Tick-borne illnesses on Martha’s Vineyard have reached possible record highs this year, as newly-ubiquitous lone star ticks and their larvae spread in the Island’s outermost reaches, carrying a menu of diseases.

Epidemiological data provided by the Island boards of health show that 2020 has already recorded the highest number of suspected Lyme disease patients — 260 — since 2015. The previous high was in 2016-2017, when the boards of health reported 232 Lyme disease patients.

This year has also seen the most confirmed cases of babesiosis — a red blood cell disease with symptoms similar to malaria — since 2015. With 31 confirmed, six probable and one suspected case of babesiosis, the number is nearly double previous reported highs in the past five years.

High rates of human granulocytic anaplasmosis — a tick-borne illness with a frightening range of symptoms that include loss of basic motor skills, fever, diarrhea and changes of mental state — were also reported, with 15 confirmed and two suspected cases already in 2020. The Island also has had one probable and 13 suspected cases of tularemia this year, a dangerous bacterial illness which can be fatal.

Lyme disease, babesiosis and anaplasmosis are transmitted by deer ticks, which have long had a foothold on the Island. But Dick Johnson, a leading biologist who studies ticks on the Island, said he believes the increasing prevalence of spotted fever, tularemia and erlichiosis can be tracked to once-rare lone star ticks, which have established themselves at a rapid rate on the Vineyard in recent years. “It’s not just deer ticks anymore,” said Mr. Johnson, who heads the Island tick prevention program. “A lot of places there are more lone star ticks than there are deer ticks. And it’s not just Lyme disease, you’ve got to think of this whole range of diseases now.”

Data on the incidence of tick-borne illness was provided by Tisbury health agent Maura Valley, and came from MAVEN, the state’s epidemiological database. The data for 2020 only runs through Sept. 30, meaning that the already high rates of Lyme, babesiosis and anaplasmosis could grow higher. Data for 2015 through 2018 was provided over the fiscal year, while data for 2019 was for the calendar year.

Explaining the data, Ms. Valley said probable cases have supportive lab results consistent with the disease but don’t meet criteria for lab confirmation, while suspected cases show symptoms but have no lab results.

For Lyme disease, the current testing protocol uses two different serology assays to diagnose the illness. Even if both tests come back positive, the patient is still considered a suspected case because serologic assays are not by themselves diagnostic, Ms. Valley explained. The data shows that as the Island attempts to effectively fight off one epidemic, another remains remarkably persistent — threatening the Island and its public health infrastructure on two different fronts and alarming biologists about the growing ubiquity of the pesky arachnids.

While surveying yards for ticks in Aquinnah on Tuesday this week, Mr. Johnson said he found lone star larvae in every location he visited. Towels Mr. Johnson used to pick up ticks were covered every time he went into the grass, with numbers of larvae in the thousands.

“It was like somebody took a paint brush and smeared brown all over it there were so many ticks,” he said. “Where we used to find 10, we find 50. Where we used to find 50, we find 100 
. . . This fall I’ve never seen anything like this with the larvae, it’s just crazy. ”

The Aquinnah board of health reported 13 new tick-borne illness cases since April of this year, including cases of Lyme disease, ehrlichiosis, babeosis and spotted fever.

Lone star ticks are a relatively new species on the Vineyard. Although they do not carry Lyme disease, they are known to carry other harmful pathogens, as well as STARI, a red meat/dairy allergy in some individuals.

The ticks and their larvae are normally found on the edge of woods, fields and anywhere with tall grass, making the Island — and particularly remote Chappaquiddick and Aquinnah — a prime breeding ground for the larvae, which are as small as a pepper flake and can bunch together by the thousands.

In recent years, the ticks have slowly spread inland, threatening the more populated areas of the Island.

In another challenge this year, Mr. Johnson was unable to conduct his annual yard surveys because the tick prevention program was low on funding. Last year, Mr. Johnson and his staff surveyed over 200 Island yards, finding lone star ticks in almost every Aquinnah and Chappaquiddick yard that was surveyed, and many in Chilmark, West Tisbury and Edgartown properties. Fewer lone stars have been found in Oak Bluffs and Tisbury.

Mr. Johnson called the increase in diseases frightening.

“Lone star ticks are spreading,” he said. “When we start seeing erlichiosis and that much babesiosis, that means people are getting really, really sick.”

He is adamant that the only way to decrease the tick population is by decreasing the deer population.

New efforts, like the deer subsidy program that encourages hunters to take more does, are continuing as bow season begins. But Mr. Johnson said broad-scale deer reduction initiatives will be necessary to really make a dent in the tick population.

He is also hoping to arrange a flyover this winter with a thermal camera to get a more accurate count of the Island deer population. The last one occurred about a decade ago, when lone star ticks were just establishing a presence on the Vineyard. And it doesn’t take a flyover to show they’ve gained a foothold. “Until we do something about the deer I think the lone star are just going to continue to explode,” Mr. Johnson said. “My fear is this is just part of the natural progression of the new normal.”

Corrected from an earlier version which misstated the illnesses caused by lone star ticks. Those illnesses are spotted fever, tularemia and STARI. Lyme disease, babesiosis and anaplasmosis are transmitted by deer ticks.