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1.
This study was initiated to determine the degree of susceptibility of dogs to virulent and nonvirulent spotted fever-group rickettsiae and to evaluate dogs as sources of infection for ticks. Dogs were exposed either by inoculation (syringe) or by infective tick bite to the following rickettsial serotypes: (1) Rickettsia rickettsii (Wachsmuth and Sawtooth female 2 strains), (2) R montana (M/5-6 B strain), and (3) R rhipicephali (3-7-female 6 strain). Results indicated that dogs inoculated with 1,000 or 10,000 egg infective doses of virulent R rickettsii developed a rickettsemia that was detectable as early as 4 days after inoculation to as late as 10 days. Conversely, none of the dogs inoculated with R montana (M/5-6 B) or R rhipicephali (3-7-female 6) or exposed to ticks infected with these strains developed detectable rickettsemia, fever, or other observable clinical signs. None of the 394 ticks that fed on rickettsemic dogs (R rickettsii) infected by inoculation became infected, and only 3 of 348 ticks (0.9% infection rate) were infected after feeding on dogs which had been infected by tick bite. All ticks fed on dogs exposed to R rhipicephali and R montana were shown to be free of rickettsiae. The largest concentrations of plaque-forming units (PFU) in Vero cell culture from undiluted whole blood were found on day 6 and on day 7 in dogs that were inoculated with 10,000 and 1,000 R rickettsii, respectively, of the Sawtooth female 2 strain. The highest rickettsial concentration observed for the dog infected by tick feeding was on day 9.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

2.
Antibodies to spotted fever-group rickettsiae in dogs in North Carolina   总被引：1，自引：0，他引：1  
A seroepidemiologic survey was conducted to determine the prevalence of antibodies reactive with 4 spotted fever-group (SFG) rickettsiae in sera of dogs from various geographic regions in North Carolina. Serum specimens were obtained from 600 dogs, and antibody titers were determined, using microimmunofluorescence. Data analysis (setting as the criterion for a positive result, a Rickettsia rickettsii titer greater than or equal to 1:64) overestimated the actual prevalence of canine exposure to this rickettsia. When data were analyzed by considering each dog's serologic response to all 4 rickettsial antigens simultaneously, the prevalence rate for exposure to R montana was 15%, to R rhipicephali was 11%, and to R rickettsii was 5%. A definitive exposure to R bellii was not observed, and the identification of the specific inciting rickettsia could not be established for 13% of the dogs, because of identical highest titers to 2 or more antigens. Our data indicate that canine exposure to R rhipicephali is prevalent in the eastern coastal region, whereas exposure to R montana takes place uniformly throughout the state. Rickettsia rickettsii exposure appears to be more prevalent in the central Piedmont region, but rarely is encountered in the western mountains. Regional seroprevalence for canine R rickettsii exposure approximates that for human exposure. Our findings support earlier suggestions that dogs may serve as environmental sentinels for establishing the geographic prevalence of foci of spotted fever.  相似文献   

3.
Blood samples and ticks were obtained from dogs to assess canine exposure to spotted fever-group (SFG) rickettsiae during 1978-1980 in southern Connecticut. Of the 1,576 dog sera screened by microimmunofluorescence. 174 (11.0%) contained specific antibodies at titers greater than or equal to 1:64 against Rickettsia montana (n = 34), R rickettsii (n = 31), R rhipicephali (n = 19), or the unclassified 369-C rickettsia (n = 90). End points greater than or equal to 1:8,192 to R rickettsii and to R rhipicephali were recorded for 6 and 3 sera, respectively. Seropositivity rates from southwestern and southeastern Connecticut were similar (about 11%), with positive sera obtained from each region in nearly all months of the investigation. Rates were between 10% for dogs 2 to 7 years old and 14% for those greater than or equal to 8 years. Eight of 629 Dermacentor variabilis, 1 of 18 Ixodes dammini, and 2 of 3 Amblyomma americanum were positive by direct immunofluorescence for SFG rickettsiae. Thirteen D variabilis contained unidentified, long, bacillus-like organisms that differed from the short, ovoid (coccal) forms typical fo the spotted-fever agent, R rickettsii. With the exposure to infected ticks and production of type-specific antibodies against at least 4 SFG antigens, dogs may serve as suitable enzootic or epizootic indicators of rickettsial activity.  相似文献   

4.
The kinetics of specific IgM and IgG antibody response was characterized in four 9-month-old Beagles after inoculation of 2 x 10(2) plaque-forming units (PFU) of Sheila Smith strain of Rickettsia rickettsii. Immunoglobulin M antibodies were first detected by indirect immunofluorescence on postinoculation (PI) day 9, peaked by PI day 20, and were no longer detectable by PI day 80. Immunoglobulin G antibodies became detectable between PI days 22 and 28, peaked by PI day 42, and decreased gradually through PI day 130. Subsequent challenges with R rickettsii on PI days 216 (2 x 10(2) PFU/dog) and 1,029 (5 x 10(4) tissue culture infective dose [TCID50]/dog) resulted in slightly different serologic responses. The initial challenge exposure failed to increase the concentration of IgG antibodies and induced only low concentrations of IgM antibodies. After the second challenge inoculation, IgM antibodies were not detectable and the concentration IgG antibodies increased slightly. Clinical abnormalities and seroconversion were documented in control dogs following each challenge exposure. Examination of acute and convalescent serum samples from 55 dogs in which Rocky Mountain spotted fever was suspected clinically suggested that sole evaluation of IgM antibodies in acute-phase serum would result in inaccurate diagnoses because of false-positive and -negative results. Use of a composite conjugate that detects IgM and IgG antibodies to R rickettsii appears to be satisfactory for diagnostic purposes; however, concurrent quantitation of IgM antibodies may facilitate serodiagnosis in a select group of dogs in which a four-fold increase in convalescent antibody titer is not detected by use of the composite conjugate.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

5.
Spotted fever is a disease caused by bacteria from the genus Rickettsia of the spotted fever group (SFG). Rickettsia rickettsii is likely the main agent of Brazilian spotted fever (BSF). With the objective of gathering information on the circulation of SFG rickettsiae in Londrina, Parana state, ticks from dogs and horses and also blood from dogs, horses and humans were collected in a neighbourhood of the city which presented potential for circulation of rickettsiae between hosts and vectors. Amblyomma cajennense, Dermacentor nitens, and Rhipicephalus sanguineus ticks were subjected to Polymerase Chain Reaction targeting a fragment of the Rickettsia gltA gene. This specific gene encodes the enzyme citrate synthase of Rickettsia spp., and results on all ticks were negative. Human and animal sera were tested by Indirect Immunofluorescence Assay in which R. rickettsii and R. parkeri were used as antigens. Sera from 4.7% human, 2.7% canine and 38.5% equine were positive for R. rickettsii. For R. parkeri, 0.9% human, 2.7% canine and 11.5% equine samples were positive. All samples reactive to R. parkeri also reacted to R. rickettsii. An epidemiological questionnaire was applied, but there were no statistically significant results. Comparison of our serological results with previous studies in Brazil, among BSF endemic and non-endemic areas, indicates that there is no established rickettsial infection in the study area, a statement corroborated with our molecular analysis. Nonetheless, as humans of the present study are highly exposed to tick infestations, health education within the population is needed to obtain efficient tick control.  相似文献   

6.
The tick genus Haemaphysalis is represented by four species in the New World, of which only the species Haemaphysalis leporispalustris has been associated with Rickettsiae. The present study reports for the first time the presence of a Rickettsia strain in the tick Haemaphysalis juxtakochi. A free-living male of H. juxtakochi, collected in the state of Rondonia, Western Amazon, Brazil, was subjected to DNA extraction and tested by PCR targeting the four rickettsial genes: gltA, 17-kDa, ompA and ompB. The nucleotide sequences obtained from the PCR products were, by BLAST analyses, closest to Rickettsia rhipicephali sharing 99.7% (1147/1150), 98.8% (429/434), 99.0% (486/491) and 99.0% (809/817) identities with the partial sequences of the gltA, 17-kDa, ompA and ompB genes, respectively. Phylogenetic analyses inferred from the four rickettsial genes showed a high-degree of similarity of this H. juxtakochi-Rickettsia with R. rhipicephali. These two agents grouped together in all trees, always with high bootstrap support (75-96%). This study gives molecular evidence for the presence of a Rickettsia species, designated as strain R300, in the tick H. juxtakochi from the Western Amazon area of Brazil. Genetic analyses showed R300 to be closely related to R. rhipicephali.  相似文献   

7.
Rickettsia species antibodies have been detected in some cats but it is unknown whether infected cats develop clinical signs. The prevalence of Rickettsia species deoxyribonucleic acid (DNA) in blood from clinically ill cats has not been determined. The objective of this study was to determine if cats with fever (body temperature >or=102.5 degrees F [39.2 degrees C]) were more likely to have evidence of rickettsial infection than healthy, age-matched, control cats with a body temperature<102.5 degrees F. Rickettsia species polymerase chain reaction (PCR) assays were performed to detect rickettsial DNA extracted from blood (71 paired samples), indirect immunofluorescence assays (IFA) were performed to detect serum antibodies against Rickettsia felis (90 paired samples) and Rickettsia rickettsii (91 paired samples), and the results between pairs were compared. All samples were negative for Rickettsia species DNA. More cats with fever were seropositive for R felis or R rickettsii than control cats, but results were not statistically significant. Results of this pilot study failed to show an association between Rickettsia species DNA or Rickettsia species antibodies and fever.  相似文献   

8.
Canine Rocky Mountain spotted fever: a kennel epizootic   总被引：2，自引：0，他引：2  
Within a period of 5 consecutive days after the initial observation of illness was made, 7 of 12 Siberian Husky dogs developed clinical signs of Rickettsia rickettsii infection. One dog died and was necropsied. Clinical signs of infection consisted of lethargy, anorexia, ocular and nasal discharges, and neurologic disorder (incoordination and rolling). Scleral blood vessel injection, fever, lymphadenomegaly, splenomegaly, and increased bronchovesicular lung sounds were prominent findings. Clinical laboratory test results identified decreased platelet numbers, variable neutrophil counts, increased serum alkaline phosphatase activity, hyponatremia, hypokalemia, and bilirubinuria. Diagnosis of Rocky Mountain spotted fever was confirmed by serologic evaluation of acute and convalescent sera, using the micro-immunofluorescence technique, and R rickettsii antigen was determined by demonstration of intracellular rickettsial organisms in vascular endothelial cells of brain and lung (stained with carbol-basic fuchsin and aqueous malachite green) and by demonstration of spotted fever-group rickettsiae in tissues by direct fluorescent antibody technique. Near-simultaneous naturally occurring tick-borne infection of 7 dogs with R rickettsii documents an unreported occurrence.  相似文献   

9.
A survey for the prevalence of Rocky Mountain spotted fever antibodies in dogs from a well-defined endemic area in Columbus, Ohio (Franklin County), was conducted during the summer of 1981. Seventy-three blood samples from dogs in this area were tested by microimmunofluorescence for antibodies to Rickettsia rickettsii and other rickettsial antigens. Thirty-three (45.2%) of these samples were positive for R rickettsii, with titers ranging from 1:8 to 1:2,048. For comparison, 137 blood samples from dogs at the Franklin County Dog Pound also were tested. One dog (0.7%) from the comparison group was seropositive to R rickettsii, with a 1:64 titer. The results indicated a nidus of this disease within the city of Columbus, Ohio.  相似文献   

10.
Forty-nine dogs from Thailand were evaluated for serologic evidence of exposure or polymerase chain reaction (PCR) evidence of infection with vectorborne pathogens, including Ehrlichia sp. (Ehrlichia canis, Ehrlichia chaffeensis, Ehrlichia equi, and Ehrlichia risticii), Bartonella vinsonii subsp. berkhoffi (Bvb), spotted fever group (SFG) rickettsiae (Rickettsia rickettsii), Typhus group (TG) rickettsiae (Rickettsia canada, Rickettsia prowazekii, and Rickettsia typhi), and Babesia sp. (Babesia canis and Babesia gibsonii). All study dogs had at least 1 of 3 entry criteria: fever, anemia, or thrombocytopenia. By immunofluorescence antibody (IFA) testing, seroreactivity was most prevalent to E chaffeensis (74%) and E canis (71%) antigens, followed by E equi (58%), Bvb (38%), E risticii (38%), R prowazekii (24%), B canis (20%), R rickettsii (12%), R canada (4%), and B gibsonii (4%) antigens. There was 100% concordance between E canis IFA and Western blot immunoassay (WI) for 35 of 35 samples; 2 samples were IFA and WI reactive only to E equi antigens. By PCR amplification, 10 dogs were found to be infected with E canis, 5 with Ehrlichia platys, and 3 with B canis. Sequencing of PCR products was undertaken to compare Ehrlichia strains from Thailand to strains originating from the United States. Partial DNA sequence analysis confirmed infection with E canis and E platys, with identical 16S rRNA sequence alignment to E canis (U26740) and to E platys (M83801), as reported in GenBank. Partial E canis P28.1 and P28.2 amino acid sequences from Thai dogs were divergent from analogous sequences derived from North American E canis (AF082744) strains, suggesting that the Thai dogs were infected with a geographically distinct strain of E canis compared to North American strains. The results of this study indicate that dogs in Thailand have substantial exposure to vectorborne diseases and that coinfection with these pathogens may be common.  相似文献   

11.
In response to an outbreak of Rocky Mountain spotted fever (RMSF) in Baja California in early 2009, dogs at two shelters in neighbouring Imperial County, California, were evaluated for ectoparasites. Brown dog ticks (Rhipicephalus sanguineus), a recognized vector for RMSF, were found on 35 (30%) of 116 dogs but all ticks tested negative for Rickettsia rickettsii by PCR.  相似文献   

12.
Serum samples from 259 dogs were tested for antibodies to Ehrlichia canis, Ehrlichia equi, Rickettsia rickettsii, and Borrelia burgdorferi using the indirect fluorescent antibody test. The sera were obtained from submissions to the Oklahoma Animal Disease Diagnostic Laboratory during a 14-month period from June 1986 through July 1987. The rate for positive antibody titers to E. canis was 53%, to E. equi was 33%, to R. rickettsii was 38%, and to B. burgdorferi was 18%. Higher percentages of sera serologically positive to E. canis were found in the spring through the fall months, but there were no seasonal variations for E. equi, R. rickettsii, and B. burgdorferi. There was no consistent pattern of titers to the 4 antigens when age-groups of the dogs were compared. Forty-four different breeds were tested.  相似文献   

13.
Antibodies to Ehrlichia canis, Ehrlichia platys, and spotted fever group (SFG) rickettsiae were detected by indirect immunofluorescence in sera from 27 ill individually owned thrombocytopenic dogs (platelet concentrations less than 200,000 platelets/microliters) and 59 healthy kenneled dogs located in southern Louisiana. Platelet concentrations less than 100,000 platelets/microliters were detected in 63% of ill thrombocytopenic dogs and 6.8% of healthy kennel dogs. One ill thrombocytopenic dog had intracytoplasmic E platys morulae detected within platelets. The prevalence of increased serum antibody titers to E canis and E platys was 25.9% and 40.7% for the ill thrombocytopenic dogs and 20.3% and 54.2% for the healthy kennel dogs, respectively. All dogs with seropositivity to E canis had increased antibody titers of greater than or equal to 1:100 to E platys. Simultaneous examination of increased serum antibody titers (greater than or equal to 1:64) to four SFG rickettsiae indicate that Rickettsia rhipicephali and Rickettsia montana accounted for the majority of the antibodies detected in these dogs. Of 86 dogs tested, 44.2% were seronegative to E canis, E platys, and SFG rickettsiae.  相似文献   

14.
OBJECTIVE: To determine whether dogs in New York, NY are naturally infected with Rickettsia akari, the causative agent of rickettsialpox in humans. DESIGN: Serologic survey. ANIMALS: 311 dogs. PROCEDURE: Serum samples were obtained from dogs as a part of a study on Rocky Mountain spotted fever and borreliosis or when dogs were examined at area veterinary clinics for routine care. Dog owners were asked to complete a questionnaire inquiring about possible risk factors at the time serum samples were obtained. Samples were tested for reactivity to spotted fever group rickettsiae by use of an enzyme immunoassay (EIA). Twenty-two samples for which results were positive were tested by use of an indirect immunofluorescence antibody (IFA) assay followed by confirmatory cross-absorption testing. RESULTS: Results of the EIA were positive for 24 (7.7%) dogs. A history of tick infestation and increasing age were significantly associated with whether dogs were seropositive. Distribution of seropositive dogs was focal. Seventeen of the 22 samples submitted for IFA testing had titers to R rickettsii and R akari; for 11 of these, titers to R akari were higher than titers to R rickettsii. Cross-absorption testing indicated that in 6 of 7 samples, infection was caused by R akari. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that dogs can be naturally infected with R akari. Further studies are needed to determine the incidence of R akari infection in dogs, whether infection is associated with clinical illness, and whether dogs can serve as sentinels for human disease.  相似文献   

15.
Nine unrelated 12-week-old naive domestic ferrets (Mustela putorius furo) were used to evaluate the serologic responses to commercial canine distemper virus (CDV) and rabies virus (RV) vaccines. Five of the ferrets (group 1) were inoculated 3 times at 2-week intervals with a multivalent modified-live virus vaccine of canine cell-line origin, containing CDV and an inactivated RV vaccine. Four of the ferrets (group 2) were inoculated once with the multivalent modified-live virus vaccine containing CDV and were not inoculated with the RV vaccine. Both group-1 and group-2 ferrets seroconverted to the CDV component of the vaccine. Group-1 ferrets also seroconverted after RV vaccination and maintained serum antibody titers to both CDV and RV for at least 7 months. Domestic ferret sera were found to have IgG epitopes similar to sera of domestic dogs and cats. Domestic ferret sera did not contain antibodies to feline coronavirus or FeLV antigens.  相似文献   

16.
New endemic areas of spotted fever-like rickettsial disease have been found in south-eastern Australia (Gippsland, Victoria and Flinders Island, Tasmania). The rickettsia responsible is currently unknown although it may be Rickettsia australis. To investigate serological evidence of rickettsial exposure in various wild animal species, a competitive ELISA was developed which detected antibodies to R. australis. It was based on inhibition of an indirect ELISA detecting antibody to R. australis in guinea pig sera. Pre- and post-infection sera from 2 dogs, 2 rabbits, 5 mice and 6 rats, experimentally infected with R. australis, were tested by competitive ELISA. The results showed that all pre-infection sera were negative and all post-infection sera positive for antibody to R. australis. To test the utility of the competitive ELISA for detecting natural rickettsial infection in non-laboratory animals, 51 dog sera, negative for rickettsial antibody by immunofluorescence (IF) and 20 IF positive dog sera (collected from various locations on the east coast of Australia) were tested. Compared to the IF test the competitive ELISA was 90% sensitive and 96% specific. This new test has potential for detecting antibody to R. australis in the sera of different wild animal species.  相似文献   

17.
A sero-epidemiological study of cats and dogs in the Launceston area of Tasmania, Australia was undertaken to determine the prevalence of antibodies to spotted fever group (SFG) rickettsiae. Results showed that 59% of cats and 57% of dogs were positive for antibodies, but there was no correlation between the animal's health and seropositivity at the time of testing, suggesting that rickettsial exposure is unrelated to ill-health in these two species of domestic animals.  相似文献   

18.
Nineteen purebred Beagles of various ages (4, 5, 13, and 47 weeks) were inoculated with North American Trypanosoma cruzi isolates obtained from an opossum (Tc-O), an armadillo (Tc-A), or a dog (Tc-D). Dogs were grouped on the basis of clinical outcome of infection. During the acute stage of disease, dogs of group 1 (n = 7 inoculated with Tc-O or Tc-A) died or were euthanatized because of the severity of disease. Dogs of group 2 (n = 5 inoculated with Tc-O or Tc-A) developed acute disease, but survived to develop chronic disease. Dogs of group 3 (n = 7 Tc-D-inoculated dogs) developed neither acute nor chronic disease. Dogs of group 4 (n = 4--2 dogs 13 weeks old and 2 dogs 47 weeks old) served as noninoculated controls. Clinical signs associated with severe acute myocarditis developed in dogs of groups 1 and 2 between postinoculation day (PID) 15 and 28. Generalized lymphadenopathy and lymphocytosis were observed in all dogs of groups 1, 2, and 3 between PID 14 and 17. Serum alanine transaminase and aspartate transaminase activities and urea nitrogen concentration were high, and glucose concentration was low prior to death of dogs in group 1. Serum activities of isoenzymes of creatine kinase were significantly (P less than 0.05) high in only 1 dog (group 1), whereas serum lactate dehydrogenase isoenzyme activities were not significantly high in any dog.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

19.
Rocky Mountain spotted fever (RMSF) was diagnosed in 30 dogs examined at North Carolina State University, Veterinary Teaching Hospital between 1984 and 1997. Historical, physical examination, and laboratory abnormalities were reviewed. Diagnostic criteria included a four-fold rise in antibody titer to Rickettsia rickettsii (R. rickettsii) (n=15) or a single R. rickettsii antibody titer of 1:1,024 or greater (n=15; when this initial titer was determined one week or more after the onset of clinical signs). Fifteen (50%) dogs were greater than seven years of age, and 13 (43%) dogs were between two and seven years of age. There was no sex predilection. Only five (17%) dogs had a history of known tick exposure. Presumably due to delayed diagnosis, dogs with antibody titers of 1:1,024 or greater at the time of presentation had a higher incidence of more severe neurological dysfunction (e.g., ataxia, hyperesthesia, vestibular disease, and seizures) and cutaneous lesions (e.g., hyperemia, edema, petechiae, ecchymoses, and necrosis). Laboratory findings included anemia, leukocytosis accompanied by toxic granulation of neutrophils, hypoalbuminemia, and coagulation abnormalities; signs were generally more severe in the 15 dogs with R. rickettsii antibody titers of 1:1,024 or greater at the time of presentation. Twelve (40%) dogs in this study were severely thrombocytopenic (less than 75 x10(3) platelets/microl; reference range, 200 to 450 x 10(3)/microl), without clinical evidence of fulminant disseminated intravascular coagulation. In this study, the survival rate following R. rickettsii infection was 100%.  相似文献   

20.
Adult dogs 1 to 5 were inoculated IV and/or SC with 3, 5, or 6 ml of a suspension containing 1.2 x 10(4) Ehrlichia risticii-infected cells (derived from primary canine monocyte cell cultures)/ml. Dogs 6 to 8 were inoculated IV and/or SC with 3 or 6 ml of 1.2 x 10(5) organism-free cultured canine monocytes/ml. Ehrlichia risticii was isolated in cultures from inoculated dogs 3, 4, and 5 on postinoculation days (PID) 10 to 16, but not from dogs 6 to 8. Dogs inoculated with E risticii seroconverted between PID 6 and 12. Clinical signs of illness were not observed in these 5 E risticii-inoculated dogs. A pony, inoculated with E risticii isolated from inoculated dog 5, developed clinical signs of equine monocytic ehrlichiosis, including fever, anorexia, depression, and diarrhea, and E risticii was isolated from the pony's blood. This E risticii isolate was then inoculated into susceptible dog 9, and E risticii was repeatedly isolated from dog 9 during PID 6 to 17. Dogs were susceptible to infection with E risticii and may serve as a reservoir of the organism in the field.  相似文献   

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