Epidemiology of Q fever in humans in four selected regions, Spain, 2016 to 2022.

BackgroundQ fever is a bacterial zoonosis caused by Coxiella burnetii. Spain has the highest number of notified human cases in Europe. Small ruminants are a key reservoir for the pathogen, transmission from animals to humans is usually airborne.AimWe aimed at exploring temporal and spatial epidemiological patterns of sporadic and outbreak cases of Q fever in four Spanish regions with the highest number of notified cases.MethodsWe extracted data on Q fever cases in the Canary Islands, Basque Country, La Rioja and Navarre between 2016 and 2022 from the Spanish National Epidemiological Surveillance Network. We calculated standardised incidence ratios (SIR), spatial relative risks (sRR) and posterior probabilities (PP) utilising Besag-York-Mollié models.ResultsThere were 1,059 notifications, with a predominance of males aged 30-60 years. In Basque Country, La Rioja and Navarre area, 11 outbreaks were reported, while no in the Canary Islands. A seasonal increase in incidence rates was observed between March and June. In the Canary Islands, elevated sRR was seen in La Palma, Gran Canaria, Lanzarote and Fuerteventura. In Basque Country, La Rioja and Navarre area, the highest sRR was identified in the south of Biscay province.ConclusionGoats were the main source for humans in outbreaks reported in the literature. Seasonal increase may be related to the parturition season of small ruminants and specific environmental conditions. Local variations in sRR within these regions likely result from diverse environmental factors. Future One Health-oriented studies are essential to deepen our understanding of Q fever epidemiology.

Zoonotic Bacteria in Fleas Parasitizing Common Voles, Northwestern Spain.

We detected Francisella tularensis and Bartonella spp. in fleas parasitizing common voles (Microtus arvalis) from northwestern Spain; mean prevalence was 6.1% for F. tularensis and 51% for Bartonella spp. Contrasted vector-host associations in the prevalence of these bacteria suggest that fleas have distinct roles in the transmission cycle of each pathogen in nature.

Zoonotic pathogens in fluctuating common vole (Microtus arvalis) populations: occurrence and dynamics.

Diseases and host dynamics are linked, but their associations may vary in strength, be time-lagged, and depend on environmental influences. Where a vector is involved in disease transmission, its dynamics are an additional influence, and we often lack a general understanding on how diseases, hosts and vectors interact. We report on the occurrence of six zoonotic arthropod-borne pathogens (Anaplasma, Bartonella, Borrelia, Coxiella, Francisella and Rickettsia) in common voles (Microtus arvalis) throughout a population fluctuation and how their prevalence varies according to host density, seasonality and vector prevalence. We detected Francisella tularensis and four species of Bartonella, but not Anaplasma, Borrelia, Coxiella or Rickettsia. Bartonella taylorii and B. grahamii prevalence increased and decreased with current host (vole and mice) density, respectively, and increased with flea prevalence. Bartonella doshiae prevalence decreased with mice density. These three Bartonella species were also more prevalent during winter. Bartonella rochalimae prevalence varied with current and previous vole density (delayed-density dependence), but not with season. Coinfection with F. tularensis and Bartonella occurred as expected from the respective prevalence of each disease in voles. Our results highlight that simultaneously considering pathogen, vector and host dynamics provide a better understanding of the epidemiological dynamics of zoonoses in farmland rodents.

A Q Fever Outbreak with a High Rate of Abortions at a Dairy Goat Farm: Coxiella burnetii Shedding, Environmental Contamination, and Viability.

This study describes a Q fever outbreak in a herd of 77 Alpine goats which suffered a high rate of abortions (81% [58/72]) in January 2017 and presents the results of monitoring the contamination and viability of Coxiella burnetii in the farm environment several months after the outbreak. Over the course of 7 months, we studied bacterial shedding by 35 dams with abortions to monitor C. burnetii infection dynamics and the duration of excretion. The highest bacterial shedding load was observed in vaginal mucus, followed by in feces and in milk. Conversely, the duration of C. burnetii shedding was longer through feces (5 months after abortion) than milk (3 months). C. burnetii DNA was detected throughout the study in aerosol samples periodically collected indoors and outdoors from the animal premises. Mouse inoculation and culture in Vero cells demonstrated the presence of viable isolates in dust collected from different surfaces inside the animal facilities during the period of time with the highest number of abortions but not in dust collected 2, 3, and 4 months after the last parturition. Some workers and visitors were affected by Q fever, with attack rates of 78% (7/9) and 31% (4/13), respectively. Affected people mostly showed fever and seroconversion, along with myalgia and arthralgia in two patients and pneumonia in the index case. The genotype identified in animal and environmental samples (SNP1/MST13) turned out to be very aggressive in goats but caused only moderate symptoms in people. After the diagnosis of abortion by Q fever in goats, several control measures were implemented at the farm to prevent contamination inside and outside the animal facilities.IMPORTANCE This work describes a 7-month follow-up of the excretion by different routes of Coxiella burnetii genotype SNP1/MST13 in a herd of goats that suffered high rate of abortions (81%), generating high environmental contamination. Some of the workers and visitors who accessed the farm were infected, with fever as the main symptom but a low incidence of pneumonia. The detected strain (SNP1/MST13 genotype) turned out to be very aggressive in goats. The viability of C. burnetii was demonstrated in the environment of the farm at the time of abortions, but 2 months after the last parturition, no viable bacteria were detected. These results highlighted the importance of implementing good biosafety measures at farms and avoiding the entrance of visitors to farms several months after the end of the kidding period.

Monkeypox virus genomic accordion strategies.

The 2023 monkeypox (mpox) epidemic was caused by a subclade IIb descendant of a monkeypox virus (MPXV) lineage traced back to Nigeria in 1971. Person-to-person transmission appears higher than for clade I or subclade IIa MPXV, possibly caused by genomic changes in subclade IIb MPXV. Key genomic changes could occur in the genome's low-complexity regions (LCRs), which are challenging to sequence and are often dismissed as uninformative. Here, using a combination of highly sensitive techniques, we determine a high-quality MPXV genome sequence of a representative of the current epidemic with LCRs resolved at unprecedented accuracy. This reveals significant variation in short tandem repeats within LCRs. We demonstrate that LCR entropy in the MPXV genome is significantly higher than that of single-nucleotide polymorphisms (SNPs) and that LCRs are not randomly distributed. In silico analyses indicate that expression, translation, stability, or function of MPXV orthologous poxvirus genes (OPGs), including OPG153, OPG204, and OPG208, could be affected in a manner consistent with the established "genomic accordion" evolutionary strategies of orthopoxviruses. We posit that genomic studies focusing on phenotypic MPXV differences should consider LCR variability.

Human infection with Rickettsia sibirica mongolitimonae, Spain, 2007-2011.

Human infection with Rickettsia sibirica mongolitimonae was initially reported in 1996, and reports of a total of 18 cases have been published. We describe 6 additional cases that occurred in the Mediterranean coast region of Spain during 2007-2011. Clinicians should consider this infection in patients who have traveled to this area.

Molecular method for the characterization of Coxiella burnetii from clinical and environmental samples: variability of genotypes in Spain.

BACKGROUND: Coxiella burnetii is a highly clonal microorganism which is difficult to culture, requiring BSL3 conditions for its propagation. This leads to a scarce availability of isolates worldwide. On the other hand, published methods of characterization have delineated up to 8 different genomic groups and 36 genotypes. However, all these methodologies, with the exception of one that exhibited limited discriminatory power (3 genotypes), rely on performing between 10 and 20 PCR amplifications or sequencing long fragments of DNA, which make their direct application to clinical samples impracticable and leads to a scarce accessibility of data on the circulation of C. burnetii genotypes. RESULTS: To assess the variability of this organism in Spain, we have developed a novel method that consists of a multiplex (8 targets) PCR and hybridization with specific probes that reproduce the previous classification of this organism into 8 genomic groups, and up to 16 genotypes. It allows for a direct characterization from clinical and environmental samples in a single run, which will help in the study of the different genotypes circulating in wild and domestic cycles as well as from sporadic human cases and outbreaks. The method has been validated with reference isolates. A high variability of C. burnetii has been found in Spain among 90 samples tested, detecting 10 different genotypes, being those adaA negative associated with acute Q fever cases presenting as fever of intermediate duration with liver involvement and with chronic cases. Genotypes infecting humans are also found in sheep, goats, rats, wild boar and ticks, and the only genotype found in cattle has never been found among our clinical samples. CONCLUSIONS: This newly developed methodology has permitted to demonstrate that C. burnetii is highly variable in Spain. With the data presented here, cattle seem not to participate in the transmission of C. burnetii to humans in the samples studied, while sheep, goats, wild boar, rats and ticks share genotypes with the human population.

Investigating the Role of Micromammals in the Ecology of Coxiella burnetii in Spain.

Coxiella burnetii, the causal agent of human Q fever and animal Coxiellosis, is a zoonotic infectious bacterium with a complex ecology that results from its ability to replicate in multiple (in)vertebrate host species. Spain notifies the highest number of Q fever cases to the ECDC annually and wildlife plays a relevant role in C. burnetii ecology in the country. However, the whole picture of C. burnetii hosts is incomplete, so this study seeks to better understand the role of micromammals in C. burnetii ecology in the country. Spleen samples from 816 micromammals of 10 species and 130 vaginal swabs from Microtus arvalis were analysed by qPCR to detect C. burnetii infection and shedding, respectively. The 9.7% of the spleen samples were qPCR positive. The highest infection prevalence (10.8%) was found in Microtus arvalis, in which C. burnetii DNA was also detected in 1 of the 130 vaginal swabs (0.8%) analysed. Positive samples were also found in Apodemus sylvaticus (8.7%), Crocidura russula (7.7%) and Rattus rattus (6.4%). Positive samples were genotyped by coupling PCR with reverse line blotting and a genotype II+ strain was identified for the first time in one of the positive samples from M. arvalis, whereas only partial results could be obtained for the rest of the samples. Acute Q fever was diagnosed in one of the researchers that participated in the study, and it was presumably linked to M. arvalis handling. The results of the study are consistent with previous findings suggesting that micromammals can be infected by C. burnetii. Our findings additionally suggest that micromammals may be potential sources to trace back the origin of human Q fever and animal Coxiellosis cases in Europe.

Rapid and Highly Sensitive DNA Flow Technology Platform to Detect Tick-Borne Bacterial Pathogens in Clinical Samples.

Zoonotic diseases represent a significant public health concern worldwide due to the emergence/re-emergence of vector-borne diseases in the last decade. Ticks are the most important vectors in the northern hemisphere and can transmit diseases such as Lyme disease, human granulocytic anaplasmosis, and spotted fever rickettsioses, among others. Therefore, there is a growing need to develop better and faster diagnostic tools that can detect zoonotic human pathogens in clinical samples. In this study, we present the results for a new kit tick-borne bacteria flow chip (TBFC), which allows the simultaneous screening of seven different bacterial pathogens in human samples using a DNA flow technology platform (hybriSpot system). The analytical sensitivity and specificity of the TBFC were calculated spiking bacterial DNA in human DNA samples, and the results were compared with an in-house single PCR-reverse line blot (RLB) routinely used for diagnosis at the National Center for Microbiology in Spain. The analytical sensitivity and specificity of the TBFC were almost identical to the PCR-RLBs used in diagnosis. In addition, samples from patients (n = 212) with a wide range of clinical signs/symptoms consistent with multisystem disorders suggestive of a tick-borne infection were tested using the TBFC, and the results were compared with those obtained by PCR-RLB. The concordance of both methods using patient samples was 97.2%. The TBFC kit is a rapid new and cost-efficient diagnostic molecular tool capable of detecting tick-borne pathogens in clinical samples.

Monitoring Coxiella burnetii Infection in Naturally Infected Dairy Sheep Flocks Throughout Four Lambing Seasons and Investigation of Viable Bacteria.

Progression of Coxiella burnetii infection in four naturally infected sheep flocks, and in their farm environment, was monitored throughout four lambing seasons. Flocks with an active infection were selected based on the presence of C. burnetii DNA in bulk-tank milk (BTM) and a high seroprevalence in yearlings during the previous milking period (Spring 2015). During four consecutive lambing seasons (2015/16-2018/19), samples were collected within 1 week after each lambing period from animals (vaginal swabs, milk and feces from ewes, and yearlings) and the environment (dust indoor sheep premises). BTM samples and aerosols (outdoors and indoors) were monthly collected between lambing and the end of milking. Real-time PCR analyses showed different trends in C. burnetii shedding in the flocks, with a general progressive decrease in bacterial shedding throughout the years, interrupted in three flocks by peaks of reinfection associated with specific management practices. A significant relationship was found between C. burnetii fecal shedding and the bacterial burden detected in dust, whereas shedding by vaginal route affected the detection of C. burnetii in indoor aerosols. Three genotypes were identified: SNP8 (three flocks, 52.9% of the samples), SNP1 (two flocks, 44.8% samples), and SNP5 (one flock, two environmental samples). Coxiella burnetii viability in dust measured by culture in Vero cells was demonstrated in two of the flocks, even during the fourth lambing season. The results showed that infection can remain active for over 5 years if effective control and biosafety measures are not correctly implemented.

Molecular Survey of Rickettsia spp., Anaplasma spp., Ehrlichia spp., Bartonella spp., and Borrelia spp. in Fleas and Lice in Ethiopia.

Bacterial arthropod-borne pathogens can often cause fever in Africa, but rural laboratories in these settings are usually too basic to provide a precise picture of their epidemiological impact. Our aim was to determine the prevalence of bacterial pathogens in fleas and lice in a rural area of southeast Ethiopia. Between July and November 2013, we extracted DNA from 91 fleas (Ctenocephalides felis [n = 50; 54.9%], Pulex irritans [n = 37; 40.1%], and C. canis [n = 4; 4.4%] and 30 lice (Pediculus humanus capitis [n = 16; 53.3%] and Pediculus humanus humanus [n = 14; 46.7%]), using two quantitative PCR (qPCR) analyses to look for bacteria from the genera: Anaplasma, Bartonella, Borrelia, Coxiella, Ehrlichia, Francisella, and Rickettsia. Of the 91 fleas analyzed, pathogens were present in 79 (86.8%), including Rickettsia felis (n = 41; 45%), Anaplasma platys (n = 40; 44.0%), Rickettsia monacensis (n = 2; 2.2%), Ehrlichia muris-like agent (n = 1; 1.1%), and Bartonella clarridgeiae (n = 1; 1.1%). P. irritans was the flea species most frequently infected with A. platys (67.7%), followed by C. felis (30.7%) (p < 0.001). Of the 30 lice identified, pathogens were present in 7 (23.3%): Bartonella quintana (n = 4; 16.7%), E. muris (n = 2, 6.7%), and Borrelia recurrentis (n = 1, 3.3%). Thus, in this rural area of Africa, fleas and lice can transmit parasitic pathogens to humans, causing febrile symptoms.

Viable Coxiella burnetii in hard cheeses made with unpasteurized milk.

Q fever is a bacterial zoonosis caused by Coxiella burnetii whose main reservoir are small ruminants. Infected animals shed the bacteria into the environment through the products of abortion as well as through feces, urine, and milk. Susceptible people are mainly infected by the inhalation of contaminated aerosols, while food-borne infection is unclear. High prevalence of C. burnetii DNA in cheeses from cattle, sheep or goat has been reported, but studies on viability of C. burnetii in hard cheeses are scarce. In this study, 67 sheep handicraft hard cheeses of different geographic origins made with unpasteurized milk were analyzed for the presence of C. burnetii DNA. To investigate viability of C. burnetii in cheese, 5 cheeses were selected among the 20 that tested DNA positive. Presence of viable C. burnetii was demonstrated in one cheese by experimental inoculation in BALB/c mice and culture in Vero cells. To further investigate the effect of cheese ripening in C. burnetii viability, another 12 cheeses elaborated in the same farm and season, and ripened for between 2.0 and 10.1 months were investigated. Results showed presence of C. burnetii DNA in all of them and viable C. burnetii in 5, indicating that C. burnetii can remain viable after at least 8 months of ripening in hard cheeses made with unpasteurized milk under the acid pH (4.96-5.41) and low water activity (0.9065-0.9533) conditions observed.

Arthropod-Borne Bacteria Cause Nonmalarial Fever in Rural Ethiopia: A Cross-Sectional Study in 394 Patients.

Bacterial arthropod-borne pathogens are a common cause of fever in Africa, but their precise impact is unknown and usually underdiagnosed in the basic rural laboratories of low-resourced African countries. Our aim was to determine the prevalence of arthropod-borne bacterial diseases causing fever among malaria smear-negative patients in a rural hospital located in Ethiopia. The study population included patients aged 2 years or older; referred to Gambo Rural General Hospital (West Arsi, Ethiopia), between July and November 2013, for fever or report of fever in the previous 48 h; attending the outpatient department; and testing negative for malaria by Giemsa-stained thin blood smears. We extracted DNA from 394 whole blood samples, using reverse line blot assays of amplicons to look for bacteria from the genera: Anaplasma, Bartonella, Borrelia, Coxiella, Ehrlichia, Francisella, and Rickettsia. Thirteen patients showed presence of DNA for these pathogens: three each by Borrelia spp., the Francisella group (F. tularensis tularensis, F. tularensis holartica, and F. novicia), Rickettsia bellii, and Rickettsia Felis, and one by Bartonella rochalimae. Thus, in this rural area of Africa, febrile symptoms could be due to bacteria transmitted by arthropods. Further studies are needed to evaluate the pathogenic role of R. bellii.

A Q fever outbreak associated to courier transport of pets.

On August 3rd, 2017, a Q fever outbreak alert was issued at a courier company that in addition to urgent freight transport offered pet delivery services. The epidemiological investigation set the exposition period between June 1 and August 8. In this period, 180 workers from two operational platforms for parcel distribution located in two provinces of the Basque Country (Bizkaia and Araba) were exposed; 64 filled a questionnaire and provided blood samples for serological testing, resulting in 10 confirmed cases (15.6%) and six (9.4%) probable cases. Nine workers (8 confirmed and 1 probable) showed Q fever symptoms, including pneumonia (five cases), and required medical care services, including one hospital admission. The attack rate was 25% (16/64), being higher among workers that visited the Bizkaia platform. This suggested that the origin of the outbreak was in the Bizkaia platform, where animals in transit waited at a pet holding site until being moved to their destination. Environmental samples consisting on 19 surface dust and two aerosol samples were collected at the Bizkaia platform to investigate the presence of C. burnetti DNA. All dust samples were positive by real time PCR, the lowest Ct values being found in dust collected at the pet holding facilities, and therefore suggesting that contamination originated at the pet holding site. The genotype identified in dust was SNP1/MST13, one of the most commonly identified genotypes in goats and sheep in the Basque Country. During the exposure period, two deliveries of miniature goats were made, of which only one could be investigated and tested negative. Although the contamination source could not be unequivocally identified, transport of ruminants was banned at the company, and Q fever was included among the occupational-associated health risks.

Molecular method for Bartonella species identification in clinical and environmental samples.

A new, efficient molecular method for detection of Bartonella, based on the 16S-23S rRNA intergenic spacer and 16S rRNA amplification by multiplex PCR combined with reverse line blotting, was designed. This assay could simultaneously detect 20 different known species and other Bartonella species not described previously.

Molecular method for discrimination between Francisella tularensis and Francisella-like endosymbionts.

Environmental studies on the distribution of Francisella spp. are hampered by the frequency of Francisella-like endosymbionts that can produce a misleading positive result. A new, efficient molecular method for detection of Francisella tularensis and its discrimination from Francisella-like endosymbionts, as well as two variants associated with human disease (unusual F. tularensis strain FnSp1 and F. tularensis subsp. novicida-like strain 3523), is described. The method is highly specific and sensitive, detecting up to one plasmid copy or 10 genome equivalents.

Stable levels of Coxiella burnetii prevalence in dairy sheep flocks but changes in genotype distribution after a 10-year period in northern Spain.

Bulk tank milk (BTM) samples were collected from 81 sheep flocks in the Basque Country, Spain, in 2015 and were analysed for antibodies against Coxiella burnetii by ELISA and for C. burnetii DNA by real-time PCR. Thirty-two percent of the flocks had BTM antibodies against C. burnetii. Presence of C. burnetii DNA in BTM was detected in 23% of the flocks, suggesting recent C. burnetii infections. Retrospective data of BTM samples obtained from 154 sheep flocks investigated in 2005 in the same geographic area were compiled to assess temporal changes in C. burnetii infection. The overall percentage of infected sheep flocks did not significantly change after the 10-year period. Among the 46 flocks sampled in both periods, 11 flocks that were negative in 2005 were positive in 2015, 18 maintained their initial status (positive or negative), and 17 positive flocks were negative in 2015. These findings indicate that C. burnetii infection is a dynamic process in dairy sheep in northern Spain. Single nucleotide polymorphism (SNP) genotyping of positive samples identified three genotypes, SNP1 being the most prevalent in 2015 and SNP8 in 2005; SNP4 was only detected once in 2005. These results suggest possible changes in the pattern of genotype infection over time.

Genotypes of Coxiella burnetii in wildlife: disentangling the molecular epidemiology of a multi-host pathogen.

Evidences point to a relevant role of wildlife in the ecology of Coxiella burnetii worldwide. The lack of information on C. burnetii genotypes in wildlife prevents tracing-back clinical animal and human Q fever cases with potential wildlife origin. To compare C. burnetii genotypes circulating in wildlife, livestock and humans, 107 samples from red deer, European wild rabbit, racoon, small mammals, goat and sheep were genotyped by polymerase chain reaction and reverse line blot hybridization. Genomic groups I, II, VI and VII were found in wildlife and groups I, II, III and IV in domestic ruminants. Livestock genotypes clustered mainly with genotypes reported previously in livestock. Genotyping confirmed previous findings that suggest that C. burnetii may display host specificity since most genotypes of sympatric deer and rabbits clustered in separate groups. Wildlife genotypes clustered with genotypes from ticks and from acute hepatitis human Q fever cases, suggesting that particular C. burnetii genotypes circulating in a wildlife-tick cycle may occasionally jump into humans through tick bites or exposure to wildlife. This finding could be behind the reported geographic variation in the clinical presentation of acute Q fever in humans in Spain: atypical pneumonia in the north and hepatitis in the south.

Coxiella burnetii total immunoglobulin G, phase I and phase II immunoglobulin G antibodies, and bacterial shedding in young dams in persistently infected dairy herds.

The current study examines Coxiella burnetii infection patterns in young dairy dams around the calving period in persistently infected high-producing dairy herds. Infection patterns were determined in terms of total immunoglobulin G (IgG) and phase-specific IgG antibodies by enzyme-linked immunosorbent assay and bacterial shedding by real-time polymerase chain reaction (qPCR). On days 171-177 of gestation, at parturition, and on days 15-21 and 91-97 postpartum, 7 first-parity cows and 7 second-parity cows were sampled for serology and qPCR. Total phase-specific I (PhI) and II (PhII) IgG antibodies were detected in 2 animals at days 171-177 of gestation. Four additional animals underwent seroconversion on days 91-97 postpartum. Three of 6 seropositive dams according to total IgG, showed a PhI+/PhII+ profile, whereas dams that seroconverted exhibited a PhI-/PhII+ (2/6) or PhI+/PhII- (1/6) profile. An indirect fluorescent antibody test for PhI and PhII immunoglobulin M (IgM) was performed on plasma samples from the shedding dams, confirming seropositivity in a first-parity dam that seroconverted, and detecting a sudden spike of PhI-IgM antibodies in 1 further dam. No relationship was detected in young C. burnetii-infected animals between total IgG, PhI and/or PhII antibodies, and bacterial shedding throughout the study period. The highest bacterial load measured by qPCR was recorded in a second-parity dam. This animal presented abnormal peripheral blood counts, which would be an indication of severe peripheral blood alterations in some infected cattle. This study suggests that young shedder cows are mostly seronegative in early stages of infection.

Molecular characterization of Rickettsia massiliae and Anaplasma platys infecting Rhipicephalus sanguineus ticks and domestic dogs, Buenos Aires (Argentina).

Rickettsioses, ehrlichioses and anaplasmoses are emerging diseases that are mainly transmitted by arthropods and that affect humans and animals. The aim of the present study was to use molecular techniques to detect and characterize those pathogens in dogs and ticks from Buenos Aires city. We studied 207 Rhipicephalus sanguineus ticks and 52 canine blood samples from poor neighborhoods of Buenos Aires city. The samples were molecularly screened for the genera Rickettsia, Ehrlichia, and Anaplasma by PCR and sequencing. DNA of Rickettsia massiliae (3.4%) and Anaplasma platys (13.5%) was detected in ticks and blood samples, respectively. For characterization, the positive samples were subjected to amplification of a fragment of the 190-kDa outer membrane protein gene (spotted fever group rickettsiae) and a fragment of the groESL gene (specific for A. platys). A phylogenetic tree was constructed using the neighbor-joining method, revealing that the sequences were closely related to those of strains from other geographic regions. The results indicate that human and animal pathogens are abundant in dogs and their ticks in Buenos Aires city and portray the potentially high risk of human exposure to infection with these agents, especially in poor neighborhoods, where there is close contact with animals in an environment of poor health conditions.