My lab has been spending a lot of time on Lyme disease over the past couple of years. It’s a fascinating (and frustrating) disease to work on, and we need to learn a lot more about it. In this region, we’re seeing clear changes in tick populations and the diseases they carry. With climate change, that’s not going to get any better. It may be -14C outside at the moment, but we have more tick-friendly weather over the course of the year than we’ve ever had.
An interesting aspect of Lyme disease surveillance is the abundant canine data we have. It dwarfs human data, in large part because annual heartworm testing is often done with a test that also detects antibodies against several tick-borne diseases including Borrelia burgdorferi (the cause of Lyme disease), Ehrlichia and Anaplasma. So, we get a lot of ancillary data, even if the animals weren’t tested because of a suspicion of disease. We’re currently working on a huge Canadian dataset, and one of the questions that comes up is “what is the relevance of canine data to humans?“. There’s some info from the US that suggests canine exposure to Borrelia can also be an indicator of the risk of human exposure, which makes sense since dogs and people are exposed the same way (i.e. being bitten by an infected Ixodes scapularis tick).
Public Health Ontario has just released a systematic review evaluating comanion animal and tickborne disease. The results aren’t astounding but it’s a comprehensive review of the subject.
Here’s the summary:
Our systematic review indicates:
1. Dogs provide suitable spatial seroprevalence data for assessing the risks of tick-borne disease in humans.
2. Companion animal ownership does not appear to pose additional Lyme disease risk to owners.
Data collected from the testing of companion animals within the veterinary health system can help establish the distribution of B. burgdorferi while identifying new areas and the direction of pathogen movement. In addition, data collected from companion animals are valuable in estimating the prevalence of a pathogen over time and can help test hypotheses of pathogen ecology and epidemiology or test the efficacy of prevention efforts.
The best way to understand the shared risks of tick-borne pathogens to humans and companion animals is to ensure ongoing information sharing between veterinary, medical and public health professionals. Continual information sharing increases overall awareness, which leads to collaborative research of tick- borne pathogens in humans and companion animals. Included within these shared efforts is assessing the distribution of pathogens in humans and animals and tick vectors, leading to improved risk assessments and prevention of disease in Ontarians and their companion animals. PHO will continue to work with partners on ways to improve tick-borne disease surveillance.