Investigation of neglected bacterial pathogens provides molecular and serological evidence of Bartonella spp. in patients with acute undifferentiated febrile illness in Villeta, Colombia

Background: 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. Methods: 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. Results: 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. Conclusions: 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.