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Interim National Surveillance Guidelines for Human Infection with Avian Influenza A(H7N9)

Table of Contents


Background

The main goal of emerging respiratory virus surveillance is early detection of any case in Canada. Subsequently, such virus surveillance informs efforts at containment and/or mitigation of the novel respiratory pathogen. This document outlines the recommended goals, objectives and activities for surveillance of human infection with avian influenza A(H7N9) in Canada.

Human illness caused by avian influenza A(H7N9) virus was first reported to the World Health Organization (WHO) by the Health and Planning Commission of the People’s Republic of China on March 31, 2013.

Influenza A(H7N9) is a low-pathogenic avian influenza subtype virus that circulates among birds and is a widespread zoonotic virus in China. Human infection with A(H7N9) has been predominantly associated with exposure to infected poultry and contaminated environments. Since emerging in the spring of 2013, annual epidemic waves of human infection have been observed in China, following a similar pattern to seasonal influenza: most cases occur between October and May, with a peak in late December to early January. An increasing number of human clusters have been reported since 2013 which suggests limited human-to-human transmission. However, there is no evidence to support sustained human-to-human transmission. To date the illness has been geographically contained to the southeastern region of China with a few cases observed in the northern region of China. The WHO website maintains the latest updates on the total number of cases.

Although the risk to Canadians is low, clinicians and public health practitioners should be alert for possible importation of avian influenza A(H7N9) to Canada.

Surveillance Goals and Objectives

Given the evidence to date, the main goal of public health response is early detection and containment.

To accomplish this goal, following national surveillance objectives have been developed:

  1. Detect human cases of avian influenza A(H7N9) infection in Canada
  2. Monitor the incidence and the geographical distribution of new cases over time
  3. Describe and monitor changes in the epidemiological and virological features of the disease (e.g. clinical features and progression, morbidity, mortality, incubation period, mode of transmission, at risk populations and antiviral resistance)
  4. Notify and disseminate information to stakeholders in order to facilitate timely and appropriate public health activities

Case Finding and Investigation

Case Definition

The Public Health Agency of Canada has developed case definitions for classification and reporting of human cases of avian influenza A(H7N9). They are located on the Public Health Agency of Canada website.

Case Identification and Interview

Laboratory-confirmation of an avian influenza A(H7N9) is an immediate trigger to launch a thorough investigation. However, because collection, shipment, and testing of specimens often require several days or longer, the investigation may need to begin before laboratory test results are available for suspected cases. Even if laboratory-confirmation is not possible, an investigation should still be launched if a patient is strongly suspected to have avian influenza A(H7N9) infection.

The patient and/or family members (if the patient is too ill to be interviewed or has died) should be interviewed within the first 24–48 hours of the investigation to collect basic demographic, clinical, and epidemiological information. A sample case investigation/reporting form for the interview can be found on the Public Health Agency’s website. Provinces and territories may choose to use this form, or a similar form developed for use within their jurisdiction.

Essential Basic Information

The following priority data elements (Box 1) should be submitted on the initial case report form or through electronic methods for confirmed and probable cases (within 24 hours of PT notification) (Figure 1). In addition to national reporting, a single case of human infection with avian influenza A(H7N9) detected in Canada must be reported to the WHO under the International Health Regulations (IHR) within 24 hours of assessment of public health information.

Box 1. Priority data elements to be reported
  • Reporting P/T
  • Outbreak or cluster related
  • Sex
  • Age
  • Date of onset
  • Symptoms
  • Whether hospitalized / Date of hospitalization

 

  • Whether in ICU/Date of ICU admission
  • If deceased/Date of death
  • Lab – date of sample collection test method and result (when available)
  • Travel history
  • Other possible exposures (e.g., ill contact, animal, food)

Contact Monitoring

Close contacts of confirmed or probable cases should be identified and monitored for the appearance of respiratory symptoms for 10 days after last exposure to the confirmed or probable case, while the case was ill (beginning 1 day prior to illness onset and continuing until resolution of illness). Any contact that becomes ill with symptoms compatible with influenza-like illness in that period of time should be tested for avian influenza A(H7N9). Ring testing (testing those with closest and most prolonged contact) should be considered, and a subset of those with progressively less contact should be identified to evaluate transmissibility and evidence of asymptomatic infection.

A line-listing of all contacts and exposed persons that records demographic information, date of first and last common exposure or date of contact with the confirmed or probable case, and date of onset if fever or respiratory symptoms develop should be maintained. The common exposures and type of contact with the confirmed or probable case should be thoroughly documented for any contacts that become infected with avian influenza A(H7N9).

Additional information can be found in the Interim Guidance for Public Health Management of Human Illness Associated with Avian Influenza A(H7N9).

Enhanced Surveillance

Surveillance in the setting under investigation should be enhanced to detect cases that might arise subsequent to the discovery of the index case. The geographical area targeted will need to be assessed and defined by the suspected exposures of the confirmed case under investigation. The duration of the enhanced surveillance will depend on the findings of the investigation and whether there is evidence indicating that sustained transmission may be occurring in the area. A minimum of one month of enhanced surveillance is a reasonable starting point.

Enhancements include:

  • Establish mechanisms for rapid transfer of specimens to the National Microbiology Laboratory (NML)
  • Inform clinicians in the community of the need for increased vigilance and triggers for identification and notification
  • Increase testing for avian influenza A(H7N9) of SARI cases at local health care facilities in the area under investigation.
  • If resources allow, consider some testing of milder cases of influenza-like illness presenting to surveillance sites.

 

Recommended surveillance objectives, and activities
PH Response Goals Scenario Surveillance, Investigation and other Epidemiological  Activities

Containment

Goal: Gather information to understand the virus (focussed on individual level intervention)

Avian influenza A(H7N9) with no or limited human transmission

Cases outside of Canada

  • Monitor disease outside of Canada (review data from origin country)
  • Develop case definitions, surveillance guidelines, testing guidelines, and reporting requirements
  • Conduct risk assessment to identify potential risk for Canadians

Cases within Canada

  • Continue routine surveillance for respiratory pathogens in Canada
  • Enhance surveillance and testing of animals if zoonotic source
  • Bilateral sharing of epidemiological information (reports) via CNPHI Public Health Alert, teleconferences etc. in a timely manner
  • Conduct active case and contact investigations
  • Collect surveillance information from cases using enhanced questionnaires to contain transmission, determine epidemiology and to inform risk assessment (report cases using the Emerging Respiratory Pathogens and SARI Case Report Form or a jurisdictional equivalent)
  • Develop and/or refine case definitions, surveillance guidelines, testing guidelines, and reporting requirements
  • Report case to WHO as per IHR requirements and timelines

Avian influenza A(H7N9) with sporadic human transmission

Cases outside of Canada

  • Monitor disease outside of Canada (review data from origin country)
  • Develop case definitions, surveillance guidelines, testing guidelines, and reporting requirements
  • Conduct risk assessment to identify potential risk for Canadians
  • Prepare for virus introduction and spread of virus in Canada

Cases within Canada

  • Conduct active case finding and contact tracing to determine epidemiology and to inform risk assessment (report cases using the Emerging Respiratory Pathogens and SARI Case Report Form or a jurisdictional equivalent)
  • Determine clinical spectrum of illness and mortality
  • Determine geographic spread of disease
  • Utilise laboratory surveillance networks to help to identify clusters
  • Enhance surveillance and testing of animals if zoonotic source
  • Bilateral sharing of epidemiological information (reports) via CNPHI Public Health Alert, teleconferences etc. in a timely manner
  • Mobilise resources to conduct active investigations
  • Refine case definitions, surveillance guidelines and reporting requirements
  • Report cases to WHO as per IHR requirements and timelines

Mitigation

Goal: Identify risk factors to target interventions (focussed on population level interventions)

Avian influenza A(H7N9) with sustained human transmission detected

Cases outside of Canada

  • Monitor disease outside of Canada (review data from origin country)
  • Develop case definitions, surveillance guidelines, testing guidelines, and reporting requirements
  • Conduct risk assessment to identify potential risk for Canadians
  • Prepare for virus and spread of virus in Canada

Cases within Canada

  • Intense case finding (report cases using the Emerging Respiratory Pathogens and SARI Case Report Form or a jurisdictional equivalent) until sufficient information is acquired. After the first 100 cases in Canada, report core data elements of cases using an electronic line-list format
  • Bilateral sharing of information via CNPHI Public Health Alert, teleconferences, online etc. in a timely manner
  • Conduct cluster and outbreak investigations
  • Determine geographic spread of disease
  • Enhanced surveillance of animals if zoonotic source
  • Mobilize resources to help with investigations
  • Monitor outbreaks in long-term care, schools and acute care settings to determine infectivity and severity of virus
  • Refine case definitions, surveillance guidelines and reporting requirements
  • Report cases to WHO as per IHR requirements and timelines

Avian influenza A(H7N9) with widespread human transmission detected

Cases outside of Canada

  • Prepare for virus and spread of virus in Canada
  • Monitor disease outside of Canada (review data from origin country)

Cases within Canada

  • Aggregate level national case reporting
  • Monitor health services utilization to determine the pathogenicity of virus and the impact on the health-care system. (e.g. through FluWatch sentinel hospital networks)
  • Consider the use of sentinel networks to monitor the impact of virus on primary care practices and to determine where infections are occurring.
  • Conduct special studies (e.g. household, community transmission, seroprevalence, vaccine effectiveness)
  • Bilateral sharing of information via CNPHI Public Health Alert, teleconferences, online etc. in a timely manner
  • Report case to WHO as per IHR requirements and timelines
 

Laboratory Testing

Laboratory testing should be conducted in accordance with the Canadian Public Health Laboratory Network's Protocol for Microbiological Investigations of Severe Acute Respiratory Infections (SARI).

Laboratory confirmation is obtained by detection of viral RNA or virus isolation in tissue culture. Currently, avian influenza A(H7N9) is designated a Foreign Animal Disease (FAD) requiring CL 3 or higher laboratory conditions for growth/propagation.  Confirmation of diagnosis should be sought from Canada’s National Microbiology Laboratory (NML) before being considered conclusive; such cases may be considered presumptive pending NML confirmation.
Influenza subtyping assays are typically less sensitive than identification assays. As such, it may not be possible to subtype weakly positive influenza A detections. Such “untypeable” events should be individually assessed in consultation with appropriate experts. Confirmatory laboratory tests may take up to 7 days from specimen submission. Care providers need to clarify with their laboratories which specimens have been validated for respiratory virus testing.
Limited evidence suggests that upper airway (nasopharyngeal (NP) or throat) swabs for diagnosis may not be as sensitive as lower respiratory specimens for SARI. If an NP swab tests negative for H7N9, consider retesting using lower respiratory specimens such as sputum, endotracheal aspirate, or bronchoalveolar lavage where relevant and clinically indicated.  Sero-conversion may be considered supportive evidence in identifying cases when other laboratory diagnosis is not possible; however, antibody assays for H7N9 are still under development and some caution is required in their interpretation.

Follow infection prevention and control guidelines when collecting respiratory specimens. Laboratory investigation should be according to local guidance for diagnosis and management of community-acquired pneumonia inclusive of other potentially more likely etiologies. Examples of other etiologies include Streptococcus pneumoniae, Haemophilus influenzae B, Legionella pneumophila, other recognized primary bacterial pneumonias, seasonal influenza and other respiratory viruses. As demonstrated by a case with dual influenza strain infection, co-infection can occur. Identification of one causative agent should not exclude avian influenza A(H7N9) where the index of suspicion may be high.

Data Analysis

Descriptive analysis of cases should be performed in terms of person, place, and time. For investigations that yield multiple cases, graphical and/or tabular descriptions of cases by date of onset (i.e. epidemic curve), geographical location (e.g. maps), relationship (i.e. transmission or family trees) and demographic characteristics (e.g. distribution by age and sex) should be developed.

Key epidemiological (e.g. estimation of an incubation period, description of transmission patterns, attack rates by age, occupation, exposure history etc.) and clinical (e.g. spectrum of illness severity, proportion of cases who develop pneumonia, require hospitalization, die) parameters should be characterized to enhance understanding of the spectrum and dynamics of disease associated with avian influenza A(H7N9) infection.

Studies and specific investigations

Useful protocols can also be found on the website of the Consortium for the Standardization of Influenza Seroepidemiology (CONSISE).

Infection control

Recommendations for infection prevention and control measures for patients presenting with suspected or confirmed infection or co-infection with avian influenza A(H7N9) in acute care settings are posted on the Agency’s website. This guidance will be updated as new information becomes available.

Reporting Results

Reporting Cases

Provinces and Territories are asked to report all confirmed and probable cases of avian influenza A(H7N9) within 24 hours of provincial / territorial notification to the Public Health Agency of Canada.

Provinces and Territories should use the Emerging Respiratory Pathogens and Severe Acute Respiratory Infection (SARI) Case Report Form which can be found on the Agency’s website, or a jurisdictional equivalent containing the same data fields.

Completed forms can be faxed (without first page) to 1-800-332-5584 and an email notification (do not attach form) should be sent to HSFLUEPI@phac-aspc.gc.ca.

For questions after regular business hours (8:00 – 5:00pm ET) please contact the Agency Medical Officer on-call at 613-952-7940.

Reporting of cases by provincial and territorial public health authorities and laboratories should follow the process outlined below

Figure 1. Process for national and international public health notifications for emerging respiratory pathogens

Figure 1. Process for national and international public health notifications for emerging respiratory pathogens

Text Equivalent - Figure 1

Reporting results of a study investigation

Early reporting of investigation results of avian influenza A(H7N9) cases in Canada is strongly encouraged, even before analyses are complete. In addition, even preliminary data can be critical in the early assessment of international spread and inform decision making.

Useful Links

  1. Government of Canada
  2. World Health Organization
  3. European Centre for Disease Prevention and Control
  4. United States Centres for Disease Control and Prevention