Any patient who develops an otherwise-unexplained viral-like illness in the spring or summer should be considered at high risk for one – or both – of the Borrelia illnesses, Dr. Krause said. A relapsing fever should be especially concerning. He stressed that the emblematic "bull’s-eye" rash may or may not occur.
Clinically, the B. miyamotoi spirochetes are more likely to be seen in blood smears than are their burgdorferi cousins. But B. miyamotoi can only be completely distinguished by serotyping or polymerase chain reaction, Dr. Krause said. These lab tests are not widely available now, but should be by early summer, he added.
Since effective treatment does not depend on positive identification, it’s not clinically necessary to determine the infective agent. But accurate tracking of the organism is important for epidemiologic data, and Dr. Krause encouraged physicians to pinpoint the cause of any tick-borne disease.
B. miyamotoi is certainly more widespread than the current case series suggest, Dr. Fish said in an interview. Because it’s been isolated in Japan, Germany, Russia, and now the United States, and in all of the tick species that carry Lyme, B. miyamotoi can be considered endemic in all northern hemisphere regions that harbor any of the four Lyme disease–causing tick species.
In fact, Dr. Fish said, many presumed cases of Lyme are probably due either to B. miyamotoi alone or to coinfection by both species.
"We saw it in about 2%," of ticks analyzed at the Yale lab, he said. "It appears to be widely distributed and I think it’s going to be seen more and more. This disease could actually be occurring as frequently as Lyme."
The 875-patient case series was supported by grants from the National Institutes of Health, the Gordon and Llura Gund Foundation, the Howard Hughes Medical Institute, and the G. Harold and Leila Y. Mathers Foundation. Dr. Gugliotta’s study was supported in part by grants from the National Institute of Health, the Evelyn Lilly Lutz Foundation and by a gift from Gordon and Lulie Gund. Neither Dr. Gugliotta, Dr. Krause, nor Dr. Fish had any financial disclosures.