Expanding Range of Amblyomma americanum and Simultaneous Changes in the Epidemiology of Spotted Fever Group Rickettsiosis in the United States
Expanding Range of Amblyomma americanum and Simultaneous Changes in the Epidemiology of Spotted Fever Group Rickettsiosis in the United States
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DOI：
10.4269/ajtmh.15-0580
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发表时间：
2016-01-01
影响因子：
3.3
通讯作者：
Behravesh, Casey Barton
中科院分区：
文献类型：
--
作者：
Dahlgren, F. Scott;Paddock, Christopher D.;Behravesh, Casey Barton
斑点热群立克次体是多种人类感染的病原体，从无症状或轻度感染到严重的危及生命的疾病。在美国，最近对SFG立克次体病的被动监测显示，报告病例的发病率增加，严重程度下降。其原因尚不清楚；然而，我们假设致病性较低的立克次体引起更多的人类感染，而致病性较高的立克次体，特别是立克次体引起的疾病发病率相对稳定。在同一时期，美洲钝瘤菌的范围扩大了。美国钝裂体经常感染“钝裂体候选立克次体”，这是一种致病性未知的SFG立克次体。我们通过建模1993 - 2013年的发病率、1981 - 2013年的住院率和1981 - 2013年的病死率来检验我们的假设，并根据美洲弧菌的存在、症状出现的十年和居住的县进行回归。我们的研究结果支持了这一假设，并且我们表明美洲蜂的扩大范围与被动监测报告的流行病学变化有关。我们认为，通过加强监测收集到的病例的流行病学和人类学数据可能进一步阐明SFG立克次体病流行病学变化的原因。
Spotted fever group (SFG) Rickettsia species are etiologic agents of a wide range of human infections from asymptomatic or mild infections to severe, life-threatening disease. In the United States, recent passive surveillance for SFG rickettsiosis shows an increased incidence and decreased severity of reported cases. The reasons for this are not well understood; however, we hypothesize that less pathogenic rickettsiae are causing more human infections, while the incidence of disease caused by more pathogenic rickettsiae, particularly Rickettsia rickettsii, is relatively stable. During the same period, the range of Amblyomma americanum has expanded. Amblyomma americanum is frequently infected with "Candidatus Rickettsia amblyommii", a SFG Rickettsia of unknown pathogenicity. We tested our hypothesis by modeling incidence rates from 1993 to 2013, hospitalization rates from 1981 to 2013, and case fatality rates from 1981 to 2013 regressed against the presence of A. americanum, the decade of onset of symptoms, and the county of residence. Our results support the hypothesis, and we show that the expanding range of A. americanum is associated with changes in epidemiology reported through passive surveillance. We believe epidemiological and acarological data collected on individual cases from enhanced surveillance may further elucidate the reasons for the changing epidemiology of SFG rickettsiosis.