Molecular epidemiology of Orientia tsutsugamushi in chiggers and ticks from domestic rodents in Shandong, northern China

Particle and Fibre Toxicology

Lu-Yan Zhang⁴  Li Yang⁴  Shu-Jun Ding³  Zhong Li³  Xian-Jun Wang³  Hai-Yu Zhang¹  Xiang-Peng Meng²  Xing-Qu Xu¹  Ai-Hua Zhang²  Hui-Li Yang²  Zhong-Tang Zhao⁴  Meng Zhang⁴ 

[1] Yinan Center for Disease Control and Prevention, Linyi, China;Tai’an Center for Disease Control and Prevention, Tai’an, China;Shandong Center for Disease Control and Prevention, Jinan, China;Department of Epidemiology and Health Statistics, School of Public Health, Shandong University, Jinan, China

关键词: Rodents;    Tick;    Chigger;    Orientia tsutsugamushi;    Scrub typhus;   

Others  :  824046
DOI  :  10.1186/1756-3305-6-312

 received in 2013-08-12, accepted in 2013-10-20,  发布年份 2013

【 摘 要 】

Background

Scrub typhus is endemic to a 13,000,000-km² area of the Asia-Pacific region, and causes an annual incidence of 1 million people. The mortality rate of scrub typhus ranges from 6.1% to 25% in Southeast Asia. Natural infection of Orientia tsutsugamushi has been identified in domestic rodents in Shandong Province. However, infestation of chiggers and ticks on the domestic rodents and prevalence and genotypes of O. tsutsugamushi in these Acarina remain unclear.

Methods

During September 2010 to March 2012, 3134 chiggers and 89 ticks were collected from domestic rodents captured in three counties of Shandong Province. We amplified and sequenced the 56-kDa type-specific antigen gene of O. tsutsugamushi from DNA samples of these Acarina and designated to genotype according to sequence analysis.

Results

Overall, the infestation rate of chiggers on domestic rodents was 17.0%, and the chigger index was 5.38. The infestation rate of ticks on rodents was 3.1%. Natural infection of O. tsutsugamushi was found in Leptotrombidium taishanicum, L. linhuaikongense, L. intermedium, L. scutellare, L. palpale, and Ixodes spp., the minimum positive rates of which were 5.9%, 3.2%, 1.2%, 0.8%, 0.8%, and 2.2%, respectively. Kawasaki-like genotypes were predominant in chiggers and ticks on domestic rodents, which were detected from L. taishanicum, L. intermedium, L. scutellare, L. palpale, and Ixodes spp. Shimokoshi-like genotype was detected from L. palpale.

Conclusions

In the present study we investigated the infestation of chiggers and ticks on domestic rodents in Shandong Province, and identified the prevalence and genotypes of O. tsutsugamushi in the Acarina. Infestation of vector chiggers in domestic rodents, prevalence of O. tsutsugamushi in infested chiggers, and high nucleotide homologies among the O. tsutsugamushi sequences from the Acarina, their animal hosts and scrub typhus patients, implied that domestic rodents may play an important role in the transmission of scrub typhus in Shandong, China. Further studies are needed to verify the vector significance of chiggers and ticks that tested positive for O. tsutsugamushi, and to assess the risk of human exposure to chiggers and ticks on domestic rodents.

【 授权许可】

   
2013 Zhang et al.; licensee BioMed Central Ltd.

【 图 表 】

Figure 1.

Figure 2.

【 参考文献 】

• [1]Oaks SCJ, Ridway RL, Shirai A, Twartz JC: Scrub typhus. Inst Med Res Malays Bull 1983, 21:1-98.
• [2]Watt G, Parola P: Scrub typhus and tropical rickettsioses. Curr Opin Infect Dis 2003, 16(5):429-436.
• [3]Lee CS, Hwang JH, Lee HB, Kwon KS: Risk factors leading to fatal outcome in scrub typhus patients. Am J Trop Med Hyg 2009, 81(3):484-488.
• [4]Wang CC, Liu SF, Liu JW, Chung YH, Su MC, Lin MC: Acute respiratory distress syndrome in scrub typhus. Am J Trop Med Hyg 2007, 76(6):1148-1152.
• [5]Kelly DJ, Fuerst PA, Ching WM, Richards AL: Scrub typhus: the geographic distribution of phenotypic and genotypic variants of Orientia tsutsugamushi. Clin Infect Dis 2009, 48(Suppl 3):S203-S230.
• [6]Ohashi N, Nashimoto H, Ikeda H, Tamura A: Diversity of immunodominant 56-kDa type-specific antigen (TSA) of Rickettsia tsutsugamushi. Sequence and comparative analyses of the genes encoding TSA homologues from four antigenic variants. J Biol Chem 1992, 267(18):12728-12735.
• [7]Yang YF, Wang JL, Yao YC: Investigation of the first scrub typhus epidemic in Shandong Province. Chin J Epidemiol 1987, 8(5):280.
• [8]Zhang M, Zhao ZT, Wang XJ, Li Z, Ding L, Ding SJ: Scrub typhus: surveillance, clinical profile and diagnostic issues in Shandong, China. Am J Trop Med Hyg 2012, 87(6):1099-1104.
• [9]Kweon SS, Choi JS, Lim HS, Kim JR, Kim KY, Ryu SY, Lee SD, Im HK, Kwon JW: A community-based case-control study of behavioral factors associated with scrub typhus during the autumn epidemic season in South Korea. Am J Trop Med Hyg 2009, 80(3):442-446.
• [10]Lyu Y, Tian L, Zhang L, Dou X, Wang X, Li W, Zhang X, Sun Y, Guan Z, Li X, et al.: A case-control study of risk factors associated with scrub typhus infection in Beijing, China. PLoS One 2013, 8(5):e63668.
• [11]Lee HI, Shim SK, Song BG, Choi EN, Hwang KJ, Park MY, Park C, Shin EH: Detection of Orientia tsutsugamushi, the causative agent of scrub typhus, in a novel mite species, Eushoengastia koreaensis, in Korea. Vector Borne Zoonotic Dis 2011, 11(3):209-214.
• [12]Shim SK, Choi EN, Yu KO, Park HJ, Kim CM, Lee KH, Park JK, Park PH, Yoon MH, Park SH, et al.: Characterisation of Orientia tsutsugamushi genotypes from wild rodents and chigger mites in Korea. Clin Microbiol Infect 2009, 15(Suppl 2):311-312.
• [13]Takahashi M, Misumi H, Urakami H, Nakajima S, Furui S, Yamamoto S, Furuya Y, Misumi M, Matsumoto I: Mite vectors (Acari: Trombiculidae) of scrub typhus in a new endemic area in northern Kyoto, Japan. J Med Entomol 2004, 41(1):107-114.
• [14]Ding L, Wang XJ, Li Z, Ding SJ, Zhang M, Zhao ZT: Epidemic characteristics and related factors of autumn-winter type scrub typhus in Shandong area, 2010. Chin J Publ health 2013, 29(4):543-545.
• [15]Zhang M, Zhao ZT, Wang XJ, Li Z, Ding L, Ding SJ, Yang HL: Genetic variants of orientia tsutsugamushi in Domestic Rodents, Northern China. Emerg Infect Dis 2013, 19(7):1135-1137.
• [16]Furuya Y, Yoshida Y, Katayama T, Yamamoto S, Kawamura A Jr: Serotype-specific amplification of Rickettsia tsutsugamushi DNA by nested polymerase chain reaction. J Clin Microbiol 1993, 31(6):1637-1640.
• [17]Enatsu T, Urakami H, Tamura A: Phylogenetic analysis of Orientia tsutsugamushi strains based on the sequence homologies of 56-kDa type-specific antigen genes. FEMS Microbiol Lett 1999, 180(2):163-169.
• [18]Yu ES, Chen XR, Wu GH, Guo HB: Study on scrub typhus in China. 2000, 13-15.
• [19]Kawamura A, Tanaka H, Tamura A: Tsutsugamushi disease. Tokyo (Japan): University of Tokyo Press; 1995.
• [20]Li JC, Zheng XY, Xi ZY, Ni H, Zhang HH, Chen CF: Basic studies on trombiculid mites and vector chiggers mites in the transmission of tsutsugamushi disease for 45 years. Acad J SUMS 2002, 23(1):1-9.
• [21]Liu YX, Zhao ZT, Gao Y, Jia CQ, Zhang JL, Yang ZQ, Wang SM, Jiang BF: Characterization of Orientia tsutsugamushi strains isolated in Shandong Province, China by immunofluorescence and restriction fragment length polymorphism (RFLP) analyses. Southeast Asian J Trop Med Public Health 2004, 35(2):353-357.
• [22]Tamura A, Takahashi K, Tsuruhara T, Urakami H, Miyamura S, Sekikawa H, Kenmotsu M, Shibata M, Abe S, Nezu H: Isolation of Rickettsia tsutsugamushi antigenically different from Kato, Karp, and Gilliam strains from patients. Microbiol Immunol 1984, 28(8):873-882.
• [23]Ikegaya S, Iwasaki H, Takada N, Yamamoto S, Ueda T: Tsutsugamushi disease caused by Shimokoshi-Type Orientia tsutsugamushi: the first report in Western Japan. Am J Trop Med Hyg 2013, 88(6):1217-1219.