Pathfinder
Editor, Senior Moderator
Summary of Assessment of Public Health Risk to Canada Associated with Middle East Respiratory Syndrome Coronavirus (MERS-CoV)
02 Jul 2013
The risk assessment is reviewed on a regular basis and updated as required.
Risk Assessment
Cases of Middle East Respiratory Syndrome (MERS-CoV) have been reported in Saudi Arabia, Qatar, Jordan, the United Arab Emirates, the United Kingdom, France, Tunisia, and Italy since April 2012. There have been no cases identified in Canada.
As of 26 June 2013, 77 laboratory-confirmed cases and one probable case of human infection with MERS-CoV have been reported to the World Health Organization (WHO): 2 from Jordan, 2 from Qatar, 62 from Saudi Arabia, 3 from the United Kingdom (UK), 1 from the United Arab Emirates (UAE), 2 from France, 2 confirmed and 1 probable from Tunisia, and 3 from Italy. Most patients are male (64%; 47 of 73 cases with sex reported) and range in age from 2 to 94 years (median 50years). Seven paediatric cases have been reported. Most patients presented with severe acute respiratory disease requiring hospitalization and eventual mechanical ventilation or other advanced respiratory support, however, asymptomatic illness has been reported in four children and four health care workers. Forty confirmed cases have died (case fatality rate 52%). Animal exposures were suspected in early cases, but the majority of cases do not have this history. For the latest updates on the total number of cases and deaths please visit the Global Alert and Response website
.
Three major epidemiological patterns were identified in the Joint Kingdom of Saudi Arabia/WHO Mission: sporadic cases occur in communities; clusters of infections occur in families; and clusters of infections in health care facilities. There has been no evidence of widespread human-to-human transmission, and there have been fewer infections reported in healthcare workers than expected based on the experience with Severe Acute Respiratory Syndrome (SARS)<SUP>Footnote 1</SUP>. Recently however, as part of outbreak investigation and contact tracing, four asymptomatic healthcare workers have tested positive for MERS-CoV (reported 21 and 26 June 2013 by WHO).
All clusters reported to date have occurred among close contacts (e.g. family, work) or in health care settings. While human-to-human transmission has occurred in at least some of these clusters, the source of the infection in the community is unknown. The large number of cases with reported co-morbidities suggests that increased susceptibility from underlying medical conditions may play a role in transmission.
A few of the clusters of MERS CoV are described in more detail below:
On 1 June 2013, WHO reported the first confirmed case of MERS-CoV in Italy in a resident who had recently returned from a trip to Jordan on 25 May 2013. The case was reported to have had contact with a family member with an unspecified illness while in Jordan. Two additional lab confirmed-cases of MERS-CoV were found in close contacts of the index case, a female co-worker and a niece. The niece is 2 years of age and the first reported paediatric case of MERS-CoV.
Between 1 April 2013 and 23 May 2013, 23 laboratory-confirmed cases of MERS-CoV, were identified in Saudi Arabia in the region of Al-Ahsa located in the Eastern Province (17 males and 6 females, median age 56 years); fifteen have died. All confirmed cases, and 11 probable cases were part of a single outbreak involving four health care facilities. Seventeen of the cases were associated with a medical ward, hemodialysis unit or ICU in one hospital. Among 217 household contacts and more than 200 health care worker contacts identified, MERS-CoV infection developed in five family members (three laboratory confirmed) and two health care workers (both laboratory confirmed). An outbreak investigation has identified that one patient transmitted infection to seven persons, another patient transmitted to three persons, and four patients transmitted to two persons each. The incubation period of confirmed cases was 5.2 days (95% confidence interval 1.9-14.7 days).<SUP>Footnote 2</SUP>
In France, two cases have been reported. The first case, became ill after a 9-day vacation to Dubai, UAE, and subsequently died on 28 May 2013 due to refractory multiple organ failure. The second case, reported on 12 May, is a patient who shared a room at a health care facility with the first case for three days. The incubation period was estimated to be 9-12 days for the second case<SUP>Footnote 3</SUP>. Among 120 persons identified as contacts of the first laboratory-confirmed case in France, laboratory tests were conducted on five suspected cases, of which four tested negative and one (mentioned above) tested positive. No infected healthcare workers have been identified.
Tunisia reported two laboratory-confirmed cases and one probable case on May 21, 2013. These are the first cases of infection with MERS-CoV in Tunisia. The two laboratory-confirmed cases are a 34 year old man and a 35 year old woman who are siblings; both had mild respiratory illness and did not require hospitalization. Their father became ill after returning from Qatar and Saudi Arabia on 3 May 2013, and developed acute respiratory disease and died on 10 May 2013 following ICU admission. He had an underlying medical condition, and initial laboratory tests were negative for MERS-CoV. He is currently considered a probable case as his laboratory test in Tunisia was interpreted as negative. Details of exposure history for the confirmed cases are not yet available, but both are currently in good health. Investigations are on-going.
Preliminary results of the serological study on the Jordanian cluster in April 2012 have identified eight positive cases out of 124 individual specimens thus far. Six were previously identified as probable cases in the outbreak investigation. The seventh is an additional healthcare worker, and the eighth a household member of a probable case not identified earlier. Laboratory results for all specimens are still pending.
No vaccine or effective antiviral treatment is currently available for MERS-CoV.
<HR><DL class=footnotes-list><DT id=footnote1>Footnote 1<DD>World Health Organization Regional Office of the Eastern Mediterranean. Middle East respiratory syndrome coronavirus: Joint Kingdom of Saudi Arabia/WHO mission [press release]. http://www.emro.who.int/press-releases/2013/corona-virus-who-saudi-arabia-mission.html <DT id=footnote2>Footnote 2<DD>Assiri A, McGeer A, Perl TM, et al. Hospital outbreak of Middle East Respiratory Syndrome Coronavirus. New England Journal of Medicine. DOI: 10.1056/NEJMoa1306742.<DT id=footnote3>Footnote 3<DD>Guery B, Poissy J, el Mansouf L, et al. Clinical features and viral diagnosis of two cases of infection with Middle East Respiratory Syndrome coronavirus: a report of nosocomial transmission. Lancet. 2013. http://download.thelancet.com/flatcontentassets/pdfs/S0140673613609824.pdf.</DD></DL>Virus Characteristics
Five viruses have been cultured and genome sequences have been made publicly available. All five of the sequenced viruses have a high degree of genetic similarity. Preliminary analyses show that the viruses are genetically somewhat similar to bat coronaviruses, but distinct from the Severe Acute Respiratory Syndrome coronavirus (SARS-CoV) which caused an international outbreak in 2003 in humans.
It should be noted, however, that the similarity does not necessarily imply that bats are the reservoir for the human virus or that direct exposure to bats or bat excreta were responsible for infection. In vitro studies suggest that MERS-CoV has the potential to have a broad host range. This likely permits its zoonotic behaviour but means that a wide range of natural and domesticated animal reservoir species is possible. MERS-CoV itself has not yet been found in an animal.
Recommendations for Canada
Surveillance
Health care professionals are encouraged to maintain vigilance for cases of MERS-CoV infection, and notify the appropriate Public Health Departments of any persons under investigation. The national interim case definition for MERS-CoV is to be used for the surveillance of MERS-CoV.
Provinces and Territories are asked to report confirmed cases of MERS-CoV infection to the Public Health Agency of Canada using the Emerging Respiratory Pathogens and Severe Acute Respiratory Infection (SARI) Case Report Form.
Laboratory
Limited evidence suggests that the use of nasopharyngeal swabs for diagnosis may not be as sensitive as the use of lower respiratory specimens. Lower respiratory specimens should be used for diagnosis in addition to nasopharyngeal swabs when they are available. If a nasopharyngeal swab tests negative, consider retesting using lower respiratory specimens such as sputum, endotracheal aspirate, or bronchoalveolar lavage. (Source: Novel coronavirus summary and literature update ? as of 20 June 2013)
Travel Health Notice
A travel health notice is posted on the Agency?s website. It does not recommend any restrictions on travel but encourages travelers to take routine precautions.
Infection Control
Recommendations for infection prevention and control measures for patients presenting with suspected or confirmed infection or co-infection with MERS-CoV in acute care settings is posted on the Agency?s website. This guidance will be updated as new information becomes available.
Biosafety
MERS-CoV is classified as a Risk Group 3 human pathogen given that this virus can cause serious illness in humans, while the public health risk is low since the risk of spread of the virus in the community appears to be low.
Containment Level 3 is required for all proliferative work (in vitro or in vivo), and non-proliferative diagnostic activities can be conducted at Containment Level 2 with the use of additional operational practices as outlined in Biosafety Advisory for HCoV-EMC/2012.
The WHO has published interim recommendations for laboratory testing for MERS-CoV (19 February 2013).
http://www.phac-aspc.gc.ca/eri-ire/coronavirus/risk_assessment-evaluation_risque-eng.php
02 Jul 2013
The risk assessment is reviewed on a regular basis and updated as required.
Risk Assessment
- The public health risk posed by MERS-CoV to Canada is considered low based on available information at this time. Further investigation of basic epidemiological indicators is required to guide effective control measures, and the risk may change as new information arises.
- Some of the infections have occurred in clusters of close contacts or in health care settings. This provides good evidence of human-to-human transmission possibly involving different modes of transmission. To date, no sustained human-to-human transmission has been observed.
- There is no indication that international spread has occurred, although when infected people from affected areas travel, their infection may be detected in another country.
Cases of Middle East Respiratory Syndrome (MERS-CoV) have been reported in Saudi Arabia, Qatar, Jordan, the United Arab Emirates, the United Kingdom, France, Tunisia, and Italy since April 2012. There have been no cases identified in Canada.
As of 26 June 2013, 77 laboratory-confirmed cases and one probable case of human infection with MERS-CoV have been reported to the World Health Organization (WHO): 2 from Jordan, 2 from Qatar, 62 from Saudi Arabia, 3 from the United Kingdom (UK), 1 from the United Arab Emirates (UAE), 2 from France, 2 confirmed and 1 probable from Tunisia, and 3 from Italy. Most patients are male (64%; 47 of 73 cases with sex reported) and range in age from 2 to 94 years (median 50years). Seven paediatric cases have been reported. Most patients presented with severe acute respiratory disease requiring hospitalization and eventual mechanical ventilation or other advanced respiratory support, however, asymptomatic illness has been reported in four children and four health care workers. Forty confirmed cases have died (case fatality rate 52%). Animal exposures were suspected in early cases, but the majority of cases do not have this history. For the latest updates on the total number of cases and deaths please visit the Global Alert and Response website
.Three major epidemiological patterns were identified in the Joint Kingdom of Saudi Arabia/WHO Mission: sporadic cases occur in communities; clusters of infections occur in families; and clusters of infections in health care facilities. There has been no evidence of widespread human-to-human transmission, and there have been fewer infections reported in healthcare workers than expected based on the experience with Severe Acute Respiratory Syndrome (SARS)<SUP>Footnote 1</SUP>. Recently however, as part of outbreak investigation and contact tracing, four asymptomatic healthcare workers have tested positive for MERS-CoV (reported 21 and 26 June 2013 by WHO).
All clusters reported to date have occurred among close contacts (e.g. family, work) or in health care settings. While human-to-human transmission has occurred in at least some of these clusters, the source of the infection in the community is unknown. The large number of cases with reported co-morbidities suggests that increased susceptibility from underlying medical conditions may play a role in transmission.
A few of the clusters of MERS CoV are described in more detail below:
On 1 June 2013, WHO reported the first confirmed case of MERS-CoV in Italy in a resident who had recently returned from a trip to Jordan on 25 May 2013. The case was reported to have had contact with a family member with an unspecified illness while in Jordan. Two additional lab confirmed-cases of MERS-CoV were found in close contacts of the index case, a female co-worker and a niece. The niece is 2 years of age and the first reported paediatric case of MERS-CoV.
Between 1 April 2013 and 23 May 2013, 23 laboratory-confirmed cases of MERS-CoV, were identified in Saudi Arabia in the region of Al-Ahsa located in the Eastern Province (17 males and 6 females, median age 56 years); fifteen have died. All confirmed cases, and 11 probable cases were part of a single outbreak involving four health care facilities. Seventeen of the cases were associated with a medical ward, hemodialysis unit or ICU in one hospital. Among 217 household contacts and more than 200 health care worker contacts identified, MERS-CoV infection developed in five family members (three laboratory confirmed) and two health care workers (both laboratory confirmed). An outbreak investigation has identified that one patient transmitted infection to seven persons, another patient transmitted to three persons, and four patients transmitted to two persons each. The incubation period of confirmed cases was 5.2 days (95% confidence interval 1.9-14.7 days).<SUP>Footnote 2</SUP>
In France, two cases have been reported. The first case, became ill after a 9-day vacation to Dubai, UAE, and subsequently died on 28 May 2013 due to refractory multiple organ failure. The second case, reported on 12 May, is a patient who shared a room at a health care facility with the first case for three days. The incubation period was estimated to be 9-12 days for the second case<SUP>Footnote 3</SUP>. Among 120 persons identified as contacts of the first laboratory-confirmed case in France, laboratory tests were conducted on five suspected cases, of which four tested negative and one (mentioned above) tested positive. No infected healthcare workers have been identified.
Tunisia reported two laboratory-confirmed cases and one probable case on May 21, 2013. These are the first cases of infection with MERS-CoV in Tunisia. The two laboratory-confirmed cases are a 34 year old man and a 35 year old woman who are siblings; both had mild respiratory illness and did not require hospitalization. Their father became ill after returning from Qatar and Saudi Arabia on 3 May 2013, and developed acute respiratory disease and died on 10 May 2013 following ICU admission. He had an underlying medical condition, and initial laboratory tests were negative for MERS-CoV. He is currently considered a probable case as his laboratory test in Tunisia was interpreted as negative. Details of exposure history for the confirmed cases are not yet available, but both are currently in good health. Investigations are on-going.
Preliminary results of the serological study on the Jordanian cluster in April 2012 have identified eight positive cases out of 124 individual specimens thus far. Six were previously identified as probable cases in the outbreak investigation. The seventh is an additional healthcare worker, and the eighth a household member of a probable case not identified earlier. Laboratory results for all specimens are still pending.
No vaccine or effective antiviral treatment is currently available for MERS-CoV.
<HR><DL class=footnotes-list><DT id=footnote1>Footnote 1<DD>World Health Organization Regional Office of the Eastern Mediterranean. Middle East respiratory syndrome coronavirus: Joint Kingdom of Saudi Arabia/WHO mission [press release]. http://www.emro.who.int/press-releases/2013/corona-virus-who-saudi-arabia-mission.html <DT id=footnote2>Footnote 2<DD>Assiri A, McGeer A, Perl TM, et al. Hospital outbreak of Middle East Respiratory Syndrome Coronavirus. New England Journal of Medicine. DOI: 10.1056/NEJMoa1306742.<DT id=footnote3>Footnote 3<DD>Guery B, Poissy J, el Mansouf L, et al. Clinical features and viral diagnosis of two cases of infection with Middle East Respiratory Syndrome coronavirus: a report of nosocomial transmission. Lancet. 2013. http://download.thelancet.com/flatcontentassets/pdfs/S0140673613609824.pdf.</DD></DL>Virus Characteristics
Five viruses have been cultured and genome sequences have been made publicly available. All five of the sequenced viruses have a high degree of genetic similarity. Preliminary analyses show that the viruses are genetically somewhat similar to bat coronaviruses, but distinct from the Severe Acute Respiratory Syndrome coronavirus (SARS-CoV) which caused an international outbreak in 2003 in humans.
It should be noted, however, that the similarity does not necessarily imply that bats are the reservoir for the human virus or that direct exposure to bats or bat excreta were responsible for infection. In vitro studies suggest that MERS-CoV has the potential to have a broad host range. This likely permits its zoonotic behaviour but means that a wide range of natural and domesticated animal reservoir species is possible. MERS-CoV itself has not yet been found in an animal.
Recommendations for Canada
Surveillance
Health care professionals are encouraged to maintain vigilance for cases of MERS-CoV infection, and notify the appropriate Public Health Departments of any persons under investigation. The national interim case definition for MERS-CoV is to be used for the surveillance of MERS-CoV.
Provinces and Territories are asked to report confirmed cases of MERS-CoV infection to the Public Health Agency of Canada using the Emerging Respiratory Pathogens and Severe Acute Respiratory Infection (SARI) Case Report Form.
Laboratory
Limited evidence suggests that the use of nasopharyngeal swabs for diagnosis may not be as sensitive as the use of lower respiratory specimens. Lower respiratory specimens should be used for diagnosis in addition to nasopharyngeal swabs when they are available. If a nasopharyngeal swab tests negative, consider retesting using lower respiratory specimens such as sputum, endotracheal aspirate, or bronchoalveolar lavage. (Source: Novel coronavirus summary and literature update ? as of 20 June 2013)
Travel Health Notice
A travel health notice is posted on the Agency?s website. It does not recommend any restrictions on travel but encourages travelers to take routine precautions.
Infection Control
Recommendations for infection prevention and control measures for patients presenting with suspected or confirmed infection or co-infection with MERS-CoV in acute care settings is posted on the Agency?s website. This guidance will be updated as new information becomes available.
Biosafety
MERS-CoV is classified as a Risk Group 3 human pathogen given that this virus can cause serious illness in humans, while the public health risk is low since the risk of spread of the virus in the community appears to be low.
Containment Level 3 is required for all proliferative work (in vitro or in vivo), and non-proliferative diagnostic activities can be conducted at Containment Level 2 with the use of additional operational practices as outlined in Biosafety Advisory for HCoV-EMC/2012.
The WHO has published interim recommendations for laboratory testing for MERS-CoV (19 February 2013).
http://www.phac-aspc.gc.ca/eri-ire/coronavirus/risk_assessment-evaluation_risque-eng.php