Banca de QUALIFICAÇÃO: OLGA LUCIA HERRAN RAMIREZ

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : OLGA LUCIA HERRAN RAMIREZ
DATE: 28/03/2022
TIME: 13:00
LOCAL: Google Meet
TITLE:

Seroepidemiological, a molecular and spatial study of species of the Brucella genus from the northern region of Antioquia, Colombia.

KEY WORDS:

Brucellosis, cattle, PCR, molecular epidemiology

PAGES: 149
BIG AREA: Ciências Agrárias
AREA: Medicina Veterinária
SUBÁREA: Medicina Veterinária Preventiva
SPECIALTY: Epidemiologia Animal
SUMMARY:

Brucella spp. are the etiological agents of brucellosis, an old, neglected disease, and of zoonotic importance, due to the transmissibility through the consumption of food of animal origin without cooking or pasteurization, as well as by aerosols, representing a risk to public health. In Colombia, bovine brucellosis is an endemic disease, but an unusual increase in the number of seropositive in a leading dairy region, given an alarm and caused the Colombian Institute of Agriculture (ICA) to quarantine for brucellosis in the Antioquia region. in 2018. This epidemiological study was conducted to determine the seroprevalence and molecular prevalence of bovine brucellosis in the leading dairy region of Colombia declared in quarantine for brucellosis, and to evaluate the factors associated with the presence of antibodies against Brucella spp, as well as the presence of Brucella-DNA. at the animal and the herd level. The samples were collected during the routine diagnosis of brucellosis. A total of 656 serum and whole blood samples from ≥2-year-old cows in 40 herds were used. The Rose Bengal Test was used as the screening test. Positives RBT samples were confirmed by the Fluorescence Polarization Assay and c ELISA at the National Veterinary Diagnostic Laboratory of the Colombian Agricultural Institute (ICA). Molecular detection was performed by Probe-based Real-time PCR (Probe-qPCR) assay. The assay was accomplished in 32 min using the bcsp31 gene amplification. Brucella-DNA field strains and vaccine strains were genotyped employing the SNP-based assay markers. The geoprocessing tool QGIS was used to trace the area of influence of roads about the presence of positive animals. Factors associated with the presence of Brucella-DNA were evaluated using logistic regression models. In the results obtained, it was observed that all positive herds by serology tests were also positive by the qPCR. However, not all positive herds by the qPCR were positive on the serology test. The Cohen´s Kappa test determined a weak agreement between methods. The diagnostic accuracy of the qPCR by the area under the Receiver-Operator Curve (ROC), had performance equal to 0.75 ±0.047 (95% CI: 0.65, 0.84). All positive samples were identified as field Brucella abortus strains employing the SNP-based assay. In logistic regression models, it was observed that management practices, mainly associated with reproduction, offer favorable conditions for the process of dissemination of Brucella spp. among animals and in herds. This research concluded that the introduction of molecular techniques from clinical samples collected in the field act as tools to complement the diagnosis of bovine brucellosis, improving the sensitivity and specificity of the results, when compared with serological techniques, allowing early detection of Brucella spp. circulating and. to know epidemiological factors associated with the presence of the etiological agent in the animal and not associated only with the presence of antibodies.

BANKING MEMBERS:
Interno - 3701492 - HUARRISSON AZEVEDO SANTOS
Interna - 2860277 - ISABELE DA COSTA ANGELO
Externo ao Programa - 2181418 - CLAYTON BERNARDINELLI GITTI
Externo ao Programa - 3688704 - TIAGO MARQUES DOS SANTOS
Externa à Instituição - MARIEL A. MARLOW
Externa à Instituição - MARLYN ROMERO PEÑUELA