New Hampshire residents have long known the risks of contracting diseases like Lyme and West Nile from a tick or mosquito bite, but a recent report from the federal Centers for Disease Control and Prevention says there’s even more to worry about.
The CDC is now tracking 16 of these “vector-borne diseases” and says the number of cases has tripled between 2004 and 2016.
The Exchange looked into the rise in tick and mosquito-borne illness in New England, including what may be causing the increase in these pests and the diseases they carry, and what residents can do to protect themselves.
Dr. Elizabeth Talbot, associate professor of medicine at Geisel School of Medicine at Dartmouth College, specializing in infectious disease and international health, says there are more tick-borne diseases than many people may be aware of.
“Everyone has heard about Lyme disease,” she said. “But we’re also steep on the learning curve for anaplasma, babesia, powassan virus, and there’s a new kid on the block: borrelia miyamotoi. Many experts believe that we’re probably actually under-diagnosing that.”
Talbot said there are now five major tick-borne diseases being monitored in New Hampshire. This increase in disease is combined with a tick population that is larger than usual.
Jonathan Winter, assistant professor of geography at Dartmouth College, has studied the impact of climate change on Northern New England. He says changes in land use contribute to a spike in tick populations.
“The Northeast stopped farming as much,” he said. “So you’ve had reforestation, and then you’ve also had this habitat fragmentation. This is us moving with our suburbs and our rural areas to get more into the forest.”
"Everyone has heard about Lyme disease," Talbot said. "But we're also steep on the learning curve for anaplasma, babesia, powassan virus, and there's a new kid on the block: borrelia miyamotoi. Many experts believe that we're probably actually under-diagnosing that."
When builders break up the forest with developed residential areas, they limit the bio-diversity in some sections. This ultimately drives up the population of two of the ticks’ favorite hosts: deer and mice.
Another major factor, Winter said, is the potential impact of a warming climate, which widens the natural range of ticks.
“Ticks don’t like cold weather,” he said. “As we have warmer winters, the ticks no longer get killed, so they can expand their range northward.”
An increase in rainfall may also have an effect.
“Ticks in particular like humidity,” Winter said. “Over the last 30 years or so, the Northeast has received more rainfall than it had previous to that, and that could be a contributing factor.”
Although the tick population and tick-borne diseases have been on the rise for many years, Winter says it’s still too early to know for certain how this summer will stack up.
“So really you have May, June, and July that will be your main tick months ? where you’ll be seeing the most bites.”
Whether or not this summer will continue the trend of increased bug-borne illness, Talbot says that New Englanders should be thinking about disease prevention.
The prospect of a vaccine to prevent Lyme and other tick-borne diseases has many people excited, but, so far, it’s proven to be a complicated issue.
“We had a vaccine,” Talbot said. “It was called Lymerix. It was unanimously FDA-approved for use and it had a tremendous uptake when it was released.”
Talbot said that after Lymerix’s release, a theoretical concern was raised that the vaccine might engender an autoimmune disease, and, although it was only theoretical, the uptake fell dramatically. Now, Talbot says any new vaccine must protect the public not only from Lyme, but also the other tick-borne illnesses.
“I have not heard that there’s anything particularly imminent to cover all of these diseases we know about, and all of these diseases we don’t know about, that these ticks can transmit,” she said.
In the meantime, there are other ways to protect yourself against the threat of tick and mosquito bites.
“I truly believe that there are ways that people can effectively prevent these diseases,” Talbot said, noting that many of these practices are under-used.
She mentioned DEET, which is effective at repelling bugs when applied to the skin, and the lesser-known permethrin, which can be used to treat fabrics, such as pant-legs, socks, and shoelaces.
“It’s routinely available in most hardware stores or Walmart-type stores,” she said, adding that the chemical binds to the fibers of cloth and lasts through many washes.
Talbot also suggested wearing light-colored clothing while hiking, walking, or working outside, as this makes it easier to spot ticks before they reach the skin and bite.
To learn more about the increase in bug-borne illnesses and what you can do to protect yourself this summer, listen to the full conversation here.
