{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,28]],"date-time":"2026-10-28T03:44:43Z","timestamp":1793159083338,"version":"4.5.0"},"reference-count":50,"publisher":"American Society of Tropical Medicine and Hygiene","issue":"1","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2016,1,6]]},"abstract":"<jats:p>\n                    Spotted fever group (SFG)\n                    <jats:italic>Rickettsia<\/jats:italic>\n                    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\n                    <jats:italic>Rickettsia rickettsii<\/jats:italic>\n                    , is relatively stable. During the same period, the range of\n                    <jats:italic>Amblyomma americanum<\/jats:italic>\n                    has expanded.\n                    <jats:italic>Amblyomma americanum<\/jats:italic>\n                    is frequently infected with \u201c\n                    <jats:italic>Candidatus<\/jats:italic>\n                    Rickettsia amblyommii\u201d, a SFG\n                    <jats:italic>Rickettsia<\/jats:italic>\n                    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\n                    <jats:italic>A. americanum<\/jats:italic>\n                    , the decade of onset of symptoms, and the county of residence. Our results support the hypothesis, and we show that the expanding range of\n                    <jats:italic>A. americanum<\/jats:italic>\n                    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.\n                  <\/jats:p>","DOI":"10.4269\/ajtmh.15-0580","type":"journal-article","created":{"date-parts":[[2015,10,26]],"date-time":"2015-10-26T21:53:37Z","timestamp":1445896417000},"page":"35-42","source":"Crossref","is-referenced-by-count":116,"title":["Expanding Range of Amblyomma americanum and Simultaneous Changes in the Epidemiology of Spotted Fever Group Rickettsiosis in the United States"],"prefix":"10.4269","volume":"94","author":[{"given":"F. Scott","family":"Dahlgren","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Christopher D.","family":"Paddock","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yuri P.","family":"Springer","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Rebecca J.","family":"Eisen","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Casey Barton","family":"Behravesh","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"2795","reference":[{"key":"ref1","series-title":"Am J Trop Med Hyg","first-page":"405","article-title":"National surveillance for Rocky Mountain spotted fever, 1981\u20131992: epidemiologic summary and evaluation of risk factors for fatal outcome","volume":"52","author":"Dalton","year":"1995"},{"key":"ref2","series-title":"J Infect Dis","first-page":"1437","article-title":"Analysis of risk factors for fatal Rocky Mountain spotted fever: evidence for superiority of tetracyclines for therapy","volume":"184","author":"Holman","year":"2001"},{"key":"ref3","series-title":"Am J Trop Med Hyg","first-page":"174","article-title":"Rocky Mountain spotted fever in the United States, 2000\u20132007: interpreting contemporary increases in incidence","volume":"83","author":"Openshaw","year":"2010"},{"key":"ref4","series-title":"MMWR","first-page":"885","article-title":"Consequences of delayed diagnosis of Rocky Mountain spotted fever in children\u2014West Virginia, Michigan, Tennessee, and Oklahoma, May\u2013July 2000","volume":"49","author":"Centers for Disease Control and Prevention","year":"2000"},{"key":"ref5","series-title":"Clin Infect Dis","first-page":"1650","article-title":"Rocky Mountain spotted fever characterization and comparison to similar illnesses in a highly endemic area\u2014Arizona, 2002\u20132011","volume":"60","author":"Traeger","year":"2015"},{"key":"ref6","series-title":"Clin Infect Dis","first-page":"1659","article-title":"Risk factors for fatal outcome from Rocky Mountain spotted fever in a highly endemic area\u2014Arizona, 2002\u20132011","volume":"60","author":"Regan","year":"2015"},{"key":"ref7","series-title":"MMWR Recomm Rep","first-page":"1","article-title":"Diagnosis and management of tickborne rickettsial diseases: Rocky Mountain spotted fever, ehrlichiosis, and anaplasmosis\u2014United States","volume":"55","author":"Centers for Disease Control and Prevention","year":"2006"},{"key":"ref8","series-title":"Am J Trop Med Hyg","first-page":"26","article-title":"National surveillance of spotted fever group rickettsioses in the United States, 2008\u20132012","volume":"94","author":"Drexler","year":"2016"},{"key":"ref9","series-title":"Public Health Rep","first-page":"777","article-title":"Rickettsialpox: a newly recognized rickettsial disease: V. 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