results of a passive tick surveillance system in alberta

Results of a Passive Tick Surveillance System in Alberta

Allison N Scott, Daniel Fitzgerald, Lisa Lachance, Kimberley Simmonds, and the

Arthropod-Borne Diseases Committee (AABDC)

Government of Alberta

2014 Canadian Public Health Association Conference

Toronto, Ontario

May 29, 2014

Collaborators

Agriculture and Rural Development, GOA

Rashed Cassis

Daniel Fitzgerald

Alberta Health, GOA

Dean Blue

Patti Kowalski

Lisa Lachance

Martin Lavoie

Kimberley Simmonds

Theresa St. Jean2

The Arthropod-Borne Diseases Committee

Alberta Health Services

Lance Honish

First Nations and Inuit Health Branch

And Many More!

Outline

• Ticks & Lyme Disease• Tick Surveillance Program in Alberta• Results• Discussion & Next Steps

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Ticks & Lyme Disease

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Lyme Disease

• Borrelia burgdorferi– Vector: Ixodes spp ticks

• Identified in 1976 in Lyme, Connecticut– Cluster of juvenile arthritis cases

• Multi-system inflammatory disease– Early symptoms: Rash, headache, fever, fatigue– Can affect heart, joints, brain– Small number of patients can have pain, fatigue, or

other symptoms chronically after treatment

• Best if treated early

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http://en.wikipedia.org/wiki/Borrelia_burgdorferi

http://www.cdc.gov/ticks/symptoms.html

Lyme Disease – Key Point

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• Can be difficult to diagnosis as the symptoms can be non-specific, especially if characteristic rash absent

• Knowing that the individual has been in an endemic area and exposed to ticks is important for diagnosis

http://www.cdc.gov/ticks/symptoms.html

Ixodes scapularis

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• Black-Legged Tick– Carrier of Borrelia burgdorferi

• Feeding– Insert mouthparts– Several days

• Drop off

Ixodes spp Ticks

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• Endemic in the United States• Establishing themselves in Eastern Canada• Climate change: warm, mixed forest/grassland

Ogden 2014 CCDR Volume 40-5

Adventitious Tick: Going where no Ixodes has gone before

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• One method of spread: migratory birds• Flyway over Edmonton• Key: Suitable habitat to overwinter/reproduce

birding.about.comodbirdingbasicsssNorth-America-Migration-Flyways.htm

Tick Surveillance Program

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Objectives:

1. Determine if Ixodes ticks can be found in Alberta

2. Determine the percentage of Ixodes ticks that carry Borrelia burgdorferi

3. Utilize geographic information to pick sites for active surveillance

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Passive Surveillance

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Companion Animals

Veterinarian

Humans and the Environment

AHS Environmental Health Office

Agriculture and Rural

Development Lab

Alberta Health

Methods

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• Standardized lab methods– Dichotomous identification key to speciate ticks– Established PCR protocol utilized to identify Borrelia

burgdorferi

• Descriptive statistics (SAS)• Mapped postal code of residence (ARC GIS)

• Restricted to hosts that were Alberta residents and had not travelled in the previous 2 weeks.

• Finding nymph or larva would suggest a population capable of reproducing

Results

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Results

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All Tick species

Ixodes species

B. burgdorferi positive

Ixodes spp Total Ticks Submitted 960 171 (18%) 27 (16%)

Ticks Submitted by Alberta Residents With No Travel Outside of Alberta

580 139 (24%) 25 (18%)

Tick Submitted by Alberta Residents With No Travel

378 105 (28%) 21 (20%)

• Only adult Ixodes ticks found from individuals who had not travelled

Results

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• 54% of Ixodes ticks submitted by Alberta residents with no travel history reside in Edmonton Zone

– Submitter’s Postal Code of Residence

– No travel in previous two weeks

Results

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• Submitter’s Postal Code of Residence• No travel in previous two weeks

Discussion & Next Steps

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Discussion

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• Ixodes ticks found in Alberta• Mostly in Edmonton Zone• 20% of Ixodes positive for Borrelia

burgdorferi

• Only adults found• But more than one tick likely acquired in

certain areas

Active Surveillance Triggered

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Criteria Reasonable Evidence Strong EvidenceSame Submitter *

1 or more nymph or larval blacklegged ticks

>1 blacklegged tick of any stage from the same person or animal in a suitable environment

Different Submitter*

>1 blacklegged tick of any stage from a different submitter in a suitable environment

>2 blacklegged tick submissions of any stage found at least 1 year apart

AND The ticks were found in a

suitable environmentHuman Cases

Single locally acquired human case

Cluster of locally acquired human cases

* In the same location. The location is in the same town, city or geographic area not defined by a specific surface area size.

Active Surveillance for Ticks

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• Drag sampling 5 sites weekly, May-June 2014• If Ixodes found: Heightened

Active Surveillance • Likely include small mammal

trapping

http://www.youtube.com/watch?v=QfKhopJNuj0

Strengths and Limitations

• Strengths:– Strong partnership between Alberta Agriculture, Alberta

Health Services, and Alberta Health– Collaborating with municipalities

• Limitations:– Residential postal codes, not locations– Unable to interview companion animal owners– Postal codes for companion animals currently only

available for 2013– Small sample size

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Next Steps

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• Active surveillance

• Changes to forms– Enhanced information on outdoor locations pets/people

had been in previous two weeks

• Continued passive surveillance– Increase sample sizes

• Enhanced advertising for 2014 season

Questions?

• www.health.alberta.ca/health-info/lyme-disease

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Ixodes spp – Life cycle

25CDC

Tick Surveillance

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• Surveillance: – “Systematic ongoing collection, collation, and analysis

of data and the timely dissemination of information to those who need to know so that action can be taken.”

• Passive Surveillance and Active Surveillance

Last, John M. 2001. A Dictionary of Epidemiology, 4th edition. Oxford University Press, Inc

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