The 14th species of the Lyme disease group of Borrelia

The cluster of genetically related Borrelia species that includes the Lyme disease spirochete B. burgdorferi is known in the scientific community as Borrelia burgdorferi sensu lato ("in the wider sense"). Three members of B. burgdorferi sensu lato account for most cases of Lyme disease worldwide. They are B. burgdorferi sensu stricto ("in the stricter sense"), B. garinii, and B. afzelii. Several other species of the cluster are suspected of causing a small number of Lyme disease cases in Europe and Asia.

The United States is home to at least four species of B. burgdorferi sensu lato. They are B. burgdorferi sensu stricto (the only species known to cause Lyme disease in the U.S.), B. bissettii, B. andersonii, and B. californiensis. The discovery of a fifth named U.S. species, christened Borrelia carolinensis, was published in the Journal of Clinical Microbiology earlier this year. The new species hails from South Carolina. Most of the isolates were cultured from cotton mice and eastern wood rats, but one isolate was obtained from an Ixodes minor tick feeding on an eastern wood rat. Whether B. carolinensis is capable of inducing Lyme disease is unknown.

The number of named species of B. burgdorferi sensu lato found worldwide now stands at 14:

• B. burgdorferi sensu stricto
• B. garinii
• B. afzelii
• B. andersonii
• B. bissettii
• B. californiensis
• B. carolinensis
• B. japonica
• B. lusitaniae
• B. sinica
• B. spielmanii
• B. tanukii
• B. turdi
• B. valaisiana

If you read my last post, you will notice that Borrelia lonestari, detected in one case of the Lyme-like illness STARI, is missing from the list. Although STARI clinically resembles a mild form of Lyme disease, genetically B. lonestari is more closely related to the set of Borrelia that causes relapsing fever.

Featured article

Rudenko, N., Golovchenko, M., Grubhoffer, L., and Oliver, J.H. (2009). Borrelia carolinensis sp. nov., a new (14th) member of the Borrelia burgdorferi sensu lato complex from the southeastern region of the United States. Journal of Clinical Microbiology 47(1):134-141. DOI: 10.1128/JCM.01183-08