Joining sunburn and heat stroke as summer health hazards are ticks with the potential to be carrying Lyme disease.

Recent reports suggest tick populations in Pennsylvania may be particularly high this summer, leading to an increased risk of Lyme disease in the state.

But tracking down hard numbers is trickier than finding a tick in a brush pile.

Jack Layne, a biologist/entomologist at Slippery Rock University, said of the so-called tick population explosion “ It's mostly anecdotal evidence.

“Everything that I hear is based on the fact that there has been a mild winter,” said Layne. “There's no one time for peak tick populations. They are really overlapping generations.”

“There are all stages of a tick's life out there — tick nymphs, adults — although the biggest pulse is in the spring,” said Layne.

“There has been expansion of the white-footed mouse population,” Layne noted, adding the immature tick nymphs favor infesting mice before growing to move to other mammals, deer, raccoons, rabbits and chipmunks.

Tom Simmons, a professor of biology at Indiana University of Pennsylvania and a specialist in the ecology of disease, conducted a population study of ticks in Indiana County in 2015.

“Butler County would be about the same as Indiana County,” Simmons said. What he found was one adult tick in every two square yards and three nymph stage ticks in every two square yards.

“About half of all ticks examined were infected with Lyme disease,” Simmons said. “That's about as bad as it's going to get, but it's still bad.”

That's why it's always a good idea to take precautions to avoid ticks and the diseases they can transmit, according to entomologists in Penn State's College of Agricultural Sciences.

“Some people believe a perceived increase in ticks can be blamed on a mild winter, an early spring, certain precipitation patterns, or a large crop of acorns that leads to an overabundance of mice that host ticks,” said Steven Jacobs, senior extension associate in entomology. “However, some of these theories have little scientific basis, and most scientists agree that nature is too complex to attribute a rise or fall in the tick population to any one factor.”

Joyce Sakamoto, a research associate in entomology who studies tick biology, said the impression that tick populations were higher this spring may have come from the fact that ticks emerged earlier than usual from winter dormancy.

“The number of ticks I'm finding in Centre County is comparable to previous years,” she said. “But I did start seeing active adult ticks earlier than usual — in February — both this year and last year.”

Sakamoto added that public awareness also has increased.

According to Penn State's College of Agricultural Sciences, the primary vector of the Lyme disease bacterium is the blacklegged tick — often called the “deer tick.”

Adult ticks can be active from fall through spring if temperatures remain above 28 degrees. Ticks in the nymph stages are active in May, June and July.

Whether there's been a spike this year or not, there's no question about the long-term trend. “Fifteen or 20 years ago, the ticks that carry Lyme disease were rare in many Pennsylvania counties, but unfortunately that has changed,” Jacobs said. “Today, they are found in all counties in the state.”

Nymphs will attach to mice, chipmunks, birds and other small animals. Adults typically attach to white-tailed deer or other large mammals.

While awaiting a suitable host, the ticks are usually found on leaf litter or low branches in wooded areas.

IUP's Simmons said, “Ticks prefer the woods or the edge of woods and yards. They don't like yards, they are too hot and dry. They won't last long crawling out onto a yard.”

“But if you are gardening, or working in a wood pile or cutting brush,” Simmons said, “you need to take precautions.”

“We keep expanding into habitats where ticks are found,” she said. “And as that continues, we need to change our behavior to avoid them,” Sakamoto said.

Simmons recommends wearing long, light colored pants tucked into white tube socks and a light-colored shirt stuck into the pants.

Spray your clothes with permethrin and your skin with DEET, Simmons said.

After working outside, check your body for bumps or new freckles, Simmons said. That could be a nymph, which is about the size of a poppy seed, hitching a ride.

Even though ticks can transmit a variety of pathogens, it's no secret why Lyme disease gets the most attention — Pennsylvania leads the nation in the number of confirmed cases.

Simmons said an adult tick can remain on a host seven to eight days before dropping off. A nymph can remain up to four days.

Unfortunately, either stage can pass Lyme disease on to its host in 48 hours.

Lyme disease can cause a variety of symptoms, including a bull's-eye-like rash, fever, stiff neck, muscle aches and headaches. Michael Skvarla of Penn State's College of Agricultural Sciences, said, “Lyme disease can be cured in its early stages, say within 30 days. It can be treated easily with antibiotics.”

“But if untreated, it can become chronic with a whole lot of complications like arthritis,” said Skvarla.

Victims can suffer facial palsy and even paralysis. Lyme disease normally is treated with antibiotics, but recovery can be slow and difficult.

That's why it's important to check yourself and your pet regularly for ticks.

Young ticks can be as small as pinheads and can move about a body before deciding to dig in and feed, Skvarla said.

In certain highly endemic areas of New York and New Jersey dogs exhibit almost a 90 percent rate of exposure.However, only about 4 percent of the dogs exhibit signs of Lyme disease including lameness, poor appetite and fever. Treatment of these animals with antibiotics typically results in rapid recovery.A few dogs can develop lesions on the kidneys (Lyme nephropathy) and may not respond to antibiotic treatment.Interestingly, dogs susceptible to this condition may not be protected by the Lyme vaccines currently available. In fact, there are concerns that the vaccine may possibly sensitize a genetically predisposed individual to having a more intense immune-mediated reaction to Lyme antigens, or the vaccine may add to antigen-antibody complex deposition in tissuesKennels, runs, or yards can be treated with a variety of residual insecticides labeled for tick control at these locations.Do not apply materials labeled for kennels, yards and other exterior sites on your pets.— Penn State College of Agricultural Studies Department of Entomology.