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Center for Disease Control Patient Under Investigation Definition

>>View the CDC definition for a “Patient Under Investigation (PUI)”

A PUI is a person with the following characteristics -

CDC Category A

  • fever (≥ 38°C, 100.4°F) and pneumonia or acute respiratory distress syndrome (based on clinical or radiological evidence);


  • a history of travel from countries in or near the Arabian Peninsula within 14 days before symptom onset;


  • close contact with a symptomatic traveler who developed fever and acute respiratory illness (not necessarily pneumonia) within 14 days after traveling from countries in or near the Arabian Peninsula;


  • is a member of a cluster of patients with severe acute respiratory illness (e.g., fever and pneumonia requiring hospitalization) of unknown etiology in which MERS-CoV is being evaluated, in consultation with State and local health departments.

CDC Category B:

  • close contact with a confirmed or probable case of MERS while the case was ill AND has a fever (> 100°F) or symptoms of respiratory illness within 14 days following the close contact.  NOTE: This is a lower threshold than Category A.

Close Contact

Close contact is defined as:

  • Any person who provided care for the patient, including a healthcare worker or family member, or had similarly close physical contact.
  • Any person who stayed at the same place (e.g., lived with, visited) as the patient while the patient was ill.

Probable Case

A probable case is a PUI with absent or inconclusive laboratory results for MERS-CoV infection who is a close contact of a laboratory-confirmed MERS-CoV case.

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