Abstract
BackgroundScrub 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.MethodsFrom 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.ResultsA 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).ConclusionsWe 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.
Highlights
Scrub typhus is an important public health problem in China, especially in Guangzhou city
In China, outbreaks of scrub typhus are typically reported in rural areas, and it is primarily farmers are who are infected
All 29 cases were confirmed by Weil–Felix test, of which the genotype Karp type was identified by nested polymerase chain reaction (NPCR) in the 4 fatal cases (Table 1)
Summary
Scrub typhus is an important public health problem in China, especially in Guangzhou city. 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. Scrub typhus (Tsutsugamushi disease) is a febrile illness caused by the rickettsial bacterium, Orientia tsutsugamushi. It is transmitted by the bites of infected chiggers of the Trombiculidae family, especially those of the genus Leptotrombidium [1]. It is estimated that over half (55%) of the world’s population live in scrub typhus endemic areas, and that about one million cases occur annually [12]. The incident population have spread from occupational population to general population such as the elderly, children, pregnant women and tourists [2,15,16,17]
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