NR 503 EPIDEMIOLOGY MIDTERM QUESTIONS &
ANSWERS
1. The population of a city on February 15, 2005, was 36,600. The city has a passive surveillance
system that collects hospital and private physician reports of influenza cases every month.
During the period between January 1 and April 1, 2005, 2,200 new cases of influenza occurred in
the city. Of these cases, 775 persons were ill with influenza according to surveillance reports on
April 1, 2005. The prevalence rate of active influenza as of April 1, 2005, was:
Correct! 20 per 1,000 population
2. The population of a city on February 15, 2005, was 36,600. The city has a passive surveillance
system that collects hospital and private physician reports of influenza cases every month.
During the period between January 1 and April 1, 2005, 2,200 new cases of influenza occurred in
the city. Of these cases, 775 persons were ill with influenza according to surveillance reports on
April 1, 2005. The monthly incidence rate of active cases of influenza for the 3-month period
was:
Correct! 20 per 1,000 population
3. What would be the effect on age-specific incidence rates of uterine cancer if women with
hysterectomies were excluded from the denominator of incidence calculations assuming that
most women who have had hysterectomies are older than 50 years of age?
Correct!: Rates would increase in women older than 50 years of age but may decrease in
younger women as they get older.
, 4. The ability of a single person to remain free of clinical illness following exposure to an infectious
agent is known as:
Correct!: Immunity
5. Which of the following reasons can explain why a person who did not consume the infective
food item got sick?
Correct: All of the above
6. Which of the food items (or combination of items) is most likely to be the infective item(s)?
Correct!: Ice cream only
7. The case-fatality rate associated with plague is lowest in which community?
Correct Answer: Community C
8. The incidence and prevalence rates of a chronic childhood illness for a specific community are
given below.
Correct Answer: The duration of disease is becoming longer.
9. The following table gives the mean annual age-specific mortality rates from measles during the
first 25 years of life in successive 5-year periods. You may assume that the population is in a
steady state (i.e., migrations out are equal to migrations in).
Based on the information above, one may conclude:
Correct Answer: Children ages 5 to 9 had the highest rate of death in all periods
10. In a country with a population of 16 million people, 175,000 deaths occurred during the year
ending December 31, 2005. These included 45,000 deaths from tuberculosis (TB) in 135,000
persons who were sick with TB. Assume that the population remained constant throughout the
year. Not all 135,000 cases of TB were contracted during 2005. Which of the following
statements is true?
ANSWERS
1. The population of a city on February 15, 2005, was 36,600. The city has a passive surveillance
system that collects hospital and private physician reports of influenza cases every month.
During the period between January 1 and April 1, 2005, 2,200 new cases of influenza occurred in
the city. Of these cases, 775 persons were ill with influenza according to surveillance reports on
April 1, 2005. The prevalence rate of active influenza as of April 1, 2005, was:
Correct! 20 per 1,000 population
2. The population of a city on February 15, 2005, was 36,600. The city has a passive surveillance
system that collects hospital and private physician reports of influenza cases every month.
During the period between January 1 and April 1, 2005, 2,200 new cases of influenza occurred in
the city. Of these cases, 775 persons were ill with influenza according to surveillance reports on
April 1, 2005. The monthly incidence rate of active cases of influenza for the 3-month period
was:
Correct! 20 per 1,000 population
3. What would be the effect on age-specific incidence rates of uterine cancer if women with
hysterectomies were excluded from the denominator of incidence calculations assuming that
most women who have had hysterectomies are older than 50 years of age?
Correct!: Rates would increase in women older than 50 years of age but may decrease in
younger women as they get older.
, 4. The ability of a single person to remain free of clinical illness following exposure to an infectious
agent is known as:
Correct!: Immunity
5. Which of the following reasons can explain why a person who did not consume the infective
food item got sick?
Correct: All of the above
6. Which of the food items (or combination of items) is most likely to be the infective item(s)?
Correct!: Ice cream only
7. The case-fatality rate associated with plague is lowest in which community?
Correct Answer: Community C
8. The incidence and prevalence rates of a chronic childhood illness for a specific community are
given below.
Correct Answer: The duration of disease is becoming longer.
9. The following table gives the mean annual age-specific mortality rates from measles during the
first 25 years of life in successive 5-year periods. You may assume that the population is in a
steady state (i.e., migrations out are equal to migrations in).
Based on the information above, one may conclude:
Correct Answer: Children ages 5 to 9 had the highest rate of death in all periods
10. In a country with a population of 16 million people, 175,000 deaths occurred during the year
ending December 31, 2005. These included 45,000 deaths from tuberculosis (TB) in 135,000
persons who were sick with TB. Assume that the population remained constant throughout the
year. Not all 135,000 cases of TB were contracted during 2005. Which of the following
statements is true?
