Epidemic status and clinical profile in a new epidemic area of scrub typhus in northern China
Scrub typhus, a mite-borne rickettsiosis, is widely endemic in the Asia-Pacific region. In China, it was prevalent only in tropics and subtropics before 1986; however, it has emerged and spread rapidly in temperate zone. Vigilance of genetic variation of Orientia tsutsugamushi and development of ecotourism in Shandong become new impetuses for better identification of epidemic status and clinical profile of scrub typhus.
METHODS:
We analyzed the surveillance data of scrub typhus during 2006 to 2011, and conducted a hospital-based disease survey. Considering the incidence and cases distribution, stratified cluster sampling was adopted for the survey. A structured questionnaire was applied to scrub typhus cases in 9 districts of Shandong province.
RESULTS:
Analysis of 1722 reported cases revealed a fluctuation of annual incidence between 0.23 and 0.47 per 100,000 people. Scrub typhus was clustered in mountainous and coastal areas , with an epidemic period from September to November. Among 102 (43 from coastal, 59 from inland ) confirmed cases,the most common manifestations were fever (100%), eschar or skin ulcer (86.3%), fatigue (71.6%), anorexia (71.6%) and rash (68.6%). Predominant complications included bronchopneumonia, toxic hepatitis, and acute cholecystitis in 21.6%, 3.9% and 2.9% of the cases, respectively. Difference was significant in the presence of eschar or skin ulcer (P = 0.023), liver percussion pain (P = 0.024), chill (P = 0.008), cough (P = 0.023) and complications (P = 0.016) between patients from coastal and inland areas.
CONCLUSIONS:
Scrub typhus should be highly suspected in patients with fever and eschar, particularly in those with a history of exposure to endemic areas during autumn and winter in Shandong. Alarm should be raised on changes of epidemic status and clinical features of the disease in newly developed endemic areas.