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The rabbit tick, Haemaphysalis leporispalustris Packard, is known for its association with Rickettsia rickettsii as it harbors both virulent and avirulent strains of this pathogen. In this manuscript we report findings and preliminary characterization of a novel spotted fever group rickettsia (SFGR) in rabbit ticks from California, USA. Rickettsia sp. CA6269 (proposed "Candidatus Rickettsia lanei") is most related to known R. rickettsii isolates but belongs to its own well-supported branch different from those of all R. rickettsii including strain Hlp2 and from Rickettsia sp. 364D (also known as R. philipii) and R. peacockii. This SFGR probably exhibits both transovarial and transstadial survival since it was found in both questing larvae and nymphs. Although this rabbit tick does not frequently bite humans, its role in maintenance of other rickettsial agents and this novel SFGR warrant further investigation., (Copyright © 2018 Elsevier GmbH. All rights reserved.)

AbstractFlea-borne (murine) typhus is a global rickettsiosis caused by Rickettsia typhi . Although flea-borne typhus is no longer nationally notifiable, cases are reported for surveillance purposes in a few U.S. states. The infection is typically self-limiting, but may be severe or life-threatening in some patients. We performed a retrospective review of confirmed or probable cases of fatal flea-borne typhus reported to the Texas Department of State Health Services during 1985-2015. When available, medical charts were also examined. Eleven cases of fatal flea-borne typhus were identified. The median patient age was 62 years (range, 36-84 years) and 8 (73%) were male. Patients presented most commonly with fever (100%), nausea and vomiting (55%), and rash (55%). Respiratory (55%) and neurologic (45%) manifestations were also identified frequently. Laboratory abnormalities included thrombocytopenia (82%) and elevated hepatic transaminases (63%). Flea or animal contact before illness onset was frequently reported (55%). The median time from hospitalization to administration of a tetracycline-class drug was 4 days (range, 0-5 days). The median time from symptom onset to death was 14 days (range, 1-34 days). Flea-borne typhus can be a life-threatening disease if not treated in a timely manner with appropriate tetracycline-class antibiotics. Flea-borne typhus should be considered in febrile patients with animal or flea exposure and respiratory or neurologic symptoms of unknown etiology.