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Tick-borne rickettsiosis in the Altai region of Russia

Abstract number: P1845

Shpynov S., Fournier P.E., Rudakov N., Arseneva I., Granitov M., Tarasevich I., Raoult D.

Objectives: North Asian tick typhus (NATT) is a tick-borne zoonosis caused by Rickettsia sibirica ssp. sibirica (R. sibirica) in the Asiatic part of Russia. More than 66,000 cases of NATT have been registered in Russia from 1936 to summer 2007. In the Altai region of West Siberia, the average morbidity is 50 100,000 inhabitants per year. NATT is transmitted to humans by Dermacentor nuttalli, D. silvarum, D. marginatus, D. reticulatus, Haemaphysalis concinna and Ixodes persulcatus. In addition, R. sibirica and R. raoultii were detected using PCR in D. nuttalli ticks collected in the Altai Republic. We carried out molecular identification of a collection of 15 spotted fever group (SFG) rickettsiae cultivated from patients and from ticks from Altai from 1965 to 1989. We also screened ticks collected in forest-steppe zone of Altai region (Aleiskiy, Byiskiy and Shypunovskiy districts) for alpha-protobacteria from the order Rickettsiales.

Methods: Rickettsial strains were identified using partial amplification of the 5'-end of the ompA gene (190–70 and 190–701 primers). alpha-protobacteria were detected in ticks by amplifying the gltA gene (CS1d-CS535r and CS409d-RP1258n primer pairs). Positive PCR products were sequenced and compared to GenBank.

Results: Fourteen strains were identified as R. sibirica. These strains were isolated from humans (2) and six ticks species (D. nuttalli [2], D. silvarum [2], D. marginatus [4], D. reticulatus [2], H. concinna [1] and I. persulcatus [1]). The remaining strain, isolated from H. concinna, was identified as R. heilongjiangensis.

In D. reticulatus and D. marginatus ticks, we detected R. raoultii. In I. persulcatus collected in Aleiskiy district, we detected "Candidatus R. tarasevichiae", Ehrlichia muris, Anaplasma phagocytophilum, a rickettsia closely related to R. tamurae, bacterium "Montezuma" and R. raoultii. Several of these ticks were co-infected by two or more of these bacteria. In H. concinna, we detected a co-infection with R. heilongjiangensis and R. raoultii.

Conclusion: We confirm the aetiological role R. sibirica as agent of NATT, and the role of six tick species as vectors for this agent. However, we detected several other members of the order Rickettsiales, some of which being recognised pathogens, in ticks from Altai. Our results highlight the need to pursue molecular identification of tick-borne human infections in this region.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Subject:
Location: Barcelona, Spain
Presentation type:
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