Epidemiological aspects of human granulocytic Ehrlichiosis in Southern Germany

Human granulocytic Ehrlichiosis (HGE) is a newly emerging acute febrile ill ness which is likely transmitted by ticks of the Ixodes ricinus l l. persul catus complex. First seroepidemiological surveys on the prevalence of HGE a ntibodies, detection of DNA of granulocytotropic ehrlichiae in l. ricinus a nd one case of HGE from Slovenia confirmed by serology and PGR (polymerase chain reaction) suggest that HGE might exist all over Europe. The purpose o f the present study was a) to determine the prevalence of antibodies agains t the HGE agent in sera collected from persons at high risk for exposure to l. ricinus with that of a control population and b) to determine the preva lence of granulocytic Ehrlichiae in l. ricinus ticks from Southern Germany. We studied sera from 150 forestry workers and 105 patients with an establis hed diagnosis of Lyme disease as tick-exposed populations. Sera from 103 he althy blood donors without a history of known tick bites served as controls . A significantly higher prevalence of HGE antibodies (P less than or equal to 0.01) was present among patients with Lyme borreliosis (12 of 105 were positive; 11.4%) and forestry workers (21 of 150 were positive; 14%) compar ed to blood donors (2 of 103 were positive; 1.9%). Furthermore, 510 adult a nd nymphal l. ricinus were investigated by PCR for the presence of granuloc ytic Ehrlichiae with primers specific for the E. phagocytophila group. In e ight (1.6%) of the investigated ticks the expected amplification product wa s detectable, indicating a low prevalence of infected ticks especially when compared with B. burgdorferi The presented data strongly suggests that the HGE agent or a closely related organism exists in Southern Germany and the refore HGE should be considered in the differential diagnosis of febrile il lnesses. However, final evidence can be provided only after isolation of th e organism from patients.