Seroprevalence of Borrelia burgdorferi sensu lato and Anaplasma phagocytophilum in dogs with neurological signs

A retrospective cohort study was carried out to evaluate whether seropositivity for the tick-transmitted bacterial species Borrelia burgdorferi sensu lato and/or Anaplasma phagocytophilum was associated with one or more specific categories of nervous system disorders in dogs. A total of 248 dogs with nervous system disorders were serotested for these agents and categorised into six main diagnostic categories: degenerative diseases of the spine, epilepsy, inflammatory diseases, neoplasia, peripheral neuropathies, and other diseases. Multivariable analysis using logistic regression was used to model whether a dog was diagnosed as being in any of these categories. The independent variables included were sex, age, year of serological testing, and whether the animal tested positive for B burgdorferi sensu lato and/or A phagocytophilum. In one model, a statistically significant association was found between a positive titre for A phagocytophilum and the risk of a dog developing neoplastic disease. Although statistically significant, it was concluded that the association was not of clinical relevance.     

Association of urine protein excretion and infection with Borrelia burgdorferi sensu lato in Bernese Mountain dogs

Bernese Mountain dogs (BMDs) are prone to develop a familial glomerulonephropathy and a pathogenic role of Borrelia burgdorferi sensu lato in this disease has been suspected. Glomerular disease in many affected dogs is clinically inapparent and proteinuria is found incidentally. In this study, urine protein excretion was evaluated in 122 clinically healthy BMDs and 55 controls. The seroprevalence of B. burgdorferi in BMDs was 57%, compared to 16% in controls. There were no significant differences in the occurrence of positive dipstick results, microalbuminuria, urine protein-to-urine creatinine ratio or abnormal urine protein pattern (determined by sodium dodecyl sulphate agarose gel electrophoresis) between BMDs and controls and BMDs with and without antibodies against B. burgdorferi. It was concluded that antibodies against B. burgdorferi are not associated with proteinuria as an early sign of renal disease in BMDs.     

Seroprevalence of Borrelia burgdorferi sensu lato and Anaplasma phagocytophilum in Danish horses

Background

Borrelia burgdorferi sensu lato and Anaplasma phagocytophilum are able to infect horses. However, the extend to which Danish horses are infected and seroconvert due to these two bacteria is unknown. The aim of the present study was to evaluate the seroprevalence of B. burgdorferi sensu lato and A. phagocytophilum in Danish horses.

Methods

A total of 390 blood samples collected from all major regions of Denmark and with a geographical distribution corresponding to the density of the Danish horse population were analyzed. All samples were examined for the presence of antibodies against B. burgdorferi sensu lato and A. phagocytophilum by the use of the SNAP^®4DX ^® ELISA test.

Results

Overall, 29.0% of the horses were seropositive for B. burgdorferi sensu lato whereas 22.3% were seropositive for A. phagocytophilum.

Conclusions

Antibodies against B burgdorferi sensu lato and A. phagocytophilum are commonly found among Danish horses thus showing that Danish horses are frequently infected by these organisms.     

Seroprevalence against Borrelia burgdorferi sensu lato and occurence of antibody co-expression with Anaplasma phagocytophilum in dogs in Latvia

Background

Lyme disease is commonly diagnosed in humans in Latvia, but up to date no studies have been performed to investigate its prevalence in dogs. The aim of this study was to evaluate if seroprevalence against B. burgdorferi sensu lato (B. burgdorferi s.l.) and co-expression of antibodies against B.burgdorferi s.l. and A. phagocytophilum is higher in dogs with clinical suspicion of tick-borne diseases compared to healthy dogs.

Findings

Venous blood was taken from healthy dogs (n=441) and dogs suspected to have borreliosis and/ or canine granulocytic anaplasmosis (n=29). The presence of antibodies was detected with SNAP 4Dx test (IDEXX, Westbrook, Maine, USA). The seroprevalence against B. burgdorferi s.l. in healthy dogs was 2.49% (11/441) and 36% (4/11) of seropositive dogs had antibodies against both of investigated bacteria. None of the dogs in sick dog group had detectable antibodies against B. burgdorferi s.l.

Conclusions

We conclude that seroprevalence to B. burgdorferi s.l. in dogs in Latvia is low and that dogs with suspicion of tick-borne disease do not have higher B. burgdorferi s.l. seroprevalence than healthy dogs. Dogs that express antibodies against B. burgdorferi s.l. frequently co-express antibodies against A. phagocytophilum.     

Seroprevalence,spatial distribution and risk factors of Borrelia burgdorferi sensu lato in Jordan

Lyme borreliosis has not been studied in Jordan or in much of the Middle East. However, limited research indicates that the tick vector, Ixodes ricinus, exists in the region. This study examined the seroprevalence of B. burgdorferi s.l. in Jordan and potential demographic and zoonotic risk factors for seropositivity. Serum samples of 824 apparently healthy participants from 11 governorates in Jordan were tested for B. burgdorferi s.l. using Enzygnost Lyme link VlsE/IgG enzyme-linked immunosorbent assay. A validated questionnaire was used to collect demographic and animal exposure data. Univariate and multivariate logistic regression were used to identify factors associated with seropositivity. The results showed that 11.7 % (95 % CI, 9.3–14.0 %) of the participants were seropositive for B. burgdorferi s.l.. There was a bimodal age distribution of seroprevalence with higher seroprevalence among individuals <20 and>60 years old. After controlling for governorate of residence, females had 2.77 (95 % CI 1.53–5.00) times greater odds of seropositivity compared to males. Individuals living in the southeastern part of Jordan (Ma’an) had 2.32 (95 % CI, 1.02−5.31) greater odds of seropositivity compared to those living in Amman, the Capital of Jordan, while those living in the northeast had significantly lower odds of seropositivity. This study presents the first evidence of B. burgdorferi s.l. seropositivity in Jordan and suggests several risk factors which were reported in studies conducted elsewhere. This study suggests that Lyme borreliosis should be considered in the differential diagnosis for patients presenting with skin lesions in Jordan.     

Prevalence of Borrelia burgdorferi sensu lato and Anaplasma phagocytophilum in questing Ixodes ricinus ticks in relation to the density of wild cervids

Background

Borrelia burgdorferi sensu lato and Anaplasma phagocytophilum have been considered as pathogens in animals and humans. The role of wild cervids in the epidemiology is not clear. We analyzed questing Ixodes ricinus ticks collected in spring for these pathogens from sites with high (Fjelløyvær and Strøm) and low density (Tjore, Hinnebu and Jomfruland) of wild cervids to study the spread of the pathogens in questing ticks.

Methods

For detection of Anaplasma phagocytophilum a 77-bp fragment in the msp2 gene was used. Detection of Borrelia burgdorferi sensu lato was performed using the FL6 and FL7 primers according to sequences of conserved regions of the fla gene. The OspA gene located on the linear 49-kb plasmid was used as target in multiplex PCR for genotyping. Genospecies-specific primers were used in the PCR for Borrelia burgdorferi sensu stricto, B. afzelii and B. garinii.

Results

Infection rates with Borrelia spp. were significantly lower at Fjelløyvær and Strøm compared to Tjore and Hinnebu; Fjelløyvær vs. Tjore (χ² = 20.27, p < 0.0001); Fjelløyvær vs. Hinnebu (χ² = 24.04, p < 0.0001); Strøm vs. Tjore (χ² = 11.47, p = 0.0007) and Strøm vs. Hinnebu (χ² = 16.63, p < 0.0001). The Borrelia genospecies were dominated by. B. afzelii (82%) followed by B. garinii (9.7%) and B. burgdorferi sensu stricto (6.9%). B. burgdorferi s.s. was only found on the island of Jomfruland. The infection rate of Anaplasma phagocytophilum showed the following figures; Fjelløyvær vs Hinnebu (χ² = 16.27, p = 0.0001); Strøm vs. Tjore (χ² = 13.16, p = 0.0003); Strøm vs. Hinnebu (χ² = 34.71, p < 0.0001); Fjelløyvær vs. Tjore (χ² = 3.19, p = 0.0742) and Fjelløyvær vs. Støm (χ² = 5.06, p = 0.0245). Wild cervids may serve as a reservoir for A. phagocytophilum. Jomfruland, with no wild cervids but high levels of migrating birds and rodents, harboured both B. burgdorferi s.l. and A. phagocytophilum in questing I. ricinus ticks. Birds and rodents may play an important role in maintaining the pathogens on Jomfruland.

Conclusion

The high abundance of roe deer and red deer on the Norwegian islands of Fjelløyvær and Strøm may reduce the infection rate of Borrelia burgdorferi sensu lato in host seeking Ixodes ricinus, in contrast to mainland sites at Hinnebu and Tjore with moderate abundance of wild cervids. The infection rate of Anaplasma phagocytophilum showed the opposite result with a high prevalence in questing ticks in localities with a high density of wild cervids compared to localities with lower density.     

Evaluation of a commercial enzyme-linked immunosorbent assay for detection of Borrelia burgdorferi exposure in dogs

OBJECTIVE: To evaluate the effectiveness of a commercially available ELISA kit for detecting antibodies against Borrelia burgdorferi in dogs. SAMPLE POPULATION: Banked sera from 440 military working dogs were used for serologic analyses. PROCEDURE: Serum samples were analyzed for antibodies against B burgdorferi by use of a commercially available ELISA and subsequently by western blot analysis as a confirmatory test. RESULTS: Results from the ELISA indicated that 89 (20%) samples were positive for exposure to B burgdorferi or canine Lyme disease vaccine, and 351 (80%) were negative. Follow-up testing by western blot analysis indicated that results for 109 (25%) samples were positive and 331 (75%) were negative for exposure. All samples that had positive results on the ELISA also had positive results on western blot analysis (true positives). Of the 351 samples that had negative results on the ELISA, only 331 had negative results on western blot analysis (true negatives). The remaining 20 samples had positive results on western blot analysis. By use of a standard 2 x 2 table, it was determined that the ELISA had a sensitivity of 82%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 94%. CONCLUSIONS AND CLINICAL RELEVANCE: The commercial ELISA kit evaluated in this study appeared to lack adequate sensitivity for detecting all potential cases of borreliosis in dogs. The ELISA was also unable to discriminate natural exposure from exposure attributable to vaccination, which could complicate interpretation of positive results and treatment of dogs with clinical signs.     

Evidence of Bartonella sp. in questing adult and nymphal Ixodes ricinus ticks from France and co-infection with Borrelia burgdorferi sensu lato and Babesia sp

Ticks are known vectors for a wide range of pathogenic microorganisms. Their role in the transmission of some others is so far only suspected. Ticks can transmit multiple pathogens, however, little is known about the co-existence of these pathogens within questing ticks. We looked for the presence of DNA from three micro-organisms, Bartonella sp., Borrelia burgdorferi sensu lato and Babesia sp. which are known or suspected tick-borne pathogens, using a cohort of 92 questing Ixodes ricinus ticks collected from pastures in northern France. DNA was extracted from each individual tick and the presence of the three pathogens was investigated using Polymerase Chain Reaction (PCR) amplification. Nine among 92 samples (9.8%) demonstrated PCR products using Bartonella specific primers, 3 among 92 (3.3%) using Borrelia burgdorferi sensu lato specific primers and 19 among 92 (20.6%) using Babesia specific primers. Seven among 92 samples (7.6%) were PCR positive for at least two of the pathogens and one sample was positive for all three. Adult ticks (12/18; 67%) showed significantly higher infection rates compared to nymphs (11/74; 15%) for all three pathogens (P < 0.001). This study is the demonstration of the simultaneous presence of Bartonella sp., Borrelia burgdorferi sensu lato and Babesia sp. in questing Ixodes ricinus ticks.     

Prevalence of antibodies against Borrelia burgdorferi sensu lato and Anaplasma phagocytophilum and their clinical relevance in dogs in Munich, Germany

Although prevalences of antibodies against Borrelia (B.) burgdorferi sensu lato (sl) and Anaplasma (A.) phagocytophilum have been reported to be high in the German dog population, the importance of the diseases caused by both agents is still not well characterized in a field situation.The aim of this study was (1) to determine the prevalence of antibodies to B. burgdorferi sl and A. phagocytophilum in dogs in Munich, Germany, and (2) to assess the clinical presentation and laboratory values of antibody-positive dogs and compare them to a negative control group. In total, 448 randomly selected dogs were screened for antibodies to B. burgdorferi sl and A. phagocytophilum with the SNAP 4Dx assay (IDEXX, Laboratories, Inc., USA). Dogs carrying antibodies against B. burgdorferi sl and/or A. phagocytophilum were classified as "positive"(n=100), the following 100 negative dogs served as control group. In both groups, physical examination and laboratory parameters were compared. 22 (4.9%) dogs had antibodies to B. burgdorferi sl, 78 (19.4%) to A. phagocytophilum, nine (2.0%) to both agents. Bernese Mountain Dogs had significantly more often antibodies against B. burgdorferi sl. Negative dogs were more often diagnosed as "healthy" compared to A. phagocytophilum antibody-positives that showed more often elevated body temperature and poor general condition; beyond that, there were no differences in clinical and laboratory abnormalities between both groups. Although dogs tested negative were more often considered healthy, there were no differences in parameters considered "specific" for both infections between dogs with and without antibodies. Hence, tests detecting antibodies against both agents are not able to detect animals with the clinical disease.     

Borrelia burgdorferi sensu lato and Rickettsia spp. infections in hard ticks (Ixodes ricinus) in the region of Hanover (Germany)

In a total of 605 Ixodes (I.) ricinus ticks collected in the spring-months March, April and May 2005, quantitative real time PCR (qPCR) revealed 26.6% Borrelia (B.) burgdorferi sensu lato (sl)-positive ticks, i. e. divided by sex and stage into 31.9% positive adults (34.8% females and 29.0% males) and 18.5% positive nymphs. Mono-infections with genospecies from the B. burgdorferi sl-complex were found in over two thirds of the positive individuals, whereas almost one third showed double- or even triple-infections. Genospecies-specific conventional PCR determined B. afzelii as the most frequent genospecies followed by B. garinii, B. spielmanii, B. valaisiana and B. burgdorferi sensu stricto (ss). Rickettsia spp. were found in 34.2% of the collected ticks, divided into 37.6% adults (42.5% females and 32.8% males) and 29.0% nymphs. Co-infections of Rickettsia-positive ticks with B. burgdorferi sl spirochaetes were present in 10.1% of the ticks. Thereby, adult ticks exhibited a co-infection rate of 13.4% (15.5% females and 11.3% males) and nymphs of 5.0%. Independently of the above mentioned study, 3939 Ixodes ticks, sent in between 2006 and 2010 for B. burgdorferi sl-diagnostic, were examined by qPCR exclusively for B. burgdorferi sl. The resulting B. burgdorferi sl prevalence was 23.1% and 24.4% in 2006 and 2007, respectively, followed by a continuous decrease to 12.8% in 2010. To analyse whether this observed decrease in infection frequency is due to sampling bias, in a current study randomly sampled ticks collected from defined sites equally distributed over the city of Hanover are investigated in a statistically relevant sample size.     

Prevalence of antibodies to Borrelia burgdorferi sensu lato in southern chamois (Rupicapra pyrenaica) in Spain

Ungulates are involved in the epidemiology of Borreliosis as maintenance hosts for vector tick species. We evaluated the prevalence of antibodies to Borrelia burgdorferi sensu lato in two different populations of southern chamois in Spain. Forty-six sera (40.4%) were positive at titres >/=1 : 64 using an indirect immunofluorescence assay (IFAT).     

Molecular detection of tick-borne haemopathogens in shelter dogs and Rhipicephalus sanguineus (sensu lato) ticks from Peninsular Malaysia

Ticks are important vectors in transmitting various pathogens and they could jeopardize the health and welfare of humans and animals worldwide. The present study aimed to investigate the presence of important tick-borne haemopathogens (TBH) in dogs and ticks via polymerase chain reaction (PCR) assays. A total of 220 blood samples and 140 ticks were collected from 10 animal shelters in Peninsular Malaysia. Of 220 blood samples, 77 (35 %) were positive to TBH, of which 20 % were E. canis, 12 % were A. platys, 7 % were B. gibsoni and 7 % were B. vogeli. All ticks were identified as Rhipicephalus sanguineus with five samples (3.57 %) positive with TBH. Co-infections of TBH (0.45–9.55 %) in dogs were also observed in this study.     

Cerebrospinal Fluid PCR and Antibody Concentrations against Anaplasma phagocytophilum and Borrelia burgdorferi sensu lato in Dogs with Neurological Signs

Background: The tick-borne bacteria Borrelia burgdorferi sensu lato (sl) and Anaplasma phagocytophilum have been suspected to cause neurological signs in dogs. Diagnosis often has been made based on positive antibody titers in serum of dogs with neurological signs, but a high seroprevalence in dogs in at-risk populations makes diagnosis difficult.
Objective: To determine if the neurological signs in dogs examined were caused by any of these bacteria.
Animals: Fifty-four dogs presented to a board-certified neurologist.
Methods: Prospective study. We divided dogs into 2 groups: those with inflammatory diseases of the central nervous system (CNS) and those with neurological signs from other diseases. Blood and cerebrospinal fluid (CSF) from all dogs were analyzed.
Results: Dogs with inflammatory CNS diseases showed no serum antibodies against any of the agents. Among dogs with neurological signs from other diseases, 10.3% had serum antibodies for B. burgdorferi sl and 20.5% for A. phagocytophilum . All blood samples analyzed for bacterial deoxyribonucleic acid (DNA) and all CSF analyzed for antibodies and bacterial DNA for the 2 agents were negative.
Conclusions and Clinical Importance: Based on this study, these bacteria are unlikely causes of neurologic disease in dogs and the presence of serum antibodies alone does not document or establish a definitive diagnosis of CNS disease caused by these organisms. Dogs that have neurologic disease and corresponding serum antibodies against these agents should have additional tests performed to assess for other potential etiologies of the signs.     

Experimental infection of laboratory mice and rabbits with several isolates of Borrelia burgdorferi sensu lato; comparison of antigens from different genospecies in serological measurement of immune responses

Infectivity of and immune responses to 28 Finnish Borrelia burgdorferi sensu lato isolates was studied in 3-4-week-old outbred NMRI and inbred BALB/c/Hy laboratory mice; rabbits were also inoculated. Twenty-one isolates were found to detectably infect mice. A variation among isolates in degree of infectivity was observed. Higher infection rate and higher average ELISA readings were recorded for intradermal than intraperitoneal inoculations. The results suggest differences between Borrelia genospecies in organotropism. The ear was frequently infected by representatives of all genospecies; among high infectivity experiments, this rate was highest, 100%, in infections by Borrelia afzelii. Further differences between genospecies specific organ distributions: B. burgdorferi sensu stricto and Borrelia garinii isolates seemed to infect the bladder relatively more frequently than B. afzelii did; B. afzelii isolates infected heart relatively more frequently than others did. Genospecies specific differences were demonstrated between antigens in reactivity, i.e. in their 'sensitivity' as reagents of ELISA and IFA methods to measure isolate specific immune responses. Antigens from two B. afzelii isolates differed clearly in sensitivity.     

Presence and distribution of Borrelia burgdorferi sensu lato species in internal organs and skin of naturally infected symptomatic and asymptomatic dogs, as detected by polymerase chain reaction.

Tissues from Dutch family dogs symptomatic for borreliosis according to established criteria and from infected but asymptomatic dogs were tested for Borrelia burgdorferi sensu lato DNA using a polymerase chain reaction. Subsequently, B. burgdorferi sensu stricto, B. garinii, B. afzelii, and B. valaisiana were identified by hybridization. Symptomatic dogs showed a higher prevalence of Borrelia in liver samples (9 of 15) than asymptomatic dogs (9 of 43) p = 0.0049. Overall, B. garinii was the most prevalent species and occurred together with up to three other species in on liver sample. B. burgdorferi sensu stricto however, was predominantly detected in samples of synovial membranes, skin, cerebrospinal fluid, bladder, heart, and bone marrow. Nine out of 10 symptomatic dogs with a very high antibody titre were positive for Borrelia DNA by PCR in one or more of these tissues. We conclude that dissemination in naturally infected European dogs occurs and that the two most prevalent species, B. burgdorferi sensu stricto and B. garinii, differ in their tropism.     

Ability of an oral formulation of afoxolaner to protect dogs from Borrelia burgdorferi infection transmitted by wild Ixodes scapularis ticks

A randomized, blinded, negative controlled study was conducted to determine whether treatment with afoxolaner (NexGard^®, Merial, Inc.) would prevent the transmission of Borrelia burgdorferi to dogs by wild caught Ixodes scapularis ticks. Twenty healthy dogs were randomly assigned to two groups of ten dogs each. Ten dogs were treated orally on Day 0 at a dose near the minimum recommended dose of afoxolaner of 2.5 mg/kg (actual doses 2.5–3.1 mg/kg) and ten control dogs were not treated. On Day 28, each dog was infested with approximately 50 adult unfed wild caught I. scapularis that had a 67% B. burgdorferi infection rate (determined by polymerase chain reaction). On Day 33, live ticks were counted and removed. No ticks were found on treated dogs while control dogs had an average of 21.4 ticks. To detect infection, the B. burgdorferi-specific C6 antibody SNAP^® 4Dx^® test (IDEXX) was performed on serum collected before infestation (all dogs seronegative on Days -6 and 27) and on Days 48, 63, 77 and 92. The ten treated dogs remained seronegative through the end of the study (Day 92), while nine out of the ten control dogs were infected, as demonstrated by their seroconversion to being positive for the presence of the B. burgdorferi-specific C6 antibody starting on Day 48. In this study, all dogs treated with NexGard^® 28 days prior to challenge with wild caught I. scapularis ticks were protected from B. burgdorferi infection, while nine out of the ten untreated control dogs were infected.     

Cross-sectional study of the seroprevalence to Borrelia burgdorferi sensu lato and granulocytic Ehrlichia spp. and demographic, clinical and tick-exposure factors in Swedish horses

A cross-sectional study of the seroprevalence to Borrelia burgdorferi sensu lato and granulocytic Ehrlichia spp. in Swedish horses was conducted to evaluate associations with demographic, clinical and tick-exposure factors. From September 1997–1998, blood samples from 2018 horses were collected from the animals presented to veterinary clinics affiliated with the Swedish Horserace Totalizator Board (regardless of the primary cause for consultation). Standardized questionnaires with information both from owners and attending veterinarians accompanied each blood sample. The apparent seroprevalences to B. burgdorferi s. l. and granulocytic Ehrlichia spp. were 16.8 and 16.7%, respectively. The northern region had the lowest seroprevalences. Four logistic models were developed (controlling for demographic variables). In the disease model of seropositivity to B. burgdorferi s. l., age, breed, geographic region, the serologic titer to granulocytic Ehrlichia spp., season and the diagnosis coffin-joint arthritis were significant. In the tick-exposure model of B. burgdorferi s. l., pasture access the previous year and gender were significant. Age, racing activity, geographic region, season and the serologic titer to B. burgdorferi s. l. were associated with positivity to granulocytic Ehrlichia spp. In the tick-exposure model of granulocytic Ehrlichia spp., pasture access was a risk factor. An interaction between racing activity and geographic region showed that the risk of positive serologic reactions to Ehrlichia spp. was increased in the horse population in the south and middle of Sweden, but only among horses not used for racing. Except for the positive association between coffin-joint arthritis and serologic reactions to B. burgdorferi s. l., there were no significant associations in the multivariable models between non-specific or specific clinical sign or disease with seropositivity to either of these agents.     

Detection of Borrelia burgdorferi DNA in tissues from dogs with presumptive Lyme borreliosis

OBJECTIVE: To develop a quantitative PCR assay for detection of Borrelia burgdorferi DNA in formalin-fixed, paraffin-embedded tissues; compare results of this assay with results of immunohistochemical staining of tissues from seropositive dogs; and determine whether B burgdorferi DNA could be detected in renal tissues from dogs with presumptive Lyme nephritis. DESIGN: Cohort study. SAMPLE POPULATION: Archived tissue samples from 58 dogs. PROCEDURES: A quantitative PCR assay was performed on formalin-fixed, paraffin-embedded tissue sections from the dogs. Results were compared with results of immunohistochemical staining, B burgdorferi serostatus, clinical signs, and necropsy findings. RESULTS: 38 dogs were classified as having positive or equivocal results for Lyme borreliosis, and 20 were classified as having negative results on the basis of clinical signs, serologic findings, and pathologic abnormalities. Borrelia burgdorferi DNA was amplified from tissue samples from only 4 (7%) dogs, all of which had been classified as having positive or equivocal results for Lyme borreliosis and had signs of presumptive Lyme nephritis. Results of PCR assays of renal tissue were positive for only 1 dog, and there was no agreement between results of immunohistochemical staining (ie, detection of B burgdorferi antigen) and results of the PCR assay (ie, detection of B burgdorferi DNA) for renal tissues. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that detection of B burgdorferi DNA in formalin-fixed, paraffin-embedded tissues is feasible, but that intact B burgdorferi DNA is rarely found in tissues from naturally infected dogs, even tissues from dogs with presumptive Lyme borreliosis. Further, findings support the contention that Lyme nephritis may be a sterile, immune complex disease.