
Babesiosis is a relatively new tick-borne illness in Canada that's really only just started to earn its way into the mainstream news. And yet, like Lyme disease and anaplasmosis, babesiosis cases are already on the rise in this country and are expected to escalate for many decades still to come.
If you've never heard of babesiosis, you're not alone. The first confirmed case in Canada wasn't documented until 2013 when a seven-year-old boy in Manitoba with no recent history of travel outside the province was diagnosed with the illness a few weeks after returning from a two-day stay at a family cabin in southeastern Manitoba.
However, if you ask around you'll find there are quite a few Canadians who are more than willing to inform you they were diagnosed with babesia well in advance of 2013 even if their cases weren't officially recognized. The reasons for this are complicated and have a lot to do with the myriad of challenges involved with identifying and tracking emerging pathogens.
Regardless, babesiosis is a malaria-like illness caused by a parasite that lives inside red blood cells. More than 100 hundred species of babesia have been identified in wildlife, humans and domestic animals, but only a handful are known to cause illness in humans. Of those Babesia microti is the most common cause of babesiosis in North America. Babesia duncani is a distant second and although the first case of babesiosis caused by Babesia duncani was documented in a 70-year-old male in Ontario in 2017, Babesia duncani is more often associated with BC.
Babesia odocoilei has also caused a stir in recent years and is being detected in Canada with increasing frequency. However, there continues to be some dispute over whether it causes human illness. Stay tuned on that one.
Babesiosis is transmitted by blacklegged ticks (Ixodes scapularis) in most of Canada east of the Rocky Mountains and western blacklegged ticks (Ixodes pacificus) as well as Ixodes angustus in BC.
One of the difficulties of diagnosing and treating babesiosis is that it can be acquired in combination with other pathogens carried by same ticks, including Lyme disease and anaplasmosis. All three pathogens are maintained in nature by the same small mammal populations although not necessarily to the same degree, so your risk of contracting one or more of these tick-borne illnesses from a single tick bite is highly variable from one geographic region to the next and even within a single geographic region.
The severity of the symptoms caused by babesiosis are highly variable. Some people become profoundly ill while others show no symptoms at all.
Symptoms can include chills, coughing, headaches, joint and muscle pain and sweats. Severe cases can cause heart, kidney, liver, or respiratory failure.
Notably, patients who acquire Lyme disease and babesia infections concurrently tend to be more severely ill. Since the two diseases are treated with different medications, it's important determine which infections are present.
And it's not just ticks we need to worry about. Babesia can also be transmitted through transfusions as a result of blood being donated by someone who was unaware they were infected with babesia. Though mostly theoretical in Canada at this point, that scenario has played out on a number of occasions in the US.
Because of this, public health researchers have been monitoring the blood supply for babesia in addition to Ixodes ticks and small mammal populations for more than a decade in order to gain a solid handle on the degree of risk the babesia represents to humans, domestic animals and wildlife in Canada which, for the moment, is very low. And although babesia has been found in most provinces, it has so far been most commonly identified in blacklegged tick and small mammal populations in Manitoba, where illness has been reportable since 2015. However, that could change as blacklegged ticks continue to gain more territory in Canada bringing with them the pathogens they are infected with, including babesia.