Identification ofEhrlichiaspp. andBorrelia burgdorferiinIxodesTicks in the Baltic Regions of Russia

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Abstract
The presence and distribution ofEhrlichiaspp. andBorrelia burgdorferisensu lato was demonstrated among ixodid ticks collected in the Baltic regions of Russia, where Lyme borreliosis is endemic. A total of 3,426Ixodes ricinusand 1,267Ixodes persulcatusspecimens were collected, and dark-field microscopy showed that 265 (11.5%)I. ricinusand 333 (26.3%)I. persulcatusticks were positive. From these samples, 472 dark-field-positive and 159 dark-field-negative ticks were subjected to PCR and subsequent reverse line blot hybridization. Fifty-four ticks (8.6%) carriedEhrlichiaspecies, and 4 (0.6%) carried ehrlichiae belonging to theEhrlichia phagocytophilacomplex, which includes the human granulocytic ehrlichiosis agent. TheE. phagocytophilacomplex and anEhrlichia-like species were detected only inI. ricinuswhereasEhrlichia muriswas found exclusively inI. persulcatus, indicating a possible vector-specific infection.Borrelia gariniiwas found predominantly inI. persulcatus, butBorrelia afzeliiwas evenly distributed among the two tick species. Only twoI. ricinusticks carriedB. burgdorferisensu stricto, whileBorrelia valaisianaand a newly identifiedB. afzelii-like species were found in 1.7 and 2.5% of all ticks, respectively. Of the dark-field-positive ticks, only 64.8% yielded aBorreliaPCR product, indicating that dark-field microscopy may detect organisms other thanB. burgdorferisensu lato. These observations show that the agent of human granulocytic ehrlichiosis may be present in ticks in the Baltic regions of Russia and that clinicians should be aware of this agent as a cause of febrile disease.
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