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，日本还有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，东南亚地区的疾病又死灰复燃。本研究的目的在于探讨台湾地区介于北方与南方之间的恙虫病常见流行因素. 1985-1990年6年来，塔威县报告的恙虫病病例（确诊病例）为660（340）例，但死亡病例仅为2例。5 ~ 11月为发病高峰期，6 ~ 7月为发病高峰期，11月为发病小高峰期.用3株恙虫病原毒株对全岛居民426份血清进行间接荧光抗体试验和免疫过氧化物酶试验，阳性率为54.9%。结果显示，台湾地区恙虫病立克次体对3种原型株及日本分离的弱毒株的特异性较低，提示台湾地区恙虫病立克次体可能具有不同于日本株的抗原特性.在平地和低山丘陵区采集到小型兽类和纤恙螨Leptotrombidium（L.）主要媒介为deliense，占总虫量的90%以上。山上阿里山采集到恙螨7种，但L.（L.）未检测到deliense。L.（L.）asanumai与L.（L.）收集了日本新型恙虫病的主要媒介之一--小盾蚧。从6只野生鼠和2只恙虫病立克次体中分离到恙虫病立克次体。（L.）deliense，其多肽组成和抗原成分正在详细研究中。

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.