RMSF 仅发生于西半球,是最常见的斑疹热型 (SFG) 立克次体病。通过被动监测,发现美国 2008 到 2012 年间的 SFG 立克次体病的平均年发病率为 8.9 例/百万人。[2]Drexler NA, Dahlgren FS, Heitman KN, et al. National surveillance of spotted fever group rickettsioses in the United States, 2008-2012. Am J Trop Med Hyg. 2016;94:26-34.http://www.ncbi.nlm.nih.gov/pubmed/26324732?tool=bestpractice.com RMSF 和其他 SFG 立克次体病的发病率正在增加,在 1997-2002 和 2004-2007 之间已增加三倍。[2]Drexler NA, Dahlgren FS, Heitman KN, et al. National surveillance of spotted fever group rickettsioses in the United States, 2008-2012. Am J Trop Med Hyg. 2016;94:26-34.http://www.ncbi.nlm.nih.gov/pubmed/26324732?tool=bestpractice.com[3]Openshaw JJ, Swerdlow DL, Krebs JW, et al. Rocky mountain spotted fever in the United States, 2000-2007: interpreting contemporary increases in incidence. Am J Trop Med Hyg. 2010;83:174-182.http://www.ajtmh.org/content/83/1/174.longhttp://www.ncbi.nlm.nih.gov/pubmed/20595498?tool=bestpractice.com在此期间,报告的 SFG 立克次体病病例中有 63% 来自美国的阿肯色州、密苏里州、北卡罗莱纳州、俄克拉何马州和田纳西州。[2]Drexler NA, Dahlgren FS, Heitman KN, et al. National surveillance of spotted fever group rickettsioses in the United States, 2008-2012. Am J Trop Med Hyg. 2016;94:26-34.http://www.ncbi.nlm.nih.gov/pubmed/26324732?tool=bestpractice.com但是,美国大多数州都有病例报告,而且,最近发现亚利桑那州的报告病例数出现了显著的区域性增高,尤其是在美国印第安人的保留区。由于发现晚或根本未能识别,因此亚利桑那州的病死率尤其高。[7]Traeger MS, Regan JJ, Humpherys D, et al. Rocky Mountain spotted fever characterization and comparison to similar illnesses in a highly endemic area - Arizona, 2002-2011. Clin Infect Dis. 2015;60:1650-1658.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4699465/http://www.ncbi.nlm.nih.gov/pubmed/25697743?tool=bestpractice.com加拿大、墨西哥、中美洲以及南美洲也有确诊病例。[8]Galvao MA, Dumler JS, Mafra CL, et al. Fatal spotted fever rickettsiosis, Minas Gerais, Brazil. Emerg Infect Dis. 2003;9:1402-1405.http://wwwnc.cdc.gov/eid/article/9/11/03-0193_articlehttp://www.ncbi.nlm.nih.gov/pubmed/14718082?tool=bestpractice.com50~69 岁的成年人发病率最高,儿童发病高峰期在 5~9 岁之间。[2]Drexler NA, Dahlgren FS, Heitman KN, et al. National surveillance of spotted fever group rickettsioses in the United States, 2008-2012. Am J Trop Med Hyg. 2016;94:26-34.http://www.ncbi.nlm.nih.gov/pubmed/26324732?tool=bestpractice.com[3]Openshaw JJ, Swerdlow DL, Krebs JW, et al. Rocky mountain spotted fever in the United States, 2000-2007: interpreting contemporary increases in incidence. Am J Trop Med Hyg. 2010;83:174-182.http://www.ajtmh.org/content/83/1/174.longhttp://www.ncbi.nlm.nih.gov/pubmed/20595498?tool=bestpractice.com一半偏多的报告病例为男性患者。[2]Drexler NA, Dahlgren FS, Heitman KN, et al. National surveillance of spotted fever group rickettsioses in the United States, 2008-2012. Am J Trop Med Hyg. 2016;94:26-34.http://www.ncbi.nlm.nih.gov/pubmed/26324732?tool=bestpractice.com[3]Openshaw JJ, Swerdlow DL, Krebs JW, et al. Rocky mountain spotted fever in the United States, 2000-2007: interpreting contemporary increases in incidence. Am J Trop Med Hyg. 2010;83:174-182.http://www.ajtmh.org/content/83/1/174.longhttp://www.ncbi.nlm.nih.gov/pubmed/20595498?tool=bestpractice.com87% 的患者为白种人,黑种人占 8%,美洲原住民占 4%。[3]Openshaw JJ, Swerdlow DL, Krebs JW, et al. Rocky mountain spotted fever in the United States, 2000-2007: interpreting contemporary increases in incidence. Am J Trop Med Hyg. 2010;83:174-182.http://www.ajtmh.org/content/83/1/174.longhttp://www.ncbi.nlm.nih.gov/pubmed/20595498?tool=bestpractice.com由于 RMSF 经蜱虫传播,被诊断患有 RMSF 的人群通常居住在(或近期去过)丛林或乡村。这种蜱暴露可能发生在农村、郊区或市区,包括花园或房屋周边物业。应注意,在疫区旅行有过户外活动的返回人群中,可能有此病例。[9]Salgo MP, Telzak EE, Currie B, et al. A focus of Rocky Mountain spotted fever within New York City. N Engl J Med. 1988;318:1345-1348.http://www.ncbi.nlm.nih.gov/pubmed/3130574?tool=bestpractice.com[1]Biggs HM, Behravesh CB, Bradley KK, et al. Diagnosis and management of tickborne rickettsial diseases: Rocky Mountain spotted fever and other spotted fever group rickettsioses, ehrlichioses, and anaplasmosis - United States. MMWR Recomm Rep. 2016;65:1-44.http://www.cdc.gov/mmwr/volumes/65/rr/rr6502a1.htmhttp://www.ncbi.nlm.nih.gov/pubmed/27172113?tool=bestpractice.com在春季和夏季(美国)最为常见,主要在此时发生蜱咬伤,90% 病例在 4 月 1 日到 9 月 30 日之间发生。[2]Drexler NA, Dahlgren FS, Heitman KN, et al. National surveillance of spotted fever group rickettsioses in the United States, 2008-2012. Am J Trop Med Hyg. 2016;94:26-34.http://www.ncbi.nlm.nih.gov/pubmed/26324732?tool=bestpractice.com[6]Buckingham SC, Marshall GS, Schutze GE, et al. Clinical and laboratory features, hospital course, and outcome of Rocky Mountain spotted fever in children. J Pediatr. 2007;150:180-184.http://www.ncbi.nlm.nih.gov/pubmed/17236897?tool=bestpractice.com 但是,全年均可发病,甚至在气候更寒冷的冬季。