Epidemiological Survey on the Tsutsugamushi Disease in Taiwan, in Connection with its High Prevalence in Recent Japan

除了典型的夏季型恙虫病外，日本还发现了一种主要发生在春季和秋季的新型恙虫病。自1976年以来，后者在日本各地急剧增加，成为一个严重的问题。另一方面，已知该疾病在东南亚区域死灰复燃。本研究的目的是为了了解台湾恙虫病在南北地区之间的几个共同流行病学因素。1985-1990年6年间，台湾报告（确诊）恙虫病病例660例（340例），但死亡病例仅有2例。发病时间以5 ~ 11月为主，6 ~ 7月为主高峰，10月为小高峰。采用3株恙虫病原型株，采用间接荧光抗体试验和免疫过氧化物酶试验对全岛居民采集的426份血清进行了反应性检测，其中54.9%为阳性。结果表明，台湾恙虫病立克次体对3个原型株和日本分离的低毒力菌株的反应性特异性较低，表明台湾恙虫病立克次体可能具有与日本菌株不同的抗原性。在平地和低丘采集到小兽恙虫7种，主要病媒轻恙螨（Leptotrombidium (L.) deliense）为主要媒介，占总数的90%以上。在阿里山共采集到恙虫7种，未检出恙虫。采集到与日本新型恙虫病主要病媒之一褐斑恙虫病螨相近的浅尾恙虫。从6只野生啮齿动物和2只家鼠中分离到恙虫立克次体，目前正在对其多肽组成和抗原成分进行详细分析。

Besides the classical summer type of tsutsugamushi disease, Japan has a new type which occurs mainly in spring and autumn. The latter has increased sharply since 1976 in various parts of Japan and becomes a serious problem. On the other hand, a resurgence of the disease is known in the Southeast Asian Region. The purpose of this field research is to obtain several common epidemiological factors of tsutsugamushi disease in Taiwan located between those northern and southern regions.1. The reported cases (confirmed cases) of tsutsugamushi disease in Tawian were 660 (340) for 6 years (1985-1990) but fatal cases were only 2. Most of the patients occurred between May to November, showing the main peak of June to July and small one of October.2. The reactivities of 426 sera collected from inhabitants of the whole island were examined by indirect fluorescent antibody test and immunoperoxidase test using 3 prototype strains of tsutsugamushi disease, and 54.9% were positive among them. The relatively low specificity in the reactivity to 3 prototypes and also to the low-virulent strains isolated in Japan were obtained, indicating that Rickettsia tsutsugamushi in Taiwan might have antigenic properties distinctive from Japanese strains.3. In the level lands and low hills 7 species of trombiculids were collected from small mammals and Leptotrombidium (L.) deliense, main vector of the disease, was predominant, occupying over 90% of the total number of them. On Mt. Alishan, 7 species of trombiculids were collected, but L. (L.) deliense was not detected. L. (L.) asanumai, which is close to L. (L.) scutellare, one of the main vectors of Japanese new type tsutsugamushi disease, was collected. Rickettsia tsutsugamushi was isolated from 6 wild rodents and 2 L. (L.) deliense, and their polypeptide composition and antigenic componentsare now being examined in detail.