2013 Science Olympiad NC Tournament – Disease Detectives, Div. B
Be specific and detailed in your answers, but full sentences aren’t necessary. For full points, SHOW WORK
FOR ALL CALCULATIONS. Certain questions will be used for tiebreakers.
Part I: Vocabulary (15 pts)
Match the following to the correct definition:
1. Epidemic
2. Quarantine
3. Cluster
4. Pandemic
5. Endemic
A. An aggregation of cases closely grouped in time and space
B. More cases of a particular disease than expected in a given
area or among a group of people over a particular period of
time
C. An epidemic occurring over a very wide area (several
countries or continents) and usually affecting a large
proportion of the population
D. The separation of well persons who have been exposed or
are thought to have been exposed to an infectious disease
E. Constant presence of an agent or health condition within a
given geographic area or population
Determine whether the following examples are fomites or vectors. (Write “F” or “V” in the blanks.)
6. Lice-infested hairbrush
7. Female Anopheles mosquito carrying malaria
8. Tick carrying Lyme disease
9. Dust particle carrying sneeze droplet
Fill in the blanks of the epidemiological chain of infection.
10.______
Agent
________
________
._____
______
______
11
Mode of
transmission
12.______
________
________
13. Disease detectives use three pieces of information to characterize an outbreak. What are they?
Host
Part II: Diseases (10 pts)
Match the following diseases to the appropriate disease-causing agent. (Note: some agents may be used
more than once.)
1. Salmonellosis
A. Bacteria
2. Influenza
B. Virus
3. Ebola Hemorrhagic Fever
C. Protozoa
4. HIV/AIDS
D. Other
5. Cholera
6. Lung Cancer
7. Malaria
8. Mad Cow Disease
Which of the following are zoonotic diseases? Circle ALL correct answers.
a. Malaria
b. Rabies
c. Swine Flu
d. West Nile
Part III: Case Study #1 (35 pts)
Answer questions about the following scenario. Remember, SHOW ALL WORK on calculations to get full
credit!
The week before the Science Olympiad State Tournament, a hospital in Raleigh receives a sudden influx
of patients with similar symptoms: cramps, nausea, vomiting, and diarrhea. Luckily, a couple of smart
Disease Detectives are in the area for the State Tournament. They quickly realize that these symptoms
are characteristic of a food-borne disease, and they decide to collect data on what the patients ate
before they got sick. It turns out most of the patients ate at the same restaurant. Being exceptionally
smart, they also decide to collect some data from the same number of people who ate at the restaurant,
but didn’t get sick for the sake of scientific comparison.
1. What is the group of people who didn’t get sick called?
2. There are a few different types of epidemiological studies. List the two main kinds of analytical
(not descriptive!) studies, and circle the one which the Disease Detectives are using.
1)
2)
3. In order to collect data on the outbreak, the Disease Detectives first need to find as many cases
as possible. Write a standard case definition for a confirmed case.
The Disease Detectives obtain the following data:
Number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
Sick? (Y/N)
Y
N
N
Y
N
Y
Y
Y
N
N
Y
Y
N
N
Y
N
N
Y
Lunch
PB&J
Grilled Cheese
PB&J
PB&J
Grilled Cheese
PB&J
PB&J
PB&J
Grilled Cheese
Grilled Cheese
Grilled Cheese
Grilled Cheese
Grilled Cheese
PB&J
PB&J
Grilled Cheese
Grilled Cheese
PB&J
Dinner
Spaghetti
Pizza
Spaghetti
Spaghetti
Pizza
Pizza
Spaghetti
Pizza
Spaghetti
Spaghetti
Pizza
Spaghetti
Pizza
Pizza
Pizza
Pizza
Pizza
Spaghetti
4. Given the above data, calculate the odds ratio of infection for each of the suspect foods.
5. Which food is the most likely source of the outbreak?
a. PB&J
b. Grilled Cheese
c. Spaghetti
d. Pizza
6. Once the source of the outbreak has been identified, list two steps that should be taken.
7. Using the following data table, construct an epi curve for the epidemic.
Day
Number of new cases
April 20
0
April 21
1
April 22
0
April 23
2
April 24
5
April 25
1
April 26
0
8. Based on the epi curve, this outbreak is most likely:
a. Common-source
b. Point-source
c. Propagated
Part IV: Case Study #2 (25 pts)
Answer questions about the following scenario. Remember, SHOW ALL WORK on calculations to get full
credit!
Cigarette smoking remains the leading cause of preventable morbidity and mortality in the United
States. Despite overall declines in cigarette smoking, a high prevalence of smoking persists among
certain subpopulations, including persons with mental illness. A mental illness is defined here as a
mental, behavioral, or emotional disorder, excluding developmental and substance use disorders, in the
past 12 months. (Source: CDC MMWR, Feb. 8 2013)
Age group (yrs)
With mental illness
Smokers
Nonsmokers
Without mental illness
Total
Smokers
Nonsmokers
Total
18–24
1347
1890
3237
3446
7565
11011
25–44
3530
5185
8715
7678
21967
29645
45–64
2920
5795
8715
6137
23508
29645
550
3683
4233
1267
13132
14399
≥65
(Source: National Survey on Drug Use and Health, United States, 2009–2011)
1. What is the prevalence of smoking among each age group for people without mental illness?
Show work for each group, and circle final answers:
18-24 years old:
25-44 years old:
45-64 years old:
65 years old:
2. Notice that the prevalence of smoking in the age group 65 years old is much lower than the
other age groups. This turns out to be true for both categories (with and without mental illness).
What is the most likely reason for this?
a. There was a lower prevalence of smoking in that generation.
b. That generation has always been more health-conscious.
c. They could not afford cigarettes during the Great Depression.
d. Many smokers in that age group have already died.
3. Create a 2x2 table (for total populations—i.e. combined age groups and genders) with smoking
as the “exposure” and mental illness as the “disease.”
4. Using your 2x2 table, calculate the appropriate relative risk.
5. What does this result mean? Circle the correct answer, and explain your answer below.
a. Smoking causes mental illness
b. Mental illness causes smoking
c. Neither
2013 Science Olympiad NC Tournament – Disease Detectives, Div. B - KEY
Be specific and detailed in your answers, but full sentences aren’t necessary. For full points, SHOW WORK
FOR ALL CALCULATIONS. Certain questions will be used for tiebreakers.
Part I: Vocabulary (15 pts)
Match the following to the correct definition: (1 pt each)
B
D
A
C
E
1. Epidemic
2. Quarantine
3. Cluster
4. Pandemic
5. Endemic
A. An aggregation of cases closely grouped in time and space
B. More cases of a particular disease than expected in a given
area or among a group of people over a particular period of
time
C. An epidemic occurring over a very wide area (several
countries or continents) and usually affecting a large
proportion of the population
D. The separation of well persons who have been exposed or
are thought to have been exposed to an infectious disease
E. Constant presence of an agent or health condition within a
given geographic area or population
Determine whether the following examples are fomites or vectors. (1 pt each)
F
V
V
F
6. Lice-infested hairbrush
7. Female Anopheles mosquito carrying malaria
8. Tick carrying Lyme disease
9. Dust particle carrying sneeze droplet
Fill in the blanks of the epidemiological chain of infection. (1 pt each)
Agent
10.(Leaves)
Reservoir
11. (Through)
Portal of
exit
Mode of
transmission
12. Portal of
Entry
13. Disease detectives use three pieces of information to characterize an outbreak. What are they?
Person (1 pt), place (1 pt), time (1 pt)
Host
Part II: Diseases (10 pts)
Match the following diseases to the appropriate disease-causing agent. (1 pt each)
A
1. Salmonellosis
A. Bacteria
B
2. Influenza
B. Virus
B
3. Ebola Hemorrhagic Fever
C. Protozoa
B
4. HIV/AIDS
D. Other
A
5. Cholera
D
6. Lung Cancer
C
7. Malaria
D
8. Mad Cow Disease
Which of the following are zoonotic diseases? Circle ALL correct answers. (1 pt for each correct answer)
a. Malaria
b. Rabies
c. Swine Flu
d. West Nile
Part III: Case Study #1 (35 pts)
Answer questions about the following scenario. Remember, SHOW ALL WORK on calculations to get full
credit!
The week before the Science Olympiad State Tournament, a hospital in Raleigh receives a sudden influx
of patients with similar symptoms: cramps, nausea, vomiting, and diarrhea. Luckily, a couple of smart
Disease Detectives are in the area for the State Tournament. They quickly realize that these symptoms
are characteristic of a food-borne disease, and they decide to collect data on what the patients ate
before they got sick. It turns out most of the patients ate at the same restaurant. Being exceptionally
smart, they also decide to collect some data from the same number of people who ate at the restaurant,
but didn’t get sick for the sake of scientific comparison.
1. What is the group of people who didn’t get sick called? (2 pts)
“Control” or “control group”
2. There are a few different types of epidemiological studies. List the two main kinds of analytical
(not descriptive!) studies, and circle the one which the Disease Detectives are using. (1 pt for
each correct listing, 2 pts for circling correct answer)
1)
Case-control
2)
Cohort
3. In order to collect data on the outbreak, the Disease Detectives first needed to find as many
cases as possible. Write a standard case definition for a confirmed case.
Tiebreaker #3
1 pt each for including: 1) clinical information about the disease (i.e. listing symptoms), 2) characteristics
of the infected people (ate at same restaurant), 3) location (Raleigh), 4) time sequence (starting
approximately a week before the State Tournament [April 20th] until now) – max 4 pts total
The Disease Detectives obtained the following data:
Number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
Sick? (Y/N)
Y
N
N
Y
N
Y
Y
Y
N
N
Y
Y
N
N
Y
N
N
Y
Lunch
PB&J
Grilled Cheese
PB&J
PB&J
Grilled Cheese
PB&J
PB&J
PB&J
Grilled Cheese
Grilled Cheese
Grilled Cheese
Grilled Cheese
Grilled Cheese
PB&J
PB&J
Grilled Cheese
Grilled Cheese
PB&J
Dinner
Spaghetti
Pizza
Spaghetti
Spaghetti
Pizza
Pizza
Spaghetti
Pizza
Spaghetti
Spaghetti
Pizza
Spaghetti
Pizza
Pizza
Pizza
Pizza
Pizza
Spaghetti
4. Given the above data, calculate the odds ratio of infection for each of the suspect foods. (8 pts,
2 pts each [one for correct work, one for answer])
PB&J:
Exposed
Unexposed
Spaghetti
Disease Yes Disease No
7 (a)
2 (b)
2 (c)
7 (d)
Exposed
Unexposed
Disease Yes Disease No
5 (a)
4 (b)
4 (c)
5 (d)
Odds ratio = ad/bc = (7*7)/(2*2) = 12.25
Odds ratio = ad/bc = (5*5)/(4*4)=1.56
Grilled Cheese:
Pizza:
Exposed
Unexposed
Disease Yes Disease No
2 (a)
7 (b)
7 (c)
2 (d)
Odds ratio = ad/bc = (2*2)/(7*7)= 0.08
Exposed
Unexposed
Disease Yes Disease No
4 (a)
5 (b)
5 (c)
4 (d)
Odds ratio = ad/bc = (4*4)/(5*5)=0.64
5. Which food is the most likely source of the outbreak? (3 pts)
a. PB&J
b. Grilled Cheese
c. Spaghetti
d. Pizza
6. Once the source of the outbreak has been identified, list two steps that should be taken. (6 pts
max, 3 per good answer)
Tiebreaker #2
Possible answers:
 Shut down restaurant
 Remove item from menu
 Report findings (i.e. send out PSAs, run newspaper ads, etc.)
7. Using the following data table, construct an epi curve for the epidemic.
Day
Number of new cases
April 20
0
April 21
1
April 22
0
April 23
2
April 24
5
April 25
1
April 26
0
(6 pts; 1 each for x-axis label, y-axis label, title; 2 each for correct plotting and histogram format)
Number of outbreak cases over time
Number of cases
6
5
4
3
2
1
0
20-Apr
21-Apr
22-Apr
23-Apr
24-Apr
25-Apr
Date
8. Based on the epi curve, this outbreak is most likely: (2 pts)
a. Common-source
b. Point-source
c. Propagated
26-Apr
Part IV: Case Study #2 (25 pts)
Answer questions about the following scenario. Remember, SHOW ALL WORK on calculations to get full
credit!
Cigarette smoking remains the leading cause of preventable morbidity and mortality in the United
States. Despite overall declines in cigarette smoking, a high prevalence of smoking persists among
certain subpopulations, including persons with mental illness. A mental illness is defined here as a
mental, behavioral, or emotional disorder, excluding developmental and substance use disorders, in the
past 12 months. (Source: CDC MMWR, Feb. 8 2013)
The following data summarizes results from 29400 people with mental illness and 84700 people without
mental illness.
Age group (yrs)
With mental illness
Smokers
Nonsmokers
Without mental illness
Total
Smokers
Nonsmokers
Total
18–24
1347
1890
3237
3446
7565
11011
25–44
3530
5185
8715
7678
21967
29645
45–64
2920
5795
8715
6137
23508
29645
550
3683
4233
1267
13132
14399
≥65
(Adapted from: National Survey on Drug Use and Health, United States, 2009–2011)
1. What is the prevalence of smoking among each age group for people without mental illness?
Show work for each group, and circle final answers: (8 pts, 2 pts each [one for correct work, one
for answer])
18-24 years old:
Prevalence =
= 3446/11011 = 31.30%
25-44 years old:
Prevalence =
= 7678/29645 = 25.90%
45-64 years old:
Prevalence =
= 6137/29645 = 20.70%
65 years old:
Prevalence =
= 1267/14399 = 8.80%
2. Notice that the prevalence of smoking in the age group 65 years old is much lower than the
other age groups. This turns out to be true for both categories (with and without mental illness).
What is the most likely reason for this? (2 pts)
a. There was a lower prevalence of smoking in that generation.
b. That generation has always been more health-conscious.
c. They could not afford cigarettes during the Great Depression.
d. Many smokers in that age group have already died.
3. Create a 2x2 table (for total populations—i.e. combined age groups) with smoking as the
“exposure” and mental illness as the “outcome.”
(5 pts – 1 for correct table format, 1 for each correct number in correct location)
Exposed
Unexposed
Outcome Yes
8347 (a)
16553 (c)
Outcome No
18528 (b)
66172 (d)
4. Using your 2x2 table, calculate the appropriate relative risk.
(2 pts for correct work, 1 pt for correct answer)
Relative risk =
= 0.31/.20 = 1.55
5. What does this result mean? Circle the correct answer, and explain your answer below.
(3 pts for choosing correct answer, 4 pts for explanation)
a. Smoking causes mental illness
b. Mental illness causes smoking
c. Neither
Tiebreaker #1 – this implies (positive) correlation/association, NOT causation