Why tick season is longer and their range is expanding
Studies have shown ticks are spreading farther and wider than ever, increasing the risk for Lyme disease dramatically since 1991 and the weather may actually be helping ticks flourish.
By
Allison Finch, AccuWeather staff writer
Updated May 20, 2024 1:43 PM EDT
As the weather warms up and we spend more time outdoors, make sure you know the best way to deal with ticks to avoid Lyme disease.
According to the most recent Intergovernmental Panel on Climate Change report, climate change spells a disaster for wildlife worldwide. The report warns that extinctions could come as temperature rises, and according to the International Union for Conservation of Nature, climate change already affects at least 10,967 species, increasing their likelihood of extinction.
But not all species are being negatively affected by climate change. At least one tiny animal is taking advantage of the shifting conditions by expanding its range and growing its population.
Recent studies prove that climate change has contributed to the expanded range of ticks, specifically deer ticks, increasing the potential risk of Lyme disease in areas where ticks previously were unable to survive.
The life cycle and prevalence of deer ticks are strongly influenced by temperature and humidity. Deer ticks are most active when the temperature is above 45 degrees Fahrenheit and thrive in areas where the humidity is at least 85% or higher. Most tick activity starts to decrease once the temperature is below 35 F, according to F&W Pest Control.
FILE - This undated file photo provided by the U.S. Centers for Disease Control and Prevention (CDC) shows a blacklegged tick, also known as a deer tick, a carrier of Lyme disease. Preliminary indicators show Lyme disease abating during the summer of 2018 in New England, and public health authorities said they are finding fewer ticks in the environment. (CDC via AP, File)
But for ticks to die, the temperature must be below 10 degrees F for a sustained number of days, and with winters becoming milder and shorter, this isn't happening as often. Additionally, if a tick is attached to a deer or another host animal, the body temperature of the host will keep them warm enough to survive a cold snap.
"Cold weather to kill the ticks is not as long or as cold," Dr. Samuel Shor, a clinical associate professor at George Washington University, told AccuWeather National Reporter Sarah Gisriel.
GET THE FREE ACCUWEATHER APP
A study published in 2019 by the U.S. Environmental Protection Agency (EPA) showed an increase in the amount of Lyme disease cases across the U.S. The occurrence nearly doubled from 3.74 reported cases per 100,000 people in 1991 to 7.21 reported cases per 100,000 people in 2018, based on data from the CDC.
Among the states where Lyme disease is most common, Maine and Vermont have experienced the most significant increase in reported cases since 1991, according to the data from the EPA. Both states are notorious for cold winters, but over the past 40 years, the average temperature during winter has warmed drastically. Without long stretches of cold weather, tick populations don't die off as frequently.
In Maine, winter temperatures have risen more than 4 degrees Fahrenheit since 1970, according to a study published by Climate Central. In Vermont, winter temperatures have risen nearly 5 F since 1970. Additionally, 2010 to 2020 was the warmest 11-year period on record for the state, and the intensity of extreme winter cold is projected to decrease, according to a study published by NOAA National Centers for Environmental Information (NCEI).
Ticks have three stages of life -- larva, nymph and adult. And while ticks are active from March to November, the peak season for nymphal ticks is May and June. According to the CDC, nymph ticks are more likely to transmit Lyme disease than adult ticks because of how tiny they are. Since nymph ticks are usually smaller than 2 mm, approximately the size of a poppy seed, they have more time than the adult tick to transmit the bacteria to the human before being discovered and removed.
These ticks are commonly found in wooded areas and on the tips of vegetation, but a blast of wind could help them find a way to their next victim.
"I've seen ticks blown by the wind," Dr. Steven Bock, the president of the International Lyme and Associated Disease Society said in an interview with Gisriel. "People on a patio, with no grass around them, all of a sudden, they have a tick."
Bock suggests wearing light-colored clothing, long pants with long socks and heavy-duty repellent for extended periods of time outside.
"If you're going camping and you're really going to be in infested tick country, then you may want to use clothing that has been sprayed with chemical DEET," Bock advised.
Experts also recommend performing a tick check after spending time outside. Many nymph ticks are too light even to feel. Early signs of Lyme disease include fever, chills, headache, muscle and joint aches, fatigue and a bull's-eye rash. Doctors say Lyme disease can be transmitted within hours and suggest getting checked out as soon as the symptoms appear.
Report a Typo
News / Climate
Why tick season is longer and their range is expanding
Studies have shown ticks are spreading farther and wider than ever, increasing the risk for Lyme disease dramatically since 1991 and the weather may actually be helping ticks flourish.
By Allison Finch, AccuWeather staff writer
Updated May 20, 2024 1:43 PM EDT
As the weather warms up and we spend more time outdoors, make sure you know the best way to deal with ticks to avoid Lyme disease.
According to the most recent Intergovernmental Panel on Climate Change report, climate change spells a disaster for wildlife worldwide. The report warns that extinctions could come as temperature rises, and according to the International Union for Conservation of Nature, climate change already affects at least 10,967 species, increasing their likelihood of extinction.
But not all species are being negatively affected by climate change. At least one tiny animal is taking advantage of the shifting conditions by expanding its range and growing its population.
Recent studies prove that climate change has contributed to the expanded range of ticks, specifically deer ticks, increasing the potential risk of Lyme disease in areas where ticks previously were unable to survive.
The life cycle and prevalence of deer ticks are strongly influenced by temperature and humidity. Deer ticks are most active when the temperature is above 45 degrees Fahrenheit and thrive in areas where the humidity is at least 85% or higher. Most tick activity starts to decrease once the temperature is below 35 F, according to F&W Pest Control.
FILE - This undated file photo provided by the U.S. Centers for Disease Control and Prevention (CDC) shows a blacklegged tick, also known as a deer tick, a carrier of Lyme disease. Preliminary indicators show Lyme disease abating during the summer of 2018 in New England, and public health authorities said they are finding fewer ticks in the environment. (CDC via AP, File)
But for ticks to die, the temperature must be below 10 degrees F for a sustained number of days, and with winters becoming milder and shorter, this isn't happening as often. Additionally, if a tick is attached to a deer or another host animal, the body temperature of the host will keep them warm enough to survive a cold snap.
"Cold weather to kill the ticks is not as long or as cold," Dr. Samuel Shor, a clinical associate professor at George Washington University, told AccuWeather National Reporter Sarah Gisriel.
GET THE FREE ACCUWEATHER APP
Have the app? Unlock AccuWeather Alerts™ with Premium+
A study published in 2019 by the U.S. Environmental Protection Agency (EPA) showed an increase in the amount of Lyme disease cases across the U.S. The occurrence nearly doubled from 3.74 reported cases per 100,000 people in 1991 to 7.21 reported cases per 100,000 people in 2018, based on data from the CDC.
Among the states where Lyme disease is most common, Maine and Vermont have experienced the most significant increase in reported cases since 1991, according to the data from the EPA. Both states are notorious for cold winters, but over the past 40 years, the average temperature during winter has warmed drastically. Without long stretches of cold weather, tick populations don't die off as frequently.
In Maine, winter temperatures have risen more than 4 degrees Fahrenheit since 1970, according to a study published by Climate Central. In Vermont, winter temperatures have risen nearly 5 F since 1970. Additionally, 2010 to 2020 was the warmest 11-year period on record for the state, and the intensity of extreme winter cold is projected to decrease, according to a study published by NOAA National Centers for Environmental Information (NCEI).
Ticks have three stages of life -- larva, nymph and adult. And while ticks are active from March to November, the peak season for nymphal ticks is May and June. According to the CDC, nymph ticks are more likely to transmit Lyme disease than adult ticks because of how tiny they are. Since nymph ticks are usually smaller than 2 mm, approximately the size of a poppy seed, they have more time than the adult tick to transmit the bacteria to the human before being discovered and removed.
These ticks are commonly found in wooded areas and on the tips of vegetation, but a blast of wind could help them find a way to their next victim.
"I've seen ticks blown by the wind," Dr. Steven Bock, the president of the International Lyme and Associated Disease Society said in an interview with Gisriel. "People on a patio, with no grass around them, all of a sudden, they have a tick."
Bock suggests wearing light-colored clothing, long pants with long socks and heavy-duty repellent for extended periods of time outside.
"If you're going camping and you're really going to be in infested tick country, then you may want to use clothing that has been sprayed with chemical DEET," Bock advised.
Experts also recommend performing a tick check after spending time outside. Many nymph ticks are too light even to feel. Early signs of Lyme disease include fever, chills, headache, muscle and joint aches, fatigue and a bull's-eye rash. Doctors say Lyme disease can be transmitted within hours and suggest getting checked out as soon as the symptoms appear.
Read more: