Determination and Characterization of (Novel) Circulating Strains of Brucella sp. Within the National Bovine Brucellosis Control Program in Ecuador

Brucellosis is a zoonotic disease caused by bacteria of the <i>Brucella</i> species. This infectious disease represents a significant public health and economic challenge in many regions of the world, including Ecuador. <i>Brucella abortus</i> is the most common species in cattle. Transmission mainly occurs through direct contact with secretions, aborted fetuses, or contaminated reproductive fluids. In this study, to evaluate the circulating strains of <i>Brucella</i> in continental Ecuador, <i>Brucella</i> strains were cultured and isolated from retromammary lymph nodes and milk samples collected over the past three years from six Ecuadorian provinces within the National Brucellosis Program of Ecuador. <i>Brucella</i> cultures were performed on two specific media, CITA and Farrell, followed by molecular identification using PCR and multiple-locus variable-number tandem repeat analysis 16 (MLVA-16) diagnostic techniques. Out of a total of 25 retromammary lymph nodes collected at slaughterhouses and 50 milk samples obtained from serologically positive animals on farms, <i>Brucella</i> was isolated from 35 milk samples and 19 retromammary lymph node samples and identified as <i>Brucella abortus</i> by PCR. Subsequent MLVA-16 genotyping enabled accurate discrimination among the <i>Brucella</i> strains present in Ecuador. This study confirmed the presence of <i>Brucella abortus</i> strains of biovars 1 and 4 and, for the first time, detected the presence of biovar 2 in Ecuador. The isolation and accurate detection of <i>Brucella</i>, along with the implementation of advanced genotyping techniques, such as MLVA, are crucial for future epidemiological studies, outbreak tracing, and the development of control strategies to mitigate animal and human infection in Ecuador.