Distribution of Chigger Mites as Tsutsugamushi Vectors Sampled in Seogwipo

Abstract

We investigated the distribution of chigger mites in Seogwipo, Jeju Island to conduct surveillance for the presence of Orientia tsutsugamushi. Using a total of 20 samplers, chigger mite larvas were sampled weekly from September to November in Rice field, Field, Waterway, and Glass field (4 locations), and we found up to 51 larvas of 3 different species of chigger mites. 64 field mice were captured when sampling for chigger mite-infested rodents in rice fields, waterways, fields, reservoirs and hills (5 locations) for 9 months from March, 2018 to November, using 100 Sherman traps with placing 20 traps in each location, and in each location the trap index was 0.08. Only back-striped field mice (Apodemus agrarius) were captured one at a time. They were most frequently captured in April with 15 mice, and then 436 chigger mites were collected from the total of 64 captured wild rodent, showing a chigger index of 6.8. The chigger index was the highest in November at 46.0, followed by 6.8 in July and 4.6 in June. PCR was performed to investigate if there were any O. tsutsugamushi hosts among the 487 chigger mites sampled from the captured rodents and this turned out to be negative.

Epidemiological characteristics of cases with scrub typhus and their correlation with chigger mite occurrence (2019–2021): A focus on case occupation and activity locations

“…Recent studies have also examined the ecological aspects and species‐specific infestation of chigger mites, the primary carriers of tsutsugamushi , during the autumn season—the main outbreak period in Korea (Kim et al . 2019; Lee & Park 2019; Lee & Park 2021). Previous research investigating the correlation between typhus outbreaks and chigger mite ecology has produced consistent results, as depicted in Figure 4 (Lee et al .…”

“…Furthermore, other investigations focusing on the occurrence of typhus in Korea have reported similar findings, while spanning different time periods and considering geographical and climatic factors (Jeong et al 2013;Kong et al 2007). Recent studies have also examined the ecological aspects and species-specific infestation of chigger mites, the primary carriers of tsutsugamushi, during the autumn season-the main outbreak period in Korea (Kim et al 2019;Lee & Park 2019;Lee & Park 2021). Previous research investigating the correlation between typhus outbreaks and chigger mite ecology has produced consistent results, as depicted in Figure 4 (Lee et al 2009;Noh et al 2013).…”