Human Health Issues related to Avian Influenza in Canada
Upon notification of an avian/animal influenza outbreak with human health implications, public health authorities should initiate an investigation and implement appropriate public health measures to protect human health. These measures will include primary prevention (e.g., infection control measures and antiviral prophylaxis), case finding and management activities. Investigations would also include identification, understanding and containing sources of human infection. Public health measures (to be implemented by the local public health authority with the support of the province/territory) will largely depend on the initial findings from the epidemiologic assessment of the outbreak.
Risk communication and the provision of educational materials are public health measures that should be started immediately with key messages updated as the event unfolds. These measures may play an important role in facilitating compliance with other public health actions.
Public health measures should include:
- Rapid completion of a preliminary risk assessment for human health including examination of the available epidemiological data, a review of historical experience and current scientific knowledge regarding the specific avian virus subtype, and exposure assessments. This task could be completed by P/T public health authorities or PHAC as part of supportive activities. Process for ongoing review and, if necessary, updating of the risk assessment should be established.
- Confirmation of roles and responsibilities with respect to the human health response including the provision/delivery of occupational health services, and similar services to those with no occupational health resources.
- The provision of information on avian influenza, which highlights the potential human health risk and appropriate infection control measures. A sample "Dear Farmer letter" is provided in Appendix F. See also section 9 for Infection Control recommendations.
- Investigation and management of ill individuals/cases (see recommendations in section 8.3 below)
- Investigation and management of potential or known contacts based on human illness risk for the avian influenza virus subtype and the exposure risk attributed to the contact (see recommendations in section 8.2 below).
- Activities to ensure the local availability of antiviral drugs (see section 10). This may include overseeing delivery from a central supplier to the appropriate location(s) for distribution and establishment of a centralized prescription and dispensing clinic.
- Provision of the current human influenza vaccine for the purposes identified in
As contacts are identified through the surveillance activities in the outbreak investigation, it is essential that they receive clear recommendations from public healthFootnote 15. A sample information letter for contacts of an avian source of virus is provided in Appendix G and a letter for physicians that may be seeing these individuals is provided in Appendix H.
Recommendations should be provided in a format that is appropriate for the reading/educational level and language of the intended recipients. Modifications and translation may be necessary for foreign workers employed on the affected site/farm. It is recommended that contacts at a minimum:
- be instructed to self-monitor for the development of fever, respiratory symptoms, and/or conjunctivitis (eye infection) for 10 days after the last exposure to a known or suspected source of avian influenza virusFootnote 16
- be evaluated for antiviral prophylaxis as indicated in section 10
- be immunized with the current human influenza vaccine if they have not received it already (see section 11)
- strictly adhere to all infection control precautions described in section 9 below.
Potentially exposed children in an affected farm setting (i.e., child contacts) should be monitored by an adult who has received information on what symptoms to look for and how to take a temperature, should fever be suspected.
The local public health authority may decide on more active monitoring depending on:
- the epidemiology of the outbreak (e.g., if the avian virus is highly pathogenic or is currently or previously known to cause severe illness in humans),
- if there was a significant delay in the implementation of control measures,
- familiarity with the strain causing the outbreak, and
- level of confidence that public health recommendations are being followed.
More active monitoring might include:
- implementation of active surveillance in which there will be some form of individual consultation with exposed individuals initiated or overseen by the local public health authority. (The frequency, format and implementation of such interactions should be determined at the time by the local public health authority. It should include identifying any symptoms of AI-compatible illness in the individual, and for individuals receiving antiviral prophylaxis, compliance monitoring and adverse drug reactions.)
- requests for daily temperature recording, especially if fever has been identified as an early symptom,
- restriction of movement of contacts -this would initially involve recommendations not to visit other farms or unaffected locations, to avoid serving as a vehicle for the spread of contaminated materials (see infection control recommendations in section 9.1),
- more strict quarantine measures would be considered if the outbreak involved a virus that was causing severe illness in humans or there was evidence that it could be spread efficiently from person to person.
The guidance provided in this document is intended for use when AI is detected in Canada during Pandemic Phases 1, 2, or 3, that is, in the absence of more than sporadic human to human transmission (which occurs in WHO Pandemic Phase 4, 5 and 6). Once an AI virus is transmitting efficiently between humans, the exposure risk from contact with human cases will be increased and therefore the contact management recommendations for the appropriate phase in the Canadian Pandemic Influenza Plan for the Health Sector should be used.
If the illness requires hospitalization, then the infection control measures should consist of droplet and contact precautions as recommended in Section 9.1 (bullet v). The need for public health follow-up upon discharge from hospital will depend on whether the illness has completely resolved at discharge, and any other individual risk factors that may influence the period of communicability.
Public health authorities, as part of surveillance activities should ensure that hospitalized cases are reported and may also facilitate appropriate laboratory testing and access to antiviral drugs for hospitalized patients. The following recommendations, however, are mainly intended for individuals with mild illness that are residing in the community or for cases that remain symptomatic following discharge from hospital.
Upon receipt of a report of an ill person, it is recommended that the local public health authority:
- contacts the ill person and completes a case report form (classifying them as a suspect or confirmed case for surveillance purposes)
- facilitates collection of appropriate laboratory specimens (see Appendix C)
- facilitates access to early antiviral treatment (which should be offered regardless of viral sub-type)
- reports the person as "under investigation/ probable case/ confirmed case" as per previously established protocol
- provides information to the ill individual and/or their family members about their illness and who to call and where to go if their illness becomes more severe
- instructs the ill individual (in the community) to self-isolateFootnote 17 for 24 hours after symptom resolution
- provides information on infection control measures (i.e., respiratory and hand hygiene etc.)
- conducts active surveillanceFootnote 18 and documents course of illness
- Identifies any close contacts
Note: Employees should notify their health and safety representative of their illness and these activities should be conducted in collaboration with the respective occupational health services.
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