Case Study: West Nile Virus -Taking an Integrated National Public Health Approach to an Emerging Infectious Disease in Canada

Transcription

1 2008/SOM3/HWG/WKSP/003 Case Study: West Nile Virus -Taking an Integrated National Public Health Approach to an Emerging Infectious Disease in Canada Submitted by: Canada Health Working Group Policy Dialogue and Risk Communications Workshop Lima, Peru August 2008

2 APEC One Health Workshop, Lima, Peru (August 13-15, 2008) Case Study: West Nile Virus Taking an Integrated National Public Health Approach to an Emerging Infectious Disease in Canada Case Study Overview 1. What is West Nile Virus (WNV)? 2. Will WNV be a problem in Canada? 3. What were the barriers? 4. How were the barriers overcome? 5. What are the long term outcomes/benefits to overcoming the problem? 1

3 1) What is West Nile Virus? WNV belongs to a genus of approximately 70 viruses called flaviviruses, half of which are associated with human disease. Some closely related viruses cause well known diseases such as Yellow fever, dengue, Japanese encephalitis, Tick-borne encephalitis and St. Louis encephalitis WNV is spread by mosquitoes that have fed on the blood of infected birds WNV amplification cycle Infected mosquitoes can transmit WNV to incidental hosts 1) What is West Nile Virus? WNV was identified in the West Nile district of Uganda in 1937 WNV was initially primarily associated with fevers but, particularly since the 1990s, WNV has become increasingly associated with epidemics involving neurological manifestations such as encephalitis To date, there have been outbreaks of WNV in Egypt, Israel, South Africa, and in parts of Europe, Asia and the Americas 2

4 2) Will WNV be a problem in Canada? WNV was found for the first time in North America (the United States of America) in 1999 Given the apparent WNVcompetent mosquito and bird species in North America, it was anticipated that the virus might adapt to this continent and become an emerging issue that could have implications for Canada WNV It was recognized that a coordinated team of crossdisciplinary specialists would be needed to address and manage this complex issue 3) What Were the Barriers? At that time, it was unknown if the newly introduced virus would successfully overwinter, be introduced into Canada and, if introduced, whether it could persist There was no surveillance/monitoring system in place for WNV in Canada and it was unclear how and where to introduce one Laboratory techniques for identifying WNV were not in place in provincial labs and available only in limited capacity in federal labs Therefore: Cross-disciplinary partnerships to combat WNV in Canada needed to be formed 3

5 4) How Were the Barriers Overcome? A national face-to-face meeting, followed by regularly scheduled teleconferences, was held with the provincial and territorial departments of health to monitor the situation in the USA and discuss strategies and plans for Canada - Representatives from other federal departments as well as blood agencies, and individuals from academia were also brought in as partners 4) How Were the Barriers Overcome? WNV Partners Federal Departments: Public Health Agency of Canada Several branches of Health Canada Canadian Food Inspection Agency Department of National Defence Environment Canada Parks Canada Non-Governmental Canadian Cooperative Wildlife Health Centre Academia Blood Agencies Industry Infectious Disease Physicians Mosquito Control Experts Zoos Provincial/Territorial Departments: Health Environment Natural Resources Conservation Agriculture and Food International Centres for Disease Control WHO Collaborating Centre Network Bilateral collaborations e.g. Dr Arron Brault, University of California 4

6 4) How Were the Barriers Overcome? WNV Partners Public involvement Communication of disease risk and measures for the public to take is an important part of the Canadian WNV disease prevention strategy 4) How Were the Barriers Overcome? i) Will WNV be a problem in Canada? - Planning meetings & teleconferences - Formation of subcommittees and development of specific recommendations e.g. Mosquito Subcommittee - National response plan drafted in consultation with partners - Development of risk levels and response categories - Initiation of surveillance Lead for laboratory-based surveillance and diagnostic testing undertaken by the National Microbiology Laboratory (federal) with limited provincial involvement 5

7 4) How Were the Barriers Overcome? Human Cases ii) WNV will be a problem in Canada Yearly number of WNV cases in Canada > ) How Were the Barriers Overcome? ii) WNV will be a problem in Canada - Transfer of testing responsibilities to the provinces - Training and technology transfer - Maintenance of reference functions - Quality assurance - Evaluation of newly introduced commercial kits e.g. IgM kits - Development of weekly surveillance reports & surveillance maps - Research focus: improved diagnostic tests, population-based serosurveys, antivirals, evaluation of changes in virus properties 6

8 4) How Were the Barriers Overcome? Provincial/Territorial Partnerships The WNV National Surveillance Program is coordinated through the WNV National Steering Committee (NSC) The NSC, and its sub-committees, continue to be a forum for the Provinces/Territories to discuss their surveillance programs and exchange timely information The annual national meetings provide an opportunity for the Provinces/Territories to address new and emerging issues as well as challenges and successes The relationships made with Provincial/Territorial partners, and other key partners, is the key factor in the success of the WNV National Surveillance Program From: Dudley JP, Gubler DJ, Enria DA, Morales MA, Pupo M, Bunning ML, Artsob H. West Nile in the New World. Zooonoses and Public Health. In Press 7

9 5) What are the Outcomes/Benefits? New knowledge: Processes of spread of a new emerging disease in Canadian ecology Development of laboratory diagnostic technology Rapid technology transfer Development of a successful template for response to an emerging zoonoses: National steering committee National collaborations including Provinces/Territories, multiple government Departments/Branches; multiple nongovernmental agencies Development of multi-media public education approaches Early development of risk management plan and supporting documents Rapid development of national multi-species surveillance program Evaluation of Risk: Response Levels and Definitions (1) Level 0: In the absence of confirmed West Nile virus infection in a bird, animal or mosquito pool, and West Nile virus activity is unlikely Level I: In the absence of confirmed West Nile virus infection in a bird, animal or mosquito pool, and West Nile virus activity is possible or the risk is unknown Level IIa: Based on an assessment of risk following detection of West Nile virus activity in a neighbouring jurisdiction, in Canada or the United States, based on laboratoryconfirmed identification in a bird, animal, mosquito pool or human Level IIb: Based on an assessment of risk following detection of West Nile virus activity within a jurisdiction based on laboratory-confirmed identification in a bird, animal or mosquito pool 8

10 Evaluation of Risk: Response Levels and Definitions (2) Level IIIa: Detection of a single laboratory-confirmed human case of West Nile virus (with no history of travel to an area with confirmed West Nile virus activity within 21 days of onset of symptoms) within a jurisdiction. Level IIIb: Detection of multiple laboratory-confirmed human cases of West Nile virus (with no history of travel to an area with confirmed West Nile virus activity within 21 days of onset of symptoms) within a jurisdiction. 9

11 5) What are the Outcomes/Benefits? Surveillance in Canada: Monitoring activities include surveillance in: Dead and Nesting Birds Mosquitoes Horses Humans National Surveillance for WN virus: Submission of Specimens Avian Public Local Health Unit/Natural Resource/ Conservation/Animal Control National Microbiology Laboratory CCWHC/Provincial Veterinary Laboratories 10

12 National Surveillance for WN virus: Submission of Specimens Mosquitoes Local Health Unit/Mosquito Contractor Mosquito Contractor/University-based Contractor National Microbiology Laboratory Laboratory-based surveillance: detection of WNV in bird and mosquito samples WNV RNA Purification Real-Time RT-PCR 5' C prm E NS1 NS2A NS2B NS3 NS4A NS4B NS5 3' Structural Non-Structural 11

13 National Surveillance for WN virus: Submission of Specimens Horse Owner Local Veterinarian Commercial Laboratory Provincial Laboratory CFIA National Surveillance for WN virus: Submission of Specimens Human Health Care Provider Provincial Laboratory National Microbiology Laboratory 12

14 Simplified WNV Testing Algorithm Acute Sample (Suspect Cases) IgM ELISA + (IgG ELISA, Avidity Testing if IgG Positive) 10k 1k Convalescent Sample Rn 400 bp 10, Rn 10k 1k Cycle Confirmatory Serology* Ct PCR (Tilley et al) (Eg. Plaque Reduction Neutralization Test-PRNT) (Demonstration of Seroconversion, HI, IgG ELISA) *Confirmation of first 5 cases in jurisdiction or province Additional probables will not require PRNTs to be designated cases 5) What are the Outcomes/Benefits? Overall Benefits of Response to WNV: A template for proactive/active response to an emerging zoonotic disease or outbreak Effective Fed/Provincial/Territorial health portfolio collaboration Enhanced data sharing with key stakeholders Better understanding of the dynamics of spread and establishment of a new vector-borne disease Federal Government continues to have a visible leadership role in protecting the health of Canadians from continued health threat Strengthened Canada-US collaboration on a continent-wide disease issue. Now being broadened to the Americas 13

15 Developed a model for a cross-disciplinary approach to address a zoonotic disease threat Provincial Departments Teamwork International Oganizations Canadian Cooperative Wildlife Health Centre Federal Departments e.g. PHAC Universities Industry Epidemiologists Clinicians 14

16 Case Study: West Nile Virus Taking an Integrated National Public Health Approach to an Emerging Infectious Disease in Canada Questions? 15