Bartonellosis,an increasingly recognized zoonosis

Cat scratch disease is the most common zoonotic infection caused by Bartonella bacteria. Among the many mammals infected with Bartonella spp., cats represent a large reservoir for human infection, as they are the main reservoir for Bartonella henselae, Bartonella clarridgeiae and Bartonella koehlerae. Bartonella spp. are vector‐borne bacteria, and transmission of B. henselae by cat fleas occurs mainly through infected flea faeces, although new potential vectors (ticks and biting flies) have been identified. Dogs are also infected with various Bartonella species and share with humans many of the clinical signs induced by these infections. Although the role of dogs as source of human infection is not yet clearly established, they represent epidemiological sentinels for human exposure. Present knowledge on the aetiology, clinical features and epidemiological characteristics of bartonellosis is presented.     

The effect of ecological and temporal factors on the composition of Bartonella infection in rodents and their fleas

The composition of Bartonella infection was explored in wild Gerbillus andersoni rodents and their Synosternus cleopatrae fleas. Rodent blood samples and fleas were collected in two periods (two different seasons; 4 months apart) from juveniles and adult hosts, and their bartonellae lineages were identified by a 454-pyrosequencing analysis targeting a specific Bartonella citrate synthase gene (gltA) fragment. The rate of Bartonella spp. co-infection was estimated and the assemblage and distribution of bartonellae lineages across the samples with respect to ecological and phylogenetic distance similarities were analyzed. Moreover, environmental factors that could explain potential differences between samples were investigated. Out of the 91 bartonellae-positive samples, 89% were found to be co-infected with more than two phylogenetically distant Bartonella genotypes and additional closely related (but distinguishable) variants. These bartonellae lineages were distributed in a non-random manner, and a negative interaction between lineages was discovered. Interestingly, the overall composition of those infections greatly varied among samples. This variability was partially explained by factors, such as type of sample (blood versus fleas), flea sex and period of collection. This investigation sheds light on the patterns of Bartonella infection and the organization of Bartonella lineages in fleas and rodents in nature.     

Acquisition and excretion of Bartonella quintana by the cat flea,Ctenocephalides felis felis

Bartonella quintana is transmitted by the infected faeces of body lice. Recently, this bacterium was detected in cat fleas (Ctenocephalides felis) and in two humans with chronic adenopathy whose only risk factor was contact with cat fleas. In this study, a total of 960 C. felis were divided into 12 groups (2 control groups and 10 infected groups) each containing 80 fleas. The fleas were fed B. quintana‐inoculated human blood at different dilutions (≈3.6 × 10⁴ ? 8.4 × 10⁹ bacteria) for 4 days via an artificial membrane. Subsequently, all flea groups were fed uninfected blood until day 13 postinfection (dpi). On day 3 pi, B. quintana was detected with two specific genes by quantitative PCR in 60–100% of randomly chosen fleas per dilution: 52% (26/50) in the infected fleas in Trial 1 and 90% (45/50) of the fleas in Trial 2. B. quintana was also identified by molecular and culture assays in flea faeces. The average number of B. quintana as determined by qPCR decreased until the 11th dpi and was absent in both trials at the 13th dpi. Bacteria were localized only in the flea gastrointestinal gut by specific immunohistochemistry. Our results indicate that cat fleas can acquire B. quintana by feeding and release viable organisms into their faeces. Therefore, fleas may play a role as vectors of trench fever or other clinical manifestations that are caused by B. quintana. However, the biological role of C. felis in the transmission of B. quintana under natural conditions is yet to be defined.     

Molecular detection of zoonotic bartonellae (B. henselae,B. elizabethae and B. rochalimae) in fleas collected from dogs in Israel

Fleas represent an acknowledged burden on dogs worldwide. The characterization of flea species infesting kennel dogs from two localities in Israel (Rehovot and Jerusalem) and their molecular screening for Bartonella species (Rhizobiales: Bartonellaceae) was investigated. A total of 355 fleas were collected from 107 dogs. The fleas were morphologically classified and molecularly screened targeting the Bartonella 16S–23S internal transcribed spacer (ITS). Of the 107 dogs examined, 80 (74.8%) were infested with Ctenocephalides canis (Siphonaptera: Pulicidae), 68 (63.6%) with Ctenocephalides felis, 15 (14.0%) with Pulex irritans (Siphonaptera: Pulicidae) and one (0.9%) with Xenopsylla cheopis (Siphonaptera: Pulicidae). Fleas were grouped into 166 pools (one to nine fleas per pool) according to species and host. Thirteen of the 166 flea pools (7.8%) were found to be positive for Bartonella DNA. Detected ITS sequences were 99–100% similar to those of four Bartonella species: Bartonella henselae (six pools); Bartonella elizabethae (five pools); Bartonella rochalimae (one pool), and Bartonella bovis (one pool). The present study indicates the occurrence of a variety of flea species in dogs in Israel; these flea species are, in turn, carriers of several zoonotic Bartonella species. Physicians, veterinarians and public health workers should be aware of the presence of these pathogens in dog fleas in Israel and preventive measures should be implemented.     

Detection of Rickettsia spp. and Bartonella spp. in Ctenocephalides felis fleas from free‐ranging crab‐eating foxes (Cerdocyon thous)

Fleas are insects with a worldwide distribution that have been implicated in the transmission of several pathogens. The present study aimed to investigate the presence of Rickettsia spp. (Rickettsiales: Rickettsiaceae) and Bartonella spp. (Rhizobiales: Bartonellaceae) in fleas from free‐ranging crab‐eating foxes Cerdocyon thous (Linnaeus, 1766) (Carnivora: Canidae) from Rio Grande do Sul, southern Brazil. Fleas were collected manually from animals and used for the molecular detection of Rickettsia spp. and Bartonella spp. Twenty‐nine C. thous were sampled in six municipalities. Four foxes were parasitized by 10 fleas, all of which were identified as Ctenocephalides felis (Bouché, 1935) (Siphonaptera: Pulicidae). DNA from Rickettsia felis Bouyer et al., 2001 and Rickettsia asembonensis Maina et al., 2016 were found in three and eight fleas, respectively. In four fleas, DNA of Bartonella sp. was identified. Phylogenetic analysis grouped Bartonella sp. together with other genotypes previously reported in C. felis worldwide. The scenario described in the present study highlights a Neotropical canid parasitized by the invasive cosmopolitan cat flea, which in turn, is carrying potentially invasive vector‐borne microorganisms. These findings suggest that C. felis is adapted to wild hosts in wilderness areas in southern Brazil, hypothetically exposing the Neotropical fauna to unknown ecological and health disturbances.     

Molecular detection of Bartonella in fleas (Hexapoda,Siphonaptera) collected from wild rodents (Cricetidae,Sigmodontinae) from Argentina

Bartonella are facultative intracellular Gram‐negative bacteria, transmitted mainly by hematophagous arthropods, and the rodents act as a natural reservoir. Different species of Bartonella associated with rodents have been implicated as causing human disease. Studies from Argentina are scarce and no Bartonella from fleas have been reported previously. The present study investigated the presence of Bartonella spp. in fleas associated with sigmodontine rodents in four localities of the Santa Cruz Province, Argentina. In total, 51 fleas (four species) were analysed of which 41.2% were found to be positive for the gltA gene fragment via a nested polymerase chain reaction. All positive fleas were of the species Neotyphloceras crackensis from three different localities. Eight of the 21 amplified samples were sequenced, and the presence of three different genotypes was detected with an identity of 95.5–98.8% amongst themselves. Bartonella genotypes from American rodents and rodent fleas were recovered in a monophyletic group. Similarly, most of the Peruvian and all Argentinean variants constitute a natural group sister of the American remainder. The importance of the Bartonella spp. with respect to public health is unknown, although future studies could provide evidence of the possible involvement of N. crackensis in the Bartonella transmission cycles.     

Prevalence of Rickettsia and Bartonella species in Spanish cats and their fleas

The aim of this study was to determine the prevalence of Bartonella henselae, Rickettsia felis, and Rickettsia typhi in fleas and companion cats (serum and claws) and to assess their presence as a function of host, host habitat, and level of parasitism. Eighty‐nine serum and claw samples and 90 flea pools were collected. Cat sera were assayed by IFA for Bartonella henselae and Rickettssia species IgG antibodies. Conventional PCRs were performed on DNA extracted from nails and fleas collected from cats. A large portion (55.8%) of the feline population sampled was exposed to at least one of the three tested vector‐borne pathogens. Seroreactivity to B. henselae was found in 50% of the feline studied population, and to R. felis in 16.3%. R. typhi antibodies were not found in any cat. No Bartonella sp. DNA was amplified from the claws. Flea samples from 41 cats (46%) showed molecular evidence for at least one pathogen; our study demonstrated a prevalence rate of 43.3 % of Rickettsia sp and 4.4% of Bartonella sp. in the studied flea population. None of the risk factors studied (cat's features, host habitat, and level of parasitation) was associated with either the serology or the PCR results for Bartonella sp. and Rickettsia sp.. Flea‐associated infectious agents are common in cats and fleas and support the recommendation that stringent flea control should be maintained on cats.     

Investigation of Bartonella acquisition and transmission in Xenopsylla ramesis fleas (Siphonaptera: Pulicidae)

Bartonella are emerging and re-emerging pathogens affecting humans and a wide variety of animals including rodents. Horizontal transmission of Bartonella species by different hematophagous vectors is well acknowledged but vertical transmission (from mother to offspring) is questionable and was never explored in fleas. The aim of this study was to investigate whether the rodent flea, Xenopsylla ramesis, can acquire native Bartonella from wild rodents and transmit it transovarially. For this aim, Bartonella-free laboratory-reared X. ramesis fleas were placed on six naturally Bartonella-infected rodents and six species-matched Bartonella-negative rodents (three Meriones crassus jirds, two Gerbillus nanus gerbils and one Gerbillus dasyurus gerbil) for 7 days, 12-14h per day. The fleas that were placed on the Bartonella-positive rodents acquired four different Bartonella genotypes. Eggs and larvae laid and developed, respectively, by fleas from both rodent groups were collected daily for 7 days and molecularly screened for Bartonella. All eggs and larvae from both groups were found to be negative for Bartonella DNA. Interestingly, two of five gut voids regurgitated by Bartonella-positive fleas contained Bartonella DNA. The naturally infected rodents remained persistently infected with Bartonella for at least 89 days suggesting their capability to serve as competent reservoirs for Bartonella species. The findings in this study indicate that X. ramesis fleas can acquire several Bartonella strains from wild rodents but cannot transmit Bartonella transovarially.     

Host distribution and pathogen infection of fleas (Siphonaptera) recovered from small mammals in Pennsylvania

The number of recognized flea‐borne pathogens has increased over the past decade. However, the true number of infections related to all flea‐borne pathogens remains unknown. To better understand the enzootic cycle of flea‐borne pathogens, fleas were sampled from small mammals trapped in central Pennsylvania. A total of 541 small mammals were trapped, with white‐footed mice (Peromyscus leucopus) and southern red‐backed voles (Myodes gapperi) accounting for over 94% of the captures. Only P. leucopus were positive for examined blood‐borne pathogens, with 47 (18.1%) and ten (4.8%) positive for Anaplasma phagocytophilum and Babesia microti, respectively. In addition, 61 fleas were collected from small mammals and tested for pathogens. Orchopeas leucopus was the most common flea and Bartonella vinsonii subspecies arupensis, B. microti, and a Rickettsia felis‐like bacterium were detected in various flea samples. To the best of our knowledge, this is the first report of B. microti DNA detected from a flea and the first report of a R. felis‐like bacterium from rodent fleas in eastern North America. This study provides evidence of emerging pathogens found in fleas, but further investigation is required to resolve the ecology of flea‐borne disease transmission cycles.     

Nutrient depletion may trigger the Yersinia pestis OmpR‐EnvZ regulatory system to promote flea‐borne plague transmission

The flea’s lumen gut is a poorly documented environment where the agent of flea‐borne plague, Yersinia pestis, must replicate to produce a transmissible infection. Here, we report that both the acidic pH and osmolarity of the lumen’s contents display simple harmonic oscillations with different periods. Since an acidic pH and osmolarity are two of three known stimuli of the OmpR‐EnvZ two‐component system in bacteria, we investigated the role and function of this Y. pestis system in fleas. By monitoring the in vivo expression pattern of three OmpR‐EnvZ‐regulated genes, we concluded that the flea gut environment triggers OmpR‐EnvZ. This activation was not, however, correlated with changes in pH and osmolarity but matched the pattern of nutrient depletion (the third known stimulus for OmpR‐EnvZ). Lastly, we found that the OmpR‐EnvZ and the OmpF porin are needed to produce the biofilm that ultimately obstructs the flea’s gut and thus hastens the flea‐borne transmission of plague. Taken as a whole, our data suggest that the flea gut is a complex, fluctuating environment in which Y. pestis senses nutrient depletion via OmpR‐EnvZ. Once activated, the latter triggers a molecular program (including at least OmpF) that produces the biofilm required for efficient plague transmission.     

Bartonella Genotypes in Fleas (Insecta: Siphonaptera) Collected from Rodents in the Negev Desert,Israel

Fleas collected from rodents in the Negev Desert in southern Israel were molecularly screened for Bartonella species. A total of 1,148 fleas, collected from 122 rodents belonging to six species, were pooled in 245 pools based on flea species, sex, and rodent host species. Two Bartonella gene fragments, corresponding to RNA polymerase B (rpoB) and citrate synthase (gltA), were targeted, and 94 and 74 flea pools were found positive by PCR, respectively. The Bartonella 16S-23S internal transcribed spacer (ITS) region was also targeted, and 66 flea pools were found to be positive by PCR. Sixteen different Bartonella gltA genotypes were detected in 94 positive flea pools collected from 5 different rodent species, indicating that fleas collected from each rodent species can harbor several Bartonella genotypes. Based on gltA analysis, identified Bartonella genotypes were highly similar or identical to strains previously detected in rodent species from different parts of the world. A gltA fragment 100% similar to Bartonella henselae was detected in one flea pool. Another 2 flea pools contained gltA fragments that were closely related to B. henselae (98% similarity). The high sequence similarities to the zoonotic pathogen B. henselae warrant further investigation.Bartonellae are small Gram-negative bacilli belonging to the alpha-2 subdivision of the Proteobacteria. Different Bartonella species were detected in a wide range of vertebrate animals. There are currently 30 known species or subspecies, among which 14 have been associated with human diseases (7). Bartonella organisms are parasites of mammalian erythrocytes and endothelial cells and are transmitted by fleas and lice and potentially by other blood-feeding arthropods such as ticks and flies (2). Infection in the natural host commonly causes a chronic bacteremia, which is asymptomatic in most cases.Rodents are being extensively studied and were found to have a high prevalence of Bartonella infection, with a high diversity of Bartonella spp. and strains (3). The close contacts between human and rodent populations around the world create excellent conditions for transmission of Bartonella spp. from animals to humans (28). The transmission routes of Bartonella bacteria by arthropod vectors among rodents and between rodents and other mammalian hosts have public health implications. In order to understand the extent to which rodents serve as source of human infections, investigations of rodent-borne Bartonella are essential (28). A few cases of human infections with Bartonella bacteria of rodent origin have been reported: B. elizabethae was associated with endocarditis, B. washoensis was associated with cases of myocarditis and meningitis, B. vinsonii subsp. arupensis was reported to cause fever and neurologic symptoms, and B. grahamii was isolated from the intraocular fluids of a patient with neuroretinitis (5, 11, 12, 25, 29).An earlier survey carried out in the Tel Aviv region, Israel, demonstrated the occurrence of Bartonella strains closely related to B. elizabethae and B. tribocorum in commensal rats (Rattus rattus) (8). Another study has surveyed wild rodents and their fleas for Bartonella spp. in 19 geographical locations in Israel from the Upper Galilee in the north to Beer Sheba in the south. Bartonella DNA was detected in spleen samples of 19 out of 79 (24%) black rats (R. rattus), in 1 of 4 (25%) Cairo spiny mice (Acomys cahirinus), and in 15 of 34 (44%) flea pools collected from black rats (R. rattus) (21). The objectives of the current study were to screen fleas collected from rodents inhabiting the Negev Desert south to Beer Sheba for Bartonella infection and to compare Bartonella prevalences between male and female fleas.     

Real‐time and multiplex real‐time polymerase chain reactions for the detection of Bartonella henselae within cat flea,Ctenocephalides felis,samples

Bartonella henselae (Rhizobiales: Bartonellacae), the agent of cat‐scratch disease, is an emerging bacterial pathogen which can be transmitted via infective faecal material of Ctenocephalides felis Bouché (Siphonaptera: Pulicidae). Worldwide, B. henselae has been identified in 1–53% of felines and 2.9–17.4% of fleas. Although culture is the routine method for detection, the procedure is time‐consuming and is rarely used for isolation directly from flea vectors. The current study reports the development of a quantitative real‐time polymerase chain reaction (qPCR) to detect and quantify B. henselae organisms from vector samples. The qPCR is specific and detects as few as 2.5 genome copies. To enable direct quantification of Bartonella organisms in different vector samples, we developed a qPCR to detect C. felis DNA that also acts as an extraction control. Combining both PCRs into a multiplex format validates B. henselae results when sampling flea populations, although there is a reduction in sensitivity. This reduction might be counteracted by a different combination of probe fluorophores.     

Fleas from domestic dogs and rodents in Rwanda carry Rickettsia asembonensis and Bartonella tribocorum

Fleas (Siphonaptera) are ubiquitous blood‐sucking parasites that transmit a range of vector‐borne pathogens. The present study examined rodents (n = 29) and domestic dogs (n = 7) living in the vicinity of the Volcanoes National Park, Rwanda, for fleas, identified flea species from these hosts, and detected Bartonella (Rhizobiales: Bartonellaceae) and Rickettsia (Rickettsiales: Rickettsiaceae) DNA. The most frequently encountered flea on rodents was Xenopsylla brasiliensis (Siphonaptera: Pulicidae). In addition, Ctenophthalmus (Ethioctenophthalmus) calceatus cabirus (Siphonaptera: Hystrichopsyllidae) and Ctenocephalides felis strongylus (Siphonaptera: Pulicidae) were determined using morphology and sequencing of the cytochrome c oxidase subunit I and cytochrome c oxidase subunit II genes (cox1 and cox2, respectively). Bartonella tribocorum DNA was detected in X. brasiliensis and Rickettsia asembonensis DNA (a Rickettsia felis‐like organism) was detected in C. felis strongylus. The present work complements studies that clarify the distributions of flea‐borne pathogens and potential role of fleas in disease transmission in sub‐Saharan Africa. In the context of high‐density housing in central sub‐Saharan Africa, the detection of B. tribocorum and R. asembonensis highlights the need for surveillance in both rural and urban areas to identify likely reservoirs.     

Efficacy of a fipronil bait in reducing the number of fleas (Oropsylla spp.) infesting wild black‐tailed prairie dogs

Bubonic plague (Yersinia pestis) is a deadly zoonosis with black‐tailed prairie dogs (Cynomys ludovicianus) as a reservoir host in the United States. Systemic insecticides are a promising means of controlling the vectors, Oropsylla spp. fleas, infesting these prairie dogs, subsequently disrupting the Y. pestis cycle. The objective of this study was to conduct a field trial evaluating the efficacy of a grain rodent bait containing fipronil (0.005%) against fleas infesting prairie dogs. The study was performed in Larimer County, CO, where bait was applied to a treatment area containing a dense prairie dog population, three times over a three‐week period. Prairie dogs were captured and combed for fleas during four study periods (pre‐, mid‐, 1^st post‐, and 2^nd post‐treatment). Results indicated the use of bait containing fipronil significantly reduced flea burden. The bait containing fipronil was determined to reduce the mean number of fleas per prairie dog >95% for a minimum of 52 days post‐initial treatment application and 31 days post‐final treatment application. These results suggest the potential for this form of treatment to reduce flea population density on prairie dogs, and subsequently plague transmission, among mammalian hosts across the United States and beyond.     

Cat fleas (Ctenocephalides felis) carrying Rickettsia felis and Bartonella species in Hong Kong

Fleas are commonly recorded on stray as well as domestic dogs and cats in Hong Kong. Fleas can be a major cause of pruritus in dogs and cats and also vectors of potentially zoonotic bacteria in the genera Rickettsia and Bartonella. Morphological examination of 174 fleas from dogs and cats living in Hong Kong revealed only cat fleas (Ctenocephalides felis). Cytochrome c oxidase subunit 1 gene (cox1) genotyping of 20 randomly selected specimens, revealed three cox1 haplotypes (HK-h1 to HK-h3). The most common haplotype was HK-h1 with 17 specimens (17/20, 85%). HK-h1 was identical to cox1 sequences of fleas in Thailand and Fiji. HK-h1 and HK-h2 form a distinct cat flea cox1 clade previously recognized as the Clade 3. HK-h3 forms a new Clade 6. A multiplex Bartonella and Rickettsia real-time PCR of DNA from 20 C. felis found Bartonella and Rickettsia DNA in three (15%) and ten (50%) C. felis, respectively. DNA sequencing confirmed the presence of R. felis, B. clarridgeiae and Bartonella henselae. This is the first reported study of that kind in Hong Kong, and further work is required to expand the survey of companion animals in the geographical region. The sampling of fleas on domestic cats and dogs in Hong Kong revealed them to be exclusively infested by the cat flea and to be harbouring pathogens of zoonotic potential.     

Ecological characteristics of flea species relate to their suitability as plague vectors

The ability of vector-borne diseases to persist and spread is closely linked to the ecological characteristics of the vector species they use. Yet there have been no investigations of how species used as vectors by pathogens such as the plague bacterium differ from closely related species that are not used as vectors. The plague bacterium uses mammals as reservoir hosts and fleas as vectors. The ability of different fleas to serve as vectors is assumed to depend on how likely they are to experience gut blockage following bacterial multiplication; the blockage causes fleas to regurgitate blood into a wound and thus inject bacteria into new hosts. Beyond these physiological differences, it is unclear whether there exist fundamental ecological differences between fleas that are effective vectors and those that are not. Here, using a comparative analysis, we identify clear associations between the ability of flea species to transmit plague and their ecological characteristics. First, there is a positive relationship between the abundance of flea species on their hosts and their potential as vectors. Second, although the number of host species exploited by a flea is not associated with its potential as a vector, there is a negative relationship between the ability of fleas to transmit plague and the taxonomic diversity of their host spectrum. This suggests a correlation between some ecological characteristics of fleas and their ability to develop the plague blockage. The plague pathogen thus uses mainly abundant fleas specialized on a narrow taxonomic range of mammals, features that should maximize the persistence of the disease in the face of high flea mortality, and its transmission to suitable hosts only. This previously unrecognized pattern of vector use is of importance for the persistence and transmission of the disease.Electronic Supplementary Material Supplementary material is available to authorised users in the online version of this article at .     

Novel evidence suggests that a ‘Rickettsia felis‐like’ organism is an endosymbiont of the desert flea,Xenopsylla ramesis

Fleas are acknowledged vectors and reservoirs of various bacteria that present a wide range of pathogenicity. In this study, fleas collected from wild rodents from the Negev desert in southern Israel were tested for RickettsiaDNA by targeting the 16S rRNA (rrs) gene. Thirty‐eight Xenopsylla ramesis, 91 Synosternus cleopatrae and 15 Leptopsylla flea pools (a total of 568 fleas) were screened. RickettsiaDNA was detected in 100% of the X. ramesis and in one S. cleopatrae flea pools. None of L. algira flea pools was found positive. All positive flea pools were further characterized by sequencing of five additional genetic loci (gltA, ompB, ompA, htrA and fusA). The molecular identification of the positive samples showed all sequences to be closely related to the ‘Rickettsia felis‐like’ organisms (99–100% similarities in the six loci). To further investigate the association between ‘R. felis‐like’ and X. ramesis fleas, ten additional single X. ramesis adult fleas collected from the wild and five laboratory‐maintained X. ramesis imago, five larva pools (2–18 larvae per pool) and two egg pools (18 eggs per pool) were tested for the presence of ‘R. felis‐like’ DNA. All samples were found positive by a specific ompAPCR assay, confirming the close association of this Rickettsia species with X. ramesis in all its life stages. These results suggest a symbiotic association between ‘Rickettsia felis‐like’ and X. ramesis fleas.     

Bartonella species in fleas from Palestinian territories: Prevalence and genetic diversity

Bartonellosis is an infectious bacterial disease. The prevalence and genetic characteristics of Bartonella spp. in fleas of wild and domestic animals from Palestinian territories are described. Flea samples (n=289) were collected from 121 cats, 135 dogs, 26 hyraxes and seven rats from northern (n=165), central (n=113), and southern Palestinian territories (n=11). The prevalent flea species were: Ctenocephalides felis (n=119/289; 41.2%), Ctenocephalides canis (n=159/289; 55%), and Xenopsylla sp. (n=7/289; 2.4%). Targeting the Intergenic Transcribed Spacer (ITS) locus, DNA of Bartonella was detected in 22% (64/289) of all fleas. Fifty percent of the C. felis and 57% of the Xenopsylla sp. contained Bartonella DNA. DNA sequencing showed the presence of Bartonella clarridgeiae (50%), Bartonella henselae (27%), and Bartonella koehlerae (3%) in C. felis. Xenopsylla sp. collected from Rattus rattus rats were infected with Bartonella tribocorum, Bartonella elizabethae, and Bartonella rochalimae. Phylogenetic sequence analysis using the 16S ribosomal RNA gene obtained four genetic clusters, B. henselae and B. koehlerae as subcluster 1, B. clarridgeiae as cluster 2, while the rat Bartonella species (B. tribocorum and B. elizabethae) were an outgroup cluster. These findings showed the important role of cat and rat fleas as vectors of zoonotic Bartonella species in Palestinian territories. It is hoped that this publication will raise awareness among physicians, veterinarians, and other health workers of the high prevalence of Bartonella spp. in fleas in Palestinian territories and the potential risk of these pathogens to humans and animals in this region.     

Mixed Infections, Cryptic Diversity, and Vector-Borne Pathogens: Evidence from Polygenis Fleas and Bartonella Species

Coinfections within hosts present opportunities for horizontal gene transfer between strains and competitive interactions between genotypes and thus can be a critical element of the lifestyles of pathogens. Bartonella spp. are Alphaproteobacteria that parasitize mammalian erythrocytes and endothelial cells. Their vectors are thought to be various biting arthropods, such as fleas, ticks, mites, and lice, and they are commonly cited as agents of various emerging diseases. Coinfections by different Bartonella strains and species can be common in mammals, but little is known about specificity and coinfections in arthropod vectors. We surveyed the rate of mixed infections of Bartonella in flea vectors (Polygenis gwyni) parasitizing cotton rats (Sigmodon hispidus) in which previous surveys indicated high rates of infection. We found that nearly all fleas (20 of 21) harbored one or more strains of Bartonella, with rates of coinfection approaching 90%. A strain previously identified as common in cotton rats was also common in their fleas. However, another common strain in cotton rats was absent from P. gwyni, while a rare cotton rat strain was quite common in P. gwyni. Surprisingly, some samples were also coinfected with a strain phylogenetically related to Bartonella clarridgeiae, which is typically associated with felids and ruminants. Finally, a locus (pap31) that is characteristically borne on phage in Bartonella was successfully sequenced from most samples. However, sequence diversity in pap31 was novel in the P. gwyni samples, relative to other Bartonella previously typed with pap31, emphasizing the likelihood of large reservoirs of cryptic diversity in natural populations of the pathogen.     

Field efficacy of rodent bait containing the systemic insecticide imidacloprid against the fleas of California ground squirrels

The efficacy of rodent bait containing the insecticide imidacloprid was evaluated for controlling fleas on the California ground squirrel, Spermophilus beecheyi. The bait was designed to deliver an oral dose of insecticide resulting in flea mortality when obtaining a blood meal. During the five‐week trial, performed at Vandenberg Air Force Base, Santa Barbara County, CA, a spot‐baiting technique was used to apply bait to ground squirrel burrows. Bait was applied six times throughout the trial. Results indicated that the use of a host‐targeted bait was effective in significantly reducing the flea burden on S. beecheyi. Efficacy at reducing flea abundance was near 100% at both day 15 and day 29 of the trial. Use of the bait also reduced the prevalence of flea‐infested S. beecheyi. Our results indicate that the use of rodent bait containing insecticide could provide an effective, economical method of controlling the fleas of S. beecheyi, the primary vectors of human plague in California.