Iwasa M, Kasuya S, Noda N, Hioki A, Ito A, Ohtomo H
Department of Parasitology, Gifu University School of Medicine, Japan.
J Med Entomol. 1990 Jul;27(4):501-8. doi: 10.1093/jmedent/27.4.501.
Investigations of trombiculid mites and Rickettsia tsutsugamushi in wild rodents were made in southern Gifu Prefecture where patients infected with tsutsugamushi disease recently have been found. A total of 16,396 trombiculid mites, consisting of 10 species from three genera, was collected from 170 Apodemus speciosus in two locations. Kani-Sakahogi and Kuze. Leptotrombidium scutellare (Nagayo et al.) (44.0%) was most predominant, followed by L. pallidum (Nagayo et al.) (26.9%); L. fuji (Kuwata et al.) (13.6%); and Gahrliepia saduski Womersley (14.2%). These four species constituted the bulk of the chigger mite fauna. L. scutellare was present from October to February with a remarkably high peak in November, whereas pallidum occurred from November to March with the highest peak in December. L. fuji and G. saduski showed their highest peaks in December and moderate peaks in early summer (April and May). Positive identification of Rickettsia tsutsugamushi in wild rodents from Kani-Sakahogi were found to be 50 and 58.3% in November 1985 and 1986, respectively, and 38.5% in November 1986 from Kuze. R. tsutsugamushi was isolated from chigger mites of an L. pallidum-rich group, displaying the highest titer to Karp strain. Serological investigation of rodents to R. tsutsugamushi antibodies were calculated as 41.6 and 50% positive in November 1985 and 1986 in Kani-Sakahogi, respectively, and 50% in November 1986 in Kuze. The Karp strain was dominant in specificity to antibodies. These results indicate that the surveyed areas have a high probability of occurrence of tsutsugamushi disease, and L. scutellare and L. pallidum may serve as the vectors in these areas. Particularly, we suggest that L. scutellare is the most important vector which has caused a recent outbreak of this disease in southern Gifu Prefecture.
在岐阜县南部进行了野生啮齿动物中恙螨和恙虫病立克次体的调查，该地区近期发现了恙虫病感染患者。在两个地点（Kani-Sakahogi和Kuze）从170只日本田鼠身上共采集到16396只恙螨，分属于3个属的10个物种。小板纤恙螨（Nagayo等人）（44.0%）最为常见，其次是苍白纤恙螨（Nagayo等人）（26.9%）；富士纤恙螨（Kuwata等人）（13.6%）；以及佐杜斯盖氏恙螨（Womersley）（14.2%）。这4个物种构成了恙螨动物区系的主体。小板纤恙螨在10月至2月出现，11月有一个非常高的峰值，而苍白纤恙螨在11月至3月出现，12月有最高峰。富士纤恙螨和佐杜斯盖氏恙螨在12月出现最高峰，在初夏（4月和5月）有中等峰值。在Kani-Sakahogi的野生啮齿动物中，1985年11月和1986年11月恙虫病立克次体的阳性鉴定率分别为50%和58.3%，1986年11月在Kuze为38.5%。恙虫病立克次体从富含苍白纤恙螨的一组恙螨中分离出来，对Karp株显示出最高滴度。1985年11月和1986年在Kani-Sakahogi对啮齿动物进行的恙虫病立克次体抗体血清学调查中，阳性率分别计算为41.6%和50%，1986年11月在Kuze为50%。Karp株在抗体特异性方面占主导地位。这些结果表明，调查区域恙虫病发生的可能性很高，小板纤恙螨和苍白纤恙螨可能是这些地区的传播媒介。特别是，我们认为小板纤恙螨是导致岐阜县南部近期该病爆发的最重要传播媒介。
