The Bug Geek

Insects. Doing Science. Other awesome, geeky stuff.

Tag Archives: Lyme Disease in Ontario

Photo Friday – Deer Tick (Ixodes scapularis)

Lesson learned this week: people get really excited about parasites (holy page-hits, batman!!!) I’d already planned this post for today, but it fits nicely with the gross-out trend started on Wednesday.

A few days ago my wife was snuggling with Solomon, our fat, grouchy, old, outdoor boy-cat, when she felt a lump at the nape of his neck.  “Sol’s got a tick!” she announced. Ticks may not be as exotic as brain-bending beetle-banes, but they’re still pretty nasty (and therefore also cool).

I gleefully ran to get my tick tool, an ingenious little plastic do-dad that lets me literally twist a tenacious tick off the victim’s skin intact (leaving mouthparts embedded in skin can be bad news in terms of infection).  Fur was parted, tick scooped, twisted, and voila – off.

Usually Sol’s hitchhikers are common Dog Ticks (Dermacentor variabilis).  This one looked just a bit different.

tick 4_small

It is smaller than the ticks I usually see (this animal was about 6mm long), and the shape and color of the shield (the roundish area behind the head) were different. Also, see those super-long (creepy) palps?

After having done a bit of googling, I’m pretty sure that this is a Deer Tick (Ixodes scapularis), which is not particularly awesome, since they are known vectors of Lyme disease. The only other time I’ve seen this species was when I plucked a very tiny one off my wife’s leg after a walk in the woods. I brought it to our local health unit, and thankfully it tested negative.

A recent study of Deer Ticks collected from people’s pets in my home province (Ontario) showed that about 1 in 10 were infected with Borrelia burgdorferi , the bacteria actually responsible for the sometimes debilitating disease.

Results of tick-testing in Ontario, Canada, from 1993-2002

We live just to the east of that great big red circle by Kingston.  Although I am a teensy bit comforted by all the white dots closer to our area, I have to suspect that the range of Lyme-carriers has shifted eastward since these data were collected. (Eep.)

My wife’s reaction upon discovering this tick was, “Shouldn’t these be gone by now? It’s November!” While a lot of 6- and 8-legged critters are indeed out of commission for the winter by this time, mature Deer Ticks are most commonly found on pets in October and November. This is because the ticks are mostly in the larval stage during the warmest summer months of July-September. The larvae are incredibly tiny, not much bigger than the period at the end of this sentence, so they’re easily overlooked.

Although I’m not thrilled about having this species lurking around my home, I have to admit I was rather taken with one of its features. I didn’t notice this until I was processing my pictures:

Microsculpture of spiracle and side on Ixodes scapularis, the Deer tick

Mega-closeup of the tick's integument - cool!

This is an extreme closeup of a small area just above the spiracle (the little hole on its side through which oxygen enters its body). You can see what was turning my crank: the really cool sculpturing – all those little wavy lines on the upper regions, and the concentric circles around the spiracle. Sculpture (which is often visible to the naked eye), and even microsculpture (which usually requires a microscope to be seen), can be an incredibly useful tool when identifying insects to the species level.

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ResearchBlogging.org

Morshed MG, Scott JD, Fernando K, Geddes G, McNabb A, Mak S, & Durden LA (2006). Distribution and characterization of Borrelia burgdorferi isolates from Ixodes scapularis and presence in mammalian hosts in Ontario, Canada. Journal of medical entomology, 43 (4), 762-73 PMID: 16892637

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