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Difficulty: MediumDisease Surveillance and Outbreak Management

A public health physician is assisting a 150-bed skilled nursing facility with an outbreak of acute gastroenteritis. The illness is characterized by the abrupt onset of nausea, severe vomiting, and non-bloody diarrhea that typically resolves with supportive care within 48 hours. The first case was identified in a nursing assistant on day 1. Subsequently, 5 cases occurred on day 3, 22 cases on day 5, and 45 cases on day 7, spreading across three separate wards. The facility's meals are centrally prepared, but the kitchen staff have remained entirely asymptomatic. Based on the progressive epidemic curve and transmission dynamics, which of the following is the most appropriate next step in managing this outbreak?

  1. Cohorting of symptomatic residents and implementation of strict contact precautionsAnswer
  2. B
    Empiric administration of prophylactic broad-spectrum fluoroquinolones to all residents
  3. C
    Disciplinary dismissal of the index case nursing assistant to strictly enforce infection control
  4. D
    Administration of a live-attenuated viral gastroenteritis vaccine to all facility residents
  5. E
    Disclosure of the infected nursing assistant's identity to residents' families to aid in contact tracing

Answer

The most appropriate next step is the cohorting of symptomatic residents and the implementation of strict contact precautions.
The correct answer addresses the specific transmission dynamics described. An outbreak featuring successive, expanding waves of illness over time is a propagated epidemic curve, indicative of person-to-person spread. In a long-term care facility, highly contagious pathogens like Norovirus require immediate source control through isolating or cohorting symptomatic individuals and applying strict contact precautions to halt the chain of transmission.

Step-by-Step Solution

1
Analyze the clinical presentation.
The acute onset of severe vomiting, nausea, and non-bloody diarrhea resolving in 48 hours is highly characteristic of Norovirus infection.
Identifying the likely pathogen helps determine the mode of transmission.
2
Interpret the epidemic curve described in the stem.
The pattern of cases (1 on day 1, 5 on day 3, 22 on day 5, and 45 on day 7) represents a series of progressively larger peaks.
This pattern defines a propagated outbreak, confirming person-to-person transmission rather than a single point-source (like contaminated food).
3
Determine the most appropriate public health intervention based on the transmission dynamic.
Because the outbreak is propagated person-to-person, the intervention must focus on interrupting this spread via cohorting and contact precautions.
Environmental and foodborne interventions (e.g., throwing out food) are incorrect because the curve points away from a common source.

Key Concept

Outbreak Management: Differentiating Epidemic Curves
Estimated Time:1m 15s
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Topics

Disease Surveillance and Outbreak Management

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