National Institute for Public Health and the Environment, Centre for Infectious Disease Control, Bilthoven, Netherlands.
Appl Environ Microbiol. 2012 Aug;78(16):5661-5. doi: 10.1128/AEM.01169-12. Epub 2012 Jun 8.
Beginning in 2007, the largest human Q fever outbreak ever described occurred in the Netherlands. Dairy goats from intensive farms were identified as the source, amplifying Coxiella burnetii during gestation and shedding large quantities during abortions. It has been postulated that wild rodents are reservoir hosts from which C. burnetii can be transmitted to domestic animals and humans. However, little is known about the infection dynamics of C. burnetii in wild rodents. The aim of this study was to investigate whether brown rats (Rattus norvegicus) can be experimentally infected with C. burnetii and whether transmission to a cage mates occurs. Fourteen male brown rats (wild type) were intratracheally or intranasally inoculated with a Dutch C. burnetii isolate obtained from a goat. At 3 days postinoculation, a contact rat was placed with each inoculated rat. The pairs were monitored using blood samples and rectal and throat swabs for 8 weeks, and after euthanasia the spleens were collected. Rats became infected by both inoculation routes, and detection of C. burnetii DNA in swabs suggests that excretion occurred. However, based on the negative spleens in PCR and the lack of seroconversion, none of the contact animals was considered infected; thus, no transmission was observed. The reproduction ratio R(0) was estimated to be 0 (95% confidence interval = 0 to 0.6), indicating that it is unlikely that rats act as reservoir host of C. burnetii through sustained transmission between male rats. Future research should focus on other transmission routes, such as vertical transmission or bacterial shedding during parturition.
自 2007 年以来，荷兰发生了有史以来最大规模的人类 Q 热疫情。集约化农场的奶山羊被确定为传染源，在妊娠期间扩增了贝氏柯克斯体，并在流产时大量排出。有人推测，野生啮齿动物是库存储宿主，贝氏柯克斯体可以从这些宿主传播给家畜和人类。然而，人们对野生啮齿动物中贝氏柯克斯体的感染动态知之甚少。本研究旨在调查是否可以用贝氏柯克斯体实验感染褐家鼠（Rattus norvegicus），以及是否会传播给笼内同伴。14 只雄性褐家鼠（野生型）通过气管内或鼻内接种了从山羊中分离得到的荷兰贝氏柯克斯体分离株。在接种后 3 天，将一只接触鼠与每只接种鼠放在一起。通过血液样本和直肠及咽喉拭子监测这些配对动物 8 周，然后对处死的动物进行脾脏收集。通过两种接种途径，这些老鼠都被感染，并且拭子中贝氏柯克斯体 DNA 的检测表明存在排泄。然而，基于 PCR 检测到的阴性脾脏和缺乏血清转化，没有一只接触鼠被认为感染，因此没有观察到传播。繁殖比 R(0) 估计为 0（95%置信区间=0 至 0.6），这表明老鼠不太可能通过雄性老鼠之间的持续传播作为贝氏柯克斯体的宿主。未来的研究应集中在其他传播途径上，如垂直传播或分娩时的细菌排放。
