Wineland N E, Detwiler L A, Salman M D
Center for Animal Health Monitoring, Veterinary Services, USDA-APHIS, Fort Collins, CO 80521, USA.
J Am Vet Med Assoc. 1998 Mar 1;212(5):713-8.
To determine epidemiologic features associated with reported cases of scrapie in sheep in the United States.
Retrospective study.
Records for scrapie-positive sheep flocks and sheep with clinical signs consistent with scrapie reported to the USDA from 1947 through 1992.
Records from the USDA's scrapie control and eradication program were abstracted, entered into a computer database, and statistically analyzed.
1,117 sheep from 657 flocks located in 39 states were scrapie positive during the study period. Seasonal or spatial trends were not evident. Mean yearly proportion of scrapie-positive flocks increased slightly from 1965 through 1992. One hundred sixty-eight rams and 949 ewes were reported to be scrapie positive during the study period, which was slightly more rams than expected if the disease was equally likely to affect rams and ewes. Suffolks (972/1,117; 87%) and Hampshires (68/1,117; 6%) were most commonly affected.
The prevalence of scrapie in sheep in the United States is unknown. Bias in this study may have resulted from inconsistencies in available information, misclassification of sheep with clinically suspicious signs of scrapie, and changes in the national scrapie control and eradication program that likely affected willingness of owners and veterinarians to report potentially infected sheep.
确定与美国绵羊痒病报告病例相关的流行病学特征。
回顾性研究。
1947年至1992年期间向美国农业部报告的痒病阳性绵羊群以及有与痒病相符临床症状的绵羊的记录。
提取美国农业部痒病控制与根除计划的记录，录入计算机数据库并进行统计分析。
在研究期间，来自39个州657个羊群的1117只绵羊痒病呈阳性。未发现明显的季节性或空间趋势。从1965年到1992年，痒病阳性羊群的年平均比例略有增加。在研究期间，报告有168只公羊和949只母羊痒病呈阳性，如果该病对公羊和母羊的影响几率相同，公羊数量略高于预期。萨福克羊（972/1117；87%）和汉普夏羊（68/1117；6%）受影响最为常见。
美国绵羊痒病的患病率未知。本研究中的偏差可能源于现有信息的不一致、对有痒病临床可疑症状绵羊的错误分类，以及国家痒病控制与根除计划的变化，这些变化可能影响了羊主和兽医报告潜在感染绵羊的意愿。
