Over time, as the CDC gathers new evidence, their guidance documents on the handling of various diseases evolves. We saw rapid evolution of advice during the first couple of months of the 2009 H1N1 pandemic, and we are seeing it now with the Ebola virus outbreak in West Africa.
Often these changes are minor adjustments or clarifications, designed to make earlier guidance clearer.
Just over two weeks ago we saw the CDC Issue New Ebola Case Definitions, along with Interim Guidance for Monitoring and Movement of Persons with Ebola Virus Disease Exposure. We took a closer look at the CDC’s risk groups in Ebola: Parsing The CDC’s Low Risk vs High Risk Exposures.
Although they incorporate only relatively minor changes, last night the CDC posted updates to both documents.
The first involves the risks of exposure and the case definition for EVD. A side-by-side comparison with the previous guidance shows relatively minor changes, mostly to the format, and to some definitions (i.e.. `Low risk’ = `some risk’).
Updated: August 22, 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:
- 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
- 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.
A PUI whose epidemiologic risk factors include high or low risk exposure(s) (see below)
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
- 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)
- having direct brief contact (e.g., shaking hands) with an EVD case 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 22 August 2014, countries with EVD outbreaks are Guinea, Liberia, and Sierra Leone. There are also cases of EVD in Lagos, Nigeria. For more information about specific districts where the EVD outbreak is occurring, visit: www.cdc.gov/vhf/ebola/outbreaks/guinea/
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
The second update, fleshes out the public Health response for those who may have have had an Ebola exposure, but who are currently asymptomatic. The bottom line is:
At this time, CDC is NOT recommending that asymptomatic contacts of EVD cases be quarantined, either in facilities or at home.
For the purposes of this document, the following definitions are used:
Conditional release means that people are monitored by a public health authority for 21 days after the last known potential Ebola virus exposure to ensure that immediate actions are taken if they develop symptoms consistent with EVD during this period. People conditionally released should self-monitor for fever twice daily and notify the public health authority if they develop fever or other symptoms.
Controlled movement requires people to notify the public health authority about their intended travel for 21 days after their last known potential Ebola virus exposure. These individuals should not travel by commercial conveyances (e.g. airplane, ship, long-distance bus, or train). Local use of public transportation (e.g. taxi, bus) by asymptomatic individuals should be discussed with the public health authority. If travel is approved, the exposed person must have timely access to appropriate medical care if symptoms develop during travel. Approved long-distance travel should be by chartered flight or private vehicle; if local public transportation is used, the individual must be able to exit quickly.
Quarantine is used to separate and restrict the movement of persons exposed to a communicable disease who don’t have symptoms of the disease for the purpose of monitoring.
Far less draconian than many people might expect, for either High or Low (some) risk exposures – as long as the person remains asymptomatic - the guidance simply recommends:
It is a lengthy document, and so you’ll want to read it in its entirety on the website. The decision chart can be expanded using the Chart icon at the bottom of the page.
Updated: August 22, 2014
The world is facing the biggest and most complex Ebola virus disease (EVD) outbreak in history. On August 8, 2014, the EVD outbreak in West Africa was declared by the World Health Organization (WHO) to be a Public Health Emergency of International Concern (PHEIC) because it was determined to be an ‘extraordinary event’ with public health risks to other States. The possible consequences of further international spread are particularly serious considering the following factors:
- the virulence of the virus,
- the intensive community and health facility transmission patterns, and
- the strained health systems in the currently affected and most at-risk countries.
Coordinated public health actions are essential to stop and reverse the spread of Ebola virus. Due to the complex nature and seriousness of the outbreak, CDC has created guidance for monitoring people exposed to Ebola virus and for evaluating their travel, including the application of movement restrictions when indicated.
The CDC also released an info service (lowest level) HAN Notice with an updated list of Ebola Resources: