Descriptive epidemiology of rickettsial infections in Japan: Scrub typhus and Japanese spotted fever, 2007–2016

• Published in: International journal of infectious diseases Vol. 105; pp. 560 - 566
• Main Authors: Kinoshita, Hitomi, Arima, Yuzo, Shigematsu, Mika, Sunagawa, Tomimasa, Saijo, Masayuki, Oishi, Kazunori, Ando, Shuji
• Format: Journal Article
• Language: English
• Published: Canada Elsevier Ltd 01.04.2021; Elsevier
• Subjects: Japan; Japanese spotted fever; Rickettsia; Scrub typhus; Surveillance; Vector-borne disease; Scrub typhus; Vector-borne disease; Surveillance; Rickettsia; Japanese spotted fever; Japan
• ISSN: 1201-9712; 1878-3511; 1878-3511
• DOI: 10.1016/j.ijid.2021.02.069

[Display omitted] •Annual notifications of ST have been stable but JSF have been increasing.•While both ST and JSF occur in most of Japan, their geographic distributions differ.•ST was more common in spring/summer in the north and autumn/winter in the south.•Overall notification rates and fatal case reports were higher among the elderly. This study aimed to describe the epidemiological and clinical characteristics of endemics of two rickettsial diseases, scrub typhus (ST) and Japanese spotted fever (JSF), in Japan. We conducted a retrospective, descriptive epidemiological assessment of cases notified via national surveillance from 2007–2016. Over the 10-year period, 4185 ST and 1765 JSF cases were notified; of these, 20 (0.48%) cases of ST and 16 (0.91%) cases of JSF were fatal at the time of reporting. The elderly had higher notification rates and fatalities. While the annual number of ST notifications was stable and cases were reported from a broad geographic range, the number of JSF reports increased three-fold, expanding from the southwest to the east. The seasonality of ST varied by region and was more common during spring/summer in the north and autumn/winter in the south; 78% of cases occurred during autumn/winter, mainly in the southern region. Most of the fatal ST cases occurred in the spring/summer and occurred in the northern region. Our analysis identified seasonal and regional variations in the distribution of rickettsiosis. These variations were most likely to be related to the ecology of the vectors and etiological agents. Knowing the recent epidemiological and clinical features of ST and JSF can support clinical diagnosis and guide preventative activities against these vector-borne diseases.