Electrophoretic analysis of the proteins and genomic DNA of spotted fever-group Rickettsiae isolated from ticks and a human in Western Sicily show that at least two distinct subtypes other than R. conorii are present in this region. All of the spotted fever-group isolates share common features with other, well-defined spotted fever-group rickettsial species, e.g. R. sibirica, Thai Tick Typhus, and R. rickettsii. Based on these data, caution is recommended when identifying species by the more traditional and less specific tests. Studies of the ecology and epidemiology of spotted fever-group Rickettsiae in regions where R. conorii infections occur would benefit and be challenged by intensive antigenic analyses of the proteins and genomic DNA of the various strains of the spotted fever-group Rickettsiae present in those areas.
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PLoS One
January 2025
Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America.
Tick-borne spotted fever rickettsioses (SFRs) continue to cause severe illness and death in otherwise-healthy individuals due to lack of a timely and reliable diagnostic laboratory test. We recently identified a diagnostic biomarker for SFRs, the putative N-acetylmuramoyl-l-alanine amidase RC0497. Here, we developed a prototype laboratory test that targets RC0497 for diagnosis of SFRs.
View Article and Find Full Text PDFmBio
January 2025
Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, USA.
is an obligate intracellular, tick-borne bacterial pathogen that can cause eschar-associated rickettsiosis in humans. invades host cells, escapes from vacuoles into the cytosol, and undergoes two independent modes of actin-based motility mediated by effectors RickA or Sca2. Actin-based motility of enables bacteria to enter protrusions of the host cell plasma membrane that are engulfed by neighboring host cells.
View Article and Find Full Text PDFTicks Tick Borne Dis
January 2025
Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA USA. Electronic address:
Rickettsiae are a family of ectoparasite-borne bacteria that can produce high morbidity and mortality among humans. There are scarce data on rickettsial ecology in rural areas of the Peruvian Amazon basin, where seroprevalence has not been determined, and the identities of animals acting as reservoirs of these bacteria are not known. We conducted a cross-sectional study in Zungarococha (between 2019 and 2021), a rural community located approximately 20 km away from Iquitos city.
View Article and Find Full Text PDFPathogens
December 2024
Centro di Referenza Nazionale per Anaplasma, Babesia Rickettsia, e Theileria (C.R.A.Ba.R.T.), Istituto Zooprofilattico Sperimentale della Sicilia "A. Mirri", 90129 Palermo, Italy.
Vector-borne diseases represent a serious threat to human and animal health, especially where environmental conditions favor pathogen-carrying vectors. Dogs serve as natural hosts for two tick-borne pathogens: , which causes canine monocytic ehrlichiosis, and spotted fever group (SFG) spp., a zoonotic threat in the Mediterranean region.
View Article and Find Full Text PDFActa Trop
January 2025
Professor, Department of Paediatrics, All India Institute of Medical Sciences [AIIMS], Bhubaneswar 751019, Odisha, India. Electronic address:
Spotted fever group Rickettsia (SFGR) infections remain largely under-investigated as causative agents of acute undifferentiated febrile illness (AUFI) in resource-limited settings. Few studies are available on the prevalence of SFGR infections in India, especially in eastern India. In a cross-sectional study conducted in 192 hospitalized adult and paediatric patients with AUFI, the frequency of SFGR using sequential PCR targeting genes encoding citrate synthase (gltA), 17 kDa lipoprotein precursor antigen (17kDa), outer membrane proteins A and B (omp A & omp B) was 6.
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