U.S. Researchers Find New Disease Carried by Deer Ticks

January 17, 2013

By Zach Howard

(Reuters) - U.S. scientists have discovered a new deer tick-borne disease in humans, with the viral-like illness sharing similarities both with Lyme disease and relapsing fever infections.

The as-yet unnamed ailment is one of five caused by the Borrelia miyamotoi pathogen carried by blacklegged ticks, said Dr. Peter Krause, senior research scientist at Yale School of Public Health and lead author of a letter to the editor today in the New England Journal of Medicine.

Also published in the journal today was a case report of an immunocompromised patient with meningoencephalitis from B. miyamotoi.

The bacterium was first found in ticks in Japan in 1995, and then was identified by Yale researchers in Connecticut in 2001 and again in Russia in 2011, the study said. The illness also can resemble another disease caused by a bacterium in the Borrelia family transmitted by ticks and body lice that is marked by repeated episodes of fever.

The letter from researchers at Yale, New York Medical College and other institutions is the first report of the unique type of Borrelia bacterium that causes the disease and the first report of its symptoms.

The study said blood tests identified B. miyamotoi in 18 human patients in southern New England and neighboring New York in recent years. Symptoms of the resulting illness can include fever, muscular aches and pains, headaches and fatigue, with a small portion also developing a rash such as with Lyme disease.

One complication experienced by multiple patients, however, was repeated episodes of fever - a significant difference from what has been reported by people diagnosed with Lyme disease, said Dr. Krause.

"We think that if this organism is untreated it probably would lead to relapsing fever," Dr. Krause said in a phone interview.

The new study found that patients who were not treated with antibiotics after a first bout of fever could see their body temperature spike again after a week or two.

Drugs such as doxycycline and amoxicillin, effective in combating Lyme disease, seem to clear symptoms and the infection, Dr. Krause said.

Borrelia bacteria are found wherever deer ticks and Lyme disease are found, with most occurring in the U.S. Northeast and the northern Midwest. Ticks infected with the bacteria also were found in the far western U.S., he added.

The disease tends to occur in late spring, summer or early autumn, and experts say that lab testing is required to confirm its presence.

The bacterium differs from some other similar types, including Ehrlichia, which were discovered in Minnesota and Wisconsin in 2011 and also causes flu-like symptoms, Dr. Krause said. That type of Ehrlichia has not yet been seen in the eastern U.S.

SOURCES: http://bit.ly/WkjSu5 and http://bit.ly/WkjSu5

N Engl J Med 2013.