MILWAUKEE -- A new species of bacteria has been found in deer ticks in Wisconsin and Minnesota that, left untreated, could lead to kidney, gastrointestinal, lung, and central nervous system complications.
Researchers at the Mayo Clinic report in Thursday's New England Journal of Medicine that the unknown bacterial species was identified in three patients from Wisconsin and one from Minnesota who sought treatment for a flu-like illness.
Since those cases were reported in 2009, the number of cases in the two states has increased to 25. The new species -- called ehrlichia species Wisconsin -- is present in an estimated 6.5 per 1,000 ticks tested in Wisconsin and causes the tick-borne illness ehrlichiosis, which until now has gone undetected in this part of the country.
Symptoms include fever, headache, and body aches, said Bobbi Pritt, director of the clinical parasitology and virology lab at Mayo Clinic and the study's lead investigator. Like Lyme disease, ehrlichiosis is treated with the antibiotic doxycycline. Pritt said that although it is possible that a mild case might clear up without treatment, in some individuals untreated infection could lead to serious complications.
A test to detect the new bacteria has been developed by the Centers for Disease Control and Prevention, but it is not yet widely available. She said, however, that the test used to discover the new organism is published and available for other labs to use.
"Your doctor can determine if a lab uses methods for detecting the new organism. It is a test that requires a certain level of expertise," she said.
Joe Rapacz, 54, of Eau Claire, said he has no recollection of being bitten by a tick, although it may have happened during a visit to his lake home in Bayfield County. There was no rash -- a sign of Lyme disease.
Instead, Rapacz said he remembers feeling feverish and weak one day in early June 2009. An outdoor enthusiast, Rapacz began to struggle physically.
"I couldn't do things," he said. "I was having trouble maintaining energy."
Rapacz said he sought medical treatment at Mayo Clinic Health System in Eau Claire, where a physician there screened him for Lyme disease and anaplasmosis, which are transmitted by the deer tick and prevalent in Wisconsin. Rapacz tested negative for Lyme disease.
Carol Werner was a lab technician at the clinic Rapacz visited that June day. Werner performed a highly specialized molecular test to identify the presence of bacterial DNA in humans. She isolated DNA from a sample of blood and used a technology called real time polymerase chain reaction, or real time PCR, to detect specific bacterial genes. The presence of a bacterial gene would appear as a curve on a graph and likely indicate a tick-borne illness.
When she analyzed a sample of Rapacz's blood, real time PCR revealed an unexpected curve, suggesting the presence of another type of bacteria -- something she had never before seen.
Days later, as she analyzed another patient's blood sample, Werner observed the same curve and alerted her boss, Joni Franson.
"It couldn't be ignored," said Franson, a supervisor at the hospital lab. After consultation with a hospital pathologist, Werner -- who is now retired -- and Franson reached scientists at the Mayo Clinic in Minnesota.
Samples that produced the mysterious curve at the clinic in Eau Claire were sent to Minnesota so the suspicious bacterial DNA could be sequenced. The DNA sequence of the unknown bacterium resembled a species of erhlichia bacteria found in Asia. It differed from the Asian ehrlichia by about 2 percent, enough to prompt Pritt to suspect that the patients from Wisconsin and Minnesota had been infected by a new species.
The new tick-borne bacterial species was subsequently identified in the deer tick. Pritt said the Mayo Clinic has since screened thousands of blood samples and ticks collected from across the country and the new species appears to reside only in deer ticks in Wisconsin and Minnesota.
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