There's an article in The New York Times today about a new tickborne disease caused by Borrelia miyamotoi:
While they're reporting this as a new illness, this strain of Borrelia was found in the United States in 2001, and at the time, it wasn't known for certain whether or not it caused disease in human hosts.
Now, Russians have evidence of human infection, and it is suspected a small percentage of people in the United States are infected with Borrelia miyamotoi. A Borrelia miyamotoi infection differs from a Borrelia burgdorferi one in that there is no bulls-eye rash and there are fevers that come and go (relapsing). Patients are also negative on standard Lyme disease tests.
Here's a link to the new paper from Russian researchers:
Platonov AE, Karan LS, Kolyasnikova NM, Makhneva NA, Toporkova MG, Maleev VV, et al. Humans infected with relapsing fever spirochete Borrelia miyamotoi, Russia. Emerg Infect Dis. 2011 Oct; [Epub ahead of print]
Borrelia miyamotoi is distantly related to B. burgdorferi and transmitted by the same hard-body tick species. We report 46 cases of B. miyamotoi infection in humans and compare the frequency and clinical manifestations of this infection with those caused by B. garinii and B. burgdorferi infection. All 46 patients lived in Russia and had influenza-like illness with fever as high as 39.5°C; relapsing febrile illness occurred in 5 (11%) and erythema migrans in 4 (9%). In Russia, the rate of B. miyamotoi infection in Ixodes persulcatus ticks was 1%–16%, similar to rates in I. ricinus ticks in western Europe and I. scapularis ticks in the United States. B. miyamotoi infection may cause relapsing fever and Lyme disease–like symptoms throughout the Holarctic region of the world because of the widespread prevalence of this pathogen in its ixodid tick vectors.
Someone will have to design a blood test that will include Borrelia miyamotoi infections. And for doctors who have been relying on a bulls-eye rash for a diagnosis of Borreliosis, it's way past time to look at the bigger picture.
Edit January 23, 2013:
To read more about Borrelia miyamotoi, relapsing fever spirochete, and how an infection with it can present differently from many cases of Lyme disease, check out: