Bovine brucellosis is a worldwide zoonotic contagious disease. According to World Animal Health Information System reports Ecuador has presented an increasing number of bovine brucellosis outbreaks in the continental territory over the past years (756 in 2018 versus 964 in 2021), generating economic losses for producers and causing a risk to public health. A cross-sectional study was conducted to investigate the seroprevalence of bovine brucellosis and associated risk or protective factors between May and June 2018. This stratified random study was implemented in 290 cattle herds located in the 23 provinces of continental Ecuador, which represents a total of 3737 cows aged 24 months or older. A competitive ELISA was used to detect Brucella antibodies. Simultaneously, an epidemiological survey was implemented to assess the brucellosis risk or protective factors. The apparent prevalence of bovine brucellosis at the herd level was 21.3% (95% CI: 16.8–26.6) and 6.2% (95% CI: 5.5–7) at the animal level. Univariate and multivariate logistic regression analyses were performed to determine the relationship between the potential factors associated with the presence of bovine brucellosis. The risk factors identified after multivariate analysis were a surface in ha per herd > 70 ha (OR = 2.73; 95% CI: 1.18–6.32) and the number of parturitions per animal (two or more with OR ≥ 1.8 and p-value ≤ 0.047). On the contrary, the protective factors were the region (farms located in the eastern region) and the absence of reported clinical signs. In addition, in herds where extensive production predominates, farmers have a low level of knowledge, and the farm biosecurity level is low. These results can guide the authorities in managing the risk factors identified, understanding the current epidemiological situation in Ecuador, improving the bovine brucellosis control program and food safety, as well as increase the one-health approach.

Brucellosis is a zoonotic disease caused by bacteria of the Brucella species. This infectious disease represents a significant public health and economic challenge in many regions of the world, including Ecuador. Brucella abortus 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 Brucella in continental Ecuador, Brucella 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. Brucella 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, Brucella was isolated from 35 milk samples and 19 retromammary lymph node samples and identified as Brucella abortus by PCR. Subsequent MLVA-16 genotyping enabled accurate discrimination among the Brucella strains present in Ecuador. This study confirmed the presence of Brucella abortus 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 Brucella, 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.

Bovine brucellosis (bB) is a zoonosis mainly caused by the Brucella abortus species in cattle. Bovine brucellosis can present with either a range of clinical symptoms, including spontaneous abortions in the last trimester of pregnancy, retained fetal membranes, and decreased milk production, or it can be asymptomatic. In Ecuador, vaccination against bB with S19 and/or RB51 is not mandatory and is the responsibility of the farmer. As serology is a convenient method for detecting antibodies against Brucella, evaluating the diagnostic performance and discriminative ability of such tests in various epidemiological settings is required. To estimate and compare the diagnostic sensitivity (Se) and specificity (Sp) of two screening tests, a new competitive (cELISA) and an indirect ELISA based on a new synthetic antigen (iELISA), a randomized, stratified, cross-sectional, serological survey was performed on the cattle population (3299 bovine sera from 223 farms) in continental Ecuador. A Bayesian approach was used to evaluate the two tests by estimating their respective diagnostic Se and Sp, as well as the true prevalence of bB in different sub-populations (non-vaccinated, vaccinated with S19 or RB51). The Se of both tests was similar across Bayesian models, with values around 94%. In contrast, the Sp of the iELISA, ranging between 97 and 98%, was significantly higher than that of the cELISA, which was approximately 94–95%. The true prevalence of bB was 1.63% (95% CrI: 0.56–2.54) in non-vaccinated cattle, decreased to 0.97% (95% CrI: 0.005–2.54) in S19-vaccinated cattle and was 2.75% (95% CrI: 0.50–5.32) in RB51-vaccinated cattle. The results of this study suggest that, with similar Se and higher Sp, the iELISA based on an innovative synthetic antigen (which is more standardizable) should be recommended as a possible screening test for bB in Ecuador. Also, the proposed approach suggests insights into the quality of the vaccination campaign and highlights the need for refining the Ecuadorian national brucellosis control program.