BACKGROUND: Brucellosis is a re-emerging underdiagnosed zoonosis that has significant relevance, especially in developing countries. This study aimed to report the first cases of human brucellosis in the state of Paraíba, Brazil, and to determine the prevalence and risk factors associated with Brucella abortus infection in slaughterhouse workers. METHODS: A cross-sectional study was carried out from December 2021 to February 2022 in public and private slaughterhouses in the state of Paraíba. Blood samples were collected from 188 people and tested using the Rose Bengal Test (RBT), a screening test, and the 2-mercaptoethanol (2-ME) and standard tube agglutination test (STAT), which are confirmatory tests. Samples that tested positive were subjected to molecular analysis using qPCR. Risk factors were determined through multivariate analysis based on epidemiological questionnaires administered to the workers. After the diagnoses, results were provided to the participants, and health education campaigns were conducted for all workers in the evaluated slaughterhouses. RESULTS: The study found a serological prevalence (RBT + 2-ME + STAT) of 4.2% (16/188) (95% CI = [1.28
6.96], sensibility 90% specificity 95%)among workers. Five samples were positive in qPCR with Ct (Cycle threshold ) values ranging from 31.58 to 38.11. The ingestion of undercooked meat was identified as a risk factor, with a 2.95 times higher chance of contamination. Among the 16 individuals who tested positive in the serological tests, 15 (p<
0.0002) reported in the epidemiological questionnaire that they did not know what brucellosis is. CONCLUSION: These are the first published cases of human brucellosis in the state of Paraíba, reinforcing the hypothesis that the bacterium is circulating among slaughterhouse workers. This underscores the need to develop public policies that provide adequate medical support to the population.