CLINICAL-EPIDEMIOLOGICAL REPORT OF A BOVINE VACCINIA OUTBREAK AFFECTING HUMANS AND CATTLE IN EASTERN MINAS GERAIS, 2020–2021

Bovine vaccinia (BV) is an emerging viral zoonosis caused by vaccinia virus (VACV), with outbreaks recorded in Brazil since 1999, especially in rural areas associated with dairy cattle and milkers. It is considered a neglected disease of great sanitary importance and significant economic and social impact, yet remains underdiagnosed despite recurrent outbreaks in Brazil, particularly in Minas Gerais. This study reports a BV outbreak that occurred between 2020 and 2021 in the municipality of Joanésia, eastern Minas Gerais, involving humans and cattle. An exploratory, observational study was conducted with retrospective analysis of clinical and laboratory data, combined with an epidemiological investigation using interviews, notification forms, and medical records. Clinical samples were sent to the Virus Laboratory of Universidade Federal de Minas Gerais for molecular (PCR) and serological (PRNT) diagnosis. The index case was a 41-year-old male rural worker with multiple painful exanthematic lesions, fever, lymphadenopathy, and asthenia. He reported manual milking of cows with vesicular lesions on the teats. Subsequent investigation identified neighboring individuals with similar symptoms, triggering suspicion of BV and activation of epidemiological surveillance. Epidemiological tracing identified ten suspected human cases ‒ all male milkers, mean age 36 years (range 16–72) ‒ and ten cows with suggestive lesions. Among humans, lesion crusts from two individuals tested PCR-positive, and seven of the remaining patients had neutralizing antibodies against orthopoxviruses. All cattle tested serologically positive. This outbreak in Joanésia was notable for presenting the highest number of confirmed infected individuals (humans and cattle) in a single event recorded in Minas Gerais since 2000. This episode underscores the importance of high clinical suspicion and integration between human and animal health surveillance to contain BV spread, reduce public health impact, and mitigate economic losses for small rural producers. The epidemiological investigation was limited by restrictions imposed during the COVID-19 pandemic.