Distributions of infective spots composed of unfed larvae infected with Orientia tsutsugamushi in Leptotrombidium mites and their annual fluctuations on the soil surface in an endemic area of tsutsugamushi disease (Acari : Trombiculidae)

Misumi, Hiroyasu; Takahashi, M.; Urakami, Hiroshi; Matsumoto, Isao

doi:10.7601/mez.53.227

Cited by 5 publications

(6 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…tsutsugamushi infected voles and a changing pattern over time [210, 216, 217]. Most positive sites were positive on more than one occasion over the course of 3 years [218]. In chemoprophylaxis studies with humans, individuals seated on grass 45 cm apart had significantly differing numbers of chiggers attached, which was consistent to the location if two people changed position [88].…”

Section: Resultsmentioning

confidence: 99%

Scrub typhus ecology: a systematic review of Orientia in vectors and hosts

et al. 2019

View full text Add to dashboard Cite

Scrub typhus, caused by Orientia tsutsugamushi, is an important and neglected vector-borne zoonotic disease with an expanding known distribution. The ecology of the disease is complex and poorly understood, impairing discussion of public health interventions. To highlight what we know and the themes of our ignorance, we conducted a systematic review of all studies investigating the pathogen in vectors and non-human hosts. A total of 276 articles in 7 languages were included, with 793 study sites across 30 countries. There was no time restriction for article inclusion, with the oldest published in 1924. Seventy-six potential vector species and 234 vertebrate host species were tested, accounting for over one million trombiculid mites (‘chiggers’) and 83,000 vertebrates. The proportion of O. tsutsugamushi positivity was recorded for different categories of laboratory test and host species. Vector and host collection sites were geocoded and mapped. Ecological data associated with these sites were summarised. A further 145 articles encompassing general themes of scrub typhus ecology were reviewed. These topics range from the life-cycle to transmission, habitats, seasonality and human risks. Important gaps in our understanding are highlighted together with possible tools to begin to unravel these. Many of the data reported are highly variable and inconsistent and minimum data reporting standards are proposed. With more recent reports of human Orientia sp. infection in the Middle East and South America and enormous advances in research technology over recent decades, this comprehensive review provides a detailed summary of work investigating this pathogen in vectors and non-human hosts and updates current understanding of the complex ecology of scrub typhus. A better understanding of scrub typhus ecology has important relevance to ongoing research into improving diagnostics, developing vaccines and identifying useful public health interventions to reduce the burden of the disease.

show abstract

Section: Resultsmentioning

confidence: 99%

Scrub typhus ecology: a systematic review of Orientia in vectors and hosts

et al. 2019

View full text Add to dashboard Cite

show abstract

“…Another clinical and epidemiological opinion is that unengorged chigger mites are more critical and appropriate than engorged chigger mites, primarily in determining chigger vectors. Other researchers have used unfed chigger mites to assess the true reservoir of O. tsutsugamushi [ 11 , 13 , 20 , 21 ]. In nature, infected chigger mites have a high transmission ability.…”

Section: Discussionmentioning

confidence: 99%

“…Unfortunately, we could not test O. tsutsugamushi infections in unfed chigger mites, and further studies are needed to analyze the O. tsutsugamushi prevalence in unfed larvae in an epidemiologically meaningful manner. Other studies have used unfed larvae to identify the prevalence of O. tsutsugamushi infection, including L. scutellare (3.0%) and N. japonica (100%) in Japan [ 11 ], H. miyagawai (MIR 2.6%) in the Republic of Korea [ 13 ], L. scutellare (0.01%) in Japan [ 20 ], and L. pallidum (15.6%) and L. intermedium (0.1%) in Japan [ 21 ]. Normally, it is difficult to individually conduct both species identification and an assessment of infection rates of O. tsutsugamushi in large-scale assays of chigger mites.…”

Section: Discussionmentioning

confidence: 99%

Nationwide Incidence of Chigger Mite Populations and Molecular Detection of Orientia tsutsugamushi in the Republic of Korea, 2020

et al. 2021

View full text Add to dashboard Cite

The Korea Disease Control and Prevention Agency has established regional centers at 16 locations to monitor vectors and pathogens. We investigated the geographical and temporal distribution of chigger mite populations to understand tsutsugamushi disease epidemiology in 2020. To monitor weekly chigger mite populations, 3637 chigger mites were collected from sticky chigger mite traps in autumn. Chigger mites appeared from the first week of October to the third week of December, peaking in the fourth week of October. The predominant species were Leptotrombidium scutellare, Leptotrombidium palpale, Neotrombicula kwangneungensis, Neotrombicula tamiyai, and Leptotrombidium pallidum. To monitor Orientia tsutsugamushi infection in chigger mites, 50,153 chigger mites were collected from 499 trapped wild rodents in spring and autumn, with a chigger index of 100.5. Approximately 50% of chigger mites were pooled into 998 pools, and the minimum infection rate (MIR) of O. tsutsugamushi was 0.1%. Jeongeup had the highest MIR for O. tsutsugamushi (0.7%). The Kato-related genotype was the most common (52.2%), followed by the Karp-related (17.4%), Boryong (13.0%), JG-related (8.7%), Shimokoshi (4.3%), and Kawasaki (4.3%) genotypes. Ecological and geographical studies focusing on the basic ecology and pathology of mites will improve our understanding of tsutsugamushi disease risks in the Republic of Korea.

show abstract

“…In addition, O. tsutsugamushi acquired from these chiggers was transtadially transmitted to the adult stage, but rarely or not transmitted vertically to their progeny (Takahashi et al 1994). Because of those opinions, some researchers used unfed chigger to determine the true reservoir of O. tsutsugamushi (Pham et al 2001, Misumi et al 2002, Takahashi et al 2002. To determine vector species more clearly, we need to collect unfed chiggers by soil collection or black clothes/plates methods and test the infection status of each chigger.…”

Section: Discussionmentioning

confidence: 99%

Detection ofOrientia tsutsugamushi, the Causative Agent of Scrub Typhus, in a Novel Mite Species,Eushoengastia koreaensis, in Korea

Lee

Shim

Song

et al. 2011

Vector-Borne and Zoonotic Diseases

View full text Add to dashboard Cite

To identify potential vector species of scrub typhus in the Republic of Korea (ROK), chigger mites were harvested from wild rodents captured at nine localities in October 2005. The bodies of the chigger mites were individually punctured with a fine pin, squeezed out internal contents, and examined for Orientia tsutsugamushi DNA by nested polymerase chain reaction. The exoskeleton of associated chiggers was mounted on glass slides with polyvinylalcohol (PVA) medium for identification. Among 830 individuals belonging to 4 genera and 14 species, O. tsutsugamushi was detected from 22 chiggers of six species, with an overall infection rate of 2.7%. The infection rate was highest for Leptotrombidium palpale (5.3%), followed by Neotrombicula japonica (4.3%), Leptotrombidium scutellare (3.7%), Leptotrombidium orientale (3.6%), Eushoengastia koreaensis (1.9%), and Leptotrombidium pallidum (1.5%). This study first reported O. tsutsugamushi infection from N. japonica and E. koreaensis larvae in the ROK. The population densities of L. pallidum (33.4 chiggers/rodent), historically confirmed as a primary vector of scrub typhus in the ROK, were high, whereas its infection rate was relatively low (1.5%). However, E. koreaensis was only collected from 154 individuals at seven collection sites and its infection rate was demonstrated relatively high (mean 1.9%). Additional studies are needed to determine the role of vector species in the epidemiology of scrub typhus.

show abstract

Distributions of infective spots composed of unfed larvae infected with Orientia tsutsugamushi in Leptotrombidium mites and their annual fluctuations on the soil surface in an endemic area of tsutsugamushi disease (Acari : Trombiculidae)

Abstract: Distributions of infective spots composed of unfed larvae infected with On-entia tsutsugamushi in Loptotrombidium mites and their annual fluctuations on the soil surface in an endemic area of tsutsugamushi disease (Acari: Trombiculidae

Cited by 5 publications

References 37 publications

Scrub typhus ecology: a systematic review of Orientia in vectors and hosts

Scrub typhus ecology: a systematic review of Orientia in vectors and hosts

Nationwide Incidence of Chigger Mite Populations and Molecular Detection of Orientia tsutsugamushi in the Republic of Korea, 2020

Detection ofOrientia tsutsugamushi, the Causative Agent of Scrub Typhus, in a Novel Mite Species,Eushoengastia koreaensis, in Korea

Contact Info

Product

Resources

About