Ectoparasite and bacterial population genetics and community structure indicate extent of bat movement across an island chain.

Few studies have examined the genetic population structure of vector-borne microparasites in wildlife, making it unclear how much these systems can reveal about the movement of their associated hosts. This study examined the complex host­vector­microbe interactions in a system of bats, wingless ectoparasitic bat flies (Nycteribiidae), vector-borne microparasitic bacteria (Bartonella) and bacterial endosymbionts of flies (Enterobacterales) across an island chain in the Gulf of Guinea, West Africa. Limited population structure was found in bat flies and Enterobacterales symbionts compared to that of their hosts. Significant isolation by distance was observed in the dissimilarity of Bartonella communities detected in flies from sampled populations of Eidolon helvum bats. These patterns indicate that, while genetic dispersal of bats between islands is limited, some non-reproductive movements may lead to the dispersal of ectoparasites and associated microbes. This study deepens our knowledge of the phylogeography of African fruit bats, their ectoparasites and associated bacteria. The results presented could inform models of pathogen transmission in these bat populations and increase our theoretical understanding of community ecology in host­microbe systems.

Bartonella in Norway rats (Rattus norvegicus) from the urban slum environment in Brazil.

Bartonella are rodent-borne bacteria that cause varied human etiologies. Studies on synanthropic rodents are rare, causing gaps in epidemiological knowledge. We tested bloodclot samples from 79 rats from an urban slum in Salvador, Brazil through PCR targeting gltA gene. Nine samples (11.4%) were positive: six had 100% identity with Bartonella sp. isolate JF429580 and 99.5% with B. queenslandensis strain AUST/NH8; three were 100% identical to isolate JF429532 and 99.7% to B. tribocorum. This is the second report on urban rat Bartonella indicating bacterial circulation at detectable rates. Its presence in rats from vulnerable human settlements demands public health attention.

Bartonella species in medically important mosquitoes, Central Europe.

Here, we provide the first mass molecular screening of medically important mosquitoes for Bartonella species using multiple genetic markers. We examined a total of 72,115 mosquito specimens, morphologically attributed to Aedes vexans (61,050 individuals), Culex pipiens (10,484 individuals) and species of the Anopheles maculipennis complex (581 individuals) for Bartonella spp. The initial screening yielded 63 Bartonella-positive A. vexans mosquitoes (mean prevalence 0.1%), 34 Bartonella-positive C. pipiens mosquitoes (mean prevalence 0.3%) and 158 Bartonella-positive A. maculipennis group mosquitoes (mean prevalence 27.2%). Several different Bartonella ITS sequences were recovered. This study highlights the need for molecular screening of mosquitoes, the most important vectors of arthropod-borne pathogens, for potential bacterial agents.

Human Exposure to Novel Bartonella Species from Contact with Fruit Bats.

Twice a year in southwestern Nigeria, during a traditional bat festival, community participants enter designated caves to capture bats, which are then consumed for food or traded. We investigated the presence of Bartonella species in Egyptian fruit bats (Rousettus aegyptiacus) and bat flies (Eucampsipoda africana) from these caves and assessed whether Bartonella infections had occurred in persons from the surrounding communities. Our results indicate that these bats and flies harbor Bartonella strains, which multilocus sequence typing indicated probably represent a novel Bartonella species, proposed as Bartonella rousetti. In serum from 8 of 204 persons, we detected antibodies to B. rousetti without cross-reactivity to other Bartonella species. This work suggests that bat-associated Bartonella strains might be capable of infecting humans.

Prevalence and clinical presentation of Rickettsia, Coxiella, Leptospira, Bartonella and chikungunya virus infections among hospital-based febrile patients from December 2008 to November 2009 in Bangladesh.

BACKGROUND: We conducted a study to identify Rickettsia, Coxiella, Leptospira, Bartonella, and Chikungunya virus infections among febrile patients presenting at hospitals in Bangladesh. METHODS: We collected blood samples from patients at six tertiary hospitals from December 2008 to November 2009 and performed laboratory tests at the United States Centers for Disease Control and Prevention (CDC). RESULTS: Out of 720 enrolled patients, 263 (37%) were infected with Rickettsia; 132 patients had immunofluorescence antibody titer >64 against spotted fever, 63 patients against scrub typhus fever and 10 patients against typhus fever. Ten patients were identified with Coxiella. We isolated Leptospira from two patients and Bartonella from one patient. Ten patients had antibodies against Chikungunya virus. The proportion of patients who died was higher with rickettsial fever (5%) compared to those without a diagnosis of rickettsial infection (2%). None of the patients were initially diagnosed with rickettsial fever. CONCLUSIONS: Rickettsial infections are frequent yet under-recognized cause of febrile illness in Bangladesh. Clinical guidelines should be revised so that local clinicians can diagnose rickettsial infections and provide appropriate drug treatment.

Declines in large wildlife increase landscape-level prevalence of rodent-borne disease in Africa.

Populations of large wildlife are declining on local and global scales. The impacts of this pulse of size-selective defaunation include cascading changes to smaller animals, particularly rodents, and alteration of many ecosystem processes and services, potentially involving changes to prevalence and transmission of zoonotic disease. Understanding linkages between biodiversity loss and zoonotic disease is important for both public health and nature conservation programs, and has been a source of much recent scientific debate. In the case of rodent-borne zoonoses, there is strong conceptual support, but limited empirical evidence, for the hypothesis that defaunation, the loss of large wildlife, increases zoonotic disease risk by directly or indirectly releasing controls on rodent density. We tested this hypothesis by experimentally excluding large wildlife from a savanna ecosystem in East Africa, and examining changes in prevalence and abundance of Bartonella spp. infection in rodents and their flea vectors. We found no effect of wildlife removal on per capita prevalence of Bartonella infection in either rodents or fleas. However, because rodent and, consequently, flea abundance doubled following experimental defaunation, the density of infected hosts and infected fleas was roughly twofold higher in sites where large wildlife was absent. Thus, defaunation represents an elevated risk in Bartonella transmission to humans (bartonellosis). Our results (i) provide experimental evidence of large wildlife defaunation increasing landscape-level disease prevalence, (ii) highlight the importance of susceptible host regulation pathways and host/vector density responses in biodiversity-disease relationships, and (iii) suggest that rodent-borne disease responses to large wildlife loss may represent an important context where this relationship is largely negative.

Human Lymphadenopathy Caused by Ratborne Bartonella, Tbilisi, Georgia.

Lymphadenopathy and fever that developed in a woman in Tbilisi, Georgia, most likely were caused by a ratborne Bartonella strain related B. tribocorum and B. elizabethae. The finding suggests that this Bartonella strain could be spread by infected rats and represents a potential human risk.

Molecular Survey of Bartonella Species and Yersinia pestis in Rodent Fleas (Siphonaptera) From Chihuahua, Mexico.

Rodent fleas from northwestern Chihuahua, Mexico, were analyzed for the presence of Bartonella and Yersinia pestis. In total, 760 fleas belonging to 10 species were tested with multiplex polymerase chain reaction analysis targeting the gltA (338-bp) and pla genes (478-bp) of Bartonella and Y. pestis, respectively. Although none was positive for Y. pestis, 307 fleas were infected with Bartonella spp., resulting in an overall prevalence of 40.4%. A logistic regression analysis indicated that the presence of Bartonella is more likely to occur in some flea species. From a subset of Bartonella-positive fleas, phylogenetic analyses of gltA gene sequences revealed 13 genetic variants clustering in five phylogroups (I­V), two of which were matched with known pathogenic Bartonella species (Bartonella vinsonii subsp. arupensis and Bartonella washoensis) and two that were not related with any previously described species or subspecies of Bartonella. Variants in phylogroup V, which were mainly obtained from Meringis spp. fleas, were identical to those reported recently in their specific rodent hosts (Dipodomys spp.) in the same region, suggesting that kangaroo rats and their fleas harbor other Bartonella species not reported previously. Considering the Bartonella prevalence and the flea genotypes associated with known pathogenic Bartonella species, we suggest that analysis of rodent and flea communities in the region should continue for their potential implications for human health. Given that nearby locations in the United States have reported Y. pestis in wild animals and their fleas, we suggest conducting larger-scale studies to increase our knowledge of this bacterium.

Molecular survey of arthropod-borne pathogens in sheep keds (Melophagus ovinus), Central Europe.

In the study, we screened a total of 399 adult sheep keds (Melophagus ovinus) for the presence of RNA and DNA specific for arboviral, bacterial, and protozoan vector-borne pathogens. All investigated keds were negative for flaviviruses, phleboviruses, bunyaviruses, Borrelia burgdorferi, Rickettsia spp., Anaplasma phagocytophilum, "Candidatus Neoehrlichia mikurensis," and Babesia spp. All ked pools were positive for Bartonella DNA. The sequencing of the amplified fragments of the gltA and 16S-23S rRNA demonstrated a 100 % homology with Bartonella melophagi previously isolated from a sheep ked and from human blood in the USA. The identification of B. melophagi in sheep keds in Central Europe highlights needs extending a list of hematophagous arthropods beyond ticks and mosquitoes for a search of emerging arthropod-borne pathogens.

HGTector: an automated method facilitating genome-wide discovery of putative horizontal gene transfers.

BACKGROUND: First pass methods based on BLAST match are commonly used as an initial step to separate the different phylogenetic histories of genes in microbial genomes, and target putative horizontal gene transfer (HGT) events. This will continue to be necessary given the rapid growth of genomic data and the technical difficulties in conducting large-scale explicit phylogenetic analyses. However, these methods often produce misleading results due to their inability to resolve indirect phylogenetic links and their vulnerability to stochastic events. RESULTS: A new computational method of rapid, exhaustive and genome-wide detection of HGT was developed, featuring the systematic analysis of BLAST hit distribution patterns in the context of a priori defined hierarchical evolutionary categories. Genes that fall beyond a series of statistically determined thresholds are identified as not adhering to the typical vertical history of the organisms in question, but instead having a putative horizontal origin. Tests on simulated genomic data suggest that this approach effectively targets atypically distributed genes that are highly likely to be HGT-derived, and exhibits robust performance compared to conventional BLAST-based approaches. This method was further tested on real genomic datasets, including Rickettsia genomes, and was compared to previous studies. Results show consistency with currently employed categories of HGT prediction methods. In-depth analysis of both simulated and real genomic data suggests that the method is notably insensitive to stochastic events such as gene loss, rate variation and database error, which are common challenges to the current methodology. An automated pipeline was created to implement this approach and was made publicly available at: https://github.com/DittmarLab/HGTector. The program is versatile, easily deployed, has a low requirement for computational resources. CONCLUSIONS: HGTector is an effective tool for initial or standalone large-scale discovery of candidate HGT-derived genes.

Risk factors for human lice and bartonellosis among the homeless, San Francisco, California, USA.

Homeless persons in San Francisco, California, USA,have been shown to have head and body lice infestations and Bartonella quintana infections. We surveyed a self selected population of homeless persons in San Francisco to assess infestations of head and body lice, risks of having body lice, and presence of B. quintana in lice. A total of 203 persons who reported itching were surveyed during 2008-2010 and 2012: 60 (30%) had body lice, 10 (4.9%)had head lice, and 6 (3.0%) had both. B. quintana was detected in 10 (15.9%) of 63 body lice pools and in 6 (37.5%)of 16 head lice pools. Variables significantly associated(p<0.05) with having body lice in this homeless population included male sex, African-American ethnicity, and sleeping outdoors. Our study findings suggest that specific segments of the homeless population would benefit from information on preventing body lice infestations and louse borne diseases.

Infective endocarditis in northeastern Thailand.

Despite rigorous diagnostic testing, the cause of infective endocarditis was identified for just 60 (45.5%) of 132 patients admitted to hospitals in Khon Kaen, Thailand, during January 2010-July 2012. Most pathogens identified were Viridans streptococci and zoonotic bacteria species, as found in other resource-limited countries where underlying rheumatic heart disease is common.

Transmission and maintenance cycle of Bartonella quintana among rhesus macaques, China.

We detected Bartonella quintana in 48.6% of captive rhesus macaques from an animal facility in Beijing, China. Prevalence of infection increased over the period of observation. Our findings suggest that macaques may serve as reservoir hosts for B. quintana and that Pedicinus obtusus lice might act as efficient vectors.

Genetic diversity of Bartonella quintana in macaques suggests zoonotic origin of trench fever.

Bartonella quintana is a bacterium that causes a broad spectrum of diseases in humans including trench fever. Humans were previously considered to be the primary, if not the only, reservoir hosts for B. quintana. To identify the animal reservoir and extend our understanding of the ecological and evolutionary history of B. quintana, we examined blood samples from macaques and performed multilocus sequence typing (MLST) analysis. We demonstrated the prevalence of B. quintana infection was common in macaques from main primate centres in mainland China. Overall, 18.0% (59/328) of rhesus macaques and 12.7% (39/308) of cynomolgus macaques were found to be infected with B. quintana by blood culture and/or polymerase chain reaction. The infection was more frequently identified in juvenile and young monkeys compared with adult animals. In contrast with the relatively low level of sequence divergence of B. quintana reported in humans, our investigation revealed much higher genetic diversity in nonhuman primates. We identified 44 new nucleotide variable sites and 14 novel sequence types (STs) among the B. quintana isolates by MLST analysis. Some STs were found only in cynomolgus macaques, while some others were detected only in rhesus macaques, suggesting evidence of host-cospeciation, which were further confirmed by phylogenetic analysis and Splits decomposition analysis. Our findings suggest that trench fever may primarily be a zoonotic disease with macaques as the natural hosts.

Geo-temporal patterns to design cost-effective interventions for zoonotic diseases -the case of brucellosis in the country of Georgia.

Introduction: Control of zoonosis can benefit from geo-referenced procedures. Focusing on brucellosis, here the ability of two methods to distinguish disease dissemination patterns and promote cost-effective interventions was compared. Method: Geographical data on bovine, ovine and human brucellosis reported in the country of Georgia between 2014 and 2019 were investigated with (i) the Hot Spot (HS) analysis and (ii) a bio-geographical (BG) alternative. Results: More than one fourth of all sites reported cases affecting two or more species. While ruminant cases displayed different patterns over time, most human cases described similar geo-temporal features, which were associated with the route used by migrant shepherds. Other human cases showed heterogeneous patterns. The BG approach identified small areas with a case density twice as high as the HS method. The BG method also identified, in 2018, a 2.6-2.99 higher case density in zoonotic (human and non-human) sites than in non-zoonotic sites (which only reported cases affecting a single species) -a finding that, if corroborated, could support cost-effective policy-making. Discussion: Three dissemination hypotheses were supported by the data: (i) human cases induced by sheep-related contacts; (ii) human cases probably mediated by contaminated milk or meat; and (iii) cattle and sheep that infected one another. This proof-of-concept provided a preliminary validation for a method that may support cost-effective interventions oriented to control zoonoses. To expand these findings, additional studies on zoonosis-related decision-making are recommended.

Bartonella spp. in rats and zoonoses, Los Angeles, California, USA.

Bartonella spp. were detected in rats (Rattus norvegicus) trapped in downtown Los Angeles, California, USA. Of 200 rats tested, putative human pathogens, B. rochalimae and B. tribocorum were found in 37 (18.5%) and 115 (57.5%) rats, respectively. These bacteria among rodents in a densely populated urban area are a public health concern.

Bartonella vinsonii subsp. arupensis in humans, Thailand.

We identified Bartonella vinsonii subsp. arupensis in pre-enriched blood of 4 patients from Thailand. Nucleotide sequences for transfer-messenger RNA gene, citrate synthase gene, and the 16S-23S rRNA internal transcribed spacer were identical or closely related to those for the strain that has been considered pathogenic since initially isolated from a human in Wyoming, USA.

Development of a novel genus-specific real-time PCR assay for detection and differentiation of Bartonella species and genotypes.

The genus Bartonella includes numerous species with varied host associations, including several that infect humans. Development of a molecular diagnostic method capable of detecting the diverse repertoire of Bartonella species while maintaining genus specificity has been a challenge. We developed a novel real-time PCR assay targeting a 301-bp region of the ssrA gene of Bartonella and demonstrated specific amplification in over 30 Bartonella species, subspecies, and strains. Subsequent analysis of ssrA sequences was sufficient to discriminate Bartonella species and provided phylogenetic data consistent with that of gltA, a commonly used gene for differentiating Bartonella genotypes. Using this assay, we identified Bartonella DNA in 29% and 47% of blood specimens from elk in Wyoming and cattle in the Republic of Georgia, respectively. Sequence analysis of a subset of genotypes from elk specimens revealed a cluster most closely related to Bartonella capreoli, and genotypes from cattle were identified as Bartonella bovis, both Bartonella species commonly found in wild and domestic ruminants. Considering the widespread geographic distribution and infectivity potential to a variety of hosts, this assay may be an effective diagnostic method for identification of Bartonella infections in humans and have utility in Bartonella surveillance studies.

Bartonella species in dogs and their ectoparasites from Khon Kaen Province, Thailand.

In order to access the prevalence of Bartonella species in dogs, whole blood and any associated ectoparasites were collected from 164 dogs with owners in 25 villages throughout Khon Kaen Province. DNA was extracted from dog blood, 92 ticks (Rhipicephalus sanguineus) and 137 fleas (Ctenocephalides spp) and screened by PCR using intergenic spacer region and citrate synthase gene primers. B. clarridgeiae DNA was detected in blood of 3 dogs, 4 C. felis and 1 C. canis; B. rochalimae DNA was found in 1 tick; and B. vinsonii subsp vinsonii DNA was found in 2 C. felis. The findings indicate that dogs residing in northeast Thailand are exposed to diverse Bartonella species that are also potential human pathogens.

Presence of Leptospira spp. and absence of Bartonella spp. in urban rodents of Buenos Aires province, Argentina.

Big cities of Argentina are characterized by a strong social and economic fragmentation. This context enables the presence of urban rodents in close contact to the human population, mostly in the peripheral areas of the cities. Urban rodents can harbor a large variety of zoonotic pathogens. The aim of this study was to molecularly characterize Leptospira spp. and Bartonella spp. in urban rodents from the area of Gran La Plata, Buenos Aires province, Argentina. The species of urban rodents captured and tested were Rattus norvegicus, Rattus rattus, and Mus musculus. Leptospira interrogans and L. borgpetersenii were detected in R. norvegicus and M. musculus respectively. Bartonella spp. DNA was not detected in any of the kidney samples tested. No significant differences were observed between the prevalence of bacteria and rodent and environmental variables such as host sex, presence of stream and season by Generalized Linear Model analysis. These results confirm the role of urban rodents as infection sources of Leptospira spp., suggesting the need to implement public health measures to prevent the transmission of Leptospira spp. and other zoonotic pathogens from rodents to humans. Bartonella was not detected in this set of samples.