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Implementation of a Passive Tick
Surveillance System in Alberta Allison N Scott, Daniel Fitzgerald, Lisa Lachance, Kimberley Simmonds, and the Arthropod-Borne Diseases Committee (AABDC)
Background
Ixodes scapularis ticks are endemic in eastern Canada and the eastern United States and are an important vector for Borrelia burgdorferi sensu stricto, the causative agent of Lyme disease. Recently I. scapularis ticks have been found in Alberta. As undiagnosed Lyme disease in humans can cause debilitating long-term sequelae, it is important to determine whether established populations of I. scapularis exist in Alberta. In 2013 a multi-component passive tick surveillance program was launched in Alberta.
Triggers for Active Surveillance
Triggers for active surveillance were developed based on Koffie et al (2012)1 (Table 1)
The results of passive surveillance indicated 5 sites for active surveillance
Sites dragged once per week in May & June
Results of spring/summer 2014 passive surveillance will be utilized to pick sites for fall 2014 active surveillance
Figure 1) Overview of Passive Tick Surveillance Program
Table 1) Triggers for Active Surveillance
Criteria
Reasonable Evidence
Strong Evidence
Same 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 environment
Human Cases
Single locally acquired human case
Cluster of locally acquired human cases
Companion Animals
Veterinarians
Humans and Environment
AHS Environmental Health Office
Agriculture and Rural Development Lab
Alberta Health
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Strengths of the Program
The addition of the human data provided valuable information for choosing active surveillance sites as environmental health officers were able to elicit more specific geographical information.
Collaborations with municipalities provided valuable information regarding local geography and reduced concerns regarding access and approvals.
1 Developed from Koffi et. al. Passive Surveillance for I. scapularis Ticks: Enhanced Analysis for Early Detection of Emerging Lyme Disease Risk. Journal of Medical Entomology (2):
Objectives
Determine if I. scapularis ticks can be found in Alberta
Determine the percentage of I. scapularis ticks that carry B. burgdorferi
Utilized geographic information to pick sites for active surveillance
Determine if there are established I. scapularis populations in Alberta
If established populations are found this would have immediate public health consequences as potential exposure to tick populations is an important element of the differential diagnosis for Lyme disease in humans.
Figure 2) 2014 Companion Animal Form
Figure 3) 2014 Human and the Environment Form
Challenges in the 2013 Season & Improvements for 2014
Fewer submissions than expected. More advertising planned for 2014.
The 2013 companion animal submission form only collected postal code of residence, making active site selection more difficult. The 2014 submission forms elicit more information on outdoor locations visited in prior two weeks.
Physicians attempted to submit ticks to Alberta Agriculture. Processes have been developed to reroute specimens when necessary and educate physicians on where clinical tick specimens should be submitted.
Genesis & Partnership
Alberta Agriculture began passive tick surveillance in companion animals in 2007 as part of a graduate research project.
In 2013 the tick surveillance program was expanded to include ticks found on humans and in the environment.
Collaborative effort between Alberta Health, Alberta Agriculture, First Nations and Inuit Health Branch (Health Canada) and Alberta Health Services (AHS).
Two arms of the program (Figure 1):
Ticks speciated and I. scapularis ticks tested for B. burgdorferi at Alberta Agriculture.
Companion Animals: Ticks submitted from veterinarians who encounter them on animals in their practice
Demographic and travel history collected by veterinarians and EHOs on standardized forms (Figure 2 &3).
Human and the Environment: Ticks collected by the public and submitted to EHOs at AHS
Epidemiologic data and lab data combined and analyzed at Alberta Health.
Clinical specimens are not accepted by Alberta Agriculture and are instead sent to the Provincial Laboratory for Public Health Alberta
Maps created utilizing host’s postal codes of residence and this data utilized to pick sites for active surveillance. Postal codes of individuals/animals who had travelled were excluded.
Activities