Gyllemark et al.
Are other tick-borne infections overlooked in patients investigated for Lyme neuroborreliosis? A large retrospective study from South-eastern Sweden.
Ticks Tick Borne Dis. 2021; 12(5):101759. doi: 10.1016/j.ttbdis.2021.101759

The most common vector in Europe that transmits Borrelia burgdorferi sensu lato (s.l.), is as well a vector for other pathogens like Anaplasma phagocytophilum, Rickettsia helvetica, Neoehrlichia mikurensis, Borrelia miyamotoi, Babesia spp., and tick-borne encephalitis virus. Principally, Ixodes ricinus ticks can harbor various pathogens simultaneously and thus, co-infections may occur.

A Swedish team has analyzed if in the cerebrospinal fluid (CSF) and serum samples of patients who were under investigation of Lyme borreliosis other pathogens than B. burgdorferi can be detected. In total, CSF and serum samples from 600 patients (median age of 50 years, range 4–85 years for females; median age of 49 years, range 3–87 years for males) have retrospectively been collected during 2009-2013, and the samples were either analyzed by PCR or for specific antibodies.

In summary, co-infections were rare, e.g., N. mikurensis was detected by real-time PCR in the serum of one patient only, and no A. phagocytophilium nor Rickettsia ssp. could be detected neither in CSF nor in serum samples.

In none of the 600 patients, TBE virus could be detected in the CSF by PCR. Only two patients were regarded as having a current TBE virus infection according to their symptoms, CSF analysis and serology, although the 600 patients were living in TBE endemic areas. Six patients had antibodies, two unvaccinated patients had both IgM and IgG TBE antibodies.

The authors concluded that the risk for contracting a tick-borne CNS infection, including co-infection with multiple tick-borne pathogens, appears low in South-eastern Sweden. However, a prospective study is warranted to confirm these study results.

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