Acute undifferentiated febrile illness (AUFI) is a challenging clinical condition in tropical regions, caused by a broad range of pathogens. In Villeta municipality, Colombia, data on neglected bacterial causes remain scarce, highlighting the need to expand understanding of the local etiological spectrum. Thus, the aim of the present study was to explore the presence of the neglected pathogens, Bartonella, Borrelia, and Coxiella burnetii, as potential causes of AUFI in Villeta. DNA was extracted from whole-blood samples from febrile patients. Quality and purity were assessed spectrophotometrically and by conventional polymerase chain reaction (PCR). Bartonella, Borrelia, and C. burnetii were detected using genus- and species-specific quantitative PCR (qPCR) assays. Bartonella-positive samples were further analyzed by multigene PCRs and sequencing for species identification. Anti-Bartonella and anti-C. burnetii immunoglobulin G (IgG) antibodies were evaluated by indirect immunofluorescence to assess recent or past exposure to these agents. A total of 41 febrile patients were evaluated. Bartonella DNA was detected in 9.8% (4/41) of samples. No Borrelia or C burnetii DNA was detected. Phylogenetic analysis revealed two distinct clades, although none could be assigned to species level. Serological analysis showed anti-Bartonella IgG antibodies in 29.3% (12/41) of cases, with 9.8% (4/41) exhibiting seroconversion. One patient presented both molecular and seroconversion evidence of recent Bartonella infection. None of the patients were seropositive for C. burnetii. This study provides the first molecular and serological evidence of Bartonella circulation among febrile patients in Villeta, Colombia, revealing genetically distinct lineages and indicating both active and past infections, underscoring its potential role in AUFI.

BackgroundThis research aimed to investigate the prevalence and diversity of Bartonella in small mammals and their ectoparasites from the Central Highlands of Madagascar and to refine existing information on potential associated zoonotic diseases.MethodsA retrospective analysis was performed on mammals and their ectoparasites collected in the Fandriana and Ankazobe districts, including 253 spleen samples from seven small mammal species and 183 individual ectoparasites (132 fleas and 51 ticks). Genomic DNA was extracted and amplified by polymerase chain reaction (PCR) targeting the nuoG gene (346 bp). Sanger sequencing of the PCR products was performed to assess Bartonella diversity using phylogenetic analysis.ResultsIn total, 60.1% (152/253) of small mammals and 15.9% (21/132) of fleas tested positive for Bartonella, with Rattus rattus (69.1%, 137/198) and the associated flea Synopsyllus fonquerniei (21.2%, 14/66) having the highest infection rates. At the same sampled locations, adult R. rattus were more frequently infected with Bartonella than juveniles. Phylogenetic analysis revealed five associated clades of Bartonella with two clades recognized as a potential zoonotic species (B. elizabethae and B. kosoyi).ConclusionsUsing molecular tools, we report a high prevalence of Bartonella in small mammals and their fleas in the Central Highlands of Madagascar. Two potential Bartonella zoonotic species were identified in R. rattus and their fleas. As these bacteria are generally vector-borne, they could have a significant impact on public health in the vicinity of our study areas and, in general, in Madagascar, and merit further investigation.Graphical Supplementary InformationThe online version contains supplementary material available at 10.1186/s13071-025-07233-9.

From kitten to corpus callosum: an unusual case of pediatric Bartonella infection

Understanding the drivers of seasonal disease outbreaks remains a fundamental challenge in disease ecology. Periodic outbreaks can be driven by several seasonally varying factors, including pulses of susceptible individuals through births, changes in host behaviour and social aggregation and variation in host immunity. However, when these potential drivers overlap temporally, isolating their relative contributions to outbreak patterns becomes challenging. We studied Hendra virus, a zoonotic pathogen with seasonal spillovers from bats to horses and humans. Multiple seasonal factors have been hypothesized to drive Hendra virus transmission, including food shortages, birth pulses and changes in host aggregation, but their temporal overlap has made identifying primary drivers difficult. We conducted a 4-year longitudinal study of Pteropus bats to test whether seasonal birth pulses and the resulting influx of susceptible juveniles drive Hendra virus transmission. Using a Bayesian ageing model, we aged sexually immature bats and placed them into birth cohorts. We used our age predictions to model how viral shedding and antibody responses changed as bats aged. We tracked Bartonella spp. Infection-a bacterial pathogen requiring close contact for transmission-as an indicator of transmission opportunities within each cohort for comparison. We found no evidence that seasonal birth pulses of immunologically naïve juveniles drove Hendra virus transmission. Two out of three cohorts showed substantially reduced maternal antibody transfer compared to the 2018 cohort, with seroprevalence near zero at our earliest sampling timepoints and showed no clear evidence of synchronized seroconversion. Furthermore, Bartonella infection rates were consistent across cohorts, indicating that opportunities for pathogen transmission remained consistent across cohorts despite varying viral shedding patterns. Our findings demonstrate that birth pulses alone cannot explain observed patterns of Hendra virus outbreaks. These results highlight the importance of using multiple lines of evidence to evaluate competing mechanisms underlying seasonal disease dynamics, particularly when potential drivers coincide temporally.

Case report clinical reasoning: supraclavicular lymphadenopathy in general practice Case report: A 27-year-old woman appeared at consultation with a left supraclavicular swelling. Because she had just purchased a new cat, and both ultrasound as well as blood sampling seemed to indicate an infectious process, she was treated for Bartonella infection. Many months later, she was diagnosed with Hodgkin lymphoma. Differential diagnosis: The clinical reasoning process was described step by step on how the main hypotheses from within the diagnostic landscape are assessed with the available data. Lymphoma was the differential diagnosis we initially wanted to rule out as opposed to the often harmless cat-scratch disease. Ultimately, we estimated a risk between 1% to 10% for Hodgkin lymphoma, which is relatively low and would cause many unwarranted referrals. The missing threshold crossing finding in this case was the persistence of the pathological lymph node. Case progression: No follow-up was provided after the antibiotic treatment for the suspected Bartonella infection. 6 months later our patient came back to consultation with flu-like symptoms. The lymph node had remained unchanged in the meantime. Blood sampling and ultrasound were repeated, showing a heavy inflammatory state and a suppurative lymph node which again pointed towards infection. This led to a quick hematologist referral where an initial FNAC (Fine Needle Aspiration Cytology) was performed with a false negative result. Only 8 months after the first patient contact, a classical Hodgkin lymphoma was diagnosed based on an excisional biopsy. Discussion: Diagnosis of Hodgkin lymphoma in primary care is a known difficulty. With clinical reasoning the risk of biases can be reduced. This case report was a diagnostic challenge for all physicians involved. A follow-up could have meant faster referral and treatment for this patient.

BackgroundAlthough Bartonella henselae is primarily known for causing self‐limiting cat scratch disease in immunocompetent individuals, it can also lead to severe disseminated infections, particularly in immunocompromised patients.Case PresentationWe present a rare case of disseminated B. henselae infection in a 70‐year‐old man with multiple comorbidities, including a recent aortic valve replacement and pacemaker implantation. The patient initially presented with purpuric skin lesions, progressive renal impairment, and pancytopenia, leading to a preliminary diagnosis of autoimmune glomerulonephritis and treatment with immunosuppressants. Subsequent investigations, including kidney and skin biopsies, revealed C3‐dominant glomerulonephritis and leukocytoclastic vasculitis, respectively. Further imaging uncovered a concurrent lung malignancy, treated with radiotherapy. Five months later, the patient presented with blood culture–negative endocarditis complicated by septic embolic strokes, persisting pancytopenia, and hepatosplenomegaly. Serology and B. henselae PCR of bone marrow confirmed disseminated Bartonella henselae infection.ConclusionsThis case highlights the diagnostic challenges of disseminated Bartonella infections, which can mimic autoimmune diseases and delay appropriate treatment. Clinicians should maintain a high index of suspicion to ensure timely diagnosis and management.

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a medical condition characterized by extreme fatigue lasting at least 6 months. Based upon case reports, patients infected with Babesia or Bartonella spp. have reported a history of chronic fatigue and concurrent neurological symptoms. In this study, 50 study participants reporting fatigue lasting from six months to 19 years and one or more neurological symptoms were selected. PCR assays were used to amplify Babesia and Bartonella spp. DNA from blood and enrichment blood cultures. Using targeted qPCR amplification and DNA sequencing, infection with Babesia spp., Bartonella spp. or both genera was confirmed in 10, 11, and 2 individuals, respectively. Of 50 participants, 12 (24%, 95% CI: 12–36%) were infected with a Babesia species, while Bartonella species infection was documented in 13/50 individuals (26%, 95% CI: 13.8–38.2%). This study provides documentation supporting a potential role for Babesia and Bartonella infection in patients with presentations consistent with ME/CFS. Prospective case–control studies, using highly sensitive direct pathogen detection techniques, are needed to determine whether or the extent to which infection with members of these two genera contributes to or causes ME/CFS.

Abstract Rodents play a critical role in the transmission of zoonotic pathogens, with environmental changes and increasing human-wildlife interactions further amplifying disease spillover risks. Cricetomys spp., commonly found in both human dwellings and agricultural fields, are frequently hunted for consumption, potentially facilitating pathogen transmission. However, their roles in pathogen transmission and disease ecology remain poorly understood. This study investigated the prevalence of three microparasite genera, i.e., Bartonella , Hepatozoon , and Anaplasma , in Cricetomys ansorgei from Morogoro, Tanzania. We observed a prevalence of 71.9 % for Bartonella , 17.5 % for Hepatozoon , and 1.8 % for Anaplasma . To our knowledge, this is the first study to investigate Bartonella , Hepatozoon , and Anaplasma in Cricetomys spp. in Tanzania. Furthermore, preliminary results indicate that Bartonella infection prevalence is influenced by habitat type, with a significantly higher prevalence observed in rural areas compared to urban areas. This study underscores the potential role of Cricetomys spp. as important reservoirs of infectious diseases.

Bartonella species, emerging vector-borne pathogens of dogs, are increasingly associated with severe, chronic sequelae, as well as potentially life-threatening diseases, such as endocarditis and myocarditis. Diagnosis of bartonelloses is mainly based on PCR, culture, and serological assays. Despite molecular and biotechnological advances, serological assays employing immunofluorescence antibody (IFA), Western blotting, and enzyme-linked immunosorbent assay (ELISA) technologies have encountered diagnostic limitations, primarily due to poor sensitivity. Using sera from Bartonella-infected and naïve dogs, we applied an immunoproteomic approach to develop a reliable ELISA assay for the diagnosis of bartonelloses in dogs. Five recombinant Bartonella henselae immunodominant proteins (rATP-β, rGroEL, rLemA, rSucB, and rVirB5) were tested in an ELISA format. Sensitivity and specificity of each protein were calculated based on an imperfect reference IFA assay. Dogs comprised Group I: 36 Bartonella spp. naturally infected dogs (all B. henselae IFA seroreactive) and Group II: 34 Bartonella spp. PCR-negative and IFA-negative dogs. Based upon the ELISA seroreactivity results, rATP-β and rGroEL represented the most sensitive and specific candidate peptide targets for utilization in a canine diagnostic ELISA assay. rGroEL resulted in the sensitivity of 83% and specificity of 94% at an optical density (OD) cutoff value of 0.439 and area under curve (AUC) score of 0.93 (95% CI 0.87-0.99), while the sensitivity and specificity of rATP-β were 69% and 94%, respectively, at a cutoff value of 0.565. The combination of rATP-β with rGroEL resulted in an improved sensitivity of 88% and specificity of 92% at an OD cutoff value of 0.505. A receiver operating characteristic curve analysis for the rATP-β plus rGroEL yielded an AUC score of 0.899 (95% CI 0.809-0.989). Combining rATP-β with rGroEL could potentially further improve both the diagnostic sensitivity and specificity of an ELISA assay for the diagnosis of canine bartonelloses.IMPORTANCEBartonella species are associated with a wide spectrum of clinical signs and life-threatening diseases in dogs. There is an increased risk of Bartonella transmission from dogs to dogs, and from dogs to other animals and humans via vectors, such as ticks, fleas, or direct contact with infected clinical specimens. Due to the poor sensitivity of currently available molecular and serological assays, the diagnosis, treatment, and prevention of Bartonella infection in dogs remains challenging. Developing a reliable serodiagnostic assay is essential for the clinical management of canine bartonelloses, a group of infections caused by Bartonella species in dogs. Rapid diagnosis and timely treatment of canine bartonelloses could save the lives of thousands of dogs worldwide each year. This study provides key insights into the design of diagnostic tools utilizing Bartonella henselae proteins that show promise as serological markers to improve the diagnosis of canine bartonelloses.

To describe unusual findings and management of neuroretinitis in patients with cat scratch disease (CSD), their functional outcome after a case-oriented treatment was anaylsed, and the current literature was reviewed. A retrospective monocentric case series and a literature review. Review of medical records, multimodal imaging, and literature review. Five patients (four females and one male) with a mean age of 29.75 years (range: 11–71 years) had unusual findings of ocular bartonellosis, including inner retinitis, focal choroiditis, retinal microaneurysms, and bilateral sectorial optic nerve swelling. Bartonella-related ocular infections were not limited to the posterior segment of the eye. Molecular tests, such as polymerase chain reaction (PCR), showed that elevated markers of IgG titers were used and were positive in the aqueous humour of one patient. Reference to the use of intravitreal treatment in one of the cases was useful. Case-oriented management is associated with improvement in visual acuity, retinal, and choroidal lesions. The range of ocular signs of Bartonella infection could be extended. Molecular tests, such as PCR, are useful diagnostic approaches in the diagnosis of posterior uveitis. Treatment could require intravitreal antibiotic injections in unusual ocular bartonellosis.

Bartonella species, which are globally distributed gram-negative facultative intracellular bacteria, can infect a diverse range of hosts. Rodents are crucial for the maintenance and dissemination of Bartonella spp., several of which are pathogenic to humans. Although Bartonella infections have been studied in various animals, Bartonella genetic diversity in wild rodents and their fleas has not been investigated. This study examined Bartonella prevalence and genetic diversity in wild rodents and fleas from South Korea in 2023–2024. Bartonella was predominantly detected in the rodent species, Apodemus agrarius. A total of 278 rodent blood and spleen samples, along with 22 pools derived from 33 fleas, were analyzed for the presence of Bartonella DNA. Quantitative real-time PCR (qPCR), targeting the small stable RNA A gene, identified Bartonella spp. in 133 rodents (47.84%) and 11 flea pools (50%). Phylogenetic analysis was conducted using partial sequences of the Bartonella citrate synthase gene and the 16S–23S rRNA internal transcribed spacer region. Sequencing and phylogenetic analysis using the maximum likelihood method identified eight Bartonella spp. in these rodents, including Bartonella grahamii and Bartonella elizabethae, which are pathogenic to humans. Bartonella taylorii was the species most frequently detected in the rodents. Half of the flea pools analyzed using qPCR were positive for Bartonella spp. Bartonella grahamii and taylorii were identified as the dominant species in fleas. These findings suggest that in South Korea, wild rodents serve as natural reservoirs for a diverse range of Bartonella spp., with fleas enhancing the risk of zoonotic disease transmission to humans, necessitating caution to prevent infection. This study outlines a potential vector–host relationship concerning Bartonella spp. transmission and persistence in South Korea.

Bartonella pose a significant health risk to military working dogs (MWDs), and these zoonotic organisms may also cause disease in humans. According to the U.S. Army zoonotic disease surveillance program, there was a 47.4% seroprevalence for Bartonella spp. among feral dogs in Iraq. This surveillance program identified infection with a novel species Candidatus Bartonella merieuxii (CBm) in 37% of the dogs by whole blood Bartonella DNA amplification and sequencing for the gltA and rpoB genes and intergenic spacer region. This bacterium has not been successfully cultured to date. The objectives of the present study were to (i) develop an assay to serologically detect infection with CBm in dogs, and (ii) to define the prevalence and Bartonella species acquired by MWD during deployment to Iraq. To establish a multiplex serological surveillance panel capable of assessing infection with Bartonella spp., with special emphasis on CBm, we identified in silico 20 peptides representing potential linear B cell epitopes. The newly developed serosurveillance panel was used to test paired samples (pre- and post-Iraq deployment) from 52 MWD. Conventional Bartonella diagnostic testing (PCR and indirect immunofluorescence assays [IFA]) was also performed. Twenty-seven percent (14/52) of the paired samples had statistically significant antibody differences between pre- and post-Iraq deployment, suggesting seroconversion during deployment. In conclusion, the newly developed multiplex serologic assay, with its advantages of high throughput testing, requirement of low sample volumes, and ability to adapt new Bartonella species to the panel, has the potential to serve as a new diagnostic tool and will be useful for serosurveillance.IMPORTANCEBartonella pose a significant health risk to military working dogs (MWDs), and these organisms also cause disease in humans. Bartonella has not been assessed in MWD deployed to Iraq, despite a report that a novel Bartonella, Candidatus B. merieuxii (CBm), was detected in almost half of the stray dogs in Baghdad. Infection in dogs is similar to that in humans, and to date, at least three MWDs have died of Bartonella infection. The goal of the proposed study is to develop an assay to serologically detect infection with CBm in dogs and to define the prevalence and Bartonella species acquired by MWD during deployment to Iraq. Dogs are potential reservoirs and sentinels for vector-borne infections and are implicated in the transmission of these infections to humans. Detecting the presence of Bartonella in Iraq-deployed MWDs is essential to identify and prevent the introduction of a new Bartonella species to North America.

Bartonella spp. is a Gram-negative bacterium transmitted by arthropod vectors, implicated in a range of zoonotic infections affecting both humans and animals. Among zoonotic species, B. henselae is primarily associated with domestic cats and B. vinsonii with dogs. In Italy, Bartonella infections have been reported in both southern and northern regions. This study investigates the presence of Bartonella spp. in fleas and ticks collected from companion animals in Piedmont region, northwestern Italy. A total of 176 flea and 85 tick specimens were obtained from 92 animals (dogs and cats) between May 2018 and February 2020. Arthropods were morphologically identified using identification keys, and screened for Bartonella DNA by PCR targeting the 16s rRNA gene. Positive samples were further analyzed by amplifying the rpoB gene. Selected 16s-positive and all rpoB-positive samples were sequenced and subjected to phylogenetic analysis. Fleas were mostly identified as Ctenocephalides felis, recovered from 44 cats and 12 dogs; a single C. canis specimen was found in one cat. Ticks were Ixodes ricinus (from 14 cats and 10 dogs), Rhipicephalus sanguineus s.l. (3 cats, 7 dogs), and Dermacentor marginatus (one dog). Bartonella prevalence was 38.4%, with 34.2% positivity in fleas and 45.6% in ticks. All sequences corresponded to B. henselae. These findings confirm the active circulation of B. henselae in ectoparasites of pets and raise questions about the potential role of ticks in its transmission.

Cell surface Toll-like receptor polymorphisms influence Bartonella and ectoparasite infections in striped hamsters.

An 11-year-old boy presented with seizures and sudden bilateral vision loss. Brain magnetic resonance imaging suggested central nervous system (CNS) vasculitis. Fundus examination revealed frosted branch angiitis, optic disc edema, vitritis, and patches of retinitis in both eyes. Initial treatment with valacyclovir for suspected acute retinal necrosis was ineffective, and vision worsened despite pulse steroid therapy. Further evaluation for infectious causes showed positive IgM titers for Bartonella species. Systemic treatment with doxycycline and rifampicin resulted in significant clinical improvement. This case highlights the unusual presentation of cat scratch disease, manifesting as frosted branch angiitis and CNS vasculitis.

The potential role of pathogens, particularly vector-transmitted infectious agents, as a cofactor or cause of neoplasia has not been intensively investigated. We previously reported a potential link between Bartonella spp. bacteremia and splenic hemangiosarcoma (HSA) in dogs living in the United States. The purpose of this study was to: 1/ further determine the prevalence of Bartonella spp. DNA in dogs with splenic HSA from throughout the United States; 2/ assess the impact of sample preservation methods on Bartonella spp. DNA amplification using characterized tissue samples from dogs diagnosed with HSA. In a blinded manner, we determined the presence of Bartonella spp. DNA in scrolls from biorepository formalin-fixed paraffin-embedded (FFPE) spleens from dogs living in three distant locations geographically transecting the United States. DNA extracted from non-lesional spleens (n = 249), nodular lymphoid hyperplasia spleens (n = 248), and splenic HSA (n = 330) were tested by quantitative polymerase chain reaction (qPCR), and droplet digital PCR (ddPCR). Subsequently, Bartonella PCR results from FFPE tissues and formalin-fixed tissues were compared using previously tested fresh frozen tissues from an additional 48 dogs with HSA. There was no significant difference in the proportion of Bartonella PCR positive FFPE tissues from dogs diagnosed with an alesional spleen, nodular lymphoid hyperplasia, and splenic HSA. Regardless of the histological diagnosis, the most common Bartonella species identified was B. henselae (32/38). Bartonella spp. DNA was detected in a significantly larger proportion of fresh frozen tissues compared to FFPE tissues, when tested by qPCR (22/48 versus 1/48; p <0.0001) or ddPCR (19/48 versus 1/48; p <0.0001). Using ddPCR, Bartonella DNA was more often amplified from formalin-fixed tissues compared to FFPE tissues (15/39 versus 1/39; p <0.0001). The sensitivity of qPCR on FFPE samples and formalin-fixed samples, when comparing to fresh frozen samples as the reference standard, was 4.5% and 11.8%, respectively. Due to decreased DNA amplification efficiency, FFPE scrolls should not be used for the detection of Bartonella infection in spleen samples from dogs with HSA. PCR testing of fresh frozen tissues substantially improves the detection of Bartonella spp. infection. If fresh frozen tissues are not available, formalin-fixed tissues should be tested with digital PCR to enhance Bartonella DNA detection.

Bartonellosis is a zoonotic infectious disease caused by Bartonella spp. Small mammals are the most important hosts of Bartonella and play an important role in its long-term maintenance and spread. The multi-organ studies help understand the Bartonella prevalence of hosts more systematically and comprehensively. This study aimed to investigate the prevalence of Bartonella in small mammals and explore the genetic diversity of the infected strains and the influencing factors from Mile City and Lianghe County, Yunnan Province. Small mammals were captured in Mile City and Lianghe County of Yunnan Province from July to August 2019. Spleen and kidney tissues were collected and the gltA gene was amplified to detect and analyze the prevalence of Bartonella in two regions and two organs. The prevalence of Bartonella in small mammals was 14.29% (43/301). Lianghe County's risk of infection was 3.79-fold (95%CI: 1.39-13.35) compared to that of Mile City. The risk of infection in Rattus tanezumi was increased by 90% compared to Suncus murinus (95%CI: 0.01-0.63). The small mammals with tail lengths > 132 mm infected by Bartonella were 6.34 folds than that with tail lengths ≤ 132 mm (95%CI: 1.87-23.39). The spleen had a higher infection rate of 12.11% (35/289) than the kidney at 7.33% (22/300) (χ 2 = 4.966, p = 0.026). There were no statistically significant differences in the prevalence of Bartonella among small mammals with different habitats, sex, age, flea infestation status, body weight, body length, hindfoot length, and ear height. Five Bartonella species were isolated in seven species of small mammals. Bartonella tribocorum is the dominant species in both regions, and it has a genetic relationship with the zoonotic pathogen Bartonella elizabethae. This study showed the prevalence of Bartonella in small mammals from Mile City and Lianghe County of Yunnan Province was high, and there were more types of Bartonella infection species. The spleen was more conducive to the growth and reproduction of Bartonella. The results of the study will help to prevent and control Bartonella infection and transmission to humans from small mammals in the two regions and provide a reference basis for further research on Bartonella infection in Yunnan or other similar regions.

Bartonella, a facultative intracellular pathogen, is known for causing zoonotic diseases and has been detected in a variety of mammals and arthropods. Previous research has highlighted bats as natural reservoirs for Bartonella, with bat ectoparasites acting as vectors for transmission. Moreover, studies have indicated a positive correlation between the prevalence of ectoparasites and Bartonella infection levels. However, research on Bartonella carried by bats and their ectoparasites in China is limited. In this study, we captured bats at three sites in Yunnan Province, China, and collected their ectoparasites. Using conventional PCR, we screened for Bartonella by targeting three gene fragments: the RNA polymerase subunit gene (rpoB), citrate synthase (gltA), and cell division protein (ftsZ). Further phylogenetic and genetic distance analyses indicated the presence of identical Bartonella strains in bats and their ectoparasitic mites, suggesting the high risk of bat hosts and the potential of their ectoparasites as vectors for pathogen transmission. Despite this, the mechanisms underlying the maintenance and transmission of Bartonella within bat and ectoparasite populations, as well as the process of spillover to humans, remain poorly understood. This underscores the need for further in-depth experimental studies on mammals and their ectoparasites.

Introduction: Cat Scratch Disease (CSD), caused by Bartonella henselae, is the most common Bartonella infection in humans, typically presenting as self-limiting regional lymphadenopathy following a cat scratch or bite. Case Presentation: A 10-year-old child developed an atypical form of CSD, characterized by significant elbow swelling and abscess formation. Diagnosis was confirmed through imaging and PCR testing. The case required surgical drainage and antibiotic therapy, highlighting the variability in CSD presentation. Discussion: CSD is primarily transmitted through household cats, with higher incidence in children and seasonal peaks in fall and winter. While most cases resolve without intervention, severe forms may involve systemic or visceral complications. Diagnosis relies on clinical evaluation, serology, and PCR. Imaging techniques such as ultrasound and MRI are essential for identifying atypical presentations. Conclusion: CSD can manifest beyond typical lymphadenopathy, necessitating early recognition and appropriate management. In pediatric patients with suspected hepatosplenic involvement, abdominal ultrasound is recommended. Though often self-limiting, severe cases may require prolonged antibiotic therapy and surgical intervention.

Molecular detection and diversity of Bartonella spp. in non-hematophagous bats from the Peruvian Amazon.