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We report an unexpected case of Bartonella quintana endocarditis and pauci-immune glomerulonephritis in a patient without known risk factors in Los Angeles, California, USA, highlighting that infection can occur in the general population without a history of homelessness. The diagnosis was challenging and made definitively through extensive diagnostic tests and multidisciplinary investigation.

Bartonella quintana infection can cause severe disease that includes clinical manifestations such as endocarditis, chronic bacteremia, and vasoproliferative lesions of the skin and viscera. B. quintana bacteria is transmitted by the human body louse (Pediculus humanus corporis) and is associated with homelessness and limited access to hygienic services. We report B. quintana infection in 2 kidney transplant recipients in the United States from an organ donor who was experiencing homelessness. One infection manifested atypically, and the other was minimally symptomatic; with rapid detection, both recipients received timely treatment and recovered. B. quintana was identified retrospectively in an archived donor hematoma specimen, confirming the transmission link. Information about the organ donor's housing status was critical to this investigation. Evaluation for B. quintana infection should be considered for solid organ transplant recipients who receive organs from donors with a history of homelessness or of body lice infestation.

In a US survey of infectious disease specialists, 61 respondents reported seeing >1 Bartonella quintana infection during 2014-2024. Diagnostic challenges included limited healthcare provider awareness, inadequate testing, and inconsistent healthcare access among affected populations. Early recognition of B. quintana infections is needed to improve outcomes among affected populations.

Bartonella quintana infection can lead to bacillary angiomatosis, peliosis hepatis, chronic bacteremia, and culture-negative endocarditis. Transmitted by the human body louse (Pediculus humanus humanus), B. quintana infection has become an emerging disease in recent decades among persons experiencing homelessness. By using retrospective laboratory surveillance, we identified 5 cases of left-sided, culture-negative B. quintana endocarditis among persons in New York, New York, USA, during January 1, 2020-November 23, 2023. Identifications were made by using molecular assays. All patients experienced unsheltered homelessness in the year before hospitalization. Of those patients, 4 experienced heart failure, 3 renal failure, and 2 embolic strokes; 2 died. Aortic valve replacement occurred in 4 cases. A history of possible body louse infestation was found in 4 cases. Clinicians should consider housing status and history of lice exposure in patients with suspected bartonellosis and have a low threshold for diagnostic testing and empiric treatment in patients experiencing homelessness.

Background Bartonella quintana is a body louse-borne bacterium causing bacteremia and infective endocarditis. We aimed to describe B. quintana detection among arthropods and their hosts. Methods We searched databases in PubMed Central/MEDLINE, Scopus, Embase, and Web of Science from January 1, 1915 (the year of B. quintana discovery) to January 1, 2024, to identify publications containing specific search terms relating to B. quintana detection among arthropods. Descriptive statistics and meta-analysis of pooled prevalence using random-effects models were performed for all arthropods and body and head lice. Results Of 1265 records, 62 articles were included, describing 8839 body lice, 4962 head lice, and 1692 other arthropods, such as different species of fleas, bedbugs, mites, and ticks. Arthropods were collected from 37 countries, of which 28 had arthropods with B. quintana DNA. Among articles that reported B. quintana detection among individual arthropods, 1445 of 14,088 (0.1026, 95% CI [0.0976; 0.1077]) arthropods tested positive for B. quintana DNA, generating a random-effects model global prevalence of 0.0666 (95% CI [0.0426; 0.1026]). Fifty-six studies tested 8839 body lice, of which 1679 had B. quintana DNA (0.1899, 95% CI [0.1818; 0.1983]), generating a random-effects model pooled prevalence of 0.2312 (95% CI [0.1784; 0.2843]). Forty-two studies tested 4962 head lice, of which 390 head lice from 20 studies originating from 11 different countries had B. quintana DNA (0.0786, 95% CI [0.0713; 0.0864]). Eight studies detected B. quintana DNA exclusively on head lice. Five studies reported greater B. quintana detection on head lice than body lice; all originated from low-resource environments. Conclusions Bartonella quintana is a vector-borne bacterium with a global distribution, disproportionately affecting marginalized populations. Bartonella quintana DNA has been detected in many different arthropod species, though not all of these arthropods meet criteria to be considered vectors for B. quintana transmission. Body lice have long been known to transmit B. quintana . A limited number of studies suggest that head lice may also act as possible vectors for B. quintana in specific low-resource contexts. Graphical Abstract

During the two World Wars, Bartonella quintana was responsible for trench fever and is now recognised as an agent of re-emerging infection. Many reports have indicated widespread B. quintana exposure since the 1990s. In order to evaluate its prevalence in ancient populations, we used real-time PCR to detect B. quintana DNA in 400 teeth collected from 145 individuals dating from the 1st to 19th centuries in nine archaeological sites, with the presence of negative controls. Fisher's exact test was used to compare the prevalence of B. quintana in civil and military populations. B. quintana DNA was confirmed in a total of 28/145 (19.3%) individuals, comprising 78 citizens and 67 soldiers, 20.1% and 17.9% of which were positive for B. quintana bacteraemia, respectively. This study analysed previous studies on these ancient samples and showed that the presence of B. quintana infection followed the course of time in human history; a total of 14/15 sites from five European countries had a positive prevalence. The positive rate in soldiers was higher than those of civilians, with 20% and 18.8%, respectively, in the 18th and 19th centuries, but the difference in frequency was not significant. These results confirmed the role of dental pulp in diagnosing B. quintana bacteraemia in ancient populations and showed the incidence of B. quintana in both civilians and soldiers.

Blood culture-negative endocarditis (BCNE) is a challenging disease because of the significant impact of delayed diagnosis on patients. In this study, excised heart valves and blood serum samples were collected from 50 BCNE patients in two central hospitals in Tehran, Iran. Sera were tested by IFA for the presence of IgG and IgM antibodies against Bartonella quintana and B. henselae . Genomic DNA extracted from the heart valves was examined for Bartonella -specific ssrA gene in a probe-based method real-time PCR assay. Any positive sample was Sanger sequenced. IgG titer higher than 1024 was observed in only one patient and all 50 patients tested negative for Bartonella IgM. By real-time PCR, the ssrA gene was detected in the valve of one patient which was further confirmed to be B. quintana . Bartonella -like structures were observed in transmission electron microscopy images of that patient. We present for the first time the involvement of Bartonella in BCNE in Iran. Future research on at-risk populations, as well as domestic and wild mammals as potential reservoirs, is recommended.

Background:Bartonella quintana is a body-louse-borne bacterium. Canadian B. quintana disease has been reported primarily in populations experiencing homelessness and in Indigenous communities with limited access to water. We sought to understand the epidemiology of B. quintana in Canada. Methods: This study combined an analysis of laboratory data from Canada’s National Microbiology Laboratory (NML) with a systematic review of the literature. Laboratory data included quantitative polymerase chain reaction (qPCR) cycle threshold values and indirect immunofluorescent antibody titers with the year and province of the sample acquisition. For the systematic review, we searched PubMed, Scopus, Embase, and Web of Science for articles published before 15 July 2024, with terms related to B. quintana in Canada. Results: Thirty-three individuals with qPCR-positive B. quintana were documented in seven provinces and one territory. The number of cases increased over time (p-value = 0.005), with the greatest number of cases being reported in 2022 and 2023. The percent positivity for the B. quintana qPCR performed at the NML increased over time (p-value = 0.036). The median immunoglobulin G titer demonstrated a sustained increase starting in 2017. The systematic review identified fourteen individuals with qPCR-positive B. quintana (none had a qPCR performed at the NML) and seven probable cases of B. quintana disease. Four of these twenty-one individuals from the systematic review died (19%). All fatalities were attributed to endocarditis. Conclusions: The detection of B. quintana disease in seven provinces and one territory suggests that B. quintana has a national distribution. B. quintana disease is increasingly diagnosed in Canada, indicating ongoing transmission across geographic settings.

Background Because of poor sensitivity and questionable specificity of immunofluorescent antibody assays (IFAs), serological diagnosis of Bartonella species infections in dogs remains challenging. Despite limitations, IFA testing is the historical “gold standard” for Bartonella serodiagnosis in animals and humans. Because most diagnostic laboratories test against only 1 or 2 Bartonella spp., testing against a broader panel of Bartonella antigens may enhance diagnostic sensitivity and specificity. Objective To evaluate the sensitivity and specificity of Bartonella IFA using 8 cell culture‐grown Bartonella spp. isolates. Animals Archived serum samples from 34 Bartonella spp. naturally exposed, polymerase chain reaction (PCR)‐positive dogs and from 26 PCR‐negative and IFA‐negative dogs. Methods Bartonella IFA sensitivity and specificity were assessed using cell culture‐grown whole cell antigens derived from 3 Bartonella henselae (Bh) strains (Bh Houston 1, Bh San Antonio Type 2, Bh California 1), 3 Bartonella vinsonii subsp. berkhoffii genotypes (Bvb I, II, and III), Bartonella koehlerae (Bk), and Bartonella quintana (Bq). Results Only 62% of 34 Bartonella spp. PCR‐positive dogs were seroreactive to any of the 8 Bartonella IFA antigens, indicating low IFA sensitivity. PCR‐positive dogs were most often IFA seroreactive to Bq (n = 15), to Bvb II (n = 13), or to both (n = 9) antigens. Of the 26 previously IFA‐negative/PCR‐negative dogs, 4 (15%) were seroreactive using the expanded antigen panel. Conclusion and Clinical Importance Despite IFA testing of dogs against 8 different Bartonella isolates, IFA sensitivity remained poor, and specificity was only 85%. Development of a reliable serological assay is needed to facilitate the diagnosis of Bartonella infection in dogs.

PurposeTo evaluate the clinical manifestations of intraocular inflammation associated with Bartonella infection and describe the assessment and management of patients with cat-scratch disease (CSD).MethodsThis is a retrospective review of the clinical records of patients diagnosed with Bartonella henselae and Bartonella quintana intraocular inflammation from 2011 to 2018 in the Department of Ocular Inflammations and Infections of the University Eye Clinic of Ioannina (Greece). An analysis of the current literature concerning Bartonella-related intraocular infections was also carried out.ResultsThis is a retrospective study of 13 patients (7 males and 6 females) with a mean age of 39.2 years that were diagnosed with unilateral intraocular inflammation, except one case with bilateral affection, attributed to Bartonella (either henselae or quintana). Twelve (12) patients (92.3%) had a positive history of traumatic cat contact. The main ocular clinical findings with regard to the type of uveitis included neuroretinitis in 5 eyes (38.5%), vasculitis in 3 eyes (23.1%), iridocyclitis in 2 eyes (15.4%), intermediate uveitis in 2 eyes (15.4%), posterior uveitis in 1 eye (7.7%), panuveitis in 2 eyes (15.4%), retinochoroiditis in 2 eyes (15.4%), vitritis in 1 eye (7.7%), peripheral choroidal granuloma in 1 eye (7.7%). Immunoglobulin (Ig) G was positive in all cases. All patients were treated with antibiotics (mainly rifampicin, doxycycline and azithromycin). The visual acuity was noted to be improved in all patients after treatment, but some of them experienced disturbing complications.ConclusionCSD may manifest with various ocular pathological findings. Taking into consideration the increasing frequency of infections by B. henselae and B. quintana, clinicians should always incorporate CSD in the differential diagnosis of such presentations of uveitis. Educating vulnerable groups (children, immunosuppressed, etc.) and also general population, the appropriate preventing measures can contribute in limiting the risk of infection.