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Tick-borne diseases on Block Island


OSM: Block Island
One Square Mile: Tick-borne diseases on Block Island
(2012-09-04)
Tick larvae in tube. Photo by: KRISTIN GOURLAY
(RIPR) - In February 1967, Rhode Island wildlife officials captured four deer, using drugged apples and dart guns. They brought those woozy, bewildered deer on the ferry to Block Island, where there hadn't been any deer for decades. But, like a lot of other communities, the town council thought it would be nice to bring them back. By September, this was the lead in a Providence Evening Bulletin article: "Block Island's new deer population has doubled from four to eight, including one set of twins, state conservation chief Thomas J. Wright proudly announced today."
Block Island Times co-publisher Fraser Lang was there.
"I remember how excited people were. People were always looking to sight one of the deer and everything," Lang recalls. "It seemed neat to me. It never occurred to me that this was going to be a menace."
A menace, he says, because with no natural predators or hunting on Block Island, that handful of deer multiplied to more than 500 today. And as the deer multiplied, so did the deer ticks.
"I've been coming to Block Island since the 1950s and have had Lyme disease three times," says Lang.
Lyme disease is a nasty, flu-like illness you get from the bite of an infected deer tick. "I mean, if you have it full blown," says Lang, "you are down for the count for a week. You really feel awful."
It's treatable with antibiotics in the early stages. But later stages can be debilitating. Like it was for Fred Leeder, who drives a taxi on Block Island.
"The worst case I had was probably about '89, where I wound up on intravenous antibiotics for about three weeks."
On this bright windy day, Leeder parks his cab by the pier to wait for his next fare. He says since then he's had Lyme disease many times. And on Block Island, that's not unusual. "Anyone who's been here any length of time has Lyme," he says. "It's almost a default here."
It's almost the default here to get tested for Lyme twice a year, too. Leeder and hundreds of island residents have been participating in a study designed to learn more about why it's so prevalent on the island. Scientists from Yale have been collecting blood samples from them twice a year since the early 90s. And in that time they've found something surprising: another tick-borne disease, babesiosis, has become almost as prevalent. Nationally, there are about 30 cases of Lyme for every case of babesiosis. But on Block Island, it's three to one. It's got people worried because babesiosis is harder to diagnose. It can be more serious, even fatal. So now the researchers want to know why it's on the rise. To do that, you have to look at the ticks.
"So what we are going to do is we're going to take these one meter square cloths of corduroy, and drag them along the property in 100 meter areas, and see how many ticks we can find in that area."
As part of his graduate work at Yale's school of public health, Casey Finch is spending the summer on the island collecting ticks. He and his partner are visiting the backyards of a long list of residents who gave blood for the Yale survey.
"And we use that to kind of find a density map of the tick population in that area," says Finch.
The area is the backyard of a gray-shingled summer home near the harbor. Finch and his research partner Patrick Shea head for the bushy perimeter. And there they drag a couple of flag-sized pieces of corduroy along the ground behind them. The cloth picks up burrs and seeds and bits of twigs. But it's also the perfect tick magnet. Research assistant Patrick Shea finishes a stretch and holds up the cream-colored cloth to scan for tick larvae.
"I find it's easier to look at it in the shade. See that little dot right there?"
"It's almost microscopic. It's the tiniest thing! Do you have to rest your eyes at night?"
Shea plucks the larvae from the corduroy with tweezers and plunges it into a vial of alcohol. It's headed back to a lab at Yale where it will join thousands of other ticks in various life stages.
They finish marking down the GPS locations of the ticks they've collected. And back in her office on the island, lead scientist and Yale ecologist Maria Diuk-Wasser says they're learning that the ticks are only part of the story of why so many Block Islanders get sick. The landscape itself is another part. And then there's how people behave in their environment.
"So we can really tease out how much of the risk--human risk--has to do with the ticks in their backyard, the characteristics of their backyard, and also their behavior," says Diuk-Wasser.
Yale scientists have been giving residents a questionnaire when they give blood, asking, for instance, whether they protect themselves from ticks when they go outside. "So we can get all those pieces of the puzzle together to determine who gets Lyme disease and who gets babesiosis versus people that don't. What are they doing differently?"
They can also begin to determine why babesiosis is becoming more common and where it's headed next.
Take a listen to the rest of One Square Mile: Block Island here

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