The Expanding Spectrum of Eschar-Associated Rickettsioses in the United States

Cragun, W Chad; Bartlett, Brenda L.; Ellis, Michael W.; Hoover, Aaron Z; Tyring, Stephen K.; Mendoza, Natalia; Vento, Todd J.; Nicholson, William L.; Eremeeva, Marina E.; Olano, Juan P.; Rapini, Ronald P.; Paddock, Christopher D.

doi:10.1001/archdermatol.2010.48

Cited by 70 publications

(60 citation statements)

References 18 publications

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“…The histopathology of the eschars is similar to that reported in humans, with epidermal necrosis and perivascular dermatitis being the prominent features (2,13,25). The inflammatory infiltrates associated with this murine model eschar are also analogous to the inflammation described in human patients with R. parkeri rickettsiosis (13), suggesting a similar immunological response, but this will require further investigation to confirm.…”

Section: Discussionsupporting

confidence: 68%

Susceptibility of Inbred Mice to Rickettsia parkeri

et al. 2012

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ABSTRACTRickettsia parkeri, a member of the spotted fever groupRickettsia, is the causative agent of American boutonneuse fever in humans. Despite the increased recognition of human cases, limited information is available regarding the infection of invertebrate and vertebrate hosts for this emerging tick-borne disease. Toward the development of a viable transmission model and to further characterize the pathology associated withR. parkeriinfection, inbred mouse strains (A/J, BALB/c, C3H/HeJ, and C3H/HeN) were intravenously and intradermally inoculated with 105low-passage-numberR. parkeri(Portsmouth strain), and infection, gross pathology, and histopathology were scored. Additionally, a quantitative real-time PCR (qPCR) was performed to estimate rickettsial load in heart, lung, spleen, and liver tissues of infected mice at 19 days postinoculation. Of the A/J, BALB/c, and C3H/HeN mice, none displayed universal pathology consistent with sustained infection. Compared to age-matched control mice, the intravenously inoculated C3H/HeJ mice exhibited marked facial edema and marked splenomegaly upon gross examination, while the intradermally inoculated mice developed characteristic eschar-like lesions. The C3H/HeJ mice also exhibited the greatest concentrations of rickettsial DNA from heart, lung, liver, and spleen samples when examined by qPCR. The similarity of the pathology of human disease and sustained infection suggests that the C3H/HeJ strain of mice is a promising candidate for subsequent experiments to examine the tick transmission, dissemination, and pathology ofR. parkeririckettsiosis.

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Section: Discussionsupporting

confidence: 68%

Susceptibility of Inbred Mice to Rickettsia parkeri

et al. 2012

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“…Because some cases reported as RMSF might actually be diseases caused by other SFG rickettsiae, the surveillance case definition for RMSF in the United States was modified in 2010 to encompass the broader category of spotted fever rickettsiosis. The number of reported cases of spotted fever rickettsiosis in the United States, including cases of RMSF, rose 9% during 2009 to 2010, from 1,815 to 1,985 (66)(67)(68)(69)(70).…”

Section: North and Central Americamentioning

confidence: 99%

“…The first confirmed human infection with R. parkeri was reported in 2004, and approximately 15 cases of R. parkeri rickettsiosis have been described in the literature since that initial report (66)(67)(68)(69)(70). In the United States, Amblyomma maculatum (the Gulf Coast tick) is the principal vector for these bacteria, and R. parkeri is detected in 8% to 43% of questing adult A. maculatum ticks collected in states along the Gulf Coast and the southern Atlantic region (95)(96)(97)(98)(99)(100)(101).…”

Section: North and Central Americamentioning

confidence: 99%

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Update on Tick-Borne Rickettsioses around the World: a Geographic Approach

et al. 2013

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SUMMARY Tick-borne rickettsioses are caused by obligate intracellular bacteria belonging to the spotted fever group of the genus Rickettsia . These zoonoses are among the oldest known vector-borne diseases. However, in the past 25 years, the scope and importance of the recognized tick-associated rickettsial pathogens have increased dramatically, making this complex of diseases an ideal paradigm for the understanding of emerging and reemerging infections. Several species of tick-borne rickettsiae that were considered nonpathogenic for decades are now associated with human infections, and novel Rickettsia species of undetermined pathogenicity continue to be detected in or isolated from ticks around the world. This remarkable expansion of information has been driven largely by the use of molecular techniques that have facilitated the identification of novel and previously recognized rickettsiae in ticks. New approaches, such as swabbing of eschars to obtain material to be tested by PCR, have emerged in recent years and have played a role in describing emerging tick-borne rickettsioses. Here, we present the current knowledge on tick-borne rickettsiae and rickettsioses using a geographic approach toward the epidemiology of these diseases.

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“…Until recently, A. maculatum had never been associated directly with any known tick-borne infection of humans; however, A. maculatum is now recognized as a vector of Rickettsia parkeri, a spotted fever group rickettsia (SFGR) that causes a disease similar to, but milder than, Rocky Mountain spotted fever (RMSF). Since the recognition of the index patient in 2002 (37), more than 20 cases of R. parkeri rickettsiosis have been identified in Alabama, Florida, Kentucky, Maryland, Mississippi, North Carolina, South Carolina, Virginia, and Texas (12,38,57; CDC, unpublished data). In 1923, Cowdry (11) described minute intracellular bacteria, apparently rickettsiae, in the tissues and eggs of female A. maculatum ticks collected in Jackson County, MS. Parker et al (41) subsequently isolated R. parkeri from Gulf Coast ticks collected in southeastern Texas in 1937.…”

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Isolation ofRickettsia parkeriand Identification of a Novel Spotted Fever GroupRickettsiasp. from Gulf Coast Ticks (Amblyomma maculatum) in the United States

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Fournier

Sumner

et al. 2010

Appl Environ Microbiol

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Until recently, Amblyomma maculatum (the Gulf Coast tick) had garnered little attention compared to other species of human-biting ticks in the United States. A. maculatum is now recognized as the principal vector of Rickettsia parkeri, a pathogenic spotted fever group rickettsia (SFGR) that causes an escharassociated illness in humans that resembles Rocky Mountain spotted fever. A novel SFGR, distinct from other recognized Rickettsia spp., has also been detected recently in A. maculatum specimens collected in several regions of the southeastern United States. In this study, 198 questing adult Gulf Coast ticks were collected at 4 locations in Florida and Mississippi; 28% of these ticks were infected with R. parkeri, and 2% of these were infected with a novel SFGR. Seventeen isolates of R. parkeri from individual specimens of A. maculatum were cultivated in Vero E6 cells; however, all attempts to isolate the novel SFGR were unsuccessful. Partial genetic characterization of the novel SFGR revealed identity with several recently described, incompletely characterized, and noncultivated SFGR, including "Candidatus Rickettsia andeanae" and Rickettsia sp. Argentina detected in several species of Neotropical ticks from Argentina and Peru. These findings suggest that each of these "novel" rickettsiae represent the same species. This study considerably expanded the number of low-passage, A. maculatum-derived isolates of R. parkeri and characterized a second, sympatric Rickettsia sp. found in Gulf Coast ticks.

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The Expanding Spectrum of Eschar-Associated Rickettsioses in the United States

Cited by 70 publications

References 18 publications

Susceptibility of Inbred Mice to Rickettsia parkeri

Susceptibility of Inbred Mice to Rickettsia parkeri

Update on Tick-Borne Rickettsioses around the World: a Geographic Approach

Isolation ofRickettsia parkeriand Identification of a Novel Spotted Fever GroupRickettsiasp. from Gulf Coast Ticks (Amblyomma maculatum) in the United States

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