PORTLAND, Maine — Climate change has exacerbated populations of ticks, mosquitoes and other pests that threaten health and outdoor recreation, according to a national report released in Portland on Tuesday.
Shorter winters and warmer summers have allowed problematic bugs — along with poison ivy and jellyfish — to grow in numbers and in geographic range, according to the National Wildlife Federation’s “Ticked Off” report.
A group of Maine health, conservation and wildlife professionals gathered at Portland’s Baxter Woods Trail to release the report and discuss the effects of climate change on Maine’s environment.
The Maine Medical Center Research Institute, which tracks tick populations in the state, compared annual fluctuations in their numbers to Maine’s weather over the past 2½ decades, said Susan Elias, a clinical research associate at the institute.
“What we found is that tick abundance seems to be associated with, no surprise, warmer weather,” she said. “In particular, adult deer ticks are associated with milder winters.”
In northern counties and at higher elevations, Maine’s cold winters arrive before deer ticks can complete their life cycle, Elias said. The larvae die before locating a host, such as a mouse or deer, on which to feed. But research by the University of Maine’s Climate Change Institute shows the state will grow significantly warmer by 2050, Elias said.
“Southern Maine’s going to feel more like Massachusetts, and northern Maine and central Maine are going to feel more like current southern Maine,” she said. “What that means is the deer tick will be able to complete its life cycle statewide, and what that means is more ticks.”
Bigger populations raise the risk of tick-borne illnesses in humans and pets.
Earlier this month, the Maine Center for Disease Control and Prevention announced that an emerging infection carried by the deer tick has sickened a record number of Mainers this year. So far in 2014, Maine has confirmed 108 cases of the bacterial infection anaplasmosis, already exceeding the 94 cases recorded in all of 2013.
This year Maine also has recorded 20 cases of babesiosis, a parasitic infection carried by ticks. Yet another disease, the potentially deadly Powassan virus, claimed the life of a Rockland-area artist last December. Powassan is also carried by the woodchuck tick.
Maine experienced a record year for Lyme in 2013, with 1,376 cases. Dr. Sheila Pinette, director of the Maine CDC, said Maine has confirmed 595 cases of Lyme so far this year, but she expects to end 2014 with more than 1,300.
Mosquitoes, which can carry West Nile virus and Eastern Equine Encephalitis, also pose a threat, she said. A young, healthy man from Cumberland County who contracted West Nile in 2012 suffered serious neurological effects, she said.
The majority of people infected with West Nile don’t show any symptoms. About one in five gets sick with a fever, body aches, vomiting and joint pain that can last from a few days to several weeks. Symptoms typically appear between three and 14 days after a bite from an infected mosquito.
In the rare and severe cases, the virus causes neurological problems, such as brain swelling, which can lead to confusion, coma, seizures and permanent damage.
EEE is more deadly, becoming fatal in 30 to 40 percent of cases.
None of Maine’s 25 mosquito testing pools has tested positive for West Nile or EEE this year, but that doesn’t mean the illnesses aren’t present, Pinette said.
She urged Mainers to avoid being outside during dawn and dusk, when mosquitoes are most active. While insect repellent isn’t safe for children younger than 3 years old, she said natural remedies, such as lemon and eucalyptus, are effective.
“We can all live in harmony with an environment that’s ever changing in our ecosystem. … We need to respect those little mosquitoes and those little ticks out there,” Pinette said.
George Smith, former executive director of the Sportsman’s Alliance of Maine, urged support for a $8 million bond on the November ballot that would renovate and expand a University of Maine lab that identifies pests and monitors health threats from ticks and mosquitoes.
“Turkey hunting last spring, I was guaranteed to come home and have some ticks on me,” said Smith, an outdoor writer who writes a blog for the Bangor Daily News. “I’m very diligent. … But four times I’ve had to take antibiotics because a tick embedded on me and I didn’t get it out quickly.”
He expressed concern for native brook trout, which require very cold water and have all but disappeared from southern and central Maine amid warming temperatures. The state also slashed moose hunting permits by a quarter this year in response to crippling losses last winter because of ticks, he said.
The Ticked Off report recommended several steps to limit climate change, which included supporting proposed federal limits on carbon pollution from power plants, transitioning to alternative energy sources, safeguarding wildlife and their habitats, and helping communities to respond to its effects that include rising sea levels and extreme weather.