The seroprevalence of
antibodies against the human granulocytic
ehrlichiosis agent (HGE) and Babesia microti was retrospectively determined in 76
Lyme borreliosis patients and in 44 asymptomatic individuals with a positive borreliosis serology, in comparison to 100 healthy blood donors from the
Rhein-Main area. Additionally, seroreactivity for tick-borne encephalitis virus (TBEV) was investigated. For antibody detection, commercially available immunofluorescence assays (MRL Diagnostics, USA) and a TBEV-ELISA (Immuno, Germany) were used. In the control group, the positivity rate for anti-Borrelia burgdorferi (
IgG/
IgM) and anti-Babesia microti-
antibodies in the population of the
Rhein-Main area (Midwestern Germany) may be estimated at 15% and 8%, respectively. Examination for both HGE and TBEV demonstrated seroreactivity (
IgG) in 1% of tested individuals. Specific anti-HGE
IgG and/or
IgM antibodies were more often discovered in cases of early
Borrelia infection (stage I: 13.6%, stage II: 18.4%) than in patients with stage III disease (0%) or in seropositive but asymptomatic patients (6.8%). Investigation for TBEV revealed seroreactivity for
IgG in 13% of these cases. No TBEV-
IgM was found. Interestingly, the prevalence of anti-HGE and anti-TBEV
antibodies among
Lyme borreliosis patients and seropositive patients without active
Lyme disease symptoms was significantly higher than that in the control group of healthy blood donors (p < 0.05). Likewise, antibody titers reflecting a recent
infection with Babesia microti could be demonstrated more often in patients with
Lyme borreliosis stage I or II (p < 0.05). Analysis of 50 samples from patients with florid or recent
syphilis infection revealed no crossreactivity between Babesia microti, HGE and Treponema pallidum. Our findings suggest that concomitant or serial
infection due to TOBB may be common in tick exposed patients from the
Rhein-Main area and in European countries in general. Hence, in addition to TBEV,
human babesiosis and HGE should always be considered by European physicians in the differential diagnosis of acute febrile illness following a
tick bite.