reading

Question 1

what is an outbreak?

Answer 1

• A sudden and rapid increase in the number of cases of a disease or condition among a population
• Usually defined as two or more cases of the same type of illness occurring at about the same time

Question 2

How can you recognize an outbreak?

Answer 2

• When someone first notices an unusual disease or an unusual number of cases of a disease and alerts a PBH official
• comes from surveillance data but it is uncommon for outbreaks to be detected this way

Question 3

Why should an outbreak be investigated?

Answer 3

• E might still be in progress and by identifying and eliminating the source of infection additional cases can be prevented

Question 4

Why should an outbreak be investigated when it is over?

Answer 4

= can prevent similar outbreaks
= describes the new disease and learn more about it
= Evaluating existing prevention strategies
= Teach epidemiology
= Address public concerns about the outbreak

Question 5

What is done after a decision is made to investigate an outbreak?

Answer 5

Epidemiologic investigation
Environmental investigation
Interaction with the public, press, and legal system

Question 6

What are the constraints of an epidemiological investigation?

Answer 6

• If the outbreak is ongoing at the time of the investigation there is an urgency to find the source and prevent it
• In many outbreaks, the number of cases is limited
• Early media reportings might be bias
• Legal liability and financial interests put pressure on doing quick investigations
• If detection of an outbreak is delayed, useful clinical and environmental samples might be hard to find

Question 7

order of outbreak

Answer 7

1. Establish case definition
2. Confirm cases are related
3. Establish the background rate of disease
4. Find cases, decide if there is an outbreak, and define the scope of the outbreak
5. Examine the descriptive epidemiological features of the case
6. Generate hypothesis
7. Test hypothesis
8. Collect and test environmental sample
9. Implement control measures
10. Interact with the press and inform the public

Question 8

What makes a good case definition?

Answer 8

Set of standard criteria used to determine if a person has a particular illness of disease
Person place time
Disease symptoms
Confirmed lab samples

Question 9

What is descriptive epidemiology?

Answer 9

Collecting patient data, and case finding can give important information

Question 10

how can samples be stored in enviornmental investigations?

Answer 10

Since it is expensive to test environmental samples its fine to collect and store as many samples as possible and test only a few

Question 11

What is an epi curve and how can it help an outbreak?

Answer 11

• Graphical depiction of the number of outbreak cases by date of illness onset
• Useful because it gives information on the outbreak pattern/speed, magnitude, outliers, time trend, and exposure/incubation period

Question 12

What is a histogram and bar chart ?

Answer 12

Histogram: frequency distribution of continuous data and not separated by a gap
Bar chart: compare discrete categories of data separated by a gap

Question 13

What can the pattern/shape tell you?

Answer 13

The overall shape reveals the type of outbreak - common source, point source of propagated

Question 14

common source outbreak

Answer 14

people are exposed intermittently or continuously to a common harmful source
The period of exposure may be long or short
It is common and results in irregular peaks that reflect the timing and extent of exposure

Question 15

What is a point source outbreak?

Answer 15

Sharp upward slope and gradual downward slope
It is a common one where the exposure period is brief and all cases happen within one incubation period

Question 16

What is a propagated outbreak?

Answer 16

Spreads person to person which makes them last longer than common source epidemics and leads to multiple waves of infection
Progressively taller peaks, each an incubation period apart