National Center for Zoonotic and Emerging Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Gerogia 30333, USA.
Vector Borne Zoonotic Dis. 2011 Jul;11(7):979-84. doi: 10.1089/vbz.2010.0117. Epub 2010 Dec 13.
Classic murine typhus, caused by Rickettsia typhi, is endemic in the continental United States in areas of Texas and southern California. We conducted an environmental investigation in an urban area of Los Angeles identified as the probable exposure site for a case of murine typhus. Four Rattus norvegicus heavily infested with Xenopsylla cheopis (average 32.5 fleas per animal, range 20-42) were trapped, and fleas, blood, and tissues were collected. DNAs from all specimens were tested for R. typhi and Rickettsia felis using a TaqMan assay targeting the rickettsial citrate synthase gene. Although rickettsiemia was not detected, DNA of R. felis was detected in at least one tissue from each rat. Tissues from 3 rats were also positive for R. typhi DNA. R. typhi and R. felis DNAs were detected in fleas collected from each animal with average minimal infection rates of 10% and 32.3%, respectively. Although R. typhi still circulates in urban Los Angeles in the classic Oriental flea-rat cycle, R. felis is more prevalent, even in this association.
经典鼠型斑疹伤寒由伤寒立克次体引起，在美国德克萨斯州和加利福尼亚州南部的大陆地区流行。我们对洛杉矶一个城市地区进行了环境调查，该地区被确定为一例鼠型斑疹伤寒的可能暴露地点。捕获了四只严重感染印鼠客蚤的挪威鼠（平均每只动物 32.5 只跳蚤，范围 20-42），并采集了跳蚤、血液和组织。使用针对立克次体柠檬酸合酶基因的 TaqMan 检测法，对所有标本的 DNA 进行了伤寒立克次体和猫立克次体的检测。虽然未检测到立克次体血症，但从每只老鼠的至少一种组织中均检测到猫立克次体 DNA。3 只老鼠的组织也检测到了伤寒立克次体 DNA。从每只动物采集的跳蚤中均检测到了伤寒立克次体和猫立克次体 DNA，平均最小感染率分别为 10%和 32.3%。虽然伤寒立克次体仍在洛杉矶市区的经典跳蚤-鼠循环中传播，但猫立克次体更为普遍，甚至在这种关联中也是如此。
