Mycoplasma bovis is increasingly recognized worldwide as an important cause of disease with major welfare and production impairments on cattle rearing. Although it was detected in veal calves and beef cattle, little is known on the infection impact and on its temporal morbidity pattern in Italian dairy herds. Thus, this study aimed to investigate the involvement of M. bovis on fatal calf pneumonia outbreaks that occurred during 2009-2019 in 64 Italian dairy farms. Furthermore, a deeper diagnostic workup of concurrent infection with other viral and bacterial respiratory pathogens was assessed. Out of the investigated fatal pneumonia cases, M. bovis was frequently detected (animal prevalence, 16.16%; 95%CI, 11.82-21.33; herd prevalence, 26.56; 95%CI, 16.29-39.08) either as the single agent of the disease in more than half of the positive samples (20/37) or in concurrent infections with Histophilus somni (9/37, 24.3%), Mannheimia haemolytica (6/37, 16.621%), Trueperella pyogenes (1/37, 2.70%), Pasteurella multocida (1/37, 2.70%), bovine respiratory syncytial virus (5/37, 13.51%), and bovine viral diarrhea virus (2/37, 5.55%). Based on time-series analysis, M. bovis was recorded in the area since 2009 with outbreaks displaying a clear morbidity seasonal pattern with peaks in April (43.21%) and in September (13.51%). This might be due to the stressing conditions during spring and late summer periods. Results of this study highlight that M. bovis infection warrants consideration, and control measures are needed given its involvement in lethal pneumonia outbreaks in dairy herds from an extended area.

中文翻译：

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涉及牛支原体和其他 BRD 复合物病原体的意大利奶牛群中的致命小牛肺炎爆发。

牛支原体在世界范围内越来越多地被认为是导致牛饲养福利和生产严重受损的重要疾病。尽管在小牛犊和肉牛中检测到它，但对感染影响及其在意大利奶牛群中的时间发病率模式知之甚少。因此，本研究旨在调查牛分枝杆菌对 2009-2019 年间意大利 64 个奶牛场发生的致命小牛肺炎爆发的影响。此外，还评估了对其他病毒和细菌呼吸道病原体并发感染的更深入诊断检查。在调查的致命肺炎病例中，经常检测到牛分枝杆菌（动物患病率，16.16%；95%CI，11.82-21.33；畜群患病率，26.56；95%CI，16.29-39。08) 在超过一半的阳性样本 (20/37) 中作为该疾病的单一病原体，或与睡眠嗜血杆菌 (9/37, 24.3%)、溶血曼海姆氏菌 (6/37, 16.621%) 并发感染， Trueperella pyogenes (1/37, 2.70%)、多杀巴斯德氏菌 (1/37, 2.70%)、牛呼吸道合胞病毒 (5/37, 13.51%) 和牛病毒性腹泻病毒 (2/37, 5.55%)。根据时间序列分析，自 2009 年以来，该地区记录了牛分枝杆菌，其爆发显示出明显的发病率季节性模式，峰值出现在 4 月 (43.21%) 和 9 月 (13.51%)。这可能是由于春季和夏末时期的压力条件所致。这项研究的结果强调，牛分枝杆菌感染值得考虑，鉴于其涉及来自大面积奶牛群的致命肺炎暴发，因此需要采取控制措施。