Hematological Features in Sheep with IgG and IgM Antibodies against Borrelia burgdorferi sensu lato

Exposure of sheep to Borrelia burgdorferi sensu lato (s.I.) complex, the causative agent of Lyme borreliosis (LB), has been reported in tick-abundant areas worldwide, while no data have been reported in Greece. The aim of the study was to identify the hematological alterations in sheep with seropositivity against Borrelia burgdorferi (s.I.). Blood samples were obtained from 318 tick infested sheep for blood analysis and serological determination of IgG and IgM antibodies against B. burgdorferi by indirect immunofluorescence antibody (IFA) assay after exclusion of endo-ectoparasites and other tick-borne infections. A total number of 162 sheep met the inclusion criteria, allocated in four groups based on the presence or absence of IgG and/or IgM; sheep found negative for IgM and IgG (Group A), positive for IgM (Group B), positive for both IgM and IgG (Group C) and positive for IgG (Group D). Anemia, thrombocytopenia and normal or decreased leukocyte count, mainly due to lymphopenia were the main hematological features observed in seropositive sheep. The presence of these features raises the suspicion of Borrelia infection in tick infested sheep. The seropositivity of 23.58% in sheep raises concerns of Borrelia circulation, especially in rural areas and potential risk of transmission to humans.