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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)

BackgroundIxodes 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.

Objectives1.Determine if I. scapularis ticks can be found in Alberta

2.Determine the percentage of I. scapularis ticks that carry B. burgdorferi

3.Utilized geographic information to pick sites for active surveillance

4.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.

Companion Animals

Veterinarians

Humans and Environment

AHS Environmental Health Office

Agriculture and Rural Development Lab

Alberta Health

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 environment

Human Cases

Single locally acquired human case

Cluster of locally acquired human cases

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).

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

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.

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.

Figure 1) Overview of Passive Tick Surveillance Program

Figure 2) 2014 Companion Animal Form Figure 3) 2014 Human and the Environment Form

Activities

Table 1) Triggers for Active Surveillance

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 2012 49(2): 400-409.