Last data update: May 20, 2024. (Total: 46824 publications since 2009)
Records 1-4 (of 4 Records) |
Query Trace: Sumner JW[original query] |
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Isolation of Rickettsia parkeri and identification of a novel spotted fever group Rickettsia sp. from gulf coast ticks (Amblyomma maculatum) in the United States
Paddock CD , Fournier PE , Sumner JW , Goddard J , Elshenawy Y , Metcalfe MG , Loftis AD , Varela-Stokes A . Appl Environ Microbiol 2010 76 (9) 2689-96 Until recently, Amblyomma maculatum, (the Gulf Coast tick), has garnered little attention relative 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 eschar-associated 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 from several regions of the southeastern United States. In this study, 198 questing adult Gulf Coast ticks were collected from 4 locations in Florida and Mississippi; 28% were infected with R. parkeri and 3% with a novel SFGR. Seventeen isolates of R. parkeri were cultivated in Vero E6 cells from individual specimens of A. maculatum; 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 non-cultivated 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. Our study expands considerably the number of low-passage, A. maculatum-derived isolates of R. parkeri, and characterizes a second and sympatrically distributed Rickettsia sp. found in Gulf Coast ticks. |
Rickettsia 364D: a newly recognized cause of eschar-associated illness in California
Shapiro MR , Fritz CL , Tait K , Paddock CD , Nicholson WL , Abramowicz KF , Karpathy SE , Dasch GA , Sumner JW , Adem PV , Scott JJ , Padgett KA , Zaki SR , Eremeeva ME . Clin Infect Dis 2010 50 (4) 541-8 BACKGROUND: Four spotted fever group rickettsiae (SFGR) are known to infect humans in the United States. A member of the SFGR designated 364D and detected in Dermacentor occidentalis ticks has not previously been identified as a human pathogen. METHODS: An 80-year-old man from a rural northern California community presented with an eschar on his forearm. A skin punch biopsy of the lesion was evaluated by immunohistochemistry and molecular analysis. Serum specimens obtained from the patient and 3 other area residents with similar illnesses were tested by immunofluorescence and Western immunoblot for antibodies to SFGR. Ticks were collected near the patient's residence and tested for SFGR. RESULTS: Abundant intracellular rickettsiae and fragmented rickettsial antigens were observed in the mononuclear inflammatory infiltrates of the biopsy. Nucleotide sequences of DNA fragments amplified from the biopsy were identical to those of 364D. Convalescent sera from all four patients exhibited high immunoglobulin G titers to Rickettsia rickettsii, Rickettsia rhipicephali, and 364D antigens. Three adult D. occidentalis were positive for 364D, R. rhipicephali, and an unidentified Rickettsia species. CONCLUSIONS: This is the first confirmation of human disease associated with the SFGR 364D, which was likely transmitted by D. occidentalis. Although the patients described here presented with a single cutaneous eschar as the principal manifestation, the full spectrum of illness associated with 364D has yet to be determined. Possible infection with 364D or other SFGR should be confirmed through molecular techniques in patients who present with "spotless" Rocky Mountain spotted fever or have serum antibodies to R. rickettsii with group-specific assays. |
Pathogen prevalence and blood meal identification in Amblyomma ticks as a means of reservoir host determination for ehrlichial pathogens
Pierce KA , Paddock CD , Sumner JW , Nicholson WL . Clin Microbiol Infect 2009 25 37-8 Amblyomma americanum (the lone star tick) serves as a vector for several human pathogens, including the aetiologic agent of human monocytic ehrlichiosis, Ehrlichia chaffeensis. The agent is passed transtadially in A. americanum, but not transovarially. Molecular blood meal analysis is a useful tool in the studies of vector and pathogen ecology. Questing nymphs can be collected and tested for the presence of both larval blood meal and E. chaffeensis by PCR. If the acquisition of the pathogen occurred during larval feeding, identification of the host blood meal in an unfed, infected nymph would identify a likely vertebrate reservoir of E. chaffeensis. Similar methodologies have been used to study vertebrate reservoirs of Lyme disease [1]. | Amblyomma americanum feeds on a wide range of vertebrate hosts, including ruminants. White-tailed deer can be naturally infected with E. chaffeensis, and have been shown to experimentally transmit the pathogen to feeding A. americanum [2]. While these factors suggest that white-tailed deer may serve as a reservoir species for E. chaffeensis, direct evidence through blood meal analysis has not been presented. Domestic goats, domestic cattle, and domestic sheep may also host A. americanum [3] and have the potential to serve as E. chaffeensis reservoirs. A ruminant-specific blood meal identification assay was developed to assess the role of ruminants in E. chaffeensis ecology. |
New approaches to detection and identification of Rickettsia africae and Ehrlichia ruminantium in Amblyomma variegatum (Acari: Ixodidae) ticks from the Caribbean
Robinson JB , Eremeeva ME , Olson PE , Thornton SA , Medina MJ , Sumner JW , Daschi GA . J Med Entomol 2009 46 (4) 942-51 Imported from Africa in the 1700s and despite frequent modern eradication efforts, Amblyomma variegatum (F.) spread through the Caribbean by cattle transport, small ruminants, and migrating birds. A. variegatum is a vector for Rickettsia africae, the causative agent of African tick bite fever, and Ehrlichia ruminantium, the causative agent of heartwater. We examined 95 A. variegatum and six Rhipicephalus (Boophilus) microplus (Canestrini) collected from cattle at an abattoir in Antigua. Engorged tick extracts adsorbed on Nobotu filter paper strips and new nested polymerase chain reaction (PCR) assays for E. ruminantium and Dermatophilus congolensis were used to evaluate these ticks for the presence of these pathogenic bacteria. Amblyomma ticks (62.4%) contained R. africae DNA by PCR/restriction fragment length polymorphism analysis and DNA sequencing of the OmpA and 17-kDa antigen genes. Twenty Amblyomma and two Rh. microplus contained E. ruminantium DNA. No E. chaffeensis, Anaplasma phagocytophilum, Coxiella burnetii, or D. congolensis DNA was detected in these ticks. The continued presence of Am. variegatum in the Caribbean poses a significant risk of infection in cattle with E. ruminantium and in humans by R. africae. Eradication efforts are essential to prevent the further spread of Am. variegatum. |
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