Lyme Disease Rates Down This Year, but Tick-Borne Illness Still a Concern

Oct 5, 2018

Credit Courtesy of the Cape Cod Cooperative Extension

Cooler temperatures are not far away, but even when we need to add layers to protect ourselves from frigid winds, we should also be thinking about protecting ourselves from ticks.

WCAI's Kathryn Eident checked in with county entomologist Larry Dapsis about Lyme Disease rates in Massachusetts this year, and about a new species of tick he's keeping an eye on. 

 

Eident: Larry thanks for talking with us this morning. We heard news reports a couple weeks ago from other states saying that rates of Lyme looked a little lower this year, so it made me want to give you a call to find out what's happening here in Massachusetts.

Dapsis: Oh, we've read a number of reports in other states like Maine and Vermont that they're seeing a real reduction in incidence rate of Lyme disease. And, we were wondering if we're seeing the same thing here. So, I happened to catch up with Dr. Catherine Brown at our Department of Public Health and asked her if they're seeing the same thing in their data.

Eident: She is the state epidemiologist.

Dapsis: Correct. They're looking at a very different way to evaluate incidence rates because it's way under-reported. DPH knows that they can't fix this method, so they're looking at, "OK, how can we get at this and get a more accurate tally?"

Eident: Let me stop you there. Why is it not being reported and why do they think they can't accept it?

Dapsis: It seems antiquated and involves fax machines and other steps, and it I think it's a matter of office inconvenience for a lot of MDs. So DPH is taking what I think is a pretty innovative approach. They're looking at discharge information for their patients. So how many people are coming out the door and start to undergo treatment for a tick-borne disease?

The other way that they're looking at this is patients coming in the door. How many people are going into a hospital that have experienced a tick bite.? And so, if you look at it that way compared to last year, yeah, you see during this summer months there's way fewer people being discharged with tick borne diseases compared to last year; but it's way higher than what we saw in 2016 which is when we had a major drought, as you recall.

Eident: Yes. Fire risk-- not exactly ideal conditions for ticks. This summer...quite a different story.

Dapsis: What happens during dry weather with the ticks--if you look carefully at published research on tick behavior in response to humidity-- when ambient humidity drops, they basically just burrow deeper into the leaf litter to get in contact with a higher humidity environment because ticks don't drink water, they have to absorb water vapor through their skin basically.

Eident: Ticks are questing today; it's a very moist day, we've had quite a bit of rain.

Dapsis: Well, there's another angle to the precipitation thing. When you get precipitation, you actually may have reduced opportunities for tick exposure just because people are reluctant to go outside. So, a tick forecast is not a one-factor thing.

Eident: Switching gears a little bit, you're keeping an eye on another type of tick that's been seen elsewhere in New England that you think it's just a matter of time before it shows up here.

Dapsis: Sure. Asian longhorn tick was found on a sheep farm in New Jersey last year, and then they found it in Virginia, Maryland, Arkansas, Pennsylvania. A couple weeks ago it was found in Connecticut. So, it's on our doorstep. It principally is a pest of livestock. So, for people who have horses and alpacas and things like that.

Eident: What does the tick look like; does it have any discernible features?

Dapsis: No, it's just a rusty brown color; it's got no markings that are distinctive. So, if people kind of understand what a deer tick looks like, and people are becoming more familiar with the Lone Star tick with that bright white spot on the back of the adult female, and I think most people know with a dog tick is by now. So, if you see something it doesn't fit those descriptions that's worth an investigation. So, Larry the detective is on the case.

Eident: So, no real concern with human illness from this particular species?

Dapsis: What they haven't found is the diseases that it's associated with over in Asia and some of those pathogens resemble our Babesiosis pathogen and Powassan virus. So, what the CDC is doing right now-- they're colonizing this Asian longhorn tick, and what they're going to do is feed it on reservoir hosts here, like a white-footed mice and chipmunks. See if that tick can feed on these reservoir hosts and pick up and transmit those pathogens.

Eident: And Larry, as they often like to do when we chat; tick season maybe shouldn't even be called a season anymore.

Dapsis: Be aware that tick season started January 1st is going to end December 31st. Then it's going to pick up again January 1st. So, any time you get temperatures above freezing and a break in snow cover, you're going to have tick activities.

This transcript was lightly edited for grammar and clarity.