Rickettsioses in Japan and the Far East


Address for correspondence: Fumihiko Mahara, M.D., Ph.D., Mahara Hospital, 6-1, Aratano, Anan-city, Tokushima, 779-1510, Japan. Voice: +81-884-363339; fax: +81-884-363641.


Abstract: Three rickettsial diseases are known to exist in Japan currently: Japanese spotted fever (JSF), Tsutsugamushi disease (TD; scrub typhus), and Q fever. Since April 1999, the system for infection control and prevention in Japan has changed drastically. JSF, Q fever, and TD, as emerging infectious diseases, are designated as national notifiable diseases.The geographic distribution of JSF patients is along the coast of central and southwestern Japan, whereas TD and Q fever occur almost all over the country. The number of JSF patients reported was 216 cases during 1984–1998 and 268 cases, under the revised law, in 1999–2004. About 300–1000 cases of TD occur every year, and 7–46 cases of Q fever in 1999–2004. The number of cases of JSF and its endemic area are gradually increasing. There was only one fatality due to JSF until 2003, whereas two patients died of JSF in 2004, so JSF is still a life-threatening disease in Japan. Treatment of fulminant JSF consists of prompt administration of a combination of tetracycline and quinolone. Recent tick surveys revealed that the most probable vectors of JSF are Haemophysalis flava and Haemophysalis hystericis. In addition to R. japonica, two serotypes or species of spotted fever group rickettsiae have been isolated from ticks in Japan; one is closely related to R. helvetica and the other is a new genotype of unknown genotype AT, which is closely related to a Slovakian genotype. These serotypes are of uncertain clinical significance. Epidemiology of rickettsioses in the Far East is mentioned briefly.