Krasnov Boris R, Shenbrot Georgy I, Khokhlova Irina S, Hawlena Hadas, Degen A Allan
Ramon Science Center and Mitrani Department of Desert Ecology, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, P.O. Box 194, Mizpe Ramon 80600, Israel.
Parasitol Res. 2006 Oct;99(5):541-5. doi: 10.1007/s00436-006-0201-4. Epub 2006 Apr 21.
Host individuals not infested by parasites at a given time are either permanently free from parasites or could be infested at other times. We studied temporal variation in the presence or absence of fleas (Siphonaptera) on individual rodents of two species (Gerbillus dasyurus and Acomys cahirinus) and questioned if and how an individual rodent can change its infestation status temporally. Change in infestation status by fleas over time was found in 45.5% of G. dasyurus and 35.9% of A. cahirinus. In both host species, the proportion of individuals that either changed or did not change their infestation status did not differ from the null expectation of 1:1. No difference between the proportions of infested at two consecutive captures and uninfested at two consecutive captures animals was found in A. cahirinus, whereas the proportion of G. dasyurus infested by fleas at two consecutive captures was significantly greater than that of uninfested at two consecutive captures individuals. In both host species, similar proportions of individuals changed their infestation status either from being infested to being uninfested or vice versa. Among individuals of both species that were initially infested by fleas, similar proportions changed and did not change their subsequent infestation status. The same was true for the uninfested at the first capture A. cahirinus. However, among initially uninfested G. dasyurus, the proportion of individuals that remained uninfested was significantly greater than that of the individuals newly infested by fleas. In A. cahirinus, the probability to change the infestation status did not depend on the initial status of an individual. In G. dasyurus, the probability of the initially uninfested individuals to be subsequently found still uninfested was higher than to be subsequently found harboring fleas, whereas initially infested individuals could be subsequently found either still infested or flea-free with equal probability.
在特定时间未被寄生虫感染的宿主个体，要么一直未感染寄生虫，要么在其他时间可能被感染。我们研究了两种啮齿动物（大耳沙鼠和埃及刺毛鼠）个体身上跳蚤（蚤目）有无的时间变化，并探讨了单个啮齿动物是否以及如何在时间上改变其感染状态。在45.5%的大耳沙鼠和35.9%的埃及刺毛鼠中发现了跳蚤感染状态随时间的变化。在这两种宿主物种中，感染状态发生变化或未发生变化的个体比例与1:1的零期望值没有差异。在埃及刺毛鼠中，连续两次捕获时被感染和未被感染的动物比例没有差异，而连续两次捕获时被跳蚤感染的大耳沙鼠比例显著高于连续两次捕获时未被感染的个体比例。在这两种宿主物种中，相似比例的个体改变了其感染状态，要么从被感染变为未被感染，要么反之。在最初被跳蚤感染的两种物种的个体中，相似比例的个体改变了并未改变其随后的感染状态。首次捕获时未被感染的埃及刺毛鼠也是如此。然而，在最初未被感染的大耳沙鼠中，仍未被感染的个体比例显著高于新被跳蚤感染的个体比例。在埃及刺毛鼠中，改变感染状态的概率不取决于个体的初始状态。在大耳沙鼠中，最初未被感染的个体随后仍未被感染的概率高于随后被发现携带跳蚤的概率，而最初被感染的个体随后可能仍被感染或无跳蚤，概率相等。
