Ticks have begun to emerge in the woods and fields after a rainy spring, and as the weather warms and sunny days unfold, Mainers and the tourists who begin arriving this Memorial Day weekend are facing another onslaught of Lyme disease and other tick-borne afflictions.

Experts say the rainy spring was good for tick survival, and while the severity of the Lyme season may hinge on this summer’s weather, there’s little doubt that cases will again be widespread and will likely push farther north, in keeping with a long-term trend.

The Maine Center for Disease Control and Prevention has already reported 146 Lyme cases through May 23, which is typical for this time of year but not an indicator of how bad the Lyme season will be because the bulk of cases are reported in the summer and fall. So far, 41 percent of the 400 deer ticks sent to the University of Maine’s tick lab have tested positive for Lyme, with 8 percent carrying anaplasmosis, another tick-borne disease, said Griffin Dill of the UMaine Cooperative Extension.

“The conditions are ripe for ticks to be particularly active,” said Dill, an integrated pest management professional. “As the weather gets warmer, we start seeing a lot more human-tick interactions.”

The Lyme disease threat is so persistent that U.S. Sen. Susan Collins, R-Maine, introduced a bill last week to funnel $100 million into fighting ticks and Lyme disease over a five-year period. The Ticks: Identify, Control and Knockout Act would dole out $20 million annually in grants to state health departments to collect and analyze data, support early detection and diagnosis, improve treatment, and raise awareness.

In addition, the bill directs the federal Department of Health and Human Services to set up a new office to oversee and coordinate a national response to vector-borne diseases. Tick-borne diseases now make up 75 percent of all vector-borne diseases in the U.S.

Maine is home to several species of ticks, which are arachnids, a class of carnivorous invertebrates that suck the blood of humans and animals. The deer tick is the only species in Maine that carries the bacteria that can cause Lyme disease and other infections, including anaplasmosis, babesiosis and Powassan.

Lyme disease can cause flu-like symptoms, swelling, neurological problems such as Bell’s palsy, and joint pain. Some people get a bull’s-eye rash where they were bitten by a tick. If caught early, Lyme can be treated with antibiotics, but untreated it can cause long-term health problems, especially in the joints and nervous system, according to the U.S. Centers for Disease Control and Prevention.

The state had 1,370 reported cases of Lyme in 2018, a drop from the record 1,852 cases in 2017, according to the Maine CDC. That was the first year-over-year drop since 2015, and scientists say the recent hot and dry summers may have been a factor. Most years since 2011 the number of Lyme cases has climbed, and the figure is much higher than the few hundred cases per year in the early- to mid-2000s.

Dill, at the UMaine extension, said the damp, rainy spring likely suppressed tick activity, which may have delayed their search for blood.

In fact, at some of the common spots for tick activity, park officials said that as of Friday they weren’t seeing an abundance of ticks yet.

“We’re not seeing them much right now,” said Chris Silsbee, park manager at Bradbury Mountain State Park in Pownal. “But this is the time that they start coming out.”

Scott Richardson, communications director at the Wells Reserve at Laudholm, also said ticks were not yet out in force.

“Generally speaking, there hasn’t been many ticks yet this year. That can change at any time,” he said.

To protect against Lyme, wear repellent; perform tick checks; wear long-sleeved, light-colored clothing when out in the woods; and wear gloves when raking leaves or carrying firewood. Also, property owners should remove invasive plants, such as the Japanese barberry and bittersweet, which are prime tick habitats.

Scientists are researching how weather affects tick populations, and possibly hot, dry summers in July and August could hamper the deer tick’s reproductive cycle. Also potentially affecting Lyme disease prevalence is the white-footed mouse population, Dill said, as the mice are prime vectors of tick-borne diseases.

The winters may not reduce tick populations, as snow acts as an insulator and helps the ticks survive, scientists say.

Deer ticks have increased their range in Maine over the past 20 to 30 years and are now found in all 16 counties, and researchers believe that may be a function of climate change, although there is still much to be learned about the relationship.

In the past, cooler summers made survival difficult for the deer tick, but the warming climate has made Maine a more hospitable place.

Susan Elias, research associate with the Maine Medical Center Research Institute, which studies ticks and Lyme disease, said in the summer, nymph ticks, which are about as big as a poppy seed, are especially troublesome for humans, because they are so difficult to notice. But if it’s hot and dry, that may affect nymph tick survival rates, she said.

“Tick questing activity is highly dependent on the weather. It can’t be too hot, or too wet, or too dry,” Elias said. “But if they’re not out, they’re just biding their time, waiting for later.”