Ecological diversity of Bartonella species infection among dogs and their owner in Virginia

Bartonella spp. in households with cats: Risk factors for infection in cats and human exposure

The aim of this study was to estimate the occurrence of Bartonella spp. per household in cats and the risk factors for Bartonella spp. positivity in cats and their owners from Valdivia, Chile. A total of 464 cats (distributed within 324 households) and 326 humans (control group [n = 112] and cat owner [n = 214]) distributed in 262 households were sampled. From the cat owners (n = 214), 128 humans were in households where the cat was also sampled, totaling 84 households with dual sampling. Real-time PCR (qPCR) was used for Bartonella spp. detection in blood from cats and humans, and immunofluorescent immunoassay (IFA) anti-Bartonella henselae was performed in human serum samples. Out of the total of 324 households, 20.43% presented at least one Bartonella positive cat. From the households with dual sampling, 29.7% (25/84) presented at least one qPCR-Bartonella spp. positive cat. However, Bartonella DNA was not amplified in humans, and in 7.3% (6/82) of the households was found at least one of the cat's owners exposed to B. henselae. Cats younger than one year (Odds Ratio (OR) = 5.3), non-neutered (OR 3.46), sampled at home (OR 5.82), and with improper application of tick/flea control products (OR 3.13) showed a higher risk for Bartonella spp. presence. Humans with occupational exposure involving animal contact, were more likely to exhibit B. henselae seropositivity (OR 7.5). Bartonella spp. was present in the cats a moderate number of households, but Bartonella DNA was not detected in owners' blood, inferring that there is a low risk of recent human infection in the studied population.

Detection of Bartonella spp. in dogs after infection with Rickettsia rickettsii

Background

Dynamics of infection by Bartonella and Rickettsia species, which are epidemiologically associated in dogs, have not been explored in a controlled setting.

Objectives

Describe an outbreak investigation of occult Bartonella spp. infection among a group of dogs, discovered after experimentally induced Rickettsia rickettsii (Rr) infection.

Animals

Six apparently healthy purpose‐bred Beagles obtained from a commercial vendor.

Methods

Retrospective and prospective study. Dogs were serially tested for Bartonella spp. and Rr using serology, culture, and PCR, over 3 study phases: 3 months before inoculation with Rr (retrospective), 6 weeks after inoculation with Rr (retrospective), and 8 months of follow‐up (prospective).

Results

Before Rr infection, 1 dog was Bartonella henselae (Bh) immunofluorescent antibody assay (IFA) seroreactive and 1 was Rickettsia spp. IFA seroreactive. After inoculation with Rr, all dogs developed mild Rocky Mountain spotted fever compatible with low‐dose Rr infection, seroconverted to Rickettsia spp. within 4‐11 days, and recovered within 1 week. When 1 dog developed ear tip vasculitis with intra‐lesional Bh, an investigation of Bartonella spp. infection was undertaken. All dogs had seroconverted to 1‐3 Bartonella spp. between 7 and 18 days after Rr inoculation. Between 4 and 8 months after Rr inoculation, Bh DNA was amplified from multiple tissues from 2 dogs, and Bartonella vinsonii subsp. berkhoffii (Bvb) DNA was amplified from 4 of 5 dogs' oral swabs.

Conclusions and Clinical Importance

Vector‐borne disease exposure was demonstrated in research dogs from a commercial vendor. Despite limitations, our results support the possibilities of recrudescence of chronic subclinical Bartonella spp. infection after Rr infection and horizontal direct‐contact transmission between dogs.

Bartonella spp. Bloodstream Infection in a Canadian Family

Historically, Bartonella spp. have been associated with febrile illness (Oroya fever, trench fever, and cat scratch disease), endocarditis (numerous Bartonella spp.), and vasoproliferative lesions (Bartonella bacilliformis, Bartonella quintana, Bartonella henselae, and Bartonella vinsonii subsp. berkhoffii), occurring most often but not exclusively in immunocompromised patients. Recently, bloodstream infections with various Bartonella spp. have been documented in nonimmunocompromised individuals in association with a spectrum of cardiovascular, neurologic, and rheumatologic symptoms. As documented in this family, symptoms for which the medical implications remain unclear can occur in multiple family members infected with one or more Bartonella spp. Serial serologic and molecular microbiological findings supported exposure to or infection with Bartonella spp. in all seven family members. Either antibiotics failed to eliminate bacteremic infection, resulted in partial resolution of symptoms, or potentially reinfection occurred during the 19-month study period. There is a substantial need for clinical research to clarify the extent to which Bartonella spp. bacteremia induces nonspecific cardiovascular, neurologic, or rheumatologic symptoms, for ongoing improvement in the sensitivity and specificity of diagnostic testing, and clarification as to if, when, and how to treat patients with documented Bartonella spp. bacteremia.

Bartonellosis, One Health and all creatures great and small

BACKGROUND

Bartonellosis is a zoonotic infectious disease of worldwide distribution, caused by an expanding number of recently discovered Bartonella spp.

OBJECTIVES

This review serves as an update on comparative medical aspects of this disease, including the epidemiology, pathogenesis, clinical diagnosis, treatment and challenges.

RESULTS

Of comparative medical importance, Bartonella spp. are transmitted by several arthropod vectors, including fleas, keds, lice, sand flies, ticks and, potentially, mites and spiders. Prior to 1990, there was only one named Bartonella species (B. bacilliformis), whereas there are now over 36, of which 17 have been associated with an expanding spectrum of animal and human diseases. Recent advances in diagnostic techniques have facilitated documentation of chronic bloodstream and dermatological infections with Bartonella spp. in healthy and sick animals, in human blood donors, and in immunocompetent and immunocompromised human patients. The field of Bartonella research remains in its infancy and is rich in questions, for which patient relevant answers are badly needed. Directed Bartonella research could substantially reduce a spectrum of chronic and debilitating animal and human diseases, and thereby reduce suffering throughout the world.

CONCLUSION

A One Health approach to this emerging infectious disease is clearly needed to define disease manifestations, to establish the comparative infectious disease pathogenesis of this stealth pathogen, to validate effective treatment regimens and to prevent zoonotic disease transmission.

Comparison of serological and molecular panels for diagnosis of vector-borne diseases in dogs

Background

Canine vector-borne diseases (CVBD) are caused by a diverse array of pathogens with varying biological behaviors that result in a wide spectrum of clinical presentations and laboratory abnormalities. For many reasons, the diagnosis of canine vector-borne infectious diseases can be challenging for clinicians. The aim of the present study was to compare CVBD serological and molecular testing as the two most common methodologies used for screening healthy dogs or diagnosing sick dogs in which a vector-borne disease is suspected.

Methods

We used serological (Anaplasma species, Babesia canis, Bartonella henselae, Bartonella vinsonii subspecies berkhoffii, Borrelia burgdorferi, Ehrlichia canis, and SFG Rickettsia) and molecular assays to assess for exposure to, or infection with, 10 genera of organisms that cause CVBDs (Anaplasma, Babesia, Bartonella, Borrelia, Ehrlichia, Francisella, hemotropic Mycoplasma, Neorickettsia, Rickettsia, and Dirofilaria). Paired serum and EDTA blood samples from 30 clinically healthy dogs (Group I) and from 69 sick dogs suspected of having one or more canine vector-borne diseases (Groups II-IV), were tested in parallel to establish exposure to or infection with the specific CVBDs targeted in this study.

Results

Among all dogs tested (Groups I-IV), the molecular prevalences for individual CVBD pathogens ranged between 23.3 and 39.1%. Similarly, pathogen-specific seroprevalences ranged from 43.3% to 59.4% among healthy and sick dogs (Groups I-IV). Among these representative sample groupings, a panel combining serological and molecular assays run in parallel resulted in a 4-58% increase in the recognition of exposure to or infection with CVBD.

Conclusions

We conclude that serological and PCR assays should be used in parallel to maximize CVBD diagnosis.

Serological and molecular prevalence of selected canine vector borne pathogens in blood donor candidates, clinically healthy volunteers, and stray dogs in North Carolina

Background

Canine vector borne diseases (CVBDs) comprise illnesses caused by a spectrum of pathogens that are transmitted by arthropod vectors. Some dogs have persistent infections without apparent clinical, hematological or biochemical abnormalities, whereas other dogs develop acute illnesses, persistent subclinical infections, or chronic debilitating diseases. The primary objective of this study was to screen healthy dogs for serological and molecular evidence of regionally important CVBDs.

Methods

Clinically healthy dogs (n = 118), comprising three different groups: Gp I blood donor candidates (n = 47), Gp II healthy dog volunteers (n = 50), and Gp III stray dogs (n = 21) were included in the study. Serum and ethylenediamine tetraacetic acid (EDTA) anti-coagulated blood specimens collected from each dog were tested for CVBD pathogens.

Results

Of the 118 dogs tested, 97 (82%) dogs had been exposed to or were infected with one or more CVBD pathogens. By IFA testing, 9% of Gp I, 42% of Gp II and 19% of Gp III dogs were seroreactive to one or more CVBD pathogens. Using the SNAP 4DX® assay, Gp I dogs were seronegative for Anaplasma spp., Ehrlichia spp., and B. burgdorferi (Lyme disease) antibodies and D. immitis antigen. In Gp II, 8 dogs were Ehrlichia spp. seroreactive, 2 were infected with D. immitis and 1 was B. burgdorferi (Lyme disease) seroreactive. In Gp III, 6 dogs were infected with D. immitis and 4 were Ehrlichia spp. seroreactive. Using the BAPGM diagnostic platform, Bartonella DNA was PCR amplified and sequenced from 19% of Gp I, 20% of Gp II and 10% of Gp III dogs. Using PCR and DNA sequencing, 6% of Gps I and II and 19% of Gp III dogs were infected with other CVBD pathogens.

Conclusion

The development and validation of specific diagnostic testing modalities has facilitated more accurate detection of CVBDs. Once identified, exposure to vectors should be limited and flea and tick prevention enforced.

Analysis of seroreactivity against cell culture-derived Bartonella spp. antigens in dogs

BACKGROUND

Little is known about the specificity of Bartonella spp. immunofluorescent antibody (IFA) assays in dogs. Bacteremia in sick dogs most often has been associated with Bartonella henselae (Bh), Bartonella vinsonii subspecies berkhoffii (Bvb), and Bartonella koehlerae (Bk). Clarification of the diagnostic utility of IFA serology when testing against these organisms is needed.

OBJECTIVE

To evaluate the specificity of Bartonella IFA assays utilizing 6 cell culture-grown antigen preparations.

ANIMALS

Archived sera from SPF dogs (n = 29) and from dogs experimentally infected with Bvb (n = 10) and Bh (n = 3).

METHODS

Antibodies (Abs) to Bvb genotypes I, II, and III, Bh serotype I, strains H-1 and SA2, and to Bk were determined by IFA testing.

RESULTS

Serum from naïve SPF dogs shown to be negative for Bartonella bacteremia did not react with any of the 6 Bartonella antigens by IFA testing. Dogs experimentally infected with Bvb genotype I developed Abs against homologous antigens, with no cross-reactivity to heterologous Bvb genotypes, Bh H-1, SA2 strains, or to Bk. Dogs experimentally infected with Bh serotype I developed Abs against Bh H-1, but not to Bh SA2 strain with no cross-reactive Abs to Bvb genotypes I-III or to Bk.

CONCLUSIONS AND CLINICAL IMPORTANCE

Bartonella spp. Ab responses during acute experimental infections are species and type specific.

Experimental infection of dogs with various Bartonella species or subspecies isolated from their natural reservoir

Dogs can be infected by a wide variety of Bartonella species. However, limited data is available on experimental infection of dogs with Bartonella strains isolated from domestic animals or wildlife. We report the inoculation of six dogs with Bartonella henselae (feline strain 94022, 16S rRNA type II) in three sets of two dogs, each receiving a different inoculum dose), four dogs inoculated with B. vinsonii subsp. berkhoffii type I (ATCC strain, one mongrel dog) or type II (coyote strain, two beagles and one mongrel) and B. rochalimae (coyote strain, two beagles). None of the dogs inoculated with B. henselae became bacteremic, as detected by classical blood culture. However, several dogs developed severe necrotic lesions at the inoculation site and all six dogs seroconverted within one to two weeks. All dogs inoculated with the B. v. berkhoffii and B. rochalimae strains became bacteremic at levels comparable to previous experimental infections with either a dog isolate or a human isolate. Our data support that dogs are likely accidental hosts for B. henselae, just like humans, and are efficient reservoirs for both B. v. berkhoffii and B. rochalimae.

Flea species infesting dogs in Florida and Bartonella spp. prevalence rates

Several Bartonella spp. associated with fleas can induce a variety of clinical syndromes in both dogs and humans. However, few studies have investigated the prevalence of Bartonella in the blood of dogs and their fleas. The objectives of this study were to determine the genera of fleas infesting shelter dogs in Florida, the prevalence of Bartonella spp. within the fleas, and the prevalence of Bartonella spp. within the blood of healthy dogs from which the fleas were collected. Fleas, serum, and EDTA-anti-coagulated whole blood were collected from 80 healthy dogs, and total DNA was extracted for PCR amplification of Bartonella spp. The genera of fleas infesting 43 of the dogs were determined phenotypically. PCR amplicons from blood and flea pools were sequenced to confirm the Bartonella species. Amplicons for which sequencing revealed homology to Bartonella vinsonii subsp. berkhoffii (Bvb) underwent specific genotyping by targeting the 16S-23S intergenic spacer region. A total of 220 fleas were collected from 80 dogs and pooled by genus (43 dogs) and flea species. Bartonella spp. DNA was amplified from 14 of 80 dog blood samples (17.5%) and from 9 of 80 pooled fleas (11.3%). B. vinsonii subsp. berkhoffii DNA was amplified from nine dogs and five of the flea pools. Bartonella rochalimae (Br) DNA was amplified from six dogs and two flea pools. One of 14 dogs was co-infected with Bvb and Br. The dog was infested with Pulex spp. fleas containing Br DNA and a single Ctenocephalides felis flea. Of the Bvb bacteremic dogs, five and four were infected with genotypes II and I, respectively. Of the Bvb PCR positive flea pools, three were Bvb genotype II and two were Bvb genotype I. Amplification of Bvb DNA from Pulex spp. collected from domestic dogs, suggests that Pulex fleas may be a vector for dogs and a source for zoonotic transfer of this pathogen from dogs to people. The findings of this study provide evidence to support the hypothesis that flea-infested dogs may be a reservoir host for Bvb and Br and that ectoparasite control is an important component of shelter intake protocols.

Co-infection with Anaplasma platys, Bartonella henselae and Candidatus Mycoplasma haematoparvum in a veterinarian

BACKGROUND

During a two year period, a 27-year-old female veterinarian experienced migraine headaches, seizures, including status epilepticus, and other neurological and neurocognitive abnormalities. Prior to and during her illness, she had been actively involved in hospital-based work treating domestic animals, primarily cats and dogs, in Grenada and Ireland and anatomical research requiring the dissection of wild animals (including lions, giraffe, rabbits, mongoose, and other animals), mostly in South Africa. The woman reported contact with fleas, ticks, lice, biting flies, mosquitoes, spiders and mites and had also been scratched or bitten by dogs, cats, birds, horses, reptiles, rabbits and rodents. Prior diagnostic testing resulted in findings that were inconclusive or within normal reference ranges and no etiological diagnosis had been obtained to explain the patient's symptoms.

METHODS

PCR assays targeting Anaplasma sp. Bartonella sp. and hemotopic Mycoplasma sp. were used to test patient blood samples. PCR positive amplicons were sequenced directly and compared to Gen Bank sequences. In addition, Bartonella alpha Proteobacteria growth medium (BAPGM) enrichment blood culture was used to facilitate bacterial growth and Bartonella spp. serology was performed by indirect fluorescent antibody testing.

RESULTS

Anaplasma platys, Bartonella henselae and Candidatus Mycoplasma haematoparvum DNA was amplified and sequenced from the woman's blood, serum or blood culture samples. Her serum was variably seroreactive to several Bartonella sp. antigens. Despite symptomatic improvement, six months of doxycycline most likely failed to eliminate the B. henselae infection, whereas A. platys and Candidatus M. haematoparvum DNA was no longer amplified from post-treatment samples.

CONCLUSIONS

As is typical of many veterinary professionals, this individual had frequent exposure to arthropod vectors and near daily contact with persistently bacteremic reservoir hosts, including cats, the primary reservoir host for B. henselae, and dogs, the presumed primary reservoir host for A. platys and Candidatus Mycoplasma haematoparvum. Physicians caring for veterinarians should be aware of the occupational zoonotic risks associated with the daily activities of these animal health professionals.

Experimental infection of horses with Bartonella henselae and Bartonella bovis

BACKGROUND

Experimental infection of horses with Bartonella species is not documented.

OBJECTIVES

Determine clinical signs, hematologic changes, duration of bacteremia, and pattern of seroconversion in Bartonella henselae or Bartonella bovis-inoculated horses.

ANIMALS

Twelve (2 groups of 6) randomly selected healthy adult horses seronegative and culture negative for Bartonella spp.

METHODS

Experimental/observational study: Group I: B. henselae or saline control was inoculated intradermally into 4 naïve and 2 sentinel horses, respectively. Group II: same design was followed by means of B. bovis. Daily physical examinations, once weekly CBC, immunofluorescent antibody assay serology, real-time polymerase chain reaction (PCR), and twice weekly blood cultures were performed for 6 weeks and at postinoculation day 80 and 139. Bartonella alpha-Proteobacteria growth medium (BAPGM) enrichment blood culture was performed for horses that seroconverted to B. henselae antigens.

RESULTS

Transient clinical signs consistent with bartonellosis occurred in some Bartonella-inoculated horses, but hematological alterations did not occur. Three B. henselae-inoculated horses seroconverted, whereas 1 B. bovis-inoculated horse was weakly seropositive. In Group I, B. henselae was amplified and sequenced from BAPGM blood culture as well as a subculture isolate from 1 horse, blood from a 2nd horse, and BAPGM blood culture from a 3rd horse although a subculture isolate was not obtained. All sentinels remained PCR, culture, and serology negative.

CONCLUSIONS

Detection of Bartonella sp. in blood after experimental inoculation supports bacteremia and seroconversion. Culture with BAPGM may be required to detect Bartonella sp. Although mild clinical signs followed acute infection, no long-term effects were noted for 2 years postinoculation.