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Case Definition for Ebola Virus Disease (EVD)

Updated: September 4, 2014

Early recognition is critical for infection control. Health care providers should be alert for and evaluate any patients suspected of having Ebola Virus Disease (EVD).

Person Under Investigation (PUI)

A person who has both consistent symptoms and risk factors as follows:

  1. Clinical criteria, which includes fever of greater than 38.6 degrees Celsius or 101.5 degrees Fahrenheit, and additional symptoms such as severe headache, muscle pain, vomiting, diarrhea, abdominal pain, or unexplained hemorrhage; AND
  2. epidemiologic risk factors within the past 21 days before the onset of symptoms, such as contact with blood or other body fluids or human remains of a patient known to have or suspected to have EVD; residence in—or travel to—an area where EVD transmission is active*; or direct handling of bats or non-human primates from disease-endemic areas.

Probable Case

A PUI whose epidemiologic risk factors include high or low risk exposure(s) (see below)

Confirmed Case

A case with laboratory-confirmed diagnostic evidence of Ebola virus infection

Exposure Risk Levels

Levels of exposure risk are defined as follows:

High risk exposures

A high risk exposure includes any of the following:

  • Percutaneous (e.g., needle stick) or mucous membrane exposure to blood or body fluids of EVD patient
  • Direct skin contact with, or exposure to blood or body fluids of, an EVD patient without appropriate personal protective equipment (PPE)
  • Processing blood or body fluids of a confirmed EVD patient without appropriate PPE or standard biosafety precautions
  • Direct contact with a dead body without appropriate PPE in a country where an EVD outbreak is occurring*

Low1 risk exposures

A low risk exposure includes any of the following

  • Household contact with an EVD patient
  • Other close contact with EVD patients in health care facilities or community settings. Close contact is defined as
    1. being within approximately 3 feet (1 meter) of an EVD patient or within the patient’s room or care area for a prolonged period of time (e.g., health care personnel, household members) while not wearing recommended personal protective equipment (i.e., standard, droplet, and contact precautions; see Infection Prevention and Control Recommendations)
    2. having direct brief contact (e.g., shaking hands) with an EVD patient while not wearing recommended personal protective equipment.
  • Brief interactions, such as walking by a person or moving through a hospital, do not constitute close contact

No known exposure

Having been in a country in which an EVD outbreak occurred within the past 21 days and having had no high or low risk exposures

* As of 30 August 2014, EVD outbreaks are affecting multiple countries in West Africa (see Affected Areas)

1 For purposes of monitoring and movement restrictions of persons with Ebola virus exposure, low risk is interpreted as some risk. See www.cdc.gov/vhf/ebola/hcp/monitoring-and-movement-of-persons-with-exposure.html

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