Geographical Distribution and Epidemiologic Factors of Chigger Mites on Apodemus agrarius during Autumn in Korea

Abstract

A nationwide survey of chigger mites causing scrub typhus and an investigation of epidemiologic factors for chigger mites was conducted at 16 localities in 8 provinces in Korea during autumn 2009, 2012, and 2013. A total of 233 Apodemus agrarius were captured, and all were infested with chigger mites. The chigger index was highest in Chungcheongbuk-do in 2009 (358.3) and 2012 (290.1) and Chungcheongnam-do in 2013 (294.4). The predominant chigger mite species was Leptotrombidium pallidum in the northern and central parts and L. scutellare in the southern and western parts, Korea. L. pallidum was not found in Jellanam-do and Gyeongsangnam-do and the distribution of L. scutellare had been expanded in the northern parts of Korea. The chigger index of L. pallidum was positively correlated with temperature and negatively correlated with humidity. The incidence of scrub typhus is dependent on L. scutellare index. These findings could be helpful to monitor the distribution of chigger mites and to develop a preventive measures for scrub typhus in Korea.

Prevalence of chigger mites and Orientia tsutsugamushi strains in northern regions of Gangwon-do, Korea

“…The dominating species, L. pallidum , was the most common in Hwacheon (61.3%), followed by Cheorwon (21.3%), Yanggu (8.8%), and Goseong (8.6%). These findings are consistent with prior research that found L. pallidum to be the most common chigger mite in northern Gyeonggi-do [ 18 ] and Gangwon-do [ 19 ]. L. pallidum was followed by L. orientale, L. scutellare , and L. papale in Gyeonggi-do, and L. palpale , L. orientale , and L. zetum in Gangwon-do [ 18 , 19 ].…”

“…These findings are consistent with prior research that found L. pallidum to be the most common chigger mite in northern Gyeonggi-do [ 18 ] and Gangwon-do [ 19 ]. L. pallidum was followed by L. orientale, L. scutellare , and L. papale in Gyeonggi-do, and L. palpale , L. orientale , and L. zetum in Gangwon-do [ 18 , 19 ]. In the current research, however, L. scutellare was not found, unlike in Gyeonggi-do, and L. zetum was the most prevalent after L. pallidum , with N. tamiyai and L. tectum also found in Gangwon-do.…”

The impact of meteorological parameters on the scrub typhus incidence in Baoshan City, western Yunnan, China

“…Previous studies indicated that scrub typhus exhibited varying seasonal patterns in different regions. Korea illustrated high outbreaks of scrub typhus between October to November ( 12 ). In India, the occurrence of scrub typhus spans from July to February during the monsoon and post-monsoon seasons ( 13 ).…”

Investigation of chigger mites on small mammals in Ruili, Yunnan Province, China

“…Chigger mites are thought to be the only vector of scrub typhus; however, in addition to the transmission of tsutsugamushi, chigger mites are suspected of transmitting the virus that causes hemorrhagic fever in China (Lee et al, 2009;Peng et al, 2016a;Liu & Ren, 2022). Scrub typhus, caused by the pathogen Orientia tsutsugamushi, is the second most common febrile disease after malaria and is transmitted to humans through the bite of an infected chigger mite (chigger mite larvae) (Lv et al, 2018;Ding et al, 2021b;Lee et al, 2021). The "scrub typhus triangle" is a densely populated region containing more than 1 billion people at risk of infection, and approximately 1 million new cases are reported each year, with a mortality rate of 30% or higher if not properly treated at the early stage (Xu et al, 2017;Lv et al, 2018Lv et al, , 2021.…”