Estrie residents have known Lyme disease for several years. But now they have to protect themselves from another disease transmitted by blacklegged ticks: anaplasmosis.
Last summer, 35 cases of this disease, whose symptoms resemble those of the flu, were declared in Estrie, the highest number of cases listed in the same place in Canada.
And this disease could become more and more common in Quebec, in particular because of climate change, which extends the period of activity of ticks, accelerates their life cycle and lengthens the duration of possible contact between them and humans.
This upward trend is of particular interest to a research team from the Faculty of Veterinary Medicine at the Université de Montréal, made up of professors Catherine Bouchard, Cécile Aenishaenslin, Patrick Leighton and Jean-Philippe Rocheleau, and master’s student in epidemiology at UdeM Raphaëlle Audet-Legault.
Together, the veterinarians are conducting a research project this summer aimed at better understanding which species of small wild mammals are reservoirs for anaplasmosis, and therefore which contribute to the transmission of the disease in humans.
“You have to see the tick as a dirty syringe, explains the Dre Catherine Bouchard. In a previous meal, the tick bit a mouse and, for example, let’s say that the bacterium responsible for anaplasmosis is circulating in the blood of the mouse. Then, when the tick bites the human, it infects the human with the blood of the infected mouse. The human will be contaminated if of course the mouse was carrying a zoonotic variant.
Better understand the distribution
Throughout the summer, in collaboration with the City of Bromont, the CIUSSS de l’Estrie ‒ CHUS public health department and the MRC Brome-Missisquoi, the team will capture rodents of various sizes (mice, chipmunks, squirrels) around of the municipality of Bromont to assess the species in which anaplasmosis circulates more. Veterinarians will also collect ticks from the field generally to find out the proportion of infected ones in the area.
Half of the sampling areas are in regions where there have been human cases of the disease and the other half where there have been none. “The goal is to be able to compare the proportion of infected small mammals close to the cases reported in humans with that further away, in addition to verifying whether the prevalence of the infection varies according to the different species”, specifies the Dre Raphaëlle Audet-Legault.
“We can’t wait to see how much traffic is contained or not, adds the Dre Bouchard. I would not be surprised if there is no difference between the areas close to the human cases and those far away, and that we realize that the human cases are more numerous where there is a higher residential density , but that the disease circulates just as much elsewhere. There would therefore be an issue of vigilance for residents.”
Raise awareness to prevent
As mentioned by D.re Bouchard, the explosion of human cases of anaplasmosis calls for increased efforts to promote preventive behaviors among exposed populations – such as wearing long clothing and a routine inspection after each outing.
This awareness concerns not only residents, but also health professionals, who must go beyond Lyme disease when diagnosing patients from a region at risk.
This task is not so easy considering that the symptoms of anaplasmosis are mostly non-specific and mild like fever, chills, headache and muscle aches. And unlike Lyme disease, anaplasmosis does not cause skin redness.
Raphaëlle Audet-Legault also recalls that the majority of infected people were bitten near their homes, when cleaning their yard for example. “In Estrie, residents have land on the mountainside, under a canopy of mature trees. So they are literally in the habitat of ticks. And that is why we must increase our awareness efforts, since all residents are potentially at risk.”
In this regard, the research team has already met with Bromont residents to present their research project. Interactive workshops are also planned throughout the summer.