Retrospective clinical and molecular analysis of conditioned laboratory dogs (Canis familiaris) with serologic reactions to Ehrlichia canis, Borrelia burgdorferi, and Rickettsia rickettsii.
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Dogs are susceptible to different tickborne infections, including members of the Anaplasmataceae (Ehrlichia canis, E. ewingii, E. chaffeensis, Anaplasma phagocytophilum, A. platys), Borrelia burgdorferi, and Rickettsia rickettsii. These diseases can manifest with clinical signs including fever, anorexia, malaise, lameness, rash, and bleeding episodes; however, these signs are nonpathognomonic, and infections can occur in the absence of clinical signs. Hematologic abnormalities can include leukopenia, thrombocytopenia, hyperproteinemia and hypergammaglobulinemia. In biomedical research, diseases such as canine monocytic ehrlichiosis, Lyme disease, and Rocky Mountain spotted fever may cause morbidity among exposed dogs and confound research results. Random-source dogs are susceptible to these diseases because of their increased risk of arthropod exposure. Nonpurpose bred, randomly selected conditioned dogs (n = 21) were examined; blood samples were taken for hematology, biochemistry analysis, tickborne pathogen serology, and PCR. Of these, 2 dogs (10% of the population) presented with illness characterized by fever, malaise, lameness, or hemostatic abnormalities, and 15 (71%) had antibodies to one or more tickborne pathogens. No specific hematologic or biochemical differences were apparent between seronegative dogs and seropositive dogs reactive to all 3 pathogens. E. canis and B. burgdorferi PCR of tissues and blood were negative for all dogs. PCR amplification of several Ehrlichia and Anaplasma genes yielded no positive samples. From this cohort of dogs, serologic and molecular results indicate prior exposure without active infection or clinical disease. Exposure to and potential for infection with these bacteria and other pathogens may contribute to blood and tissue alterations that could confound experiments and lead to misinterpretation of data in canine models. (+info)
Rickettsial spotted fever in capoeirao village, Itabira, Minas Gerais, Brazil.
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Molecular characterization of Rickettsia rickettsii isolated from human clinical samples and from the rabbit tick Haemaphysalis leporispalustris collected at different geographic zones in Costa Rica.
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Five strains of spotted fever group (SFG) rickettsiae previously isolated from human clinical cases and from the tick Haemaphysalis leporispalustris were used for molecular characterization in this study to establish their genetic relationship compared with the prototype Rickettsia rickettsii strain Sheila Smith. Samples were tested by polymerase chain reaction (PCR) targeting the rickettsial genes gtlA, ompA, and ompB. PCR products of the latter two genes were DNA sequenced and compared with available sequences in GenBank. The ompA partial sequences of the five Costa Rican isolates showed 100% identity to several R. rickettsii sequences available in GenBank, including the sequence of the virulent reference strain Sheila Smith, whereas the ompB partial sequences of the five Costa Rican isolates showed 99.8-100% identity to R. rickettsii sequences from GenBank. This study showed the first molecular detection of R. rickettsii isolates from Rocky Mountain Spotted Fever patients and from the rabbit tick H. leporispalustris in different geographical zones in Costa Rica. (+info)
An increase in human cases of spotted fever rickettsiosis in Yucatan, Mexico, involving children.
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The first human case of infection caused by Rickettsia in Yucatan was detected in 1996, and it was determined that the species was R. felis. Since then, passive epidemiologic surveillance was implemented to search for human cases in the public hospitals of the state, and in 2005, the first human case of Rocky Mountain spotted fever was detected. During the following 2 years, eight new confirmed cases and one probable case were identified. Seven cases involved children younger than 12 years of age, with a fatal outcome in three of the cases. Children are a particularly vulnerable population for this serious emerging infection. (+info)
Experimental infection of dogs with a Brazilian strain of Rickettsia rickettsii: clinical and laboratory findings.
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Spatial clustering by disease severity among reported Rocky Mountain spotted fever cases in the United States, 2001-2005.
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Rocky Mountain spotted fever (RMSF) occurs throughout much of the United States, ranging in clinical severity from moderate to fatal infection. Yet, little is known about possible differences among severity levels across geographic locations. To identify significant spatial clusters of severe and non-severe disease, RMSF cases reported to Centers for Disease Control and Prevention (CDC) were geocoded by county and classified by severity level. The statistical software program SaTScan was used to detect significant spatial clusters. Of 4,533 RMSF cases reported, 1,089 hospitalizations (168 with complications) and 23 deaths occurred. Significant clusters of 6 deaths (P = 0.05, RR = 11.4) and 19 hospitalizations with complications (P = 0.02, RR = 3.45) were detected in southwestern Tennessee. Two geographic areas were identified in north-central North Carolina with unusually low rates of severity (P = 0.001, RR = 0.62 and P = 0.001, RR = 0.45, respectively). Of all hospitalizations, 20% were clustered in central Oklahoma (P = 0.02, RR = 1.43). Significant geographic differences in severity were observed, suggesting that biologic and/or anthropogenic factors may be impacting RMSF epidemiology in the United States. (+info)
Rocky Mountain spotted fever in dogs, Brazil.
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