Abstract. Spotted fever group (SFG) rickettsioses are notifiable conditions in the United States caused by the highly pathogenic Rickettsia rickettsii and less pathogenic rickettsial species such as Rickettsia parkeri and Rickettsia sp. 364D. Surveillance data from 2008 to 2012 for SFG rickettsioses are summarized. Incidence increased from 1.7 cases per million person-years (PY) in 2000 to 14.3 cases per million PY in 2012. During 2008-2012, cases of SFG rickettsiosis were more frequently reported among males, persons of white race, and non-Hispanic ethnicity. Overall, case fatality rate (CFR) was low (0.4%), however, risk of death was significantly higher for American Indian/Alaska Natives (relative risk [RR] = 5.4) and Asian/Pacific Islanders (RR = 5.7) compared with persons of white race. Children aged < 10 years continue to experience the highest CFR (1.6%). Higher incidence of SFG rickettsioses and decreased CFR likely result from increased reporting of tick-borne disease including those caused by less pathogenic species. Recently, fewer cases have been confirmed using species-specific laboratory methods (such as cell culture and DNA detection using polymerase chain reaction [PCR] assays), causing a clouded epidemiological picture. Use of PCR and improved documentation of clinical signs, such as eschars, will better differentiate risk factors, incidence, and clinical outcomes of specific rickettsioses in the future.

Abstract. Human ehrlichiosis is a potentially fatal disease caused by Ehrlichia chaffeensis and Ehrlichia ewingii. Cases of ehrlichiosis are reported to Centers for Disease Control and Prevention through two national surveillance systems: Nationally Notifiable Diseases Surveillance System (NNDSS) and Case Report Forms. During 2008-2012,613 cases of E. chaffeensis infections were reported through NNDSS. The incidence rate (IR) was 3.2 cases per million person-years (PYs). The hospitalization rate (HR) was 57% and the case fatality rate (CFR) was 1%. Children aged < 5 years had the highest CFR of 4%. During 2008-2012, 55 cases of E. ewingii infection were reported through NNDSS. The national IR was 0.04 cases per million PY. The HR was 77%; no deaths were reported. Immunosuppressive conditions were reported by 26% of cases. The overall rate for ehrlichiosis has increased 4-fold since 2000. Although previous literature suggests E. ewingii primarily affects those who are immunocompromised, this report shows most cases occurred among immunocompetent patients. This is the first report to show children aged < 5 years with ehrlichiosis have an increased CFR, relative to older patients. Ongoing surveillance and reporting of tick-borne diseases are critical to inform public health practice and guide disease treatment and prevention efforts.

Abstract. Human granulocytic anaplasmosis is an acute, febrile illness transmitted by the ticks Ixodes scapularis and Ixodes pacificus in the United States. We present a summary of passive surveillance data for cases of anaplasmosis with onset during 2008-2012. The overall reported incidence rate (IR) was 6.3 cases per million person-years. Cases were reported from 38 states and from New York City, with the highest incidence in Minnesota (IR = 97), Wisconsin (IR = 79), and Rhode Island (IR = 51). Thirty-seven percent of cases were classified as confirmed, almost exclusively by polymerase chain reaction. The reported case fatality rate was 0.3% and the reported hospitalization rate was 31%. IRs, hospitalization rates, life-threatening complications, and case fatality rates increased with age group. The IR increased from 2008 to 2012 and the geographic range of reported cases of anaplasmosis appears to have increased since 2000-2007. Our findings are consistent with previous case series and recent reports of the expanding range of the tick vector I. scapularis.

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