Foci of tick-borne diseases in southwest Germany.
Presently known tick-borne diseases in Germany include Lyme borreliosis, tick-borne encephalitis (TBE-virus, western subtype), Q-fever, babesiosis and presumably ehrlichiosis. Blood samples of 4,368 forestry workers in the State of Baden-Wuerttemberg (B-W), southwestern Germany, were tested for the presence of antibodies against Borrelia burgdorferi sensu lato, TBE-virus and Ehrlichia spp. (genogroup E. phagocytophila). Furthermore 12,327 ticks (Ixodes ricinus) collected in various areas of B-W were analysed by PCR and genotyping for the prevalence of pathogen RNA and DNA. The human seroprevalence rates of antibodies to B. burgdorferi sensu lato ranged from 18% to 52%, for TBE-virus from 0% to 43% and for Ehrlichia spp. from 5% to 16% in various counties of the State. The foci of B. burgdorferi and TBE-virus as indicated by antibody prevalence in humans are only partly overlapping with each other. The highest rates of TBE-virus antibodies are in concordance with available clinical data. However antibody prevalence up to 27% in areas with no reports of clinical cases was found, suggesting that TBE occurs throughout the State of B-W. The prevalence of Ehrlichia spp. antibodies suggests that ehrlichiosis plays a role as a tick-borne disease in Germany, but as long as no clinical data are available, this will remain unclear. Investigations of ticks for TBE-virus (n = 9,189) by nested PCR showed prevalence rates from 0% to 2.3% and for Ehrlichia spp. (n = 1,963) from 2.6% to 3.1%. Examination of ticks (n = 3,138) for the presence of B. burgdorferi sensu lato DNA was performed by PCR and revealed prevalence rates from 13.9% up to 24%. Furthermore 1,106 samples positive for B. burgdorferi sensu lato were used for genotyping. B. afzelii DNA was found in 407 ticks (36.8%), followed by B. garinii (21.9%), B. valaisiana (13.7%), and B. burgdorferi sensu stricto (9.9%). Double infection was found in 6.4% and triple infection in 0.8% of the ticks. 10.5% of the positive samples could not be classified. Prevention of tick-borne diseases has to focus on behavioural intervention to reduce individual tick exposure by proper behaviour in the environment, as a large-scale control of the tick population seems impossible and thus reduction of Lyme borreliosis and TBE through tick control is unlikely. Vaccination against TBE-virus should not only be recommended for high endemic areas but also for persons with a high individual risk.
Oehme
Rainer
R
State Health Office Baden-Wuerttemberg, Stuttgart, Germany. oehmer@lga.bwl.de
Hartelt
Kathrin
K
Backe
Hannelore
H
Brockmann
Stefan
S
Kimmig
Peter
P
D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D000914:Antibodies, Viral / Q000097:blood; D001096:Arachnid Vectors / Q000382:microbiology* / Q000821:virology; D015748:Borrelia burgdorferi Group / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification; D004269:DNA, Bacterial / Q000032:analysis; D004536:Ehrlichia / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification; D004669:Encephalitis Viruses, Tick-Borne / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification; D016468:Forestry; D005838:Genotype; D005858:Germany / Q000453:epidemiology; D006801:Humans; D009784:Occupational Diseases / Q000453:epidemiology* / Q000517:prevention & control; D016133:Polymerase Chain Reaction; D012367:RNA, Viral / Q000032:analysis; D016036:Seroepidemiologic Studies; D013983:Tick Control; D017282:Tick-Borne Diseases / Q000453:epidemiology* / Q000517:prevention & control; D013987:Ticks / Q000382:microbiology* / Q000821:virology; D014611:Vaccination
D000907:Antibodies, Bacterial; D000914:Antibodies, Viral; D004269:DNA, Bacterial; D012367:RNA, Viral