Elbers A R, Stegeman J A, de Jong M C
Department of Farm Animal Health, Animal Health Service, Deventer, The Netherlands.
Vet Rec. 2001 Sep 29;149(13):377-82. doi: 10.1136/vr.149.13.377.
A matched case-control study of 135 infected and 99 uninfected pig herds from the central area of the 1997 to 1998 epidemic of classical swine fever (CSF) in The Netherlands was undertaken to identify factors associated with the introduction of the virus. The herds were matched on the basis of herd type and the shortest geographical distance between pairs of herds. Data on management, hygienic measures, experiences during the depopulation of an infected nearest neighbour, and the frequency of contact with professionals and other agencies were collected by means of a questionnaire taken by personal interview. There were no significant differences between the infected and uninfected herds in the median total number of contacts per year with professionals and other agencies either with or without contact with the pigs. On the basis of a multivariable analysis, five variables were found to be significantly associated with an increased risk of infection: (1) the presence of commercial poultry on the premises; (2) visitors entering the pig units without wearing an overcoat or overalls and boots supplied by the farm; (3) the driver of the lorry transporting pigs for the Pig Welfare Disposal Scheme (PWDS) using his own boots instead of boots supplied by the farm; (4) herds of moderate size (500 to 1,000 animals) and very large herds (>7,000 animals) were at greater risk than small herds (<500 animals); and (5) an aerosol, produced during high-pressure cleaning of the electrocution equipment used to kill the pigs on a neighbouring infected herd less than 250 m away was carried by the wind on to the premises. Two variables were significantly associated with a decreased risk of CSFV-infection: (1) more than 30 years of experience in pig farming; and (2) additional cleaning of the lorries used to transport pigs for the PWDS before they were allowed on to the premises. In the opinion of the cooperating farmers, airborne transmission of the virus and its transmission during the depopulation of an infected neighbour were among the most important routes of infection.
在荷兰，针对1997年至1998年古典猪瘟（CSF）疫情中心地区的135个受感染猪群和99个未受感染猪群开展了一项配对病例对照研究，以确定与病毒传入相关的因素。这些猪群根据猪群类型以及成对猪群之间的最短地理距离进行配对。通过个人访谈问卷收集了有关管理、卫生措施、受感染最近邻群扑杀期间的经历以及与专业人员和其他机构接触频率的数据。受感染猪群和未受感染猪群每年与专业人员和其他机构接触的中位数总数，无论是否与猪接触，均无显著差异。基于多变量分析，发现有五个变量与感染风险增加显著相关：（1）场地上存在商业家禽；（2）访客进入猪舍时未穿着农场提供的大衣、工作服和靴子；（3）为猪福利处置计划（PWDS）运输猪的卡车司机使用自己的靴子而非农场提供的靴子；（4）中等规模（500至1000头猪）和非常大的猪群（>7000头猪）比小猪群（<500头猪）面临更大风险；（5）在距离不到250米的相邻受感染猪群中用于电击杀猪的设备进行高压清洁时产生的气溶胶被风吹到了场地上。有两个变量与CSFV感染风险降低显著相关：（1）养猪经验超过30年；（2）用于PWDS运输猪的卡车在进入场地前进行额外清洁。在合作养殖户看来，病毒的空气传播及其在受感染邻居群扑杀期间的传播是最重要的感染途径之一。
