Bartonellaspp. Infection in Healthy and Sick Horses and Foals from the Southeastern United States

A comparison of Bartonella henselae infection in immunocompetent and immunocompromised mice

Bartonellosis refers to disease caused by the Bartonella genus of bacteria. The breadth of disease manifestations associated with Bartonella is currently expanding and includes regional lymphadenopathy, rheumatic, ocular, and neurological disorders. The dearth of knowledge regarding diagnosis, treatment and pathogenesis of this disease can be partially attributed to the lack of a reliable small animal model for the disease. For this study, Bartonella henselae, the most common species associated with human disease, was injected into Swiss Webster (SW) mice. When the outcome indicated that productive infection did not occur, SCID/Beige (immune compromised) mice were inoculated. While SW mice may potentially harbor an acute infection, less than 10 days in length, the SCID/Beige model provided a sustained infection lasting up to 30-days. These data indicate that SCID/Beige mice can provide a model to study Bartonella infection, therapeutics, and vector dynamics in the future.

Viability and Desiccation Resistance of Bartonella henselae in Biological and Non-Biological Fluids: Evidence for Pathogen Environmental Stability

Pathogen environmental stability is an often-neglected research priority for pathogens that are known to be vector-transmitted. Bartonella henselae, the etiologic agent of Cat Scratch Disease, has become a "pathogen of interest" in several serious human illnesses, which include neoplastic, cardiovascular, neurocognitive, and rheumatologic conditions. Survival in the flea gut and feces as well as the association with a biofilm in culture-negative endocarditis provides insight into this organism's ability to adjust to environmental extremes. The detection of B. henselae DNA in blood and tissues from marine mammals also raises questions about environmental stability and modes of pathogen transmission. We investigated the ability of B. henselae to survive in fluid matrices chosen to mimic potential environmental sources of infective materials. Feline whole blood, serum and urine, bovine milk, and physiologic saline inoculated with a laboratory strain of B. henselae San Antonio 2 were subsequently evaluated by culture and qPCR at specified time intervals. Bacterial viability was also assessed following desiccation and reconstitution of each inoculated fluid matrix. Bartonella henselae SA2 was cultured from feline urine up to 24 h after inoculation, and from blood, serum, cow's milk, and physiologic saline for up to 7 days after inoculation. Of potential medical importance, bacteria were cultured following air-desiccation of all fluid inoculates. The viability and stability of Bartonella within biological and non-biological fluids in the environment may represent a previously unrecognized source of infection for animals and human beings.

Blood Supplementation Enhances Bartonella henselae Growth and Molecular Detection of Bacterial DNA in Liquid Culture

Bacteria of the genus Bartonella, a member of the Alphaproteobacteria, are fastidious, Gram-negative, aerobic bacilli that comprise numerous species, subspecies, and genotypes. Bartonella henselae, with a worldwide distribution, infects cats, dogs, horses, humans, and other mammals. Diagnostically, direct detection of Bartonella henselae in patient blood specimens by culture or molecular methods is required to confirm infection with this bacterium. Enrichment blood culture combined with quantitative PCR (qPCR) or ddPCR enhances the sensitivity of direct detection. The addition of sheep blood to liquid culture media increased the Bartonella henselae DNA concentration compared to controls, additionally improving PCR direct detection sensitivity. IMPORTANCE This study aims to improve diagnostic detection of Bartonella henselae. Patient samples are combined with enriched bacterial cultures aimed at growing Bartonella henselae for the best possible chance at detection. However, current Bartonella growth methods could be improved. The DNA extraction method used by most laboratories should also be optimized. Sheep blood was added to increase the growth of Bartonella henselae and multiple DNA extraction methods were to be compared to each other.

A Review of Bartonella Infections in California-Implications for Public and Veterinary Health

Bartonella are vector-transmitted, intracellular bacteria that infect a wide variety of blood-feeding arthropods and their vertebrate hosts. In California, more than 13 species of Bartonella have been described from companion animals, livestock, and wildlife, of which four have been associated with human disease. Infections in humans cause a range of symptoms from relatively mild to severe, especially in immunocompromised individuals. Exposure to infected domestic animals and wildlife, and their ectoparasites, may increase the risk of cross-species transmission. The objective of this review was to compile and summarize published materials on human and animal Bartonella infections in California. Medical and veterinary case reports of bartonellosis were highlighted in an effort to increase the awareness of this poorly understood and potentially under-recognized disease among healthcare professionals and veterinarians.

First report on Bartonella henselae in dromedary camels (Camelus dromedarius)

Bartonellosis is one of the clinically underdiagnosed emerging bacterial diseases among domestic livestock, particularly in camels. Until now, the natural infection of camels with Bartonella species was not investigated in Tunisia. In the attempt of filling this gap in knowledge, a total of 412 dromedary camels (Camelus dromedarius) as well as 300 associated ticks (Hyalomma dromedarii (160; 53.4%), H. impeltatum (131; 43.6%) and H. excavatum (9; 3%) were screened for the presence of Bartonella spp. by PCR followed by a sequencing step through the amplification of the rpoB gene. Positive samples were then tested and further characterized by the combined use of the ftsZ and gltA genes. Fifteen camels (3.6%) were found to be positive to Bartonella spp. However, there was no evidence of Bartonella DNA in any of the analyzed ticks. Risk factors' analysis shows that camels derived from arid and semi-arid bioclimatic areas were more infected than those originated from desert area. Molecular characterization and phylogenetic analysis revealed the occurrence of novel B. henselae genotypes closely related to those isolated from humans, cats, and lions. By combining the characteristics of each single gene with those of concatenated sequences, we report here the first molecular detection of B. henselae in the dromedary camel suggesting a possible involvement of camelids as hosts or reservoirs in the transmission cycle of this emerging bacterium in arid and saharan areas.

Molecular identification of vector-borne organisms in Ehrlichia seropositive Nicaraguan horses and first report of Rickettsia felis infection in the horse

Certain vector-borne organisms serve as etiological agents of equine disease. After previously identifying a new Ehrlichia species in horses from Mérida, we aimed to determine the infection frequency and screen for a wide range of vector-borne organisms from 93 tick-exposed, Ehrlichia seropositive horses in this region. PCR assays were performed to identify infection by organisms within the following genera: Anaplasma, Babesia, Bartonella, Ehrlichia, Leishmania, Mycoplasma, Neorickettsia, Rickettsia and Theileria. Overall, 90/93 horses (96.8%) were infected with one or more vector-borne organisms. Ninety (96.8%) horses were infected with Theileria equi and 21 (26.8%) with Babesia caballi. Nine (9.7%) horses were infected with the novel Ehrlichia species previously designated H7, reported in horses from Nicaragua and Brazil. Two horses (2.2%) were infected with Rickettsia felis. Anaplasma, Bartonella, Leishmania, Mycoplasma, or Neorickettsia species DNA was not amplified from any horse. Ticks collected from horses infected with vector-borne organisms were identified as Amblyomma cajennense sensu lato and Dermacentor nitens. Horses in Mérida are infected by a range of vector-borne organisms, including B. caballi, T. equi, Ehrlichia species H7, and R. felis. To the authors' knowledge, this constitutes the first report of molecular detection of R. felis in horses.

Human Bartonellosis: An Underappreciated Public Health Problem?

Bartonella spp. bacteria can be found around the globe and are the causative agents of multiple human diseases. The most well-known infection is called cat-scratch disease, which causes mild lymphadenopathy and fever. As our knowledge of these bacteria grows, new presentations of the disease have been recognized, with serious manifestations. Not only has more severe disease been associated with these bacteria but also Bartonella species have been discovered in a wide range of mammals, and the pathogens’ DNA can be found in multiple vectors. This review will focus on some common mammalian reservoirs as well as the suspected vectors in relation to the disease transmission and prevalence. Understanding the complex interactions between these bacteria, their vectors, and their reservoirs, as well as the breadth of infection by Bartonella around the world will help to assess the impact of Bartonellosis on public health.

Bartonella infections in cats and dogs including zoonotic aspects

Bartonellosis is a vector-borne zoonotic disease with worldwide distribution that can infect humans and a large number of mammals including small companion animals (cats and dogs). In recent years, an increasing number of studies from around the world have reported Bartonella infections, although publications have predominantly focused on the North American perspective. Currently, clinico-pathological data from Europe are more limited, suggesting that bartonellosis may be an infrequent or underdiagnosed infectious disease in cats and dogs. Research is needed to confirm or exclude Bartonella infection as a cause of a spectrum of feline and canine diseases. Bartonella spp. can cause acute or chronic infections in cats, dogs and humans. On a comparative medical basis, different clinical manifestations, such as periods of intermittent fever, granulomatous inflammation involving the heart, liver, lymph nodes and other tissues, endocarditis, bacillary angiomatosis, peliosis hepatis, uveitis and vasoproliferative tumors have been reported in cats, dogs and humans. The purpose of this review is to provide an update and European perspective on Bartonella infections in cats and dogs, including clinical, diagnostic, epidemiological, pathological, treatment and zoonotic aspects.

Equine idiopathic hemorrhagic cystitis: Clinical features and comparison with bladder neoplasia

BACKGROUND

A new syndrome of hematuria in horses has been documented.

HYPOTHESIS/OBJECTIVES

Hemorrhagic cystitis is a novel cause of stranguria and hematuria in horses. This syndrome may be difficult to differentiate from bladder neoplasia because they share several clinical features.

ANIMALS

Eleven horses with idiopathic hemorrhagic cystitis and 7 horses with bladder neoplasia.

METHODS

Retrospective cohort study.

RESULTS

Hemorrhagic cystitis was detected on cystoscopy of affected horses, with hemorrhagic and thickened apical bladder mucosa. Clinical signs and endoscopic appearance of the bladder resolved within 3-8 weeks. Histopathology of bladder mucosal biopsy specimens featured neutrophilic and hemorrhagic cystitis. Histopathology was suggestive of dysplasia or neoplasia in 3 horses with hemorrhagic cystitis, yet the horses experienced complete resolution, suggesting that small biopsy specimens obtained by endoscopy can be difficult to interpret. Horses with bladder neoplasia had lower hematocrits, were older, more likely to be female, and more likely to have a mass detected on ultrasonographic examination of the bladder than horses with hemorrhagic cystitis syndrome.

CONCLUSIONS AND CLINICAL IMPORTANCE

Hemorrhagic cystitis represents a novel differential diagnosis for horses with hematuria, and is associated with a favorable prognosis. Although histopathology may suggest a neoplastic process, affected horses should be monitored cystoscopically, because complete resolution of hemorrhagic cystitis occurs. The cause of this disease is unknown, and warrants investigation.

Bartonella henselae infections in an owner and two Papillon dogs exposed to tropical rat mites (Ornithonyssus bacoti)

After raccoons were trapped and removed from under a house in New York, the owner and her two Papillon dogs became infested with numerous rat mites (Ornithonyssus bacoti). Two weeks later, both dogs developed pruritus, progressively severe vesicular lesions, focal areas of skin exfoliation, swelling of the vulva or prepuce, abdominal pain, and behavioral changes. Two months after the mite infestation, the owner was hospitalized because of lethargy, fatigue, uncontrollable panic attacks, depression, headaches, chills, swollen neck lymph nodes, and vesicular lesions at the mite bite sites. Due to ongoing illness, 3 months after the mite infestation, alcohol-stored mites and blood and serum from both dogs and the owner were submitted for Bartonella serology and Bartonella alpha Proteobacteria growth medium (BAPGM) enrichment blood culture/PCR. Bartonella henselae DNA was amplified and sequenced from blood or culture specimens derived from both dogs, the owner, and pooled rat mites. Following repeated treatments with doxycycline, both dogs eventually became B. henselae seronegative and blood culture negative and clinical signs resolved. In contrast, the woman was never B. henselae seroreactive, but was again PCR positive for B. henselae 20 months after the mite infestation, despite prior treatment with doxycycline. Clinicians and vector biologists should consider the possibility that rat mites may play a role in Bartonella spp. transmission.

SOLITARY IDIOPATHIC CHOROIDITIS IN THE SETTING OF EXTENSIVE ANIMAL EXPOSURE

PURPOSE

To describe solitary idiopathic choroiditis in the setting of extensive animal exposure.

METHODS

A 56-year-old asymptomatic female equestrian with an extensive history of exposure to horses and dogs and a trapper of wild animals and rodents was discovered to have an amelanotic choroidal mass in the macular region and referred for suspicious atypical nevus.

RESULTS

Funduscopy revealed a deep yellow mass with overlying retinal pigment epithelial thinning and without visible subretinal fluid or lipofuscin. Mild hyperautofluorescence represented unmasking of scleral autofluorescence. Ultrasonography showed a 1.8-mm-thick echodense lesion. Enhanced depth imaging-optical coherence tomography disclosed a dense, elevated scleral mass with "volcanic" configuration, demonstrating choroidal compression and trace overlying subretinal fluid. These features were consistent with solitary idiopathic choroiditis/scleritis. Systemic evaluation for standard cat-related bartonellosis, tuberculosis, sarcoidosis, and syphilis were negative. Horse-, dog-, and rodent-related bartonellosis testing was not available. Observation was advised, and the findings remained stable at 6 months.

CONCLUSION

Solitary idiopathic choroiditis is best imaged on enhanced depth imaging-optical coherence tomography as a scleral lesion with "volcanic" configuration and often secondary to previous Bartonella infection. Serologic positivity for cat-related Bartonella decays over time, and testing for horse-, dog-, or rodent-related Bartonella is not commonly used.

Bartonella henselae as a cause of acute-onset febrile illness in cats

Case series summary

At different time points spanning 6 months, three adopted feral flea-infested cats, residing in the household of a veterinary technician, became acutely anorexic, lethargic and febrile. Enrichment blood culture/PCR using Bartonella alpha Proteobacteria growth medium (BAPGM) confirmed initial infection with the same Bartonella henselae genotype in all three cases. With the exception of anemia and neutropenia, complete blood counts, serum biochemical profiles and urinalysis results were within reference intervals. Also, tests for feline leukemia virus, feline immunodeficiency virus, Toxoplasma gondii and feline coronavirus antibodies were negative. Serial daily temperature monitoring in one case confirmed a cyclic, relapsing febrile temperature pattern during 1 month, with resolution during and after treatment with azithromycin. Bartonella henselae Western immunoblot (WB) results did not consistently correlate with BAPGM enrichment blood culture/PCR results or B henselae indirect fluorescent antibody (IFA) titers, and WB titration results were not informative for establishing antibiotic treatment failure. During the respective follow-up periods, no illnesses or additional febrile episodes were reported, despite repeat documentation of B henselae bacteremia in two cats available for follow-up (one with the same genotype and the other with a different B henselae genotype); one cat was, unfortunately, killed by dogs before follow-up testing.

Relevance and novel information

We conclude that microbiological diagnosis and treatment of B henselae infection in cats can be challenging, that antibody titration results and resolution of clinical abnormalities may not correlate with a therapeutic cure, and that fever and potentially neutropenia should be differential diagnostic considerations for young cats with suspected bartonellosis.

Bartonella chomelii is the most frequent species infecting cattle grazing in communal mountain pastures in Spain

The presence of Bartonella spp. was investigated in domestic ungulates grazing in communal pastures from a mountain area in northern Spain, where 18.3% (17/93) of cattle were found to be positive by PCR combined with a reverse line blot (PCR/RLB), whereas sheep (n = 133) or horses (n = 91) were found not to be infected by this pathogen. Bartonella infection was significantly associated with age, since older animals showed a higher prevalence than heifers and calves. In contrast to other studies, B. chomelii was the most frequent species found in cattle (14/17), while B. bovis was detected in only three animals. Moreover, 18 B. chomelii isolates and one B. bovis isolate were obtained from nine animals. Afterwards, B. chomelii isolates were characterized by a multilocus sequence typing (MLST) method which was adapted in this study. This method presented a high discrimination power, identifying nine different sequence types (STs). This characterization also showed the presence of different STs simultaneously in the same host and that STs had switched over time in one of the animals. In addition, B. chomelii STs seem to group phylogenetically in two different lineages. The only B. bovis isolate was characterized with a previously described MLST method. This isolate corresponded to a new ST which is located in lineage I, where the B. bovis strains infecting Bos taurus subsp. taurus are grouped. Further studies on the dynamics of Bartonella infection in cattle and the potential ectoparasites involved in the transmission of this microorganism should be performed, improving knowledge about the interaction of Bartonella spp. and domestic ungulates.

Relationship between degenerative joint disease, pain, and Bartonella spp. seroreactivity in domesticated cats

Background

Recently, a potential association was identified between Bartonella exposure and arthritides in mammalian species other than cats.

Hypothesis/Objectives

We hypothesized that Bartonella exposure is associated with more severe degenerative joint disease (DJD) and a greater burden of DJD‐associated pain in client‐owned cats.

Animals

Ninety‐four client‐owned cats (6 months to 20 years old), ranging from clinically unaffected to severely lame because of DJD.

Methods

Using physical examination and radiography, pain and radiographic scores were assigned to each part of the bony skeleton. Sera were tested for Bartonella henselae, B. koehlerae, and B. vinsonii subsp. berkhoffii (genotypes I, II, and III) antibodies using immunofluorescence antibody assays. Variables were categorized and logistic regression used to explore associations.

Results

Seropositivity to Bartonella was identified in 33 (35.1%) cats. After multivariate analysis controlling for age, total DJD score (OR, 0.51; 95% CI, 0.26–0.97; P = .042), appendicular pain score (OR, 0.33; 95% CI, 0.17–0.65; P = .0011), and total pain score (OR, 0.35; 95% CI, 0.17–0.72; P = .0045) were significantly inversely associated with Bartonella seroreactivity status, indicating that cats with higher DJD and pain scores were less likely to be Bartonella seropositive.

Conclusions and Clinical Importance

Based upon this preliminary study, Bartonella spp. seropositivity was associated with decreased severity of DJD and decreased DJD‐associated pain in cats. Additional studies are needed to verify these findings, and if verified, to explore potential mechanisms.

Bartonella henselae bacteremia in a mother and son potentially associated with tick exposure

BACKGROUND

Bartonella henselae is a zoonotic, alpha Proteobacterium, historically associated with cat scratch disease (CSD), but more recently associated with persistent bacteremia, fever of unknown origin, arthritic and neurological disorders, and bacillary angiomatosis, and peliosis hepatis in immunocompromised patients. A family from the Netherlands contacted our laboratory requesting to be included in a research study (NCSU-IRB#1960), designed to characterize Bartonella spp. bacteremia in people with extensive arthropod or animal exposure. All four family members had been exposed to tick bites in Zeeland, southwestern Netherlands. The mother and son were exhibiting symptoms including fatigue, headaches, memory loss, disorientation, peripheral neuropathic pain, striae (son only), and loss of coordination, whereas the father and daughter were healthy.

METHODS

Each family member was tested for serological evidence of Bartonella exposure using B. vinsonii subsp. berkhoffii genotypes I-III, B. henselae and B. koehlerae indirect fluorescent antibody assays and for bacteremia using the BAPGM enrichment blood culture platform.

RESULTS

The mother was seroreactive to multiple Bartonella spp. antigens and bacteremia was confirmed by PCR amplification of B. henselae DNA from blood, and from a BAPGM blood agar plate subculture isolate. The son was not seroreactive to any Bartonella sp. antigen, but B. henselae DNA was amplified from several blood and serum samples, from BAPGM enrichment blood culture, and from a cutaneous striae biopsy. The father and daughter were seronegative to all Bartonella spp. antigens, and negative for Bartonella DNA amplification.

CONCLUSIONS

Historically, persistent B. henselae bacteremia was not thought to occur in immunocompetent humans. To our knowledge, this study provides preliminary evidence supporting the possibility of persistent B. henselae bacteremia in immunocompetent persons from Europe. Cat or flea contact was considered an unlikely source of transmission and the mother, a physician, reported that clinical symptoms developed following tick exposure. To our knowledge, this is the first time that a B. henselae organism has been visualized in and amplified from a striae lesion. As the tick bites occurred three years prior to documentation of B. henselae bacteremia, the mode of transmission could not be determined.

Serial testing from a 3-day collection period by use of the Bartonella Alphaproteobacteria growth medium platform may enhance the sensitivity of Bartonella species detection in bacteremic human patients

Patients with infection from bacteremic Bartonella spp., tested using Bartonella Alphaproteobacteria growth medium (BAPGM), were retrospectively categorized into one of two groups that included those whose blood was collected once (group 1; n = 55) or three times (group 2; n = 36) within a 1-week period. Overall, 19 patients (20.8%) were PCR positive for one or more Bartonella spp. using the BAPGM platform. Seven patients (12.7%) in group 1 tested positive, and 12 patients (33.3%) in group 2 tested positive. Detection was improved when the patients were tested three times within a 1-week period (odds ratio, 3.4 [95% confidence interval, 1.2 to 9.8]; P = 0.02). Obtaining three sequential blood samples during a 1-week period should be considered a diagnostic approach when bartonellosis is suspected.