Researchers have discovered a new tick-borne disease that may be infecting some Americans today, reported the New York Times.

The disease is caused by Borrelia miyamotoi, a spirochete bacterium that is related to Borrelia burgdorferi, the carrier of Lyme disease. The miyamotoi spirochete was discovered in Japan in 1995, and was first believed to be confined to those islands. In 2001, Dr. Durland Fish found it in about 2 percent of the deer ticks in the Northeast and Upper Midwest. There was also proof that mice could pick it up from tick bites.

The B. Miyamotoi has been found in the same deer tick species that transmit Lyme disease. The Yale researchers believe that 3,000 Americans per year get infected through tick bites, compared with about 25,000 who get Lyme disease.

A diagnostic test to determine whether anyone in the U.S. has become sick because of the bacterium has yet to be developed. It has been found that the same antibiotic treatment used in Lyme disease also cures infection by B. Miyamotoi.

A team in the Siberian city of Yekaterinburg in Russia was able to develop a test that distinguishes miyamotoi from other tick-borne spirochetes. It was observed to cause higher fevers than Lyme. According to their report, the fever in 10 percent of the cases disappeared only to return after one or two weeks. But it was not established if the disease can cause long-term damage like Lyme disease can.

The study "Humans Infected with Relapsing Fever Spirochete Borrelia miyamotoi, Russia," authored by the researchers from the Central Research Institute of Epidemiology in Moscow and the Municipal Clinical Hospital No. 33 in Russia, and Yale School of Public Health and Yale School of Medicine in New Haven, Connecticut, will be published in the journal Emerging Infectious Diseases.

Entomologist Durland Fish and Epidemiologist Dr. Peter Krause, the Yale researchers, have won a grant from the National Institutes of Health for further study of symptoms and the creation of a diagnostic kit for the disease.

The discovery is expected to add to the controversy involving Lyme disease. Although most Lyme victims are cured after two weeks of antibiotics, some have symptoms that stretch for years. They believe that they have infections that the antibiotics cannot treat, reported the Times.

Dr. Krause believe that the B. Miyamotoi is not responsible for chronic Lyme disease because the symptoms do not match. He expounds that people who think they have chronic Lyme disease complain of fatigue and joint pain, and not recurring fevers.

He adds that doctors might consider the new infection, especially in patients who believe that they have been bitten by ticks, if they come test negative for Lyme, but have relapsing fever.

The Russian team clarifies that the B. Miyamotoi does cause the "bull's-eye rash" that is diagnostic of Lyme disease.

"People shouldn't panic," Dr. Krause said. "And they also should not jump to the conclusion that we've found the cause of chronic Lyme disease. It's not highly likely, but it's possible. We just don't know."