experience of children in 390 families exposed to mumps by a primary case within the family:
The secondary attack rate among children aged two to four years is:

A) 18%.
B) 20%.
C) 33%.
D) 50%.
E) 60%.

Question 38

An outbreak of salmonellosis occurred after an epidemiology department luncheon, which was attended by 485 faculty and staff. Assume everyone ate the same food items. Sixty-five people had fever and diarrhea; five of these people were severely affected. Subsequent laboratory tests on everyone who attended the luncheon revealed an additional 72 cases. The attack rate of salmonellosis was:

A) 13.4%.
B) 47.4%.
C) 28.2%.
D) 7.7%.
E) 3.6%.

Question 39

An outbreak of salmonellosis occurred after an epidemiology department luncheon, which was attended by 485 faculty and staff. Assume everyone ate the same food items. Sixty-five people had fever and diarrhea; five of these people were severely affected. Subsequent laboratory tests on everyone who attended the luncheon revealed an additional 72 cases. The ratio of severe cases to other clinically apparent cases was:

A) 65/72.
B) 65/485.
C) 5/65.
D) 72/485.
E) 5/60.

Question 40

An outbreak of salmonellosis occurred after an epidemiology department luncheon, which was attended by 485 faculty and staff. Assume everyone ate the same food items. Sixty-five people had fever and diarrhea; five of these people were severely affected. Subsequent laboratory tests on everyone who attended the luncheon revealed an additional 72 cases. The virulence of salmonellosis was:

A) 13.4%.
B) 47.4%.
C) 28.2%.
D) 7.7%.
E) 3.6%.

Question 41

An outbreak of salmonellosis occurred after an epidemiology department luncheon, which was attended by 485 faculty and staff. Assume everyone ate the same food items. Sixty-five people had fever and diarrhea; five of these people were severely affected. Subsequent laboratory tests on everyone who attended the luncheon revealed an additional 72 cases. Foods served at the luncheon included home-canned olives, chicken salad, homemade flavored drink mix, freshly baked rolls, and raw vegetables. Based on your understanding of foods that potentially are capable of transmitting salmonella, the most likely source of the outbreak was:

A) home-canned olives.
B) undercooked chicken.
C) drink mix.
D) freshly baked rolls.
E) raw vegetables.

Question 42

What factors comprise the epidemiologic triangle?

A) Agent
B) Host
C) Environment
D) All are correct.
E) Agent and host only

Question 43

Someone suggests immunization as a means of reducing disease, specifically the feared UJ (uderlinger jacamoodi). What part of the disease cycle is he or she trying to affect?

A) Host
B) Fomites
C) Vector
D) Vehicle
E) Environment

Question 44

Host factors in the causation of disease include:

A) temperature and humidity.
B) chemicals in the air, water, or food.
C) genetic factors.
D) altitude.
E) All are correct.

Question 45

Which of the following infections shows a high subclinical/clinical ratio (inapparent/apparent ratio)?

A) Childhood hepatitis B infections
B) Human papillomavirus infections
C) Hepatitis A infections among children younger than 6 years old
D) Adult hepatitis A infections
E) Childhood hepatitis B infections, human papillomavirus infections, and hepatitis A infections among children younger than 6 years old

Question 46

The public health officer from Long Beach complains to you about the dreaded Pacific Pox. The health officer says, "If people catch the Pox, they suddenly get the urge to dance in the sand and fall dead on the beach within the hour." There are no survivors to interview. so you deduce:

A) the incidence rate of the Pox must be high.
B) the prevalence of the Pox must be high.
C) the infectivity of the Pox must be high.
D) the case fatality rate of the Pox must be high.
E) All are correct.

Question 47

The attack rate is:

A) number of persons who ate a specific food and became ill / total number of persons who ate the specific food
B) total number of persons who ate a specific food / number of persons who did not become ill
C) similar to the incidence rate of a disease of short duration.
D) the same as the secular trend.
E) similar to the incidence rate of a disease of short duration as well as number of persons who ate a specific food and became ill / total number of persons who ate the specific food

Question 48

With respect to a hypothetical rabies investigation conducted among veterinary workers, researchers found that rabies was almost always fatal. This finding refers to:

A) toxigenicity.
B) antigenicity.
C) virulence.
D) infectivity.

Question 49

Schistosomiasis is an example of:

A) a chemical agent: carcinogen.
B) a biological agent: helminth.
C) an allergen: pollen.
D) physical energy: ionizing radiation.

Question 50

Which of the following examples involves indirect transmission of disease?

A) Malaria
B) Hepatitis caused by needle sticks
C) HIV/AIDS
D) Pneumoconiosis
E) Malaria and hepatitis caused by needle sticks

Question 51

The site where a disease agent enters the body is the:

A) reservoir.
B) portal of entry.
C) vehicle.
D) portal of exit.

Question 52

Disease X is one that often results in severe illness but is never fatal. On March 21, 2002, 30 students enrolled in an introductory epidemiology course at a university developed disease X. (Assume all epidemiology students were exposed to the index case, the instructor). Through antibody titers, you were able to determine the following (antibody titers measure the concentration of antibodies in individuals and can be used to provide evidence of infection):
Number of exposed students not infected: 40
Number of exposed students with subclinical infection: 10
Number of exposed students with mild symptoms: 10
Number of exposed students with moderate symptoms: 10
Number of exposed students with severe symptoms: 10
Using your knowledge of infectious disease epidemiology, quantify the pattern of disease X in this group (i.e., what are the infectivity and virulence of disease X?). Assume all students were susceptible.

Question 53

Imagine you are the state epidemiologist. Sixty cases of salmonella were reported to you in the last two weeks. Describe how the iceberg model of disease would argue for or against whether this potential disease outbreak needs to be investigated.