Banca de DEFESA: OLGA LUCIA HERRAN RAMIREZ

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : OLGA LUCIA HERRAN RAMIREZ
DATE: 18/04/2022
TIME: 13:00
LOCAL: https://meet.google.com/hfx-ckhw-qep
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:

In Colombia, bovine brucellosis is an endemic disease, but an unusual increase in the number of seropositive cases in a leading dairy region, given raised an alarm and caused the Colombian Institute of Agriculture 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 that was declared quarantined 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. A cross-sectional epidemiological study was carried out, using an epidemiological questionnaire, conducted by previously trained interviewers, with epidemiological information to identify factors associated with the presence of bovine brucellosis in the study region. A total of 656 serum and whole blood samples from ≥2-year-old cows in 40 herds were used screened The Rose Bengal Test (RBT) was used as the screening test. Positives RBT samples were confirmed by the Fluorescence Polarization Assay (FPA) 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, using the bcsp31 gene amplification. Brucella-DNA field strains and vaccine strains were genotyped employing the Single Nucleotide Polimorphism (SNP). The geoprocessing tool QGIS was used to obtain the georeferencing of positive herds. Factors associated with the presence of Brucella-DNA were evaluated using logistic regression models. The qPCR assay detected 9.5% (n=62/656; 95% CI: 7.3, 12.0) of the animals with Brucella-DNA presence, while the serological test detected a 6.6% (n=43/656; CI: 4.8, 8.7). 62.5% (n=25/40; 95% CI: 45.8, 77.3) of positive cases were detected at the herd-level by the qPCR, while only 27.5% (n=11/40; 95% CI: 14.6, 43.9) were detected by the serological test. The Cohen´s Kappa test determined a weak agreement between methods. The qPCR assay was accomplished in 32 min and had an efficiency of 92.35%. 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). 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. 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, presence of wild species and the proximity of herds to the roads, 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.  Molecular techniques also provide an improvement in the confidence of the results, when compared with serological techniques, and also allow for early detection of Brucella spp. circulating in the animal. The serological and molecular prevalence were in accordance with the declaration of quarantine in the region, with the molecular prevalence being much higher. Lastly, molecular techniques allow the researcher to recognize epidemiological factors associated with the presence of the etiological agent in the animal and not associated only with the presence of antibodies, making it possible to direct prevention and control actions adjusted at the local level and detected from difficult-to-diagnose infection phases, such as initial or chronic ones.

BANKING MEMBERS:
Presidente - 2860277 - ISABELE DA COSTA ANGELO
Interno - 2545823 - WAGNER DE SOUZA TASSINARI
Externo ao Programa - 3688704 - TIAGO MARQUES DOS SANTOS
Externo ao Programa - 2181418 - CLAYTON BERNARDINELLI GITTI
Externa à Instituição - MARLYN ROMERO PEÑUELA
Externa à Instituição - MARIEL ASBURY MARLOW
Externa à Instituição - NATHALIE COSTA DA CUNHA