Ecological and Socioeconomic Factors Associated with Bartonella henselae Exposure in Dogs Tested for Vector-Borne Diseases in North Carolina.

Bartonella henselae is a zoonotic vector-borne pathogen affecting both humans and dogs. Little is known about the epidemiology of B. henselae in dogs, including risk factors associated with exposure. The objectives of this study were to map the current distribution of B. henselae in dogs in North Carolina (NC) and to identify ecological and socioeconomic factors influencing B. henselae seroreactivity. Results from 4446 B. henselae serology samples from dogs in NC submitted by veterinarians for clinical diagnostic testing to the North Carolina State University College of Veterinary Medicine Vector Borne Disease Diagnostic Laboratory between January 1, 2004 and December 31, 2015 were retrospectively reviewed. These results were used to generate a map of B. henselae seroreactivity. To account for sparsely sampled areas, statistical smoothing using head banging and areal interpolation kriging was performed. Using previously described risk factors for exposure to canine tick-borne diseases, eight multivariable logistic regression models based on biologically plausible hypotheses were tested, and a final model was selected using an Akaike's Information Criterion weighted-average approach. Seroreactivity among dogs tested for vector-borne disease was variable across the state: higher along the southern/eastern coastal plains and eastern Piedmont, and lower in the western mountains. Of 25 explanatory factors considered, the model combining demographic, socioeconomic, climatic, and land use variables fits best. Based on this model, female intact sex and increasing percentage of the county with low-intensity development and evergreen forest were associated with higher seroreactivity. Conversely, moderate development, increasing median household income, and higher temperature range and relative humidity were associated with lower seroreactivity. This model could be improved, however, by including local and host-scale factors that may play a significant role in dogs' exposure.

Molecular assessment of Bartonella in Gerbillus nanus from Saudi Arabia reveals high levels of prevalence, diversity and co-infection.

Bartonellae bacteria are associated with several re-emerging human diseases. These vector-borne pathogens have a global distribution, yet data on Bartonella prevalence and diversity in the Arabian Peninsula are limited. In this study we assessed the Bartonella infection status of the Baluchistan gerbil (Gerbillus nanus), a species associated with pastoral communities throughout the Middle East region, using a multi-gene PCR screening approach. The results demonstrated that 94 (68.1%) of the 138 gerbils trapped on a monthly basis, over a period of one year, were PCR-positive. Sequencing of the gltA gene region confirmed the presence of four discrete Bartonella lineages (I-IV) and high levels of co-infection (33.0%). Each of the four lineages, varied in overall abundance (7.5%-47.9%) and had discernible seasonal peaks. Bartonella status was significantly correlated with ectoparasite presence, but not with sex, nor with season. Statistical analyses further revealed that co-infected individuals had a significantly higher relative body condition. Multi-locus sequence analysis (MLSA) performed with a concatenated dataset of three genetic loci (gltA, nuoG, and rpoB), 1452 nucleotides (nt) in length confirmed that lineage IV, which occurred in 24 PCR-positive animals (25.5%), is most closely related to zoonotic B. elizabethae. The remaining three lineages (I-III) formed a monophyletic clade which, on the basis of gltA was shown to contain bartonellae from diverse Gerbillinae species from the Middle East, suggestive of a gerbil-associated species complex in this region. Lineage I was identical to a Candidatus B. sanaae strain identified previously in Bushy-tailed jirds (Sekeetamys calurus) from Egypt, wherease MLSA indicate that lineages II and III are novel. The high levels of infection and co-infection, together with the presence of multiple Bartonella lineages indicate that Gerbillus nanus is likely a natural reservoir of Bartonella in the Arabian Peninsula.

Assessment of a quantitative 5' nuclease real-time polymerase chain reaction using the nicotinamide adenine dinucleotide dehydrogenase gamma subunit (nuoG) for Bartonella species in domiciled and stray cats in Brazil.

OBJECTIVES: The objective of this study was to develop a quantitative 5' nuclease real-time polymerase chain reaction (PCR) assay to diagnose infections caused by Bartonella species. METHODS: Between January and April 2013 whole blood samples were collected by convenience from 151 cats (86 domiciled and 65 stray cats). The feline blood samples were subjected to a novel quantitative 5' nuclease real-time PCR (qPCR) for Bartonella species targeting the nictonamide adenine dinucleotide dehydrogenase gamma subunit (nuoG) and conventional PCR assays targeting intergenic transcribed spacer, ribC, gltA, pap31 and rpoB, followed by sequencing and basic local alignment search tool analysis. RESULTS: The qPCR assay detected as few as 10 copies of plasmid per reaction. Forty-six (54.4% domiciled and 45.6% stray cats) of 151 sampled cats showed positive results in nuoG qPCR for Bartonella species. The absolute quantification of nuoG Bartonella DNA in sampled cats ranged from 1.1 × 10(4) to 1.3 × 10(4). Eighteen (39.1%) of 46 positive samples in the qPCR were also positive in conventional PCR assays. The sequencing confirmed that Bartonella henselae and Bartonella clarridgeiae circulate in cats in midwestern Brazil. CONCLUSIONS AND RELEVANCE: The present work provides details of a novel qPCR assay to diagnose infections caused by Bartonella species.

A multi-gene analysis of diversity of Bartonella detected in fleas from Algeria.

We report the molecular detection of several Bartonella species in 44 (21.5%) of 204 fleas from Algeria collected from 26 rodents and 7 hedgehogs. Bartonella elizabethae and B. clarridgeiae were detected in the fleas collected on hedgehogs. Bartonella tribocorum and B. elizabethae were detected in fleas collected from rats and mice, and sequences similar to an unnamed Bartonella sp. detected in rodents from China were detected in rats as well as a genotype of Bartonella closely related to Bartonella rochalimae detected in fleas collected on brown rats (Rattus norvegicus).

Analysis of multi-strain Bartonella pathogens in natural host population--do they behave as species or minor genetic variants?

Modern advances in genetic analysis have made it feasible to ascertain the variant type of a pathogen infecting a host. Classification of pathogen variants is commonly performed by clustering analysis of the observed genetic divergence among the variants. A natural question arises whether the genetically distinct variants are epidemiologically distinct. A broader question is whether the different variants constitute separate microbial species or represent minor variations of the same species. These important issues were addressed in the context of analyzing dynamics of genetically distinct variants of Bartonella bacteria in cotton rat hosts. Frequencies of acquiring a new variant were measured in relation to the genetic differences between variants successively infecting an individual rodent host. Two statistical techniques were introduced for performing such analysis, and the methodologies were illustrated with a set of data collected from a particular multi-strain Bartonella system. We carried out a frequency analysis of co-infection patterns, and a Markov chain analysis of panels of successive mixed infection time series for testing some particular gene-based grouping of the Bartonella variants with a panel of observed disease data from a rodent population. Our analysis suggests that the three genogroups A, B and C of Bartonella function as independent species but the variants within each genogroup enjoy some cross-immunity against each other. The newly developed methodologies are broadly applicable for analyzing other multi-strain pathogen data which are increasingly collected for diverse infectious diseases.