A new tick-borne illness marked by recurring high fever and described for the first time in U.S. patients just this year may help explain a controversial condition known as chronic Lyme disease.
It may be easily confused with other infections transmitted by the eight-legged creatures, which have been steadily expanding their range throughout the northeastern part of the U.S.
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A tick primerA tick primer
Ÿ Ticks are significant carriers of pathogens and are associated with a wide range of infections: Lyme disease, Q fever, Rocky Mountain spotted fever, babesiosis, human granulocytic anaplasmosis and B. miyamotoi infection .
Ÿ Deer ticks transmit Lyme and are slow feeders. A single feeding may last three to five days.
Ÿ If infected, a black-legged tick must remain attached for 24 to 48 hours before it transmits Lyme, and at least 12 to 24 hours to transmit human anaplasmosis.
Ÿ A female tick requires blood to produce eggs and can consume up to 400 times her weight.
Ÿ Tick saliva is a veritable pharmacy of anesthetic and de-coagulating compounds. Ticks stay attached without substantial pain to the host as its chemical clot-busters force blood to flow freely.
Info from Thomas Daniels, Fordham University and Calder Biological Field Station; Centers for Disease Control and Prevention.
But the newly identified bacterium is associated with a Lyme-like illness marked by higher fevers that wax and wane.
Doctors say there may be no way to initially distinguish the new tick-transmitted infection -- Borrelia miyamotoi -- from Lyme disease or human granulocytic anaplasmosis, another tick-related bacterium, formerly known as ehrlichiosis. B. miyamotoi, Lyme and ehrlichiosis can be transmitted by the black-legged deer tick.
"The good news is that the treatment is the same," said Sam Telford, referring to doxycycline, a common antibiotic. He is a professor of infectious diseases at Tufts University near Boston whose research distinguished the nuanced differences among the three infections.
But even though the treatment is the same, knowing which organism infected a patient is another story, said Dr. Benjamin Luft, a leading Lyme disease expert at Stony Brook University School of Medicine.
"B. miyamotoi is different because it is more of a relapsing fever infection," Luft said.
Luft said it is impossible right now to tell if B. miyamotoi explains the controversial illness known as chronic Lyme, in which patients do not recover after a short course of antibiotic therapy. These patients say they need long-term antibiotics, sometimes for life. However most patients are cured within a few weeks. "This is something that requires further attention," Luft said.
"It has not been clearly defined what their ailment truly is," he said. "This may be a reasonable explanation," he said, referring to B. miyamotoi.
Eleven different types of infectious agents have so far been identified in ticks that range throughout the Northeastern corridor.
B. miyamotoi was first identified in a group of Russian patients two years ago. All of them had so-called relapsing fevers -- fevers that return days to weeks later -- in what initially confused scientists as an unending cycle of illness.
Meanwhile, at the Louis Calder Center's biological field station in Armonk, N.Y., professor Thomas Daniels, of Fordham University, has been tracking ticks for years, trying to find out why they can carry so many different organisms -- bacteria, viruses and protozoa -- without succumbing themselves.
Knowing the secrets of the ticks' immune system, he said, will provide insight into how they so readily transmit diseases to humans.
"There does seem to be more areas reporting black-legged ticks than there were 10 to 15 years ago," Daniels said.
"A tick has a long life span," Daniels continued. "It can get infected in the larval stage. So from the time it hatches we're looking at two years for a single tick in this part of the country."