• Parasites, Hosts and Diseases
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• 제52권2호
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• pp.225-229
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• 2014

A total of 9,281 larval chigger mites were collected from small mammals captured at Hwaseong-gun, Gyeonggi-do (Province) (2,754 mites from 30 small mammals), Asan city, Chungcheongnam-do (3,358 mites from 48 mammals), and Jangseong-gun, Jeollanam-do (3,169 for 62 mammals) from April-November 2009 in the Republic of Korea (= Korea) and were identified to species. Leptotrombidium pallidum was the predominant species in Hwaseong (95.8%) and Asan (61.2%), while Leptotrombidium scutellare was the predominant species collected from Jangseong (80.1%). Overall, larval chigger mite indices decreased from April (27.3) to June (4.9), then increased in September (95.2) and to a high level in November (169.3). These data suggest that L. pallidum and L. scutellare are the primary vectors of scrub typhus throughout their range in Korea. While other species of larval chigger mites were also collected with some implications in the transmission of Orientia tsutsugamushi, they only accounted for 11.2% of all larval chigger mites collected from small mammals.

• Parasites, Hosts and Diseases
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• 제50권4호
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• pp.327-331
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• 2012

Monthly surveys were conducted to investigate the occurrence of chigger mites and seroprevalence of scrub typhus among small mammals in Jeollanam-do, the southwestern part of Korea, from November 2006 through October 2007. Fifty-eight small mammals, including 57 Apodemus agrarius (98.3%) and 1 Crocidura lasiura (1.7%), were captured, and a total of 4,675 chigger mites representing 4 genera and 8 species were collected from them. The chigger infestation rate among small mammals was 69.0%. The most predominant species in A. agrarius was Leptotrombidium scutellare (54.0%), followed by Leptotrombidium pallidum (39.4%), Leptotrombidium orientale (4.4%), Leptotrombidium palpale (1.1%), Neotrombicula tamiyai (0.6%), Eushoengastia koreaensis (0.3%), Neotrombicula gardellai (0.3%), and Cheladonta ikaoensis (<0.1%). The chigger index of A. agrarius was the highest in October (740.0), followed by November (242.0), September (134.6), March (98.3), February (38.2), January (35.3), December (34.5), April (30.8), and May (1.7). The average antibody positive rate of scrub typhus in wild rodents was 50.0%. The seropositive rates were high in October (100.0%) and November (83.3%), whereas those in other months were relatively low (28.6-57.1%). The chigger index of L. scutellare rapidly increased in September to form an acuminate peak in October, followed by a gradual decline. These results suggest that the outbreak of scrub typhus in the southwestern part of Korean peninsula is mostly due to L. scutellare.

• Parasites, Hosts and Diseases
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• 제47권4호
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• pp.381-386
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• 2009

A survey to determine the geographical distribution and relative abundance of potential vectors of scrub typhus was conducted from October to November 2006 at 13 localities throughout the Republic of Korea. Apodemus agrarius accounted for 97.6% (80/82) of all rodents, while only 2 Myodes regulus (2/82) were collected. A total of 10,860 chiggers were collected from A. agrarius belonging to 4 genera and 8 species, while only Walehia fragilis (40) was collected from Myodes regulus. Leptotrombidium pallidum (8,137; 74.9%), a vector of scrub typhus, was the predominant species collected from A. agrarius followed by Leptotrombidium scutellare (2,057, 18.9%), Leptotrombidium palpale (279; 2.7%), Leptotrombidium orientale (232; 2.1%), and Leptotrombidium zetum (79; 0.7%), Neotrombicula tamiyai (58; 0.5%), Euschoengastica koreaensis (16; 0.1%), and Cheladonta ikaoensis (2; < 0.1 %). L. pallidum was the predominant chigger collected at collection sites in Gangwon (100%), Gyeonggi (87.2%), Chungnam (100%), Chungbuk (100%), Jeonbuk (73.9%), Jeonnam (77.0%), and Gyeongbuk (66.1%) provinces, whereas L. scutellare was the predominant chigger collected in Gyeongnam province (77.9%) and Jeju Island (62.3%). Data suggest a correlation between chigger population abundance and human cases of scrub typhus in Korea.

• The Korean Journal of Ecology
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• 제19권1호
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• pp.31-37
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• 1996

The chigger mites known as the vectors of Tsutsugamushi disease seriously increased due to the expansion of their habitats by the change of farmland into idle land, arboreta and golf courses with the progress of industrialization. These mites were surveyed for their nymphs in soil of four areas located in the northern part of Kyonggido known as the outbreak areas of Tsutsugamushi disease. Total number of the chigger mites collected in the soil of four surveyed areas was 2576, and two genera and ten species including Leptotrombidium palpale were indentified. Among them L. pallidum was the dominant species with the highest occurrence rate of 62 percent. Nine species occurred on the bank of Changrungchon that has been idled for more than ten years, but six or seven species occurred in Wonhundong and Ilsandong that hans been idled for less than five years. The number of individuals collected was also higher in Changrungchon than the other sites. Seasonal occurrence of these mites showed a peak with 166 mites in November on the west slope and another with 192 mites in February on the east slope of the bank of Changrungchon, but none in June. Component ratio of individual numbers for L. palpale, L. pallidum, L. orientalis and L.scutelaris were 19, 62, 9 and 3 percent, respectively. Individual number of L. pallidum and L. scutelaris appeared to some extent of 397 and 23 mites, respetively.

• 한국토양동물학회지
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• 제11권1_2호
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• pp.1-6
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• 2006

The chigger is of importance to humans and animals as an irritating pest and a crucial vector of disease. We observed stylostome formation by larvae of Leptotrombidium pallidum in parasitized striped-field mouse (Apodemus agarius) pinna skin. The stylostome formations were also examined in detail by electron microscopy. The proximal and middle parts of the stylostome were formed as a rod-like structure containing a canal. The stylostome was coated with thick degenerated epidermal cells, and seemed to be formed a hyperplastic epidermis. The stylostome formation may result from an interaction between larval secretions and the host tissue. According to histological and morphological characteristics, the stylostome exhibited considerable inflammation in the epidermis and similar reactivity.

• Parasites, Hosts and Diseases
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• 제27권2호
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• pp.141-144
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• 1989

1987년 10월부터 12월에 걸쳐 경기도 포천군 이개 부락과 경상남도 진해시 일개 부락에 서 채집한 등줄쥐(Apedemus agrariuscoreae)의 이개에 기생한 털진드기유를 조사하여 다음과 같은 결과를 얻었다. 채집된 171필의 등줄쥐 중 58필에서 털진드기가 잡혀 기생률은 33.9%이었다. 그 중 한 종만 발견된 숙주가 27필(46.6%)로 가장 많았고, 기생 종수가 많아질수록 감소하였으며 5종이 기생하는 쥐는 2필(3.4%)뿐이었다. 총 865개체의 털진드기 유충을 동정한 결과 Leptotrombidium Pallidum (4.3%), L. palpate(23.0%), L. orientalis(20.2%), L. wetum(19.0%), Neotrombicula tamiyai (32.9%), N. japonica(0.2%) 및 Euschongastia koreaensis(0.3%)의 7종이 확인되었다. 그 중 N. tamiyai가 285개체(32.9%)로 가장 많았으나 이 종은 일개 지역에서 12월에만 집중 채집되었으므로 우리 나라 우점종은 전 조사지역과 기간에 고루 분포되어 있는 것으로 나타난 L. palpale라 추측된다. 쭈쭈가무시병의 매개종인 L. pallidum은 37개체가 채집되어 전체의 4.3%에 불과하였다. 한 숙주에 기생하는 털진드기의 밀도는 1개체로부터 최고 207개체까지 심한 차이를 보였는데 개체마다 한 두 종이 집중 기생하는 경향을 나타내었다.

• 한국동물학회지
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• 제36권3호
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• pp.408-415
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• 1993

털진드기 개체군에 대한 지리적 분포상과 계절적 소장에 관한 조사를 1990년 8월부터 1991년 12월까지 실시하여 다음과 같은 결과를 얻었다. Sherman trap을 사용하여 포획한 325마리의 들쥐들로부터 총 15,679개체의 털진드기를 채집하여 4속 12종을 동정하였는데, 쭈쭈가무시병의 매개종인 Leptotrombidium pallidum이 4,751개체로 전체의 30.3%를 차지하여 우점종이었고, 제2의 매개종으로 알려진 L. scutellare는 1,132개체로 전체의 7.2%을 차지하였다. 털진드기 개체군의 지리적 분포상이 종에 따라 심한 차이를 보이며 각 조사 지역마다 우점종이 다르게 나타났는데, 경기도 고양군 도래 5리에서는 L. pallidum, 포천군 산정리에서는 Neotrombicula kwangneungensis, 파주군 장곡리에서는 N. tamiyai, 전북 익산군 장신리에서는 L. orientale, 이리시 신용동에서는 L. scutellare 등이었다. 털진드기 개체군의 계절적 소장을 보면, L. pallidum은 2개의 정점을 보였는데 10-11월에 큰 정점을, 4-5월에 작은 정점을 보인 후 여름에는 거의 자취를 감추었고 L. scutellare는 10월에만 집중적으로 나타났다.

• Parasites, Hosts and Diseases
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• 제54권4호
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• pp.509-518
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• 2016

Parasites are recorded from the red squirrel, Sciurus vulgaris, from Cheongju, the Republic of Korea. A total of 5 road-killed squirrels were thoroughly examined for internal and external parasites from November 2011 to May 2014. Total 4 parasite species, including 1 tapeworm and 3 ectoparasite species were recovered. They were morphologically identified as Catenotaenia dendritica (Cestoda: Catenotaeniidae), Hirstionyssus sciurinus, Leptotrombidium pallidum, and Ceratophyllus (Monopsyllus) indages. Among them, C. dendritica and H. sciurinus are recorded for the first time in the Korean parasite fauna. In addition, the possibility that the red squirrel could act as a reservoir host for a zoonotic disease like tsutsugamushi disease with L. pallidum as its vector has been raised.

• Parasites, Hosts and Diseases
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• 제59권5호
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• pp.473-479
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• 2021

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.

• Journal of Ecology and Environment
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• 제41권3호
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• pp.107-113
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• 2017

Background: As the habitat changes in Korea due to climate change, the emergence of disease-mediated vectors is increasing rapidly. Thus for the surveillance of mosquito- and chigger mite-borne disease, their seasonal prevalence and species composition were investigated at seven locations in Daegu, Gunwi and Sangju. Methods: Mosquitoes were collected twice every month from five collection sites using a black light and BG sentinel traps in Daegu and Gunwi from April through November. Chigger mites were investigated twice per month from wild rodents caught with Sherman live traps in Gunwi and Sangju from April through May and September through November. Results: A total of 2,361 female mosquitoes were collected. Cowshed (626 individuals, Trap index (TI) 44.7) and Kyungpook National University campus (846 individuals, TI 60.4) in Daegu had the highest number of mosquitoes in the black light and BG sentinel trap, respectively. The mosquitoes were collected more by BG sentinel trap than the black light trap. Nine mosquito species were trapped, and the Culex pipiens complex was the most commonly mosquito (1,397 individuals, 59.2%), followed by Anopheles sinensis (554 individuals, 23.5%). Anopheles sinensis (531 individuals, 51.9%) and Culex pipiens complex (1,142 individuals, 85.4%) were the most mosquitoes from black light and BG sentinel trap, respectively. In terms of seasonal prevalence, the highest abundance was in July, with 824 individuals collected. In chigger mites, eighty-one wild rodents of five species that are hosts of chigger mites were collected; among them, 53 and 25 individuals of Apodemus agrarius and Crocidura suaveolens, respectively were trapped. Leptotrombidium pallidum was a dominant species, with 2,467 individuals collected (67.8%). Conclusions: The mosquito was the dominant species in Culex pipiens complex and the highest in July and August. Apodemus agrarius was most abundant in wild rats and Leptotrombidium pallidum was dominant in the collected chigger mites.