Comparison of Lyme Disease in the United States and Europe

Adriana R. Marques; Franc Strle; Gary P. Wormser


Emerging Infectious Diseases. 2021;27(8):2017-2024. 

In This Article

Lyme Borrelia Co-infections

Ixodes ticks can carry multiple pathogens, and a single tick bite may result in transmission of ≥2 infectious agents. Pathogens potentially transmitted by I. scapularis ticks to humans include B. burgdorferi s.s., B. mayonii, B. miyamotoi, Anaplasma phagocytophilum, Babesia microti, Ehrlichia muris eauclairensis, and the deer tick virus subtype of Powassan virus.[48] The frequency of co-infections depends on the prevalence of the infectious agents in ticks, which will vary in different geographic areas. In the United States, A. phagocytophilum and B. microti are the most frequent co-infections in patients with Lyme disease.[49] In the northeastern United States, ≈11% of patients infected with B. miyamotoi, a relapsing fever spirochete, are co-infected with B. burgdorferi s.s.; of note, B. miyamotoi infections per se can cause positive results on first-tier tests for Lyme disease, potentially leading to diagnostic confusion. Encephalitis caused by deer tick virus is relatively rare, but cases may be increasing. In Europe, in addition to Lyme borrelia, I. ricinus ticks can transmit tick-borne encephalitis virus, A. phagocytophilum, species of the bacterial genus Rickettsia, B. miyamotoi, and Babesia protozoans. Tick-borne encephalitis virus is well recognized as a cause of co-infection in patients with Lyme disease in Europe.[50] More data are needed on the frequency of co-infections in both the United States and Europe.