Major Etiological Agents Isolated from Neonatal Calf Diarrhea Outbreaks in Northern Italy.

Neonatal calf diarrhea (NCD) represents a major cause of economic loss in dairy cattle herds worldwide. The condition is primarily associated with several key pathogens, including enterotoxigenic Escherichia coli (ETEC), viral agents such as bovine rotavirus (BRV) and bovine coronavirus (BCoV), and the protozoan Cryptosporidium parvum. This study aimed to assess the prevalence of NCD-associated pathogens in Italian dairy farms over the period 2020-2022. Among the 598 farms affected by NCD and included in the investigation, ETEC strains were detected in 17.2% of cases. The prevalence of BRV, BCoV, and Cryptosporidium spp. was 22.2%, 20.2%, and 32.3%, respectively. Co-infections were also frequently observed and are considered to significantly exacerbate the clinical severity of the disease. Ongoing surveillance of NCD pathogens is essential to generate reliable and updated epidemiological data, which are critical for guiding effective control and prevention strategies.