Disease Detectives B/C

[Alex-RCHS]

Reviving: What are the three things that characterize an agent's potential to spread and cause disease?

answer (Click to Show Hidden Text)

virulence, infectivity, pathogenicity?

[UTF-8 U+6211 U+662F]

answer (Click to Show Hidden Text)

virulence, infectivity, pathogenicity?

Yep, your turn!

[Alex-RCHS]

Sorry if this is long... I got carried away.

General questions
1. Distribution is defined as the _________ and ____________ of the disease. (fill in the blanks)
2. Define surveillance.
3. The epidemiological triangle is made up of what 3 (or 4) things?
4. Define latency period.

Outbreak investigation
5. Drake hosted a party in celebration of the launch of "More Life." 314 people at the party ate from the buffet, which contained food contaminated with a pathogen. In total, 159 people who attended the party were infected with the pathogen. Of those, 2 died as a result of the disease. Many of those infected experienced an onset of vomiting within 6 hours of exposure. Many also experienced watery diarrhea and abdominal cramps between 5 and 35 hours after exposure.
a. What is the case fatality rate for this outbreak?
b. Based on the symptoms, name one pathogen that might have caused this outbreak.
c. If 89 people at the party did not eat from the buffet, and 7 of them were infected with the pathogen, calculate the relative risk of infection associated with eating from the buffet.

[Unome]

Haven't looked at Disease since MIT so... (Click to Show Hidden Text)

1. uh... location and concentration?
2. The scientific recording of cases in order to locate abnormalities in distribution (or more specific functions, like to monitor eradication programs)
3. host, vector, agent, and something else I don't remember
4. The time during which a pathogen does not cause active disease. This may or may not be the same as the incubation period, depending on the disease.
5.
 a. 2/159 = 0.0126 or 1.26%
 b. Cholera (yay microbes knowledge!)
 c. Number of people who were exposed and did not contract the disease: 159 - 7 = 152. Number of people who were exposed = 314. Number of people unexposed - 89. Number of people unexposed and infected = 7. Relative risk = ( 152 / 314 ) / ( 7 / 89 ) = 6.15

[maxxxxx]

Sorry if this is long... I got carried away.

General questions
1. Distribution is defined as the _________ and ____________ of the disease. (fill in the blanks)
2. Define surveillance.
3. The epidemiological triangle is made up of what 3 (or 4) things?
4. Define latency period.

Outbreak investigation
5. Drake hosted a party in celebration of the launch of "More Life." 314 people at the party ate from the buffet, which contained food contaminated with a pathogen. In total, 159 people who attended the party were infected with the pathogen. Of those, 2 died as a result of the disease. Many of those infected experienced an onset of vomiting within 6 hours of exposure. Many also experienced watery diarrhea and abdominal cramps between 5 and 35 hours after exposure.
a. What is the case fatality rate for this outbreak?
b. Based on the symptoms, name one pathogen that might have caused this outbreak.
c. If 89 people at the party did not eat from the buffet, and 7 of them were infected with the pathogen, calculate the relative risk of infection associated with eating from the buffet.

I'll give this a shot (Click to Show Hidden Text)

1. Frequency and Pattern
2. The systematic collection, analysis, interpretation, and dissemination of health data on an ongoing basis
3. Agent, Host, Environment
4. A period between exposure and onset of symptoms
5. 
a. 2/159 = 1.26%
    b. Bacillus cereus
    c. (159/225)/(7/89) = 8.98

[yang573]

Sorry if this is long... I got carried away.

General questions
1. Distribution is defined as the _________ and ____________ of the disease. (fill in the blanks)
2. Define surveillance.
3. The epidemiological triangle is made up of what 3 (or 4) things?
4. Define latency period.

Outbreak investigation
5. Drake hosted a party in celebration of the launch of "More Life." 314 people at the party ate from the buffet, which contained food contaminated with a pathogen. In total, 159 people who attended the party were infected with the pathogen. Of those, 2 died as a result of the disease. Many of those infected experienced an onset of vomiting within 6 hours of exposure. Many also experienced watery diarrhea and abdominal cramps between 5 and 35 hours after exposure.
a. What is the case fatality rate for this outbreak?
b. Based on the symptoms, name one pathogen that might have caused this outbreak.
c. If 89 people at the party did not eat from the buffet, and 7 of them were infected with the pathogen, calculate the relative risk of infection associated with eating from the buffet.

Here we go (Click to Show Hidden Text)

1. [u]geographic extent[/u] and [u]prevalence[/u]
2. Surveillance is the systematic collection and analysis of public health data to monitor public health.
3. agent, host, & environment
4. latency period can mean 1. the period between exposure and onset of symptoms or 2. the period after exposure when the host is yet infectious

5. a. 2 deaths / 159 cases = 0.013 deaths/case = 1.3 deaths/100 cases
    b. Salmonella
    c .             ill     not ill
      exp.       159    155
      not exp.   7       81

      RR = (159/314) / (7/89) = 6.44

[yang573]

Whoops. I should have checked first. Give this one to Unome.

[Alex-RCHS]

Unome answered first, and mostly correctly, so I'll give this to him.

Since the three answers given were sometimes conflicting, here are

the answers that I was thinking of (Click to Show Hidden Text)

1. Frequency and pattern.
2. All of the given definitions seem good.
3. Host, agent, environment are the 3 main components, vector is often included.
4. I originally assumed that latency period was the same as incubation, but upon googling I've found different answers, so I'm not sure about that one.  :oops: 
5. a. 1.26%
b. Cholera, B. Cereus, Salmonella, and a few others are all good answers.
c. 6.15. This is how I did it, but Unome's way is better:
Risk associated with eating from the buffet: (159-7)/314 = .4841
Risk associated with not eating from the buffet: 7/89 = .07865
Relative risk = .4841/.07865 = 6.15

(but I could be wrong on some)

Did nobody realize that the numbers I gave in the outbreak question were the first 14 digits of pi? 3.1415926535897...

Your turn, Unome.

[Unome]

Question (Click to Show Hidden Text)

For each of the three major types of epi curves, give one characteristic of its histogram, and one characteristic of the outbreak itself that could cause that type of curve.

[yang573]

Question (Click to Show Hidden Text)

For each of the three major types of epi curves, give one characteristic of its histogram, and one characteristic of the outbreak itself that could cause that type of curve.

Answer (Click to Show Hidden Text)

Common Source: A single, one-time exposure results in a single peak. Food-borne illness from a convention is one example.

Continuous: A constant exposure results in a plateau of cases. The 1854 London Cholera outbreak is one example.

Propagated: A host serves as a source of exposure for other susceptible hosts, resulting in a serious of growing peaks. A flu pandemic in which no one is initially immune would be one example.