Outbreak investigation

Question 1

Describe some situations where analytical studies may be useful and ought to be considered.

Answer 1

1. They can help guide further investigations and suggest new avenues of exploration in situations in which the source of an outbreak remains unclear and control measure ineffective.
2. Might be useful in convincing clinicians that the proposed source or mechanism suggested by chart review and observations is indeed correct. Helpful when environmental cultures do not or cannot confirm.
3. They are powerful teaching tools and might be undertaken to further the educational experience of students in healthcare epidemiology, IPs, and public health officials.

Question 2

Outbreaks in healthcare are often multifactorial.

Answer 2

Ending outbreaks involves modifying one or more of the contributing factors.

Question 3

Common source or point source outbreak

Answer 3

transmission mode that involves intermittent or continuous exposure to a common harmful source.

Question 4

Propagated Source

Answer 4

Transmission mode that involves the spread from person to person; may last longer in event of secondary or tertiary waves of exposure.

Question 5

pseudo outbreak

Answer 5

increase in positive cultures without evidence of disease- frequently attributed to contaminated specimen collection, lab reporting inaccuracies, and bias.

Question 6

The epi curve is used to:

Answer 6

1. determine whether the source of infection was common, propagated (continuing), or both.
2. establish if the pathogen has a short or long incubation period.
3. Ascertain if the outbreak is increasing or waning.

Question 7

Features of Common source epi curve

Answer 7

All cases have same origin
Same person or vehicle identified as primary reservoir or means of transmission
Epi curve approximates a normal distribution if there is sufficient number of cases and if cases are limited to a short exposure with maximum incubation of a few days or less (point source).
Exposure may be continuous or intermittent.
Intermittent exposure to source creates a curve with irregularly spaced peaks.

Question 8

Features of propagated Source

Answer 8

Infections transmitted person to person
Occur over a long period of time.
If secondary or tertiary cases occur, intervals between peaks usually approximate average incubation period.