title: Rodents as sentinels for the prevalence of tick-borne encephalitis virus.
abstract: BACKGROUND
  Tick-borne encephalitis virus (TBEV) causes one of the most important flavivirus infections of the central nervous system, affecting humans in Europe and Asia. It is mainly transmitted by the bite of an infected tick and circulates among them and their vertebrate hosts. Until now, TBE risk analysis in Germany has been based on the incidence of human cases. Because of an increasing vaccination rate, this approach might be misleading, especially in regions of low virus circulation.
  
  
  METHODS
  To test the suitability of rodents as a surrogate marker for virus spread, laboratory-bred Microtus arvalis voles were experimentally infected with TBEV and analyzed over a period of 100 days by real-time (RT)-quantitative polymerase chain reaction. Further, the prevalence of TBEV in rodents trapped in Brandenburg, a rural federal state in northeastern Germany with autochthonous TBE cases, was determined and compared with that in rodents from German TBE risk areas as well as TBE nonrisk areas.
  
  
  RESULTS
  In experimentally infected M. arvalis voles, TBEV was detectable in different organs for at least 3 months and in blood for 1 month. Ten percent of all rodents investigated were positive for TBEV. However, in TBE risk areas, the infection rate was higher compared with that of areas with only single human cases or of nonrisk areas. TBEV was detected in six rodent species: Apodemus agrarius, Apodemus flavicollis, Apodemus sylvaticus, Microtus agrestis, Microtus arvalis, and Myodes glareolus. M. glareolus showed a high infection rate in all areas investigated.
  
  
  CONCLUSIONS
  The infection experiments proved that TBEV can be reliably detected in infected M. arvalis voles. These voles developed a persistent TBE infection without clinical symptoms. Further, the study showed that rodents, especially M. glareolus, are promising sentinels particularly in areas of low TBEV circulation.
authors.affiliation: Center for Biological Security (ZBS-1), Robert Koch-Institut, Berlin, Germany. achazik@rki.de
authors.forename: Katharina
authors.initials: K
authors.lastname: Achazi
authors.forename: Daniel
authors.initials: D
authors.lastname: Růžek
authors.forename: Oliver
authors.initials: O
authors.lastname: Donoso-Mantke
authors.forename: Mathias
authors.initials: M
authors.lastname: Schlegel
authors.forename: Hanan Sheikh
authors.initials: HS
authors.lastname: Ali
authors.forename: Mathias
authors.initials: M
authors.lastname: Wenk
authors.forename: Jonas
authors.initials: J
authors.lastname: Schmidt-Chanasit
authors.forename: Lutz
authors.initials: L
authors.lastname: Ohlmeyer
authors.forename: Ferdinand
authors.initials: F
authors.lastname: Rühe
authors.forename: Torsten
authors.initials: T
authors.lastname: Vor
authors.forename: Christian
authors.initials: C
authors.lastname: Kiffner
authors.forename: René
authors.initials: R
authors.lastname: Kallies
authors.forename: Rainer G
authors.initials: RG
authors.lastname: Ulrich
authors.forename: Matthias
authors.initials: M
authors.lastname: Niedrig
mesh_terms: D000818:Animals; D004669:Encephalitis Viruses, Tick-Borne / Q000235:genetics / Q000302:isolation & purification*; D004675:Encephalitis, Tick-Borne / Q000453:epidemiology / Q000662:veterinary*; D014644:Genetic Variation; D009664:Norway / Q000453:epidemiology; D009690:Nucleic Acid Conformation; D015995:Prevalence; D012367:RNA, Viral / Q000302:isolation & purification; D012376:Rodent Diseases / Q000453:epidemiology*; D012377:Rodentia; D018571:Sentinel Surveillance
chemical_list: D012367:RNA, Viral