title: Clinical characteristics of the autumn-winter type scrub typhus cases in south of Shandong province, northern China.
abstract: BACKGROUND
  Before 1986, scrub typhus was only found endemic in southern China. Because human infections typically occur in the summer, it is called "summer type". During the autumn-winter period of 1986, a new type of scrub typhus was identified in Shandong and northern Jiangsu province of northern China. This newly recognized scrub typhus was subsequently reported in many areas of northern China and was then called "autumn-winter type". However, clinical characteristics of associated cases have not been reported.
  
  
  METHODS
  From 1995 to 2006, all suspected scrub typhus cases in five township hospitals of Feixian county, Shandong province were enrolled. Indirect immunofluorescent assay (IFA) was used as confirmatory serodiagnosis test. Polymerase chain reaction (PCR) connected with restriction fragment length polymorphism (RFLP) and sequence analyses were used for genotyping of O. tsutsugamushi DNAs. Clinical symptoms and demography of confirmed cases were analyzed.
  
  
  RESULTS
  A total of 480 scrub typhus cases were confirmed. The cases occurred every year exclusively between September and December with a peak occurrence in October. The case numbers were relatively higher in 1995, 1996, 1997, and 2000 than in other years. 57.9% of cases were in the group aged 21-50. More cases occurred in male (56%) than in female (44%). The predominant occupational group of the cases was farmers (85.0%). Farm work was reported the primary exposure to infection in 67.7% of cases. Fever, rash, and eschar were observed in 100.0%, 90.4%, and 88.5% of cases, respectively. Eschars formed frequently on or around umbilicus, abdomen areas, and front and back of waist (34.1%) in both genders. Normal results were observed in 88.7% (WBC counts), 84.5% (PLT counts), and 89.7% (RBC counts) of cases, respectively. Observations from the five hospitals were compared and no significant differences were found.
  
  
  CONCLUSIONS
  The autumn-winter type scrub typhus in northern China occurred exclusively from September to December with a peak occurrence in October, which was different from the summer type in southern China. In comparison with the summer type, complications associated with autumn-winter type scrub typhus were less severe, and abnormalities of routine hematological parameters were less obvious.
authors.affiliation: Department of Nosocomial Infection Management and Disease Control, Institute of Hospital Management, Chinese People's Liberation Army General Hospital, Beijing, PR China. Yunxiliu6511@yahoo.com.cn
authors.forename: Yun-Xi
authors.initials: YX
authors.lastname: Liu
authors.forename: Dan
authors.initials: D
authors.lastname: Feng
authors.forename: Ji-Jiang
authors.initials: JJ
authors.lastname: Suo
authors.forename: Yu-Bin
authors.initials: YB
authors.lastname: Xing
authors.forename: Gang
authors.initials: G
authors.lastname: Liu
authors.forename: Li-Hua
authors.initials: LH
authors.lastname: Liu
authors.forename: Hong-Ju
authors.initials: HJ
authors.lastname: Xiao
authors.forename: Ning
authors.initials: N
authors.lastname: Jia
authors.forename: Yan
authors.initials: Y
authors.lastname: Gao
authors.forename: Hong
authors.initials: H
authors.lastname: Yang
authors.forename: Shu-Qing
authors.initials: SQ
authors.lastname: Zuo
authors.forename: Pan-He
authors.initials: PH
authors.lastname: Zhang
authors.forename: Zhong-Tang
authors.initials: ZT
authors.lastname: Zhao
authors.forename: Jing-Si
authors.initials: JS
authors.lastname: Min
authors.forename: Pei-Tian
authors.initials: PT
authors.lastname: Feng
authors.forename: Shu-Bin
authors.initials: SB
authors.lastname: Ma
authors.forename: Song
authors.initials: S
authors.lastname: Liang
authors.forename: Wu-Chun
authors.initials: WC
authors.lastname: Cao
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000907:Antibodies, Bacterial / Q000097:blood; D002648:Child; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D005260:Female; D005838:Genotype; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D012285:Orientia tsutsugamushi / Q000235:genetics / Q000302:isolation & purification*; D012150:Polymorphism, Restriction Fragment Length; D012612:Scrub Typhus / Q000175:diagnosis* / Q000453:epidemiology*; D012621:Seasons; D055815:Young Adult
chemical_list: D000907:Antibodies, Bacterial