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Mechanisms and Perspectives of recurrent outbreaks of tsutsugamushi disease

恙虫病反复暴发的机制和前景

基本信息

批准号：
62571011
负责人：
UCHIKAWA Kimito
金额：
$ 1.28万
依托单位：
Shinshu University School of Medicine
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1987
资助国家：
日本
起止时间：
1987 至 1989
项目状态：
已结题

项目摘要

In order to gain perspectives of the endemicity of tsutsugamushi disease, the present study was aimed at clarifying the mechanism of recurrent outbreaks of the disease by investigating ecological aspects of the vector chiggers, which have been suggested to have characteristic environmental requirements and restricted distributions. We have intended to specify the habitat type for Leptotrombidium pallidum to incorporate results to be obtained into discussion whether the recent trend in environmental changes is advantageous to the vector chigger to propagate abundantly or not. L. pallidum was found in many types of habitats, but the most common habitat was large paddy banks, which have been made during the recent paddy zone reconstruction program. Since the areas in which disease cases have been reported have gradually widen to cover most of the range of L. pallidum, environmental changes such as those mentioned above and, as pointed out previously, the reversion of agricultural lands to … More desolated fields in the recently depopulated districts are thought to have contributed to an increase in vector population density and are probably responsible for the recurrent outbreaks of tsutsugamushi disease transmitted by this vector, although the incidence of pathogenic rickettsiae in the chiggers has only been partially studied. So it is postulated that tsutsugamushi disease caused by L. pallidum will continue to be endemic, at least at the current scale, especially in reconstructed paddy zones as well as in further depopulated districts. The other vector chigger, Leptotrombidium scutellare, was shown to be distributed at well drained sites at the foot of mountains in the Gotenba-Oyama District, shizuoka Prefecture. The specific habitat for this species was the sparse miscanthus grassland on granular soil in sunny places, which is sporadically encountered in the district. It is difficult to incorporate these findings into the recurrent outbreak of tsutsugamushi disease transmitted by L. scutellare, but is not difficult to postulate that outbreaks of many cases at a time might readily occur within restricted areas, because of the vector's specific distributional pattern. Less

为了进一步了解恙虫病的地方性，本研究旨在通过对恙虫病媒介恙虫的生态学研究，阐明恙虫病反复暴发的机制。恙虫病媒介恙虫有其特有的环境要求和有限的分布。我们打算详细说明白衣细恙的生境类型，以便将得到的结果纳入讨论最近的环境变化趋势是否有利于媒介恙虫的大量繁殖。在多种生境中均有发现，但最常见的生境为大型水田滩，这是近年来稻田带重建工程中形成的。由于报告疾病病例的地区逐渐扩大，覆盖了苍白乳杆菌的大部分范围，环境变化，如上文所述，以及前面指出的，在最近人口减少的地区，更多的荒地被认为是导致病媒人口密度增加的原因，并可能是由该病媒传播的恙虫病反复暴发的原因，尽管对恙螨致病性立克次体的发病率只进行了部分研究。因此，至少以目前的规模，特别是在重建的水田区以及人口进一步减少的地区，由苍白螺旋体引起的恙虫病将继续流行。另一媒介恙虫scutellleptotrombidium分布于静冈县gotenbaa - oyama地区山脚下排水良好的地点。本种特有的生境为阳光充足的粒状土壤上稀疏的芒草草地，区内零星分布。很难将这些发现纳入由褐螺旋体传播的恙虫病的反复暴发，但不难假设，由于病媒的特定分布模式，一次暴发许多病例可能很容易在限制区域内发生。少