Study on vector mites of tsutsugamushi disease in Cheju Island, Korea.

Because no reference on trombiculid mites (Acarina: Trombiculidae) in Cheju Island where tsutsugamushi disease is highly endemic had been available, studies on trombiculid mites in Cheju Island were implemented during the period of August 1991-April 1992, and the results obtained are summarized as follows: (1) The species and numbers of the field rodents collected were 143 Apodemus agrarius chejuensis (92.3%), 11 Crocidura lasiura (7.1%) and 1 Micromys minutus (0.6%). From total 12,075 chiggers harvested, 9 species of 4 genera in Trombiculidae were identified. (2) The predominant species through all seasons was L. zetum (43.3%), followed by L. orientale (27.4%) and L. scutellare (26.6%). However, in autumn when the most cases of tsutsugamushi disease occur, L. scutellare was prominently predominant, having 79.8% of the collected chiggers. (3) Among 1,142 L. scutellare examined for Rickettsia tsutsugamushi by means of IFA test, 6 individuals were found positive showing 0.5% of infection rate. This is the first finding that L. scutellare is the second vector species of tsutsugamushi disease in Korea. (4) Antibody positive rate of A. agrarius chejuensis sera were 31.2% (44/139), and 1 M. minutus serum was also found positive. The seropositive rates by season were not so significantly different.     

Apodemus agrarius as a new definitive host for Neodiplostomum seoulense

A total of 1,496 rodents and insectivores were live-trapped at Yeoncheon-gun (n = 351), Paju-shi (804), and Pocheon-gun (343), Gyeonggi-do (Province), and examined for intestinal helminths, including Neodiplostomum seoulense, seasonally from December 2004 to September 2005. Six species of rodents, including Apodemus agrarius (1,366), Mus musculus (32), Micronytus fortis (28), Eothenomys regulus (9), Micronys minutus (6), and Cricetulus triton (3), and 1 species of insectivores Crocidura lasiura (54) were collected. A total of 321 adult N. seoulense were collected from 19 (1.4%) A. agrarius. The worm burden ranged from 1 to 101 per A. agrarius (mean; 16.9). No N. seoulense was observed in other rodent or insectivore species examined. The infection rate during autumn (4.5%) was higher than those during spring (0.8%), summer (0.8%), and winter (0.5%). The average number of N. seoulense in infected A. agrarius was the highest in spring (66.0 specimens), followed by autumn (15.2), winter (4.5), and summer (3.3). This study first confirms that A. agrarius is a natural definitive host for N. seoulense, and demonstrates that the infection rates and intensities vary seasonally and geographically.     

Plagiorchis muris infection in Apodemus agrarius from northern Gyeonggi-do (Province) near the demilitarized zone

The small intestines of 6 species of rodents and 1 species of insectivore were examined seasonally for Plagiorchis muris infection in 3 different localities in northern Gyeonggi-do (Province), near the demilitarized zone (DMZ). A total of 1,496 animals, including 1,366 Apodemus agrarius, 54 Crocidura lasiura (insectivore), 32 Mus musculus, 28 Micronytus fortis, 9 Eothenomys regulus, 6 Micronys minutus, and 3 Cricetulus triton, were live-trapped at Yeoncheon-gun (n = 351), Paju-shi (804) and Pocheon-gun (343) at 3-mo intervals from December 2004 to September 2005. A total of 1,647 P. muris were collected from 72 (5.3%) A. agrarius. The infection rate was the highest in Pocheon-gun (8.2%), followed by Yeoncheon-gun (5.0%) and Paju-shi (4.2%). A higher infection rate was observed in A. agrarius captured during September (19.4%) than those captured during December (3.0%), June (2.6%), or April (0%). However, the worm burden was the highest in June (av. 32.1/animal), followed by September (24.7), December (4.0), and April (0). None of the other animal species were found infected with P. muris. The results reveal that A. agrarius is a natural definitive host for P. muris, and infection rates and worm burdens vary seasonally and geographically.     

Hantaan virus surveillance targeting small mammals at Dagmar North Training Area, Gyeonggi Province, Republic of Korea, 2001-2005

In response to a hemorrhagic fever with renal syndrome case in November 2000, a seasonal rodent-borne disease surveillance program was initiated at Dagmar North Training Area (DNTA), Gyeonggi Province, Republic of Korea. From April 2001-December 2005, 1,848 small mammals were captured. Apodemus agrarius accounted for 92.5%, followed by Mus musculus (3.6%), Crocidura lasiura (2.1%), and Microtus fortis (1.1%). Three species of rodents were found to be antibody-positive (Ab+) for Hantaan virus (HTNV): A. agrarius (22.3%), M. musculus (9.1%), and M. fortis (5.0%). Ab+ rates for A. agrarius increased with increasing weight (age), except for those weighing <10 g. The peak HTNV transmission period in Korea coincided with the peak reproductive potential of A. agrarius during the fall (August/September) surveys. HTNV strains from DNTA were distinct from HTNV strains from the People's Republic of China. From these studies, more accurate risk assessments can be developed to better protect personnel from rodent-borne diseases.     

从山东费县不同季节优势恙螨分离到恙虫病立克次体(英文)

对山东费县秋冬型恙虫病疫源地恙螨进行了调查并进行恙虫病立克次体（Ｒｔ）分离。从３５２只活鼠体外收集到１１ ７６２只恙螨,隶属２属５种,太平洋无前恙螨数量最多,占３６．７３％;其次是临淮岗纤恙螨（２４．０４％）;小盾纤恙螨（２１．６５％）;须纤恙螨（１３．５７％）和泰山纤恙螨（３．９６％）。小盾纤恙螨出现在９—１２月,高峰在１１月;须纤恙螨出现在１０月一翌年４月,高峰在１２月;临淮岗纤恙螨从５月到１１月存在,高峰在８月;太平洋无前恙螨出现在４—１２月,高峰在７月。从小盾纤恙螨、须纤恙螨、临淮岗纤恙螨及太平洋无前恙螨中共分离到１２株Ｒｔ,血清分型结果分离株以Ｇｉｌｌｉａｍ型为主,但存在Ｋａｒｐ型Ｒｔ。这些结果表明,上述４种恙螨均能自然感染Ｒｔ,有在该地区充作不同季节Ｒｔ传播媒介的可能。结合以往的研究结果,当地小盾纤恙螨集中出现于发病季节,其消长与当地人群发病基本一致,且能叮刺、经卵传递Ｒｔ,从而证实小盾纤恙螨是引起该地区秋冬型恙虫病流行的最重要的媒介。     

ISOLATION OF RICKETTSIA TSUTSUGAMUSHI FROM TROMBICULID MITES (ACARI:TROMBICULIDAE) IN FEIXIAN COUNTY, SHANDONG PROVINCE, CHINA

Abstract  Investigations on trombiculid mites and isolation of Rickettsia tsutsugamushi therefrom were carried out in Feixian County, Shandong Province. A total of 11 762 trombiculid mites, consisting of 5 species from two genera, were collected from 352 rodents (including 247 Apodemus agrarius , 80 Cricetulus triton , 23 Rattus noruegicus , 2 Crocidura suaveolens ), and Walchia pacifica was the most predominant (36.73%), followed by Leptotrombididium linhuaikonense (24.04%), L. scutellare (21.65%), L. palpale (13. 57%), and L. taishanium (3. 96%). L. scutellare was found from September to December with a remarkable peak in November, whereas L. palpale occurred from October to April (the second year) with peak in December. L. linhuaikonense was found from May to November, with peak in August. W. pacifica appeared from April to December with peak in July. R. tsutsugamushi was isolated from L. scutellare, L. palpale, L. linhuaikonense and W. pacifica . The main serotypes of R. tsutsugamushi isolated from the chigger mites were of the Gilliam type, but Karp type also existed in L. linhuaikonense . These results indicate that the surveyed area has a high probability of occurrence of tsutsugamushi disease, and L. scutellare, L. palpale, L. linhuaikonense and W. pacifica may serve as the vectors in this area. It is suggested that L. scutellare is the most important vector which has caused the endemic of this disease in Feixian County.     

Determination of the vector species of tsutsugamushi disease in Korea

In order to determine the vector species of tsutsugamushi disease in Korea, chiggers were individually dissected, and internal contents were tested for Rickettsia tsutsugamushi organisms by means of indirect FA test, and each exoskeleton was mounted on slide for identification. Among 4,142 chiggers collected from 48 Apodemus agrarius at nine different localities during the period of July-November, 1989, 990 chiggers of 10 species of Trombiculidae were dissected and tested. Rickettsiae were confirmed in two Leptotrombidium pallidum larvae out of 447 tested, giving 0.4% of the infection rate. The chiggers of the other species tested were found negative.     

Identification of potential hosts and vectors of scrub typhus and tick-borne spotted fever group rickettsiae in eastern Taiwan

Scrub typhus and tick-borne spotted fever group (SFG) rickettsioses are transmitted by chiggers (larval trombiculid mites) and hard ticks, respectively. We assessed exposure to these disease vectors by extensively sampling both chiggers and ticks and their small mammal hosts in eastern Taiwan during 2007 and 2008. The striped field mouse Apodemus agrarius Pallas (Rodentia: Muridae) was the most common of the small mammals (36.1% of 1393 captures) and presented the highest rate of infestation with both chiggers (47.8% of 110 760) and ticks (78.1% of 1431). Leptotrombidium imphalum Vercammen-Grandjean & Langston (Trombidiformes: Trombiculidae) and immature Rhipicephalus haemaphysaloides Supino (Ixodida: Ixodidae) were the most abundant chiggers (84.5%) and ticks (>99%) identified, respectively. Immunofluorescent antibody assay revealed high seropositive rates of rodents against Orientia tsutsugamushi Hyashi (Rickettsiales: Rickettsiaceae), the aetiological agent of scrub typhus (70.0% of 437 rodents), and tick-borne SFG rickettsiae (91.9% of 418 rodents). The current study represents a first step towards elucidating the potential hosts and vectors in the enzootic transmission of O. tsutsugamushi and tick-borne SFG rickettsiae in Taiwan. Further studies should focus on characterizing pathogens in L. imphalum and R. haemaphysaloides, as well as the proclivity of both vectors to humans. Uncovering the main hosts of adult ticks is also critical for the prevention of SFG rickettsial infections.     

Decreased prevalence of Orientia tsutsugamushi in trombiculid mites and wild rodents in the Primorye region, Far East Russia

The isolation of Orientia tsutsugamushi was attempted from 249 rodents and approximately 14,000 trombiculid mites captured in the Primorye region, Far East Russia in 1993 and 1994, where high infection rates were recorded in both rodents and mites in the 1960s. However, no rickettsia was isolated from the samples. Low antibody titers against O. tsutsugamushi were detected in 7.1% of the rodents. These results indicate that the prevalence of O. tsutsugamushi in the Primorye region has decreased considerably in the past 30 years.     

山东部分地区小兽类寄生恙螨的群落结构

用鼠笼捕捉活鼠,收集体外恙螨,分类计数,定量分析小兽类体外寄生恙螨的群落结构。探讨山东小兽类体外寄生恙螨群落结构及其与疾病的关系。结果表明,当地5种小兽类体外共有6种寄生恙螨。黑线姬鼠、大仓鼠体外寄生螨种较丰富,各有5种寄生螨。小盾纤恙螨宿主范围广,在4种小兽的体外均有发现。大仓鼠体外太平洋无前恙螨的带螨率和带螨指数最高(72．73％、52．00),临淮岗纤恙螨、泰山纤恙螨、须纤恙螨普遍寄生于黑线姬鼠、大仓鼠体外。黑线姬鼠与大仓鼠寄生螨群落多样性指数相对较高。黑线姬鼠寄生螨群落与大仓鼠的相似系数最大(39．2)。黑线姬鼠体外恙螨群落结构随季节变化而发生变化,恙螨群落的丰富度和多样性指数以冬季(12～2月)最低,春、秋季较高。     

猕猴、食蟹猴群中STLV-1病毒感染状况研究初报

[目的]摸清STLV-1感染现状,从而有效地降低STLV-1在猕猴、食蟹猴群中的的感染率。[方法]采用STLV-1ELISA法对猕猴、食蟹猴血清进行抗体检测。结果本中心送美国BioReliance公司的2455只出口猴血清,103份血清呈STLV-1抗体阳性,19份血清呈STLV-1抗体可疑,其余血清均为STLV-1抗体阴性。[结论]猕猴、食蟹猴群中STLV-1的平均感染率为4.97%,其中猕猴STLV-1感染率为2.7%,食蟹猴STLV-1感染率为5.4%,是猕猴STLV-1感染率的2倍;随着年龄的增长,猕猴(食蟹猴)STLV-1的感染率也随之升高。     

Species composition,abundance and habitat association of rodents and insectivores from Chilalo–Galama Mountain range,Arsi, Ethiopia

A study on the ecology of rodents and insectivores on Mount Chilalo and the Galama Mountain range was conducted during August, 2007–April, 2008. Study grids were marked in nine randomly selected habitats. Sherman live traps and snap traps were used to capture the small mammals. A total of 2525 (including recaptures) individual rodents and insectivores were captured in 5488 (Sherman) and 1590 (snap) trap‐nights. Among the live‐trapped animals, 2037 (96.2%) and 80 (3.8%) were rodents and insectivores, respectively, that comprised 17 species. These were as follows: Arvicanthis abyssinicus, Arvicanthis blicki, Arvicanthis dembeensis, Lophuromys flavopunctatus, Lophuromys melanonyx, Mastomys natalensis, Mus mahomet, Otomys typus, Rattus rattus, Stenocephalemys albipes, Stenocephalemys albocaudata, Stenocephalemys griseicauda, Crocidura glassi, Crocidura flavescens and Crocidura thalia. Tachyoryctes splendens and Hystrix cristata were sighted but not captured. Endemics to Ethiopia constituted 60% of the trapped small mammals. Lophuromys flavopunctatus was the most abundant and widely distributed rodent species, while M. mahomet was the least. The altitudes between 3301 and 3400 m asl had the highest species composition and abundance although it is second in number of catches per trap‐nights. The majority of rodents and insectivores were associated with montane forest habitat, whereas the least were in the shrubland. Anthropogenic effects were witnessed affecting the distribution of small mammals.     

Epidemiological characteristics of tsutsugamushi disease in Oita Prefecture, Japan: yearly and monthly occurrences of its infections and serotypes of its causative agent, Orientia tsutsugamushi, during 1984--2005.

Using indirect immunofluorescence assay, we examined the sera of 561 patients from November 1984 to February 2005 to determine the incidence of tsutsugamushi disease (scrub typhus) in Oita Prefecture, Japan. The results obtained were positive in 384 individuals (68.4%). Municipalities where patients were presumed to have been infected with Orientia tsutsugamushi were Taketa City (41.7%), Oyama Town (13.5%), and Ogi Town (8.3%). Infections occurred most often in October, November, and December. A small number of cases occurred from January to May. The serotypes Kuroki (47.5%), Kawasaki (42.5%), and Karp (10.0%) were detected by genetic analysis of O. tsutsugamushi DNA extracted from the blood of 120 patients. The gene sequences of the Kuroki type were highly homologous to that of the Nishino strain. The gene sequences of the Kawasaki type were identical to that of the Kawasaki strain. The gene sequence of the Karp type was highly homologous to that of the JP-2 type. To determine the distribution of vector mites, 558 wild rodents were captured and 72010 mites attached to these rodents were collected from 1982 to 1998. Six genera and 16 species of trombiculid mites were collected. Leptotrombidium pallidum and L. scutellare, which are known to be mite vectors for tsutsugamushi disease, accounted for 20.5% and 5.9%, respectively, of all trombiculid mites collected. The geographical distribution of cases roughly coincided with the distribution of L. scutellare. In Oita Prefecture, L. scutellare is presumed to primarily transmit tsutsugamushi disease. In addition, our results also suggest that L. pallidum transmits the Karp type of the causative rickettsia in some municipalities.     

大麝鼩能量生态初步研究

大麝鼩(Crocidura lasiura)是一种分布较广的食虫目动物,以往的工作仅限于对其形态及分布的描述。目前大麝鼩不仅成为上海地区农田生态系统中鼠形小兽群落内的优势种,而且也是当地流行性出血热(EHF)的主要传染源之一。但对其生态学研究几乎是空白。近年来,我们对大麝鼩的繁殖、食性和越冬等生态问题作了报道,并对其种群密     

Epidemiological characteristics of tsutsugamushi disease in Oita Prefecture, Japan: Yearly and monthly occurrences of its infections and serotypes of its causative agent, Orientia tsutsugamushi, during 1984–2005

Using indirect immunofluorescence assay, we examined the sera of 561 patients from November 1984 to February 2005 to determine the incidence of tsutsugamushi disease (scrub typhus) in Oita Prefecture, Japan. The results obtained were positive in 384 individuals (68.4%). Municipalities where patients were presumed to have been infected with Orientia tsutsugamushi were Taketa City (41.7%), Oyama Town (13.5%), and Ogi Town (8.3%). Infections occurred most often in October, November, and December. A small number of cases occurred from January to May. The serotypes Kuroki (47.5%), Kawasaki (42.5%), and Karp (10.0%) were detected by genetic analysis of O. tsutsugamushi DNA extracted from the blood of 120 patients. The gene sequences of the Kuroki type were highly homologous to that of the Nishino strain. The gene sequences of the Kawasaki type were identical to that of the Kawasaki strain. The gene sequence of the Karp type was highly homologous to that of the JP-2 type. To determine the distribution of vector mites, 558 wild rodents were captured and 72 010 mites attached to these rodents were collected from 1982 to 1998. Six genera and 16 species of trombiculid mites were collected. Leptotrombidium pallidum and L. scutellare , which are known to be mite vectors for tsutsugamushi disease, accounted for 20.5% and 5.9%, respectively, of all trombiculid mites collected. The geographical distribution of cases roughly coincided with the distribution of L. scutellare . In Oita Prefecture, L. scutellare is presumed to primarily transmit tsutsugamushi disease. In addition, our results also suggest that L. pallidum transmits the Karp type of the causative rickettsia in some municipalities.     

Epidemiological studies on the background of the endemic occurrence of tsutsugamushi disease in Toyama Prefecture. II. Anti-Rickettsia tsutsugamushi antibody-positive rate in inhabitants of endemic and nonendemic areas

With a view to clarifying the actual state of inapparent infection of tsutsugamushi diseases, inhibitants of endemic and nonendemic areas were screened for anti-Rickettsia tsutsugamushi antibody (anti-Rt antibody) by the indirect immunofluorescence test. The anti-Rt antibody-positive rate in the inhabitants of the endemic area (about 50%) was statistically significantly higher than that in the nonendemic area (14.7%). The antibody titer in the inhabitants of the endemic area was 10-160, and the number of inhibitants showing a high antibody titer was 2-4 times larger than that of the nonendemic area. A total of 257 volunteers in the endemic area were analyzed for the changes in anti-Rt antibody titer over 1.5-2 years on an individual basis. An increase in the antibody titer was found in 20 inhabitants. There was no difference in the anti-Rt antibody-positive rate between male and female in either the endemic or the nonendemic area. The positive rate was also compared as to the distribution by 10 years of age. In the endemic area, there were no significant differences in the positive rate between any pair of 10-year age groups from 30s to 60s, whereas in the nonendemic area, the positive rate in the teen-age group was significantly lower than those in the age groups of 20 years or older. In Yamada district, the numbers of serum samples obtained from each age group were about the same, and the distribution of the positive rates showed a normal distribution. The nurse students having their homes in Toyama Prefecture were plotted on the map as for their anti-Rt antibody and geographical distribution. The results showed that many of them having homes in the endemic area were positive for the antibody, while some antibody-positives were scattered all over Toyama Prefecture.     

Epidemiological studies on the background of the endemic occurrence of tsutsugamushi disease in Toyama Prefecture. I. Epidemiology of infection with Rickettsia tsutsugamuchi among field rodents in endemic and nonendemic areas

In order to clarify the epidemiological background of the endemic occurrence of tsutsugamushi disease in Toyama Prefecture, Japan, since 1978, comparative surveys have been carried out between endemic and nonendemic areas. Rickettsia tsutsugamushi (Rt) was isolated at a rate of about 36% (158/439) from field rodents in the endemic area while it was not isolated from any of 280 in nonendemic areas. In all of six stations in the endemic area, a significantly high proportion of rodents were found to be Rt carriers. However, no Rt was isolated from rodents captured from July to September. The organism was isolated from rodents captured in the other months, especially in a high proportion in November when infestation of rodents with Leptotrombidium pallidum was at its peak. When the rodents were examined by indirect immunofluorescence staining, the rate of anti-Rt antibody-positive animals was about 55% (157/287) and about 17% (62/368) in endemic and nonendemic areas, respectively. Larvae of mites collected from the rodents were found to belong to four genera and 11 species. Among them L. pallidum was the only mite that had been known to be a vector of Rt. L. pallidum was found most frequently and in abundance from rodents in the endemic area, whereas it was present in very small numbers in rodents in nonendemic areas. The infestation of rodents with L. pallidum showed a seasonal variation, i.e. two peaks per year, in spring and autumn, and the number of mites detected was markedly greater in November than in spring. Rt was isolated from L. pallidum on rodents captured in the endemic area.     

捕捉法ELISA检测脊髓灰质炎IgA抗体方法的建立与应用

建立了一种检测脊髓灰质炎(简称脊灰)IgA抗体的捕捉法ELISA(Aac-ELISA)。方法敏感,快速,特异,用于检测144份脊灰可疑病人的血清,IgA抗体检出率为77.8％(112/144).而这些血清的IgM抗体检出率为65.2％(94/144)。如同时检测IgM和IgA抗体,则阳性率可达91.7％(132/144)。麻痹后1～3天内IgA的检出率为76.5％(13/17),4～7天内为95％(19/20)。最长检出IgA的一例可疑病人,其血清收集于病后第59天。本方法在一部分16天后可疑病人IgM阴性血清中查出IgA阳性,故可以作为查IgM抗体诊断方法的补充,尤其适用于诊断感染后未能及时收到血清标本,IgM已经转阴而IgA抗体仍为阳性的病人。     

Seroprevalence of hantaviruses in small wild mammals trapped in South Korea from 2005 to 2010

The seroprevalence of Hantaan virus (HTNV) in wild rodents in South Korea was analyzed. Wild rodents were trapped in 18 cities in eight provinces during 2005-2007 and on three islands and four mountains during 2008-2010. Sera were collected from 629 out of 933 trapped wild animals and examined for immunoglobulin G antibodies to HTNV using indirect immunofluorescence assays. Apodemus agrarius (80.1%) was the most frequently captured species at almost all trapping sites. The overall prevalence of HTNV antibodies was 0.26 (162/629). Seropositive individuals were more frequent in cities (32.2%, n=410) than on islands (14.0%, n=57) or mountains (13.6%, n= 162). HTNV antibody-positive rate was higher in the fall (29.6%, n=253) than in the spring (23.1%, n=376). A. agrarius had the highest prevalence of HTNV antibodies (26.9%, n=561) of all tested species. Considering all the individuals, the prevalence of HTNV antibodies was higher in males (29.2%, n=250) than in females (22.3%, n=305). Our results show that HTNV is widely distributed throughout South Korea, and that HTNV infection of wild rodents is affected by their habitat, species, sex, and season.