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Interim Patient under Investigation (PUI) Guidance and Case Definitions

Summary of Changes (December 2015)

This is an updated version of CDC’s case definitions for MERS-CoV issued June 2015. CDC has revised this document based on comments from public health partners, healthcare providers, professional organizations, and others. CDC will continue to update the document as necessary to incorporate new information that increases our understanding of MERS-CoV.

Updates:

  • Deleted reference to the Republic of Korea. More than two incubation periods have passed since the last MERS case was reported from the Republic of Korea. Also revised the MERS Patient Under Investigation (PUI) Short Form.
  • Added footnote to PUI Guidance clarifying that fever may not be present in some patients, such as those who are very young, elderly, immunosuppressed, or taking certain medications. Clinical judgement should be used to guide testing of patients in such situations.
  • Revised document title to “Interim Patient Under Investigation (PUI) Guidance and Case Definitions for MERS” from “Case Definitions” to highlight the current clinical features and epidemiologic risks that guide testing and decisions for a patient under investigation, rather than using a more absolute case definition.

Patients should be evaluated for MERS-CoV infection in consultation with the state and local health departments. For more information, see CDC’s Interim Guidance for Healthcare Professionals.

 

Patient Under Investigation (PUI)

A person who has both clinical features and an epidemiologic risk should be considered a patient under investigation (PUI) based on one of the following scenarios:

Clinical Features   Epidemiologic Risk

Severe illness
Fever1 and pneumonia or acute respiratory distress syndrome (based on clinical or radiological evidence)

and

A history of travel from countries in or near the Arabian Peninsula2 within 14 days before symptom onset, or close contact3 with a symptomatic traveler who developed fever1 and acute respiratory illness (not necessarily pneumonia) within 14 days after traveling from countries in or near the Arabian Peninsula2.

– or –

A member of a cluster of patients with severe acute respiratory illness (e.g., fever1 and pneumonia requiring hospitalization) of unknown etiology in which MERS-CoV is being evaluated, in consultation with state and local health departments in the US.

Milder illness
Fever1 and symptoms of respiratory illness (not necessarily pneumonia; e.g., cough, shortness of breath)

and

A history of being in a healthcare facility (as a patient, worker, or visitor) within 14 days before symptom onset in a country or territory in or near the Arabian Peninsula2 in which recent healthcare-associated cases of MERS have been identified.

Fever1 or symptoms of respiratory illness (not necessarily pneumonia; e.g., cough, shortness of breath)

and

Close contact3 with a confirmed MERS case while the case was ill.

The above criteria serve as guidance for testing; however, patients should be evaluated and discussed with public health departments on a case-by-case basis if their clinical presentation or exposure history is equivocal (e.g., uncertain history of health care exposure).

 

Confirmed Case

A confirmed case is a person with laboratory confirmation of MERS-CoV infection. Confirmatory laboratory testing requires a positive PCR on at least two specific genomic targets or a single positive target with sequencing on a second.

 

Probable Case

A probable case is a PUI with absent or inconclusive laboratory results for MERS-CoV infection who is a close contact3 of a laboratory-confirmed MERS-CoV case. Examples of laboratory results that may be considered inconclusive include a positive test on a single PCR target, a positive test with an assay that has limited performance data available, or a negative test on an inadequate specimen.

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Footnotes

  1. Fever may not be present in some patients, such as those who are very young, elderly, immunosuppressed, or taking certain medications. Clinical judgement should be used to guide testing of patients in such situations.
  2. Countries considered in the Arabian Peninsula and neighboring include: Bahrain; Iraq; Iran; Israel, the West Bank, and Gaza; Jordan; Kuwait; Lebanon; Oman; Qatar; Saudi Arabia; Syria; the United Arab Emirates (UAE); and Yemen.
  3. Close contact is defined as: a) being within approximately 6 feet (2 meters) or within the room or care area for a prolonged period of time (e.g., healthcare personnel, household members) while not wearing recommended personal protective equipment (i.e., gowns, gloves, respirator, eye protection– see Infection Prevention and Control Recommendations); or b) having direct contact with infectious secretions (e.g., being coughed on) while not wearing recommended personal protective equipment (i.e., gowns, gloves, respirator, eye protection – see Infection Prevention and Control Recommendations). Data to inform the definition of close contact are limited. At this time, brief interactions, such as walking by a person, are considered low risk and do not constitute close contact.

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