Detection of Francisella tularensis in ticks and identification of their genotypes using multiple-locus variable-number tandem repeat analysis.
BACKGROUND
Tularemia was reported in China over 50 years ago, however, many epidemical characteristics remain unclear. In the present study, the prevalence of Francisella tularensis in ticks was investigated during an epidemiological surveillance in China and then we measured their genetic diversity by conducting multiple-locus variable- number tandem repeat analysis (MLVA).


RESULTS
1670 ticks from 2 endemic areas (Inner Mongolia Autonomous Region and Heilongjiang Province) and 2 non-endemic areas (Jilin and Fujian Provinces) were collected and tested for evidence of tularemia by nested PCR. The prevalence of Francisella tularensis in ticks averaged 1.98%. The positive rates were significantly different among tick species, with Dermacentor silvarum and Ixodes persulatus responsible for all positive numbers. All F. tularensis that were detected in ticks belonged to F. tularensis subsp. holarctica and MLVA disclosed genetic diversity. One subtype was identified in 17 of 33 positive tick samples in three different study areas. Another subtype belonging to F. tularensis subsp. holarctica genotype was described for the first time in the current study.


CONCLUSIONS
The study showed two tick species, D. silvarum and I. persulatus harboring the pathogen of tularemia in natural environment, indicating these two tick species might have a role in tularemia existence in China. MLVA results disclosed the genetic diversity F. tularensis and identified one genotype as the most prevalent among the investigated ticks in China.
Zhang
Fang
F
Beijing Institute of Microbiology and Epidemiology, State Key Lab of Pathogen and Biosecurity, 20 Dong-Da-Jie Street, Fengtai District, Beijing 100071, PR China. fang_z760@sohu.com
Liu
Wei
W
Wu
Xiao-Ming
XM
Xin
Zhong-Tao
ZT
Zhao
Qiu-Min
QM
Yang
Hong
H
Cao
Wu-Chun
WC
D000818:Animals; D001096:Arachnid Vectors / Q000382:microbiology; D015373:Bacterial Typing Techniques; D002681:China / Q000453:epidemiology; D004269:DNA, Bacterial / Q000235:genetics; D003870:Dermacentor / Q000382:microbiology*; D004197:Disease Reservoirs / Q000382:microbiology; D005604:Francisella tularensis / Q000145:classification / Q000235:genetics*; D014644:Genetic Variation; D005838:Genotype; D018884:Ixodes / Q000382:microbiology*; D018598:Minisatellite Repeats; D017720:Molecular Epidemiology; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D015995:Prevalence; D014406:Tularemia / Q000453:epidemiology / Q000235:genetics
D004269:DNA, Bacterial
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