Kamiya H, Tada Y, Matsuda H, Tanaka H, Blas B L, Noseñas J S, Santos A T
Jpn J Exp Med. 1980 Oct;50(5):375-82.
The annual fluctuation of Schistosoma japonicum infection in field rats, Rattus rattus mindanensis, in Leyte, the Philippines was investigated. One hundrend live-traps were set for one week every month from February, 1978 to February, 1979, in and around Central Elementary School II, Diagami, Leyte. Out of 199 rats, 163 (81.9%) were infected. The prevalence rate of S. japonicum infecton in rats was high during the relatively dry season, April to July, 1978. Meanwhile, the prevalence rate of schistosome cercariae in Oncomelania quadrasi of the study area increased during the relatively rainy season, October, 1978 to February, 1979. It is supposed that miracidia hatched from eggs discharged in the feces of rats during the relatively dry season would encounter snails, following which the emerging cercariae would penetrate the mammalian hosts, such as humans and rats, during the relatively rainy season. This might be the transmission dynamics of schistosomiasis in the endemic areas of Leyte. It is also suggested that this annual prevalence rate could be used as a parameter to formulate and evaluate control works. No infection was established in the youngest age group, the weanling. Then, the prevalence increased gradually by age. All rats of the older age group were infected. According to age composition, the field rat had no definite breeding season in Leyte. COP reaction was weak in sera of infected rats, but strongly exhibited in sera from rats possessing eggs in the spleen. Consequently, field rats not only maintain the infection as reservoir hosts, but also are an important source of infection as definitive hosts in the endemic areas of Leyte Island. Specifically, the rat role must be stressed, should human schistosomiasis ever be controlled.
对菲律宾莱特省棉兰老褐家鼠体内日本血吸虫感染的年度波动情况进行了调查。1978年2月至1979年2月，每月在莱特省迪亚加米第二中央小学及其周边设置100个活捉陷阱，放置一周。在捕获的199只大鼠中，163只（81.9%）被感染。1978年4月至7月相对干燥的季节里，大鼠日本血吸虫感染率较高。同时，研究区域内拟钉螺体内血吸虫尾蚴的感染率在1978年10月至1979年2月相对多雨的季节有所上升。据推测，在相对干燥的季节，大鼠粪便中排出的虫卵孵化出的毛蚴会遇到钉螺，随后孵出的尾蚴会在相对多雨的季节侵入人类和大鼠等哺乳动物宿主。这可能是莱特省血吸虫病流行地区的传播动态。还表明，这种年度感染率可作为制定和评估防治工作的一个参数。最年幼的年龄组即断奶幼鼠未发现感染。然后，感染率随年龄逐渐上升。所有年龄较大的大鼠组均被感染。根据年龄组成，莱特省的野生大鼠没有明确的繁殖季节。感染大鼠血清中的环卵沉淀反应较弱，但脾脏中有虫卵的大鼠血清中该反应强烈。因此，野生大鼠不仅作为储存宿主维持感染，而且在莱特岛流行地区作为终末宿主也是重要的感染源。具体而言，如果要控制人类血吸虫病，必须强调大鼠的作用。
