Comparative research on epidemiological aspects of tsutsugamushi disease (scrub typhus) between Korea and Japan

In order to compare the epidemiological aspects of tsutsugamushi disease (scrub typhus) between Korea and Japan, we analyzed the current state of tsutsugamushi disease outbreaks and related risk factors. The average prevalence rate of tsutsugamushi disease from 2001 to 2005 in Korea was higher than that in Japan (7.2 and 0.3 per 100,000 population, respectively) (P<0.01). The seasonal distribution in Korea showed that the incidence of tsutsugamushi disease in autumn (94.5% of total cases) was higher than in Japan (38.2%) (P<0.01), while the incidences of outbreaks in other seasons were much higher in Japan (P<0.01). In Korea, more females (64.8%) were infected than males (35.2%) (P<0.01), while there was no significant difference in Japan. The remarkable difference between the gender distribution in Korea and Japan is believed to reflect cultural differences between the two countries in terms of work, dress and ornamentation. In both countries, elderly people (over 60 years old), especially in rural areas, showed a very high prevalence rate (50%), which is possibly due to increased outdoor activities and a decreased number of young people in those areas. These differences in tsutsugamushi disease risk factors reflect the different influences of vectors/hosts, climate, and geographical and cultural characteristics between the two countries.