As if Lyme disease weren’t enough to worry about, a new study warns about another tick-borne disease infecting people in the U.S. — and the illness is more likely to land patients in the hospital.

This scary female deer tick can give you Lyme disease and another serious infection that causes fever and severe headaches. If you find one attached to your body, be alert to symptoms. VICTORIA AROCHO / ASSOCIATED PRESS

Patients with the disease, dubbed Borrelia miyamotoi Disease by its Japanese discoverers, tend to look sicker that those with Lyme, which explains why 25 percent of those in the study were hospitalized, said the study’s lead author Dr. Philip J. Molloy, a physician in private practice in New England and also medical director at IMUGEN, Inc., the lab that performed testing for the disease.

“Fever and severe headaches caused [doctors] to have a suspicion of possible meningitis,” Molloy said.

Molloy and colleagues tested blood samples sent to IMUGEN from 11,515 patients who showed up at emergency rooms, urgent care clinics, and primary care offices in New York and the New England area complaining of symptoms that suggested a tick-borne illness.

The researchers found 97 cases of BMD and were able to gather details on 51 of them, according to the study published Monday in the Annals of Internal Medicine. Those patients had sought care for symptoms including, high fever, chills, headache, and muscle pain or joint pain. A full 25 percent were deemed so sick that doctors checked them into the hospital.

“This is an important paper,” said Dr. Peter J. Krause, who wrote an editorial accompanying the new study and a senior research scientist at the Yale School of Public Health and the Yale School of Medicine.

That’s because it puts the new disease on the radar of doctors who might see patients who test negative for Lyme, but still have similar symptoms, he said.

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“It’s another agent we’re going to have to look out for,” Krause added.

Massachusetts carpenter David Buker knows how bad BMD can make a person feel.

“It’s probably the worst thing I’ve ever encountered,” said Buker, a 54-year-old on-call firefighter from Carver, a town in the southeastern part of the state. “It really knocked me out. Normally I’m always going, going, going. I felt like I was going to die. I had no desire to eat or even get up to go to the bathroom. I didn’t want to do anything. The pain was pretty bad, too.”

The good news, Molloy said, is that this bug is susceptible to the same antibiotic that kills the Lyme bacteria.

In fact, the bacterium causing BMD is from the same family as one that causes Lyme. They are both spirochetes, named for their corkscrew appearance when observed through a microscope.

BMD is a little closer to another spirochete when it comes to the symptoms it produces: the bacterium that causes relapsing fever.

Rash not always a symptom

What is really significant about the new findings is the high rate of hospitalization, said Dr. Amesh Adalja, an infectious disease specialist at the University of Pittsburgh Medical Center. “They’re seeing one-quarter of patients hospitalized,” Adalja said. “So this can be quite a severe infection. And many do not have rashes, which we rely on heavily to diagnose Lyme.”

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Later in the summer

Another big difference between the new bug and Lyme is that it seems to strike people later in the summer, Adalja said. So doctors might not be on the lookout for a tick-borne disease when patients show up in August.

At this point the only recommendation experts can give is for people to avoid tick infested areas if possible and to carefully check themselves for ticks if they can’t.

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The upside is, the tick must be attached for quite some time before it can transfer diseases like Lyme, Adalja said.

Linda Carroll is a regular contributor to NBCNews.com and TODAY.com. She is co-author of "The Concussion Crisis: Anatomy of a Silent Epidemic” and the recently released “Duel for the Crown: Affirmed, Alydar, and Racing’s Greatest Rivalry”