title: Meteorological factors affecting scrub typhus occurrence: a retrospective study of Yamagata Prefecture, Japan, 1984-2014.
abstract: Climate change, by its influence on the ecology of vectors might affect the occurrence of vector-borne diseases. This study examines the effects of meteorological factors in Japan on the occurrence of scrub typhus, a mite-borne zoonosis caused by Orientia tsutsugamushi. Using negative binomial regression, we analysed the relationships between meteorological factors (including temperature, rainfall, snowfall) and spring-early summer cases of scrub typhus in Yamagata Prefecture, Japan, during 1984-2014. The average temperature in July and August of the previous year, cumulative rainfall in September of the previous year, snowfall throughout the winter, and maximum depth of snow cover in January and February were positively correlated with the number of scrub typhus cases. By contrast, cumulative rainfall in July of the previous year showed a negative relationship to the number of cases. These associations can be explained by the life-cycle of Leptotrombidium pallidum, a predominant vector of spring-early summer cases of scrub typhus in northern Japan. Our findings show that several meteorological factors are useful to estimate the number of scrub typhus cases before the endemic period. They are applicable to establish an early warning system for scrub typhus in northern Japan.
authors: Department of Microbiology,Yamagata Prefectural Institute of Public Health,Yamagata City,Yamagata,Japan.
authors: J
authors: J
authors: Seto
authors: Department of Microbiology,Yamagata Prefectural Institute of Public Health,Yamagata City,Yamagata,Japan.
authors: Y
authors: Y
authors: Suzuki
authors: Laboratory of Parasitology,Department of Disease Control,Graduate School of Veterinary Medicine,Hokkaido University,Sapporo,Hokkaido,Japan.
authors: R
authors: R
authors: Nakao
authors: Department of Public Health,Yamagata University Graduate School of Medicine, Yamagata,Japan.
authors: K
authors: K
authors: Otani
authors: Department of Microbiology,Yamagata Prefectural Institute of Public Health,Yamagata City,Yamagata,Japan.
authors: K
authors: K
authors: Yahagi
authors: Department of Microbiology,Yamagata Prefectural Institute of Public Health,Yamagata City,Yamagata,Japan.
authors: K
authors: K
authors: Mizuta
mesh_terms: D000818:Animals; D004199:Disease Vectors; D005260:Female; D007564:Japan / Q000453:epidemiology; D008297:Male; D008685:Meteorological Concepts; D012285:Orientia tsutsugamushi / Q000302:isolation & purification*; D012189:Retrospective Studies; D012612:Scrub Typhus / Q000453:epidemiology*; D014324:Trombiculidae / Q000254:growth & development*
keywords: 
                 Leptotrombidium pallidum
              ; life-cycle; negative binomial regression; snowfall; temperature