title: A city park as a potential epidemic site of scrub typhus: a case-control study of an outbreak in Guangzhou, China.
abstract: BACKGROUND
  Scrub typhus is an important public health problem in China, especially in Guangzhou city. Typical outbreaks of scrub typhus have been previously reported in rural areas, affecting mainly farmers. We describe an atypical outbreak of the disease with case fatalities, from a park in Haizhu District, Guangzhou, that could turn out to be a potential scrub typhus epidemic site.
  
  
  METHODS
  From May 2012 to June 2012, a case-control study was conducted to identify source and risk factors of this outbreak. Reported cases of scrub typhus in Xiaogang Park were confirmed by Weil-Felix test or a nested polymerase chain reaction (NPCR). Controls were matched with their neighbors by gender and age. Multivariate conditional logistic regression was used to identify risk factors and protective factors.
  
  
  RESULTS
  A total of 29 cases were confirmed by Weil-Felix test, including 4 deaths by both Weil-Felix test and NPCR. All patients presented with fever (100%), while 28 (96.6%) cases had eschars, 10 (34.5%) headache, 10 (34.5%) chills, 6 (20.7%) lymphadenopathy, 5 (17.2%) rash, 2 (6.9%) vomiting and 1 (3.5%) presented with conjunctival congestion. The proportion of cases with activity history in Xiaogang Park was much higher than the control group (72.4% vs 24.1%, P < 0.001), and morning exercise in park or field was also as a risk factor for scrub typhus (adjusted OR = 3.0, 95% CI: 1.1-8.2). Four factors were significantly associated with the risk of developing scrub typhus: sitting on the lawn (adjusted OR = 8.0, 95% CI: 1.4-44.5), close contact with rats (adjusted OR = 3.3, 95% CI: 1.2-9.6), sitting near the rat holes (OR = 6.8, 95% CI: 1.2-38.1) and wearing long-sleeved clothing when outside (adjusted OR = 0.3, 95% CI: 0.1-0.7).
  
  
  CONCLUSIONS
  We confirmed an atypical outbreak of scrub typhus in a park in Guangzhou city, which has the potential to develop into an important epidemic site. This public health risk should not be neglected and requires more attention from authorities.
authors.affiliation: Guangzhou Center for Disease Control and Prevention, Guangzhou, Guangdong Province, China. wei_yh0928@163.com.
authors.forename: Yuehong
authors.initials: Y
authors.lastname: Wei
authors.affiliation: Guangzhou Center for Disease Control and Prevention, Guangzhou, Guangdong Province, China. llyeyq@163.com.
authors.forename: Lei
authors.initials: L
authors.lastname: Luo
authors.affiliation: Guangzhou Center for Disease Control and Prevention, Guangzhou, Guangdong Province, China. jingqinlong@126.com.
authors.forename: Qinlong
authors.initials: Q
authors.lastname: Jing
authors.affiliation: School of Public Health, Guangdong Pharmaceutical University, Guangzhou, Guangdong Province, China. ningqzone@163.com.
authors.forename: Xiaoning
authors.initials: X
authors.lastname: Li
authors.affiliation: Guangzhou Center for Disease Control and Prevention, Guangzhou, Guangdong Province, China. hyang5556@163.com.
authors.forename: Yong
authors.initials: Y
authors.lastname: Huang
authors.affiliation: Guangzhou Center for Disease Control and Prevention, Guangzhou, Guangdong Province, China. crbfzk@gzcdc.org.cn.
authors.forename: Xincai
authors.initials: X
authors.lastname: Xiao
authors.affiliation: Guangzhou Center for Disease Control and Prevention, Guangzhou, Guangdong Province, China. liulan728@163.com.
authors.forename: Lan
authors.initials: L
authors.lastname: Liu
authors.affiliation: Guangzhou Center for Disease Control and Prevention, Guangzhou, Guangdong Province, China. tom.wu@tom.com.
authors.forename: Xinwei
authors.initials: X
authors.lastname: Wu
authors.affiliation: Guangzhou Center for Disease Control and Prevention, Guangzhou, Guangdong Province, China. yangzc@gzcdc.org.cn.
authors.forename: Zhicong
authors.initials: Z
authors.lastname: Yang
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D016022:Case-Control Studies; D002681:China / Q000453:epidemiology; D004196:Disease Outbreaks / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D051381:Rats; D012189:Retrospective Studies; D012307:Risk Factors; D012612:Scrub Typhus / Q000453:epidemiology*; D055815:Young Adult