California Animal Health and Food Safety Laboratory System, University of California, Davis, Turlock Branch, 1550 N. Soderquist Road, Turlock, CA 95381.
California Animal Health and Food Safety Laboratory System, University of California, Davis, Davis Branch, 620 W. Health Sciences Drive, Davis, CA 95616.
Avian Dis. 2020 Dec 1;64(4):482-489. doi: 10.1637/0005-2086-64.4.482.
In March 2019, the California Animal Health and Food Safety Laboratory (CAHFS), Turlock branch, received two submissions of broiler chickens from commercial flocks reporting increased mortality. Submissions consisted of either white or brown broilers. Submitted chickens appeared depressed with ruffled feathers. At necropsy, moderate to severely enlarged and pale kidneys were observed, with gross lesions indicative of dehydration. Microscopically, renal tubules were degenerated and distended with necrotic debris and tubular casts. The kidney parenchyma contained mononuclear inflammatory cell infiltrates and interstitial edema. Infectious bronchitis virus (IBV) was isolated and identified by reverse transcription quantitative PCR from kidney tissue pools and tracheal swab pools from both cases. Partial sequencing of the S1 hypervariable region was most similar to a local California variant, CA1737. The outbreak lasted roughly 1 wk in both flocks, with 2% total mortality in the brown broilers and 20% total mortality in the white broilers. Final proof of the IBV strains causing nephropathy will require fulfillment of Koch postulates. IBV associated with nephropathy has been sporadically reported in California chicken flocks and represents a significant pathogen due to its potential for inducing high flock mortality. The incidence of IBV associated with a nephropathy diagnosis in chicken necropsy submissions to the CAHFS system-wide from 1998 to 2019 is also reviewed.
2019 年 3 月，加利福尼亚州动物健康和食品安全实验室（CAHFS）特洛克分部收到了两批来自商业养殖场的肉鸡报告，称死亡率增加。提交的样本包括白色或棕色肉鸡。送检的鸡表现出抑郁，羽毛蓬乱。剖检时，观察到肾脏中度至重度肿大和苍白，具有脱水的大体病变。显微镜下，肾小管退化，充满坏死碎片和管状铸型。肾实质包含单核炎性细胞浸润和间质水肿。从两个病例的肾脏组织池和气管拭子池中通过反转录定量 PCR 分离并鉴定出传染性支气管炎病毒（IBV）。S1 高变区的部分测序与加利福尼亚当地变体 CA1737 最相似。在两个鸡群中，疫情持续了大约 1 周，棕色肉鸡的总死亡率为 2%，白色肉鸡的总死亡率为 20%。要最终证明 IBV 株引起肾病，需要满足科赫假设。与肾病相关的 IBV 在加利福尼亚的鸡群中偶有报道，因其可能导致高死亡率，因此是一种重要的病原体。还回顾了 1998 年至 2019 年期间，CAHFS 系统范围内从鸡剖检提交样本中诊断出与 IBV 相关的肾病的发病率。
