Standaert S M, Dawson J E, Schaffner W, Childs J E, Biggie K L, Singleton J, Gerhardt R R, Knight M L, Hutcheson R H
Epidemic Intelligence Service, Centers for Disease Control and Prevention, Atlanta, USA.
N Engl J Med. 1995 Aug 17;333(7):420-5. doi: 10.1056/NEJM199508173330704.
Ehrlichiosis due to Ehrlichia chaffeensis usually occurs sporadically or in small clusters, with an annual incidence estimated at 3 to 5 cases per 100,000 population in areas of endemic disease. The putative principal vector is the Lone Star tick (Amblyomma americanum). We investigated an outbreak of ehrlichiosis that occurred in June 1993 among members of a golf-oriented retirement community (community A) in Tennessee. The community is densely wooded and borders a wildlife-management area where deer are numerous.
We conducted a case-control study, using medical-history reviews, serologic testing, and testing with the polymerase chain reaction for E. chaffeensis infection. We also surveyed a sample of 10 percent of the households in community A and in another golf-oriented community (community B) more than 20 miles (32 km) from the wildlife-management area. Survey participants completed a questionnaire and provided specimens for serologic testing. In both communities, searches for ticks were undertaken.
Eleven cases of symptomatic ehrlichiosis were identified in the case-control study, 10 of which were in community A (attack rate, 330 per 100,000). Of 311 surveyed residents of community A, 12.5 percent had serologic evidence of past E. chaffeensis infection, as compared with 3.3 percent of 92 in community B (relative risk in community A as compared with community B, 3.9; 95 percent confidence interval, 1.2 to 12.2). The risk of infection was associated with tick bites, exposure to wildlife, golfing, and among golfers, retrieving lost golf balls from the rough. Persons who never used insect repellent were more likely to have had infection than persons who did. In community A, thousands of Lone Star ticks were found; in community B, only three ticks were found.
The high rate of E. chaffeensis infection in community A resulted from its proximity to a wildlife reserve. When outdoor recreational activities are common and concentrations of ticks are high, outbreaks of arthropod-borne zoonoses can be anticipated.
查菲埃立克体引起的埃立克体病通常呈散发性或小范围聚集性发病，在该病的流行地区，估计年发病率为每10万人中有3至5例。公认的主要传播媒介是孤星蜱（美洲钝缘蜱）。我们调查了1993年6月在田纳西州一个以高尔夫运动为特色的退休社区（A社区）居民中发生的一次埃立克体病暴发。该社区树木繁茂，毗邻一个野生动物管理区，那里鹿群众多。
我们进行了一项病例对照研究，采用病史回顾、血清学检测以及聚合酶链反应检测查菲埃立克体感染情况。我们还对A社区10%的家庭样本以及距离野生动物管理区20多英里（32公里）的另一个以高尔夫运动为特色的社区（B社区）进行了调查。调查参与者填写了一份问卷，并提供了血清学检测样本。在两个社区都进行了蜱虫搜索。
在病例对照研究中确定了11例有症状的埃立克体病病例，其中10例在A社区（发病率为每10万人中有330例）。在接受调查的311名A社区居民中，12.5%有既往查菲埃立克体感染的血清学证据，而B社区92名居民中有3.3%有此类证据（A社区与B社区相比的相对风险为3.9；95%置信区间为1.2至12.2）。感染风险与蜱虫叮咬、接触野生动物、打高尔夫球以及在高尔夫球手当中从草丛中找回丢失的高尔夫球有关。从不使用驱虫剂的人比使用驱虫剂的人更易感染。在A社区发现了数千只孤星蜱；在B社区仅发现了三只蜱虫。
A社区查菲埃立克体感染率高是因其靠近野生动物保护区。当户外娱乐活动频繁且蜱虫密度高时，可预期会出现节肢动物传播的人畜共患病暴发。
