A new tick-borne disease that is potentially worse than Lyme disease – and harder to diagnose – has been found in patients in Central New York.
Upstate Medical University has confirmed at least two patients who have been exposed to the disease, known informally as Borrelia miyamotoi disease, or BMD. The illness, related to Lyme disease and carried by the same species of tick, causes recurring fevers of up to 104 degrees, severe headaches and other flu-like symptoms , said Dr. Kris Paolino, an infectious disease specialist at Upstate.
“We haven’t seen a ton of cases yet,” Paolino said. “The risk now is low, but I think the potential is extreme.”
It’s such a new illness that scientists don’t know much about it’s how transmitted, and few doctors are even aware of the disease to test for it, said Brian Leydet, a professor and tick expert at SUNY College of Environmental Science and Forestry, in Syracuse.
“That’s what’s terrifying about it: knowing so little about it, and it’s in our back yard,” Leydet said.
The bacterium was discovered in Japan in the 1990s, but the disease it causes wasn’t found in humans until 2011, in Russia. The first human cases in the Northeast were discovered only in 2013, Leydet said.
So far, the miyamotoi bacterium has been found in about 2 percent of ticks in Central New York, Leydet said. In the Hudson Valley, which is also the hotbed of Lyme disease, 10 to 15% of ticks carry miyamotoi.
“It’s nothing like Lyme disease, where you’ve got 30 to 50 percent of ticks infected, but it’s still a concern,” he said.
There are plenty of unknowns about the miyamotoi bacterium, which is spread by the bite of the black-legged, or deer, tick. It’s not clear how many ticks carry the bacterium, how easily humans can get it from a tick bite, or how many people have been exposed to BMD. It’s often confused with other tick-borne diseases, such as anaplasmosis and Lyme disease, so it’s hard to diagnose without a special test.
“Patients describe a syndrome that sounds very much like Lyme disease, but there are no rashes,” Paolino said. “The symptoms are more severe, with higher fever and more severe headaches.”
Some research indicates that many people who get BMD never know it because their immune system fights it off, and many others might not have been diagnosed. One of the challenges in the future, scientists and doctors say, is finding out just how widespread the disease is and how many people get sick from it.
The disease can be treated with the same antibiotics used for Lyme disease, primarily doxycycline. Without treatment, the symptoms can disappear as the body’s immune system knocks down the bacteria and then periodically recur as the body’s immune system becomes overwhelmed by the bacteria in the blodstream.
The disease is so new it hasn’t been given a formal name. Doctors don’t have to report miyamotoi cases to the state Department of Health like they do other tick-borne disease, but tick experts in the department are hoping to add miyamotoi to the list. That would help the state get a better handle on how many people are actually contracting the illness, said Bryon Backenson, the health department’s deputy director of communicable disease control.
Few ticks in New York have been found to carry miyamotoi, but the numbers are likely to increase. Of the 7,600 ticks collected last year by the state Department of Health, just 58 had miyamotoi, Backenson said. That’s less than 1%, but Backenson noted that other tick-borne diseases, including Lyme, began with low percentages of infected ticks in a relatively small area.
“It seems that with each passing year we get a few more ticks that are positive” for miyamotoi, Backenson said. “If history is any indication, it’s one of those things that will expand and spread, and there may be more and more ticks infected as time goes on.”
Another challenge is figuring out how the interaction of miyamotoi, ticks and animals work in spreading the disease. One unsettling fact, Leydet notes, is that female ticks can pass on the miyamotoi bacteria to their eggs, meaning that emerging larvae can carry the bacterium and immediately start infecting animals.
While a female tick can lay up to 3,000 eggs, the emerging larvae are fragile and die easily, though, so it’s not clear how important they are in transmitting the disease, Leydet said.
“We’re describing this rate of transference from the female to the larva at 70 to 90%, but in nature we’re only seeing 3% of ticks infected,” he said. “There’s some complex ecology going on there.”
The Lyme disease bacterium is not passed on through the eggs, and so the larvae don’t transmit it. Instead, the larvae pick up Lyme bacteria after biting a small mammal, principally the white-footed mouse, and then can pass on that bacteria to other animals, including humans, in the later stages of the tick’s life cycle.
The role of deer in transmitting miyamotoi is unclear, too, Leydet said. While deer do not carry the Lyme bacteria, they serve as a major food source for female ticks. One research study found that ticks pulled off deer were 12 times as likely to be infected with miyamotoi than ticks found on the ground, Leydet said.
“That’s evidence that deer could potentially be a reservoir,” he said.
The best defense against miyamotoi, as it is with other tick-borne disease, is to protect yourself against tick bites, Leydet said. That includes avoiding areas of shade and high grass, using bug repellents like DEET and picardin on skin, and spraying clothing with permethrin. Leydet said people should always check their entire bodies for ticks after being in outdoor areas that might harbor ticks.