Jennifer B. Henn

Bio: Jennifer B. Henn is an academic researcher from University of California, Davis. The author has contributed to research in topics: Bartonella & Bartonella vinsonii. The author has an hindex of 12, co-authored 17 publications receiving 960 citations. Previous affiliations of Jennifer B. Henn include California Health and Human Services Agency.

Factors associated with the rapid emergence of zoonotic Bartonella infections.

Abstract: Within the last 15 years, several bacteria of the genus Bartonella were recognized as zoonotic agents in humans and isolated from various mammalian reservoirs. Based on either isolation of the bacterium or PCR testing, eight Bartonella species or subspecies have been recognized as zoonotic agents, including B. henselae, B. elizabethae, B. grahamii, B. vinsonii subsp. arupensis, B. vinsonii subsp. berkhoffii, B. grahamii, B. washoensis and more recently B. koehlerae. The present manuscript reviews the factors associated with the emergence of these zoonotic pathogens, including better diagnostic tools and methods to identify these fastidious bacteria, host immunosuppression (caused by infectious agents, cancer, aging or induced by immunosuppressive drugs), the interaction of co-infection by several infectious agents that may enhanced the pathogenecity of these bacteria, increased outdoor activity leading to exposure to wildlife reservoirs or vectors, poverty and low income associated with infestation by various ectoparasites, such as body lice and finally the dispersal of Bartonellae around the world. Furthermore, a description of the main epidemiological and clinical features of zoonotic Bartonellae is given. Finally, the main means for diagnosis, treatment and prevention of these diseases are presented.

Bartonella endocarditis: a pathology shared by animal reservoirs and patients.

Abstract: Bartonellae were first recognized to cause endocarditis in humans in 1993 when cases caused by Bartonella quintana, B. elizabethae, and B. henselae were reported. Since the first isolation of Bartonella vinsonii subspecies berkhoffii from a dog with endocarditis, this organism has emerged as an important pathogen in dogs and an emerging pathogen in people. Subsequently, four types of B. vinsonii subsp. berkhoffii have been described, all of which have been associated with endocarditis in dogs. A limited number of dog endocarditis cases have also been associated with B. clarridgeiae, B. washoensis, B. quintana, and B. rochalimae. The second canine B. clarridgeiae endocarditis case is presented. The clinical and pathological characteristics of Bartonella endocarditis in dogs are similar to disease observed in humans, more often affecting the aortic valve, presenting with highly vegetative lesions with accompanying calcification, and in most instances high antibody titers. Pathological features in dogs include a combination of fibrosis, mineralization, endothelial proliferation, and neovascularization with variable inflammation. Endocarditis has also been described in animal species, which are the natural reservoir of specific Bartonella species, once thought to be solely healthy carriers of these pathogens. A few Bartonella endocarditis cases, including B. henselae, have been reported in cats in the USA and Australia. The second case of B. henselae type Houston I identified in the USA is presented. Furthermore, two cases of B. bovis endocarditis were recently described in adult cows from France. Finally, on-going investigation of valvular endocarditis in free-ranging Alaskan sea otters suggests the involvement of Bartonella species.

Gray Foxes (Urocyon cinereoargenteus) as a Potential Reservoir of a Bartonella clarridgeiae-Like Bacterium and Domestic Dogs as Part of a Sentinel System for Surveillance of Zoonotic Arthropod-Borne Pathogens in Northern California

Abstract: Two species of Bartonella, a novel Bartonella clarridgeiae-like bacterium and B. vinsonii subsp. berkhoffii, were isolated from rural dogs and gray foxes in northern California. A novel B. clarridgeiae-like species was isolated from 3 (1.7%) of 182 dogs and 22 (42%) of 53 gray foxes, while B. vinsonii subsp. berkhoffii was isolated from 1 dog (0.5%) and 5 gray foxes (9.4%). PCR and DNA sequence analyses of the citrate synthase (gltA) gene and the 16S-23S intergenic spacer region suggested that strains infecting dogs and gray foxes were identical. Fifty-four dogs (29%) and 48 gray foxes (89%) had reciprocal titers of antibodies against Bartonella spp. of ≥64. The high prevalence of bacteremia and seroreactivity to Bartonella spp. in gray foxes suggests that they may act as a reservoir species for the B. clarridgeiae-like species in this region. Domestic dogs were also tested for other arthropod-borne infectious agents. Fifty-one dogs (28%) were positive for Dirofilaria immitis antigen, seventy-four (40%) were seroreactive to Anaplasma phagocytophilum, and five (2.7%) were seropositive for Yersinia pestis. Fourteen dogs (7.6%) were PCR positive for A. phagocytophilum. Polytomous logistic regression models were used to assess the association of Bartonella antibody titer categories with potential risk factors and the presence of other vector-borne agents in domestic dogs. Older dogs were more likely to be seroreactive to Bartonella spp. There was no association between the exposure of dogs to Bartonella and the exposure of dogs to A. phagocytophilum in this study.

Seroprevalence of antibodies against Bartonella species and evaluation of risk factors and clinical signs associated with seropositivity in dogs.

Abstract: Objective—To determine the seroprevalence of antibodies against Bartonella spp in a population of sick dogs from northern California and identify potential risk factors and clinical signs associated with seropositivity. Sample Population—Sera from 3,417 dogs. Procedure—Via an ELISA, sera were analyzed for antibodies against Bartonella vinsonii subsp berkhoffii, Bartonella clarridgeiae, and Bartonella henselae; test results were used to classify dogs as seropositive (mean optical density value ≥ 0.350 for B henselae or ≥ 0.300 for B clarridgeiae or B vinsonii subsp berkhoffii) or seronegative. Overall, 305 dogs (102 seropositive and 203 seronegative dogs) were included in a matched case-control study. Results—102 of 3,417 (2.99%) dogs were seropositive for ≥ 1 species of Bartonella. Of these, 36 (35.3%) had antibodies against B henselae only, 34 (33.3%) had antibodies against B clarridgeiae only, 2 (2.0%) had antibodies against B vinsonii subsp berkhoffiionly , and 30 (29.4%) had antibodies against a combi...

Bartonella infection in domestic cats and wild felids.

Abstract: Bartonella are vector-borne, fastidious Gram-negative bacteria causing persistent bacteremia in their reservoir hosts. Felids represent a major reservoir for several Bartonella species. Domestic cats are the main reservoir of B. henselae, the agent of cat-scratch disease. Prevalence of infection is highest in warm and humid climates that are optimal for the survival of cat fleas, as fleas are essential for the transmission of the infection. Flea feces are the likely infectious substrate. Prevalence of B. henselae genotypes among cat populations varies worldwide. Genotype Houston I is more prevalent in the Far East and genotype Marseille is dominant in western Europe, Australia, and the western United States. Cats are usually asymptomatic, but uveitis, endocarditis, neurological signs, fever, necrotic lesions at the inoculation site, lymphadenopathy, and reproductive disorders have been reported in naturally or experimentally infected cats. Domestic cats are also the reservoir of B. clarridgeiae and co-infection has been demonstrated. B. koehlerae has been isolated from domestic cats, and was identified in cat fleas and associated with a human endocarditis case. B. bovis was isolated from a few cats in the United States and B. quintana DNA was recently identified in a cat tooth. Bartonella spp. have also been isolated from free-ranging and captive wild felids from North America and Africa. Whereas, B. henselae was identified in African lions and a cheetah, some strains specific to these wild cats have also been identified, leading to the concept of a B. henselae group including various subspecies, as previously described for B. vinsonii.

Rodent-borne diseases and their risks for public health

Abstract: Rodents are the most abundant and diversified order of living mammals in the world. Already since the Middle Ages we know that they can contribute to human disease, as black rats were associated with distribution of plague. However, also in modern times rodents form a threat for public health. In this review article a large number of pathogens that are directly or indirectly transmitted by rodents are described. Moreover, a simplified rodent disease model is discussed.

Anaplasma phagocytophilum—a widespread multi-host pathogen with highly adaptive strategies

Abstract: The bacterium Anaplasma phagocytophilum has for decades been known to cause the disease tick-borne fever (TBF) in domestic ruminants in Ixodes ricinus-infested areas in northern Europe. In recent years, the bacterium has been found associated with Ixodes-tick species more or less worldwide on the northern hemisphere. A. phagocytophilum has a broad host range and may cause severe disease in several mammalian species, including humans. However, the clinical symptoms vary from subclinical to fatal conditions, and considerable underreporting of clinical incidents is suspected in both human and veterinary medicine. Several variants of A. phagocytophilum have been genetically characterized. Identification and stratification into phylogenetic subfamilies has been based on cell culturing, experimental infections, PCR and sequencing techniques. However, few genome sequences have been completed so far, thus observations on biological, ecological and pathological differences between genotypes of the bacterium, have yet to be elucidated by molecular and experimental infection studies. The natural transmission cycles of various A. phagocytophilum variants, the involvement of their respective hosts and vectors involved, in particular the zoonotic potential, have to be unravelled. A. phagocytophilum is able to persist between seasons of tick activity in several mammalian species and movement of hosts and infected ticks on migrating animals or birds may spread the bacterium. In the present review, we focus on the ecology and epidemiology of A. phagocytophilum, especially the role of wildlife in contribution to the spread and sustainability of the infection in domestic livestock and humans

Bartonella Spp. in Pets and Effect on Human Health

Abstract: Among the many mammals infected with Bartonella spp., pets represent a large reservoir for human infection because most Bartonella spp. infecting them are zoonotic. Cats are the main reservoir for Bartonella henselae, B. clarridgeiae, and B. koehlerae. Dogs can be infected with B. vinsonii subsp. berkhoffii, B. henselae, B. clarridgeiae, B. washoensis, B. elizabethae, and B. quintana. The role of dogs as an important reservoir of Bartonella spp. is less clear than for cats because domestic dogs are more likely to be accidental hosts, at least in nontropical regions. Nevertheless, dogs are excellent sentinels for human infections because a similar disease spectrum develops in dogs. Transmission of B. henselae by cat fleas is better understood, although new potential vectors (ticks and biting flies) have been identified. We review current knowledge on the etiologic agents, clinical features, and epidemiologic characteristics of these emerging zoonoses.

Factors associated with the rapid emergence of zoonotic Bartonella infections.

Abstract: Within the last 15 years, several bacteria of the genus Bartonella were recognized as zoonotic agents in humans and isolated from various mammalian reservoirs. Based on either isolation of the bacterium or PCR testing, eight Bartonella species or subspecies have been recognized as zoonotic agents, including B. henselae, B. elizabethae, B. grahamii, B. vinsonii subsp. arupensis, B. vinsonii subsp. berkhoffii, B. grahamii, B. washoensis and more recently B. koehlerae. The present manuscript reviews the factors associated with the emergence of these zoonotic pathogens, including better diagnostic tools and methods to identify these fastidious bacteria, host immunosuppression (caused by infectious agents, cancer, aging or induced by immunosuppressive drugs), the interaction of co-infection by several infectious agents that may enhanced the pathogenecity of these bacteria, increased outdoor activity leading to exposure to wildlife reservoirs or vectors, poverty and low income associated with infestation by various ectoparasites, such as body lice and finally the dispersal of Bartonellae around the world. Furthermore, a description of the main epidemiological and clinical features of zoonotic Bartonellae is given. Finally, the main means for diagnosis, treatment and prevention of these diseases are presented.