ECDC: Ebola Case Definitions

 

# 9059

 

As the West African Ebola epidemic continues unabated, countries around the world must prepare for the possibility that an infected traveler might arrive unannounced on their shores.  Having a working and deployed public health system – and a criteria for identifying infected cases and their potential contacts – greatly limits the potential for any major outbreaks in developed countries.

 

The CDC has already released, and updated, their Interim Ebola Case Definitions, as has Canada (National Case Definition: Ebola Virus Disease (EVD)).  Both are works in progress and are subject to revision as more is learned.

Today the ECDC has offered their interpretation (see below).   And while all three of these case definitions involve many of the same criteria, there are some interesting differences between CDC & ECDC assessments, particularly in what constitutes a `High Risk’ exposure.

 

 
As you can see, the ECDC’s list of High Risk exposures is longer, and more encompassing, than is the CDC’s. Unlike the CDC, the ECDC does not elucidate what constitutes `Low Risk’ exposures.  

 

The CDC considers the following scenarios to present a `Low Risk’ of infection. 

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

 

With the added proviso that the suspected or confirmed Ebola patient in question is `coughing,  vomiting, bleeding, or who had diarrhoea’  - being within 1 meter of an EVD patient is considered to have a High Risk of exposure by the ECDC; essentially recognizing the risks of droplet transmission of the virus.

 

The potential of  droplet transmission of Ebola is something we’ve discussed before, and was well addressed by Dr. Ian Mackay et al. in VDU Blog: Droplets vs Airborne - Demystifying Ebola Transmission.

 

While one can debate the `reasonableness’ of either criteria (particularly given the different populations and geographic regions involved), the differences between them – and between the various PPE standards we’ve also seen used for or recommended for use with Ebola – risk creating an environment of confusion and distrust among both the public, and healthcare workers. 

 

Here is the ECDC’s release in its entirety:

 

ECDC releases case definition for Ebola virus disease

10 Sep 2014

​A case definition for reporting cases of Ebola virus disease in the EU has been released by ECDC. The definition aims to classify cases for epidemiological reporting and not to guide investigation or clinical management of cases.

Although developed in response to the outbreak of Ebola virus disease currently affecting West Africa, the case definition is broad enough to apply to any case of EVD.

Only confirmed cases are to be reported at the European level, although the newly published case definition does include a 'probable case' definition.

Algorithms for laboratory diagnosis of EVD and for the initial assessment and management of patients have also been released. To offer further support to healthcare professionals possibly faced with a situation where the management of patients suffering from EVD becomes necessary, the algorithms are accompanied by a directory of guidance from national institutes and other public health bodies. These guidance documents provide more detailed steps for the management of any EVD patient.

By releasing the case definition and related algorithms, ECDC works to support EU Member States in their preparedness for a quick and effective response to any situation that may potentially involve an EVD case.

Read more:

EVD Case definition
Algorithm for laboratory diagnosis of EVD
Algorithm for initial assessment and management of patients for EVD
Directory of guidance on EVD patient management
Ebola and Marburg fevers health topic
Rapid Risk Assessment – EVD in West Africa (fourth update, 3 September 2014)

 

Ebola virus disease case definition for reporting in EU

The classification of cases under this definition relies on clinical, epidemiological, laboratory and high-risk exposure criteria, allowing the identification of persons required to be investigated for EVD and the differentiation of probable and confirmed cases for reporting. The definition aims to classify cases for epidemiological reporting.

Criteria

Clinical criteria

Any person currently presenting or having presented before death:

• Fever ≥38.6°C

AND any of the following:

• Severe headache
• Vomiting, diarrhoea, abdominal pain
• Unexplained haemorrhagic manifestations in various forms
• Multi-organ failure

OR a person who died suddenly and inexplicably

Laboratory criteria

Any of the following:

• Detection of Ebola virus nucleic acid in a clinical specimen and confirmation by sequencing or a second assay on different genomic targets.
• Isolation of Ebola virus from a clinical specimen.

Epidemiological criteria

In the 21 days before the onset of symptoms:

• having been in an affected area;

OR

• having had contact with a probable or confirmed EVD case.

High-risk exposure criteria

Any of the following:

• close face-to-face contact (e.g. within one metre) without appropriate personal protective equipment (including eye protection) with a probable or confirmed case who was coughing, vomiting, bleeding, or who had diarrhoea; or had unprotected sexual contact with a case up to three months after recovery;
• direct contact with any material soiled by bodily fluids from a probable or confirmed case;
• percutaneous injury (e.g. with needle) or mucosal exposure to bodily fluids, tissues or laboratory specimens of a probable or confirmed case;
• participation in funeral rites with direct exposure to human remains in or from an affected area without appropriate personal protective equipment;
• direct contact with bats, rodents, primates, living or dead, in or from affected areas, or bushmeat.

Person under investigation

A person

• meeting the clinical and the epidemiological criteria;

OR

• with high-risk exposure and any of the listed symptoms, including fever of any grade.

Case classification for reporting at EU level

Only confirmed cases are to be reported at the European level using the EWRS. The 'probable case' classification is provided for information only.

Possible case

• Not Applicable.

Probable case

• A person meeting the clinical and high-risk exposure criteria.

Confirmed case

• A person meeting the laboratory criteria.

CDC Issues New Ebola Case Definitions

Credit CDC PHIL

 

# 8928

 

The steady procession of new, or updated, guidance on dealing with Ebola continues to come from the CDC, with a revised case definition published today. Interim guidance documents are works in progress, and are subject to revision as more is learned about dealing with the disease.

 

Case Definition for Ebola Virus Disease (EVD)

Updated: August 7, 2014

Early recognition is critical for infection control. Healthcare providers should be alert for and evaluate any patients suspected of having EVD.

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, rodents, or primates from disease-endemic areas.

Person Under Investigation (PUI)

Probable Case

A PUI who is a contact of an EVD case with either a high or low risk exposure (see below).

Confirmed Case

A case with laboratory confirmed diagnostic evidence of ebola virus infection.

Contacts of an EVD Case

Contacts of an EVD case have different levels of exposure risk, as follows:

High risk exposures

A high risk exposure includes any of the following:

• Percutaneous, e.g. the needle stick, or mucous membrane exposure to body fluids of EVD patient
• Direct care or exposure to body fluids of an EVD patient without appropriate personal protective equipment (PPE)
• Laboratory worker processing body fluids of confirmed EVD patients without appropriate PPE or standard biosafety precautions
• Participation in funeral rites which include direct exposure to human remains in the geographic area where outbreak is occurring without appropriate PPE

Low risk exposures

A low risk exposure includes any of the following

• Household member or other casual contact¹ with an EVD patient
• Providing patient care or casual contact¹ without high-risk exposure with EVD patients in health care facilities in EVD outbreak affected countries^*

No known exposure

Persons with no known exposure were present in an EVD outbreak affected country^* in the past 21 days with no low risk or high risk exposures.

¹ Casual contact is defined as a) being within approximately 3 feet (1 meter) 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., droplet and contact precautions–see Infection Prevention and Control Recommendations); or b) having direct brief contact (e.g., shaking hands) with an EVD case while not wearing recommended personal protective equipment (i.e., droplet and contact precautions–see Infection Prevention and Control Recommendations). At this time, brief interactions, such as walking by a person or moving through a hospital, do not constitute casual contact.

^* Outbreak affected countries include Guinea, Liberia, Sierra Leone, and Lagos, Nigeria, as of 4-August-2014

WHO: Revised MERS-CoV Case Definitions

 

Credit WHO

 

 

# 7443

 

The World Health Organization has just posted revised MERS-CoV case definitions for reporting to WHO, based on the latest available information on the virus.

 

This revision addresses asymptomatic cases, inconclusive test results, as well as expanding the parameters for `probable cases’.

 

The WHO also released a 21 page protocol for a prospective Case Control study to assess potential risk factors related to  human illness caused by Middle East Respiratory Syndrome  Coronavirus (MERS- CoV).

 

 

 

Revised interim case definition for reporting to WHO – Middle East respiratory syndrome coronavirus (MERS-CoV)

Interim case definition as of 03 July 2013

These case definitions have been revised based on new information collected since the previous definitions were published. WHO will continue to review and update them as new information becomes available.

Probable case

Three combinations of clinical, epidemiological and laboratory criteria can define a probable case:

• A person with a febrile acute respiratory illness with clinical, radiological, or histopathological evidence of pulmonary parenchymal disease (e.g. pneumonia or Acute Respiratory Distress Syndrome)
  AND
  Testing for MERS-CoV is unavailable or negative on a single inadequate specimen¹
  AND
  The patient has a direct epidemiologic-link with a confirmed MERS-CoV case².

 

• A person with a febrile acute respiratory illness with clinical, radiological, or histopathological evidence of pulmonary parenchymal disease (e.g. pneumonia or Acute Respiratory Distress Syndrome)
  AND
  An inconclusive MERS-CoV laboratory test (that is, a positive screening test without confirmation)³
  AND
  A resident of or traveler to Middle Eastern countries where MERS-CoV virus is believed to be circulating in the 14 days before onset of illness.

• A person with an acute febrile respiratory illness of any severity
  AND
  An inconclusive MERS-CoV laboratory test (that is, a positive screening test without confirmation)³
  AND
  The patient has a direct epidemiologic-link with a confirmed MERS-CoV case².

Confirmed case

A person with laboratory confirmation of MERS-CoV infection⁴.

Notes

Inconclusive testing: Patients with an inconclusive initial testing should undergo additional virologic and serologic testing to determine if the patient can be classified as a confirmed MERS-CoV case. It is strongly advised that lower respiratory specimens such as sputum, endotracheal aspirate, or bronchoalveolar lavage fluid be used when possible. If patients do not have signs or symptoms of lower respiratory tract infection and lower track specimens are not available or clinically indicated, both nasopharyngeal and oropharyngeal swab specimens should be collected. If initial testing of a nasopharyngeal swab is negative in a patient who is strongly suspected to have MERS-CoV infection, patients should be retested using a lower respiratory specimen tract or a repeat nasopharyngeal specimen with additional oropharyngeal specimen if lower respiratory tract specimens are not possible, and paired acute and convalescent sera.

Asymptomatic cases: The demonstration of asymptomatic infection is useful for epidemiological investigations and should be pursued as part of case investigations, however, the burden of proof must be higher due to the risk misclassification because of false positive tests due to laboratory contamination. Generally, in most viral infections, an immunological response such as development of specific antibodies would be expected even with mild or asymptomatic infection and as such serological testing may be useful as additional confirmation of the diagnosis. Additional steps to reconfirm asymptomatic cases, or any case in which the diagnosis is suspect, could include re-extraction of RNA from the original clinical specimen and testing for different virus target genes, ideally in an independent laboratory.

---

¹An inadequate specimen would include a nasopharyngeal swab without an accompanying lower respiratory specimen, a specimen that has had improper handling, is judged to be of poor quality by the testing laboratory, or was taken too late in the course of illness.
²A direct epidemiological link may include:
• Close physical contact
• Working together in close proximity or sharing the same classroom environment
• Traveling together in any kind of conveyance
• Living in the same household
• The epidemiological link may have occurred within a 14 day period before or after the onset of illness in the case under consideration.
³Inconclusive tests may include:
• A positive screening test without further confirmation such as testing positive on a single PCR target
• A serological assay considered positive by the testing laboratory.
⁴Currently confirmatory testing requires molecular diagnostics including either a positive PCR on at least two specific genomic targets or a single positive target with sequencing on a second. However, the interim recommendations for laboratory testing for MERS-CoV should be consulted for the most recent standard for laboratory confirmation (http://www.who.int/csr/disease/coronavirus_infections/en/). See also notes on asymptomatic cases in this document.

H7N9: Hong Kong’s Revised Reporting Criteria

Taiwan Intl Airport – Credit China News Agency

 

# 7204

 

 

Yesterday, in H7N9: Fujian Province Reports Second Case, I posed the question : `exactly what criteria is being used (in China) to decide whether to test patients for the H7N9 virus?’

 

While the answer to that question remains elusive on the Mainland, I have run across revised criteria -issued late last week to doctors and hospitals - in Hong Kong.

 

As of today, Hong Kong’s Centre for Health Protection  has received notification of 18 cases that fulfill their reporting criteria for suspected H7N9 infection, but as of yet, none have tested positive for the virus.

 

Reporting criteria for Human Influenza A (H7N9) infection

 
(Last updated on 25 April 2013)

An individual fulfilling both the Clinical Criteria AND Epidemiological Criteria should be reported to CHP for further investigation.

Clinical Criteria

Patient with

• influenza-like-illness (fever >38 oC with cough or sore throat); OR
• person with severe pneumonia; OR
• person died of unexplained acute respiratory illness.

Epidemiological Criteria

One or more of the following exposures in the 10 days prior to symptom onset:

• contact with a human case of influenza A (H7N9); OR
• contact with poultry or wild birds or their remains or to environments contaminated by their faeces in countries/areas with documented avian influenza A (H7N9) infection in birds and/or humans in the recent 6 months (see List of affected areas); OR
• consumption of raw or undercooked poultry products in countries/areas with documented avian influenza A(H7N9) infection in poultry and/or humans in the recent 6 months (see List of affected areas), OR
• close contact with a confirmed influenza A(H7N9) infected animal other than poultry or wild birds; OR
• worked in a laboratory that is processing samples from persons or animals that are suspected from avian influenza infection

The list of affected areas is regularly uploaded to the Centre for Health Protection (CHP) website
(http://www.chp.gov.hk/files/pdf/global_statistics_avian_influenza_e.pdf

 

While an argument could be made for broader testing – with no evidence of H2H spread, and no cases reported in humans or poultry in Hong Kong – the requirement for a plausible route of exposure is not unreasonable.

 

Exactly what criteria is being used in Mainland China - in provinces where the virus has already been detected - isn’t clear. 

 

This latest letter to doctors also extends the incubation period of the virus to 10 days.

 

In view of the latest best available evidence, the longest incubation period of human infection with avian influenza A(H7N9) virus has been revised from 7 days to 10 days and the epidemiological criteria of the reporting criteria has been revised accordingly (see attached). Please also note that Taiwan has not been included as an affected area as the case recorded was classified as an imported infection

 

This week, Hong Kong – along with Mainland China and many other nations – celebrates Labor Day (May 1st).  Each year, millions of visitors from the mainland pour into Hong Kong during this `golden week’ to shop, and to visit.

 

While an economically important period for businesses in Hong Kong, this year, concerns over the possible importation of the H7N9 virus run high.

 

For more on this, the Wall Street Journal has details on Hong Kong’s plans to thwart the viruses’ arrival.

 

 

Hong Kong Steps Up Flu Fight

• Updated April 28, 2013, 3:38 p.m. ET

Hong Kong immigration and hospital officials are stepping up efforts to fend off the spread of H7N9 bird flu, which surfaced outside China for the first time last week, as floods of mainland Chinese tourists descend on Hong Kong for the Labor Day holiday.

 

The government is deploying greater manpower at the border at the mainland Chinese city of Shenzhen, one of the busiest border crossings in the world, to screen travelers for elevated body temperatures, and tour operators are being urged to monitor the condition of individual tourists.

 

(Continue . . .)

WHO Publishes Case Definition For Identifying Possible Coronavirus Cases

 

 

Coronavirus – Credit CDC PHIL

 

# 6582

 

Now that two cases of a novel coronavirus infection have been identified from patients who had a travel history in the Mid East, doctors are being asked to look for other possible cases.

 

This evening the World Health Organization has posted the following case definition to assist health care providers (and others) in indentifying potential cases.

 

 

Case Definition for Case Finding Severe Respiratory Disease associated with NOVEL CORONAVIRUS

Interim case definition as of 25 September 2012

Patient under investigation:

Clinical definition:

A person with acute respiratory syndrome which may include fever (≥ 38°C , 100.4°F) and cough
• requiring hospitalization
OR
• with suspicion of lower airway involvement (clinical or radiological evidence of consolidation)
not explained by any other infection or any other aetiology.

AND

Epidemiological criteria:

Close contact* within the last 10 days before onset of illness
• with a probable or confirmed case of novel coronavirus infection while the case-contact was ill
OR
• travel to or residence in an area** where infection with novel coronavirus has recently been reported or where transmission could have occurred.

Probable Novel Coronavirus Case:

A person fitting the clinical definition AND epidemiological criteria above but no laboratory confirmation.

Confirmed Novel Coronavirus Case:

A person with laboratory confirmation of infection with the novel coronavirus.

---

* Close contact is defined as:

• Anyone who provided care for a confirmed or probable case including HCW and family members in a health care setting or in the community.
• Anyone who stayed at the same place (e.g. lived with, visited) as a probable or confirmed case while they have been symptomatic.
• Anyone with significant casual exposure with the patient such as sitting nearby in a classroom, sharing a taxi, sitting close by on an airplane.

** Area where infection with novel coronavirus where transmission could have occurred:

Kingdom of Saudi Arabia, Qatar (as of 25 September 2012)