This study reports a severe outbreak caused by Streptococcus equi subspecies zooepidemicus (SEZ), an emerging zoonotic pathogen rarely associated with human disease, which occurred in central Italy between November 2021 and May 2022.
A total of 37 human cases were identified in the province of Pescara, with clinical manifestations ranging from mild symptoms to severe conditions such as septicemia, endocarditis and meningitis. Notably, five patients died, highlighting the potential severity of this pathogen.
SEZ is primarily an animal pathogen, commonly found in horses and livestock, but it can occasionally infect humans through direct contact with infected animals or, more frequently, through the consumption of unpasteurized dairy products.
What makes this outbreak particularly relevant is the rapid and effective response enabled by an interdisciplinary One Health approach. A coordinated task force combining physicians, veterinarians, epidemiologists and microbiologists worked together to investigate the outbreak.
By combining epidemiological data with advanced molecular techniques, including whole-genome sequencing, researchers demonstrated that all human cases were linked to a single bacterial strain. This finding allowed them to trace the source of infection to contaminated unpasteurized milk from a cow affected by mastitis, as well as to dairy products from the same producer.
Rapid identification of the source enabled public health authorities to implement control measures, including product recalls and mandatory milk pasteurization, successfully preventing further spread of the infection.
This outbreak underscores the importance of food safety, especially regarding raw milk consumption, and highlights the need for increased awareness about the risks associated with the consumption of unpasteurized dairy products. It also emphasizes the value of genomic surveillance and interdisciplinary collaboration in managing emerging infectious disease outbreaks.
Suggestest by our guest Dr. Paolo Fazii