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Emergency departments are seeing a notable increase in patients with tick bites, and the state epidemiologist said a tick species previously eradicated in the region is now spreading again in Massachusetts.

“Patients reporting tick exposure is higher this spring and early summer than at any point during the last three years. This really suggests that tick populations are increased this year,” Dr. Catherine Brown told the Public Health Council last week, as she presented available data this year through May on tick exposure and tick-borne disease visits.

“I’ve gotten a sneak peak at the June data as well, which is not quite complete, but we are still seeing a pretty significant increase in tick exposure visits to the emergency department,” Brown, who’s also the state public health veterinarian, said.

In May, less than 0.7% of emergency department visits in any week were related to tick exposures, and less than 0.2% were tied to tick-borne diseases, according to the latest DPH report. So far this year, Dukes and Nantucket counties combined had the highest number of tick-borne disease visits at 48, followed by Bristol and Plymouth counties that both had 43.

Children ages 5 to 14 and older adults are more frequently diagnosed with tick-borne diseases, including Lyme disease, according to DPH.

Factors like weather patterns, the size of animal populations that provide food for ticks, and outdoor human activities can affect the scale of tick exposures.

“You may remember that there was a significant drought last year, which is not good for tick populations — right, drying out. They don’t like that. It kills them,” Brown said. “And so I confess to being a little bit surprised at the levels that we are seeing this year.”

Massachusetts is home to three tick species that pose “particular concern to human health,” Brown said. That includes blacklegged ticks, which are also known as deer ticks, and American dog ticks.

There’s also the lone star tick, which Brown said is “sort of the newer kid on the block.”

“This is actually a species of tick whose range used to include Massachusetts, but due to historic land use changes, it was eradicated from this area for quite a while. But it is now making its way back, and it is currently re-established on Martha’s Vineyard, slightly less so on Nantucket,” said Brown, who noted the lone star tick also increasingly found in other swaths of southern Massachusetts.

Brown said a bite from a lone star tick can trigger an allergic reaction, with symptoms including hives, gastrointestinal distress and potentially life-threatening anaphylaxis. She warned that tick species, along with the deer tick, can be small and “very, very hard to find on yourself, which just emphasizes the need for use of multiple personal prevention tools.”

The State Public Health Laboratory this year now offers screening for the Powassan virus, which can be transmitted by deer ticks. Brown said that will speed up diagnostic capabilities for Massachusetts residents, with the state no longer needing to send samples to the CDC for testing.

“All of the other diseases, there is wide commercial availability of laboratory testing, but Powassan virus has really been the exception,” she said.

People should use repellants that are made with EPA-registered active ingredients, and wear permethrin-treated repellent clothing, Brown recommended. People should also shower after spending time outdoors in areas with ticks, and put their clothes in the dryer on high heat to kill any ticks.

Pet owners should contact their veterinarians about tick prevention products, Brown said. Pets can also bring ticks inside with them, which can then come into contact with owners.

“There is really no question that we are going to have to continue to address vector-borne diseases in Massachusetts, and we’re going to have to continue to monitor and adapt to changes that are due to climate change, land use changes, and human population and behavior shifts,” Brown said.