Walker D H, Fishbein D B
Department of Pathology, University of Texas Medical Branch, Galveston 77550.
Eur J Epidemiol. 1991 May;7(3):237-45. doi: 10.1007/BF00145672.
Rickettsial diseases have a diversity of epidemiologic characteristics reflective of the variety of ecologic situations in which the obligate intracellular bacteria are transmitted to humans. For the spotted fever group (SFG) rickettsiae, Rickettsia typhi, R. tsutsugamushi, Coxiella burnetii, and the human ehrlichial agent, humans are a dead-end host who plays no role in the maintenance of the organism in nature. All rickettsioses exist as zoonoses. Moreover, all rickettsiae are found in infected arthopods, which generally serve as the natural hosts and can transmit the infection to the next generation of ticks, mites, chiggers, or fleas. From our anthropocentric viewpoint, Q fever aerosol infection from parturient animals and Brill-Zinsser disease ignited epidemics of louse-borne epidemic typhus are exceptions. However, silent cycles of C. burnetii in ticks and R. prowazekii in the flying squirrel flea may have maintained these agents in transovarial or enzootic cycles for eons before humans and their domestic animals arrived on the scene. Thus, the epidemiology of rickettsial diseases must be recognized as an unfortunate aberration of the rickettsial economy. Several excellent reviews of rickettsial ecology contain a wealth of useful information.
立克次体病具有多种流行病学特征，反映了专性细胞内细菌传播给人类的各种生态环境。对于斑点热群（SFG）立克次体、伤寒立克次体、恙虫病东方体、贝纳柯克斯体和人类埃立克体病原体而言，人类是终末宿主，在自然界中对该病原体的维持不起作用。所有立克次体病均为人畜共患病。此外，所有立克次体都存在于受感染的节肢动物中，这些节肢动物通常作为自然宿主，并可将感染传播给下一代蜱、螨、恙螨或跳蚤。从我们以人类为中心的观点来看，来自分娩动物的Q热气溶胶感染以及虱传流行性斑疹伤寒的复发引发的流行是例外情况。然而，在人类及其家畜出现之前，蜱中的贝纳柯克斯体和松鼠蚤中的普氏立克次体的隐匿循环可能已经以经卵传递或动物流行病循环的方式维持这些病原体达无数年之久。因此，必须认识到立克次体病的流行病学是立克次体生态中的一个不幸的异常情况。关于立克次体生态学的几篇优秀综述包含了大量有用信息。
