Q: Dr. Vogl, your last column was about tick season. I'm worried about my dog and Lyme Disease. Should I be?
I wouldn’t say that I can come close to Carnac the Magnificent’s ability to predict events, but we certainly did pluck a lot of ticks last week, as we predicted in our last column. It wasn’t much of a stretch to guess that ticks would “pop up,” though this year has been one of the quietest for ticks that I can remember. What kind of ticks did we pull off pets this week? I’ve had them referred to as wood ticks, seed ticks, dog ticks, deer ticks, blood ticks, among a variety of other names.
Technically, the vast majority of ticks we pull off are the American dog tick (Dermacenter variabilis).
There are an estimated 820 species of ticks in the world; the U.S. has about 90 species. Indiana has approximately 15 species of which four are of any significance. These are: the American dog tick, the lone star tick (for the white spot on the middle of its back), the brown dog tick, and of course the dreaded deer tick now known as the black-legged tick, because of its…you guessed it, black legs. If you have seen a tick in this part of the state it is most certainly a “dog tick.” When not engorged it is about the size of an apple seed. When engorged it looks like a tan or grey plump grape. The black-legged tick is much smaller by comparison, smaller than the letter “D” on a dime. That is why they are so hard to find. Then there is “Tickzilla” at over an inch when engorged, found in the southeast U.S. and picks on only the poor gopher tortoise. It is called….you guessed it the “gopher tortoise tick”. See how easy this is.
So let’s finally get to Lyme Disease. To appease all the fanatics, drug companies, marketing gurus, and cousin Eddie, I will make this statement. YES, there are black-legged deer ticks (Ixodes scapularis) in Indiana, YES, there is Lyme in Indiana, YES, it is spreading from the most northwest and central western counties, YES, there have been black-legged ticks found in St. Joseph County, and YES there are Lyme cases in St. Joseph County. OK, that’s out of the way.
Now some perspective. Of the 2,590 human cases of Lyme so far this year in the U.S., three are from Indiana. In the entire state in 2010 there were 62 confirmed cases. From 1990-2008 our state has had a total of 531 cases (vs. 51,266 for Pennsylvania, 15,463 for Wisconsin, 45,938 for the tiny state of Connecticut-where Lyme originated).
Purdue University performed a study, sampling harvested white-tailed deer (the preferred host of the adult deer tick) in 2005, 2006 and 2007 from each county in the state in order to collect deer tick numbers and test these ticks to see if they carried the bacteria for Lyme (Borrelia burgdorferi). In 2006 they found a few deer ticks in the very southwest corner of St. Joseph County (none in 2005 or 2007). A total of 4,561 deer ticks were found clustered in the western-most counties and the very southern-most counties. Lyme bacteria were found only in years 2005 and 2007, in 11 counties along the western edge of the state.
There is a simple blood test to check your dog for Lyme, though the interpretation of the results can be very tricky. Routine testing and vaccinating dogs in non-endemic areas (where a disease in not prevalent) is controversial as discussed in the American College of Veterinary Medicine guidelines for Lyme disease. It states that these decisions “…should be made between owner and their veterinarian on an individual case basis.” For high risk pets that travel, go camping, or spend a lot of time in the outdoors you may want to consider vaccinating and certainly keep using your flea/tick prevention.
And don’t forget if you find one of these buggers attached just keep on pluckin’.