Tick test helps identify Harwich woman’s illness

By Cynthia McCormick
Posted Aug 17, 2019


HARWICH — When stricken with high fever, nausea and headaches, not many people would suspect a tick-borne disease as rare as miyamotoi.

Only a handful of cases of the disease similar to tick-borne relapsing fever have been reported in Massachusetts.

But Melissa Davey of Harwich already knew the tiny deer tick that bit her was carrying the pathogen that causes miyamotoi when she started coming down with symptoms July 9.

The results of a tick report from the University of Massachusetts Amherst, where Davey had mailed a tiny tick she pulled off her right leg, showed that the tick was negative for a number of known pathogens, including the bacteria that causes Lyme disease, but was positive for miyamotoi.

Davey remembered this result eight days after receiving the report, when she started feeling queasy and experiencing fevers and drenching sweats.

“At first I thought, ‘Is this the flu?’” said Davey, 52. “Then I remembered the tick report.”

Having the report enabled her physician to order the right tests, said Davey, who went on 30 days of doxycycline after testing for miyamotoi.

“My doctor thought it was fantastic I did the tick report,” Davey said.

“It’s good data to have in hand,” said Larry Dapsis, entomologist and tick project coordinator for the Cape Cod Cooperative Extension.

Having a positive tick report doesn’t mean the person who was bitten will get sick — and having a negative one is no guarantee of good health — since the individual could have missed a bite by a different tick, Dapsis said.

Davey said the nymphal tick she found on her lower right leg June 25 was the size of a poppy seed.

But the information is still helpful to doctors, Dapsis said.

“Now you can show (the tick report) to your physician and say, ‘Hey, I’ve been exposed to this pathogen,’” Dapsis said.

It’s not just patients making the link between their tick report and possible illness.

Scientists at the tick report lab at UMass increasingly are looking for links between the pathogens found in ticks and the emergence of diseases including Lyme, miyamotoi, babesiosis and anaplasmosis in the humans that the ticks fed upon.

The lab is referring tick report clients whose ticks carry miyamotoi to a scientists in New Haven, Connecticut, attempting to develop an FDA-approved test for miyamotoi.

Currently labs use polymerase chain reaction tests to detect DNA from the miyamotoi borrelia bacteria, according to officials from the Massachusetts Department of Public Health.

Another test detects a person’s antibodies to the bacteria, but neither one is approved by the FDA yet, said Michel Ledizet, senior research scientist at L2 Diagnostics LLC in New Haven.

Ledizet said in an email that he has received several dozen blood samples for the study since he started working with Stephen Rich, the microbiologist who runs the UMass lab, in 2016.

“We probably need 50 to 100 samples from people who became infected by Borrelia miyamotoi,” Ledizet said.

“However, we need to collect many more samples because the tick does not always transmit the bacteria while it feeds. In fact, transmission appears to occur less commonly than we expected,” said Ledizet, who said the final report to the National Institutes of Health is due later this year.

There are still a lot of unknowns about miyamotoi, first identified in 1995 in ticks from Japan and reported in humans six years later, in Russia. Miyamotoi infection was first identified in U.S. citizens in 2013, two years after the first human cases were reported in Russia.

Reported human cases in the U.S. are low, with the Centers for Disease Control saying there have been fewer than 60 well-documented cases in the U.S., while the number of confirmed and probable cases of Lyme disease across the country reach a record 42,743 in 2017.

State DPH officials also report low figures of miyamotoi, with 12 cases in Barnstable County in 2017, two in 2018 and two so far in 2019.

Detection rates in ticks tested at Rich’s lab are minuscule compared with cases of Lyme disease. Out of nearly 10,000 ticks tested over a year’s time, 132 were positive for miyamotoi compared with nearly 3,000 for for Borrelia burgforferi, the spirochete that causes Lyme disease.

“The number of cases is so low you can’t derive a trend,” Dapsis said.

“We continue to see miyamotoi in the tick population (in Barnstable County) at an average of 2%. There is some risk out there,” Dapsis said.

“But it’s not nearly as high as Lyme disease,” he said.

It’s important to keep learning about the disease, said Ledizet, who said he hopes to continue with his study and better experimental results and ultimately an FDA-approved test that is widely available commercially.

Falling ill with miyamotoi was scary, said Davey, whose temperature spiked to 103 degrees.

“I was miserable. I was having uncontrollable shaking chills and terrible, terrible headaches, body aches, confusion,” Davey said.

She suspects she picked up the tick while walking her family’s puppy in Hawksnest State Park, adjacent to her property.

She found the tick on her lower right leg, just below her knee.

“I’m usually very good about checking,” Davey said. “But this one got away from me.”

The tick test is subsidized by Cape Cod Healthcare for Barnstable County residents at $15.

Davey said she emailed Rich’s lab a note of appreciation for helping her make the connection between the tick that bit her and her illness.

“I just wanted to let them know, ‘What you do does matter,’” Davey said.