Publications by authors named "Elkin Forero-Becerra"

6 Publications

  • Page 1 of 1

Experimental infection and vector competence of Amblyomma patinoi, a member of the Amblyomma cajennense species complex, for the human pathogen Rickettsia rickettsii.

Ticks Tick Borne Dis 2021 May 29;12(5):101751. Epub 2021 May 29.

Departamento de Medicina Veterinária Preventiva e Saúde Animal, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo-USP, Av. Prof. Orlando Marques de Paiva, 87, São Paulo, SP 05508-270, Brazil. Electronic address:

Amblyomma patinoi ticks infected with Rickettsia rickettsii are present in Colombia, but its vector competence is unknown. Hence, we evaluated the vector competence of A. patinoi with R. rickettsii under laboratory conditions. Experimental guinea pigs and rabbits (males and females) were separated in the infected group (IG) and the control group (CG). In the IG, the filial 1 (F1) larvae (R. rickettsii-free) from Colombian A. patinoi engorged female specimens were exposed to R. rickettsii (ITU strain) by feeding on infected guinea pigs. Next, F1 nymphs and adults, and F2 larvae were allowed to feed on uninfected guinea pigs or rabbits and tested by qPCR targeting the gltA rickettsial gene. All animals used to feed the IG F1 ticks became febrile and had R. rickettsii infection (89% fatality rate) detected through serological or molecular techniques. After the F1 larvae ticks became R. rickettsii infected, subsequent IG tick stages were able to maintain the rickettsial infection by transstadial maintenance to all infested animals, indicating A. patinoi vector competence. Subsequently, almost 31% of the F1 female egg masses and only 42% of their F2 larvae were infected. Less than 50% of the infected females transmitted R. rickettsii transovarially, and only a part of the offspring were infected. This study demonstrated that A. patinoi might not be able to sustain R. rickettsii infection by transovarial transmission for successive tick generations without horizontal transmission via rickettsemic hosts. This condition might result in low R. rickettsii-infection rates of A. patinoi under natural conditions.
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http://dx.doi.org/10.1016/j.ttbdis.2021.101751DOI Listing
May 2021

Seroprevalence and Genotypic Analysis of Ehrlichia canis Infection in Dogs and Humans in Cauca, Colombia.

Am J Trop Med Hyg 2021 Mar 22. Epub 2021 Mar 22.

2Department of Pathology, University of Texas Medical Branch at Galveston, Galveston, Texas.

Ehrlichia canis infections have been reported in humans in Venezuela and Costa Rica. In this study, 506 healthy residents and 114 dogs from four municipalities (Cauca, Colombia) were surveyed and blood samples collected. Antibodies to E. canis in human and canine sera were evaluated using the Tandem repeat protein 19 (TRP19) peptide ELISA and indirect immunofluorescence assay (IFA). Ehrlichia canis TRP19 antibodies were detected in only 1/506 human sera, but the single positive sample was negative by IFA. The majority (75/114; 66%) of dogs surveyed had antibodies to the E. canis TRP19 peptide by ELISA, and eight randomly selected sera were further confirmed by E. canis IFA. Genomic DNA samples obtained from 73 E. canis TRP19 ELISA-positive dog blood samples were examined by PCR targeting the 16S rRNA gene. Ehrlichia canis 16S rRNA was amplified in 30 (41%) of the dogs, and 16 amplicons were selected for DNA sequencing, which confirmed that all were E. canis. A second PCR was performed on the 16 confirmed E. canis 16S rRNA PCR-positive samples to determine the TRP36 genotype by amplifying the trp36 gene. TRP36 PCR amplicon sequencing identified nine dogs infected with the U.S. E. canis TRP36 genotype (56%), one dog with the Brazilian genotype (6%), and six dogs with the Costa Rican genotype (38%). Moreover, these molecular genotype signatures were consistent with serologic analysis using TRP36 genotype-specific peptides. Notably, there was no serologic evidence of E. canis infection in humans, suggesting that E. canis infection in dogs in Cauca is not associated with zoonotic human infection.
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http://dx.doi.org/10.4269/ajtmh.20-0965DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8103471PMC
March 2021

Epidemiology of Spotted Fever Group Rickettsioses and Acute Undifferentiated Febrile Illness in Villeta, Colombia.

Am J Trop Med Hyg 2017 Sep 19;97(3):782-788. Epub 2017 Jul 19.

Grupo de Enfermedades Infecciosas, Departamento de Microbiología, Pontificia Universidad Javeriana, Bogotá, Colombia.

Etiology of acute undifferentiated febrile syndrome (AUFS) is often unknown, leading to inaccurate diagnosis and treatment. Villeta town has been identified as an endemic area for spotted fever group (SFG) rickettsioses but little is known about possible amplifier hosts and other species different from . Besides, few studies have approached other AUFS etiologies in the region. We investigated the role of dengue, leptospirosis, rickettsioses, human anaplasmosis, and Q fever as possible causes of AUFS in patients from Villeta. Sera specimens and ticks from animals as well as ticks from vegetation were studied for the presence of different spp. Among 104 sera from patients with AUFS, 16.4%, 24.0%, and 2.9% patients seroconverted to dengue, , and SFG , respectively, with a case of probable coinfection or cross-reaction with . None of the samples were reactive for . Sera samples from 74 horses, 118 dogs, and 62 bovines were collected and showed 33.8%, 14.4%, and 50.0% of seroprevalence for SFG , respectively. A total of 1,287 ixodid ticks were collected from animals/vegetation and processed in pools for polymerase chain reaction. Among them, 1.7% was positive for genes, and , , and spp. were found. These results confirm the circulation of dengue, different SFG species and the relevance of other etiologies like leptospirosis and human anaplasmosis. Further studies must identify different epidemiological variables to establish proper surveillance and control programs.
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http://dx.doi.org/10.4269/ajtmh.16-0442DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5590559PMC
September 2017

Identification of a T-Cell Epitope That Is Globally Conserved among Outer Membrane Proteins (OMPs) OMP7, OMP8, and OMP9 of Anaplasma marginale Strains and with OMP7 from the A. marginale subsp. centrale Vaccine Strain.

Clin Vaccine Immunol 2017 Jan 5;24(1). Epub 2017 Jan 5.

Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, Washington, USA

Within the protective outer membrane (OM) fraction of Anaplasma marginale, several vaccine candidates have emerged, including a family of OM proteins (OMPs) 7 to 9, which share sequence identity with each other and with the single protein OMP7 in the vaccine strain A. marginale subsp. centrale. A. marginale OMPs 7 to 9 are logical vaccine candidates because they are surface exposed, present in the OM immunogen and protective cross-linked OM proteins, recognized by immune serum IgG2 and T cells in cattle immunized with OM, and recognized by immune serum IgG2 from cattle immunized with the A. centrale vaccine strain. We report the identification of a globally conserved 9-amino-acid T-cell epitope FLLVDDAI/VV shared between A. centrale vaccine strain OMP7 and the related A. marginale OMPs 7 to 9, where position 8 of the peptide can be isoleucine or valine. The epitope is conserved in American A. marginale strains, in the Australia Gypsy Plains strain, and in multiple field isolates from Ghana. This epitope, together with additional T-cell epitopes that are present within these proteins, should be considered for inclusion in a multivalent vaccine for A. marginale that can provide protection against disease caused by globally distributed bacterial strains.
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http://dx.doi.org/10.1128/CVI.00406-16DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5216429PMC
January 2017

Molecular Evidence of Different Rickettsia Species in Villeta, Colombia.

Vector Borne Zoonotic Dis 2016 Feb 20;16(2):85-7. Epub 2016 Jan 20.

1 Microbiology Department, Faculty of Sciences, Pontificia Universidad Javeriana , Bogotá, Colombia .

The aim of this work was to detect and identify Rickettsia species in ticks collected in rural areas of Villeta, Colombia. Tick specimens were collected from domestic animals and walls of houses in five rural villages of Villeta town and from humans in Naranjal village (same town). Moreover, a flea collected from the same area was also processed. DNA was extracted and tested by conventional, semi-nested, and nested PCR reactions targeting rickettsial genes. In the ticks collected from humans from Naranjal village, a nymph of Amblyomma cajennense sensu lato was amplified using primers for ompA and sequenced (100% identity with "Candidatus Rickettsia amblyommii"). Last, three amplicons from the Ctenocephalides felis flea, corresponding to gltA, ompB, and 16S rRNA genes, showed high identity with R. felis (98.5%, 97.3%, and 99.2%, respectively) and "Candidatus Rickettsia asemboensis" (99.7% and 100%, respectively). To our knowledge, these results correspond to the first molecular detection in Colombia of "Candidatus Rickettsia amblyommii" and "Ca. Rickettsia asemboensis" in fleas.
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http://dx.doi.org/10.1089/vbz.2015.1841DOI Listing
February 2016

[Probable case of flea-borne spotted fever (Rickettsia felis)].

Biomedica 2013 Sep;33 Suppl 1:9-13

Grupo de Enfermedades Infecciosas, Departamento de Microbiología, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá, D.C, Colombia.

Rickettsia felis is the etiologic agent of flea-borne spotted fever, with Ctenocephalides felis as its main vector and reservoir. Typically, the disease presents as acute fever associated with headache, asthenia, generalized maculo-papular rash, and in some cases, an inoculation eschar. In recent years, R. felis has acquired an important role in the etiology of the acute febrile syndrome; it is indeed an emerging infectious disease, albeit underdiagnosed. Indirect immunofluorescence assay (IFA) is currently the reference diagnostic method. However, this technique has limitations related to the cross reactivity among different species of rickettsiae. Herein, we describe a case of a 16 year-old patient with an acute febrile syndrome secondary to probable infection with R. felis.
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September 2013