Houwers D J, König C D, Bakker J, de Boer M J, Pekelder J J, Sol J, Vellema P, de Vries G
Central Veterinary Institute, Lelystad.
Vet Q. 1987 Nov;9 Suppl 1:29S-36S.
The results of the first four years of the Dutch national voluntary maedi-visna control program, which was launched on January 1, 1982, are presented. At the end of the observation period, 1711 breeding flocks representing 70% of the registered breeding flocks participated. The program is based on accreditation of flocks that have passed two successive serological tests with an interval of six months between and post-accreditation tests every 12 months. The flocks have to conform to a set of specific regulations. Sheep sold from such flocks receive a certificate stating that their origin was accredited. A total of 1212 flocks gained accreditation. Of these flocks, 29.5% were free from infection from the beginning, 35.6% were created by total replacement of the original stock, 19.6% employed repeated testing and culling of positives, and 15.3% were created by artificial rearing of colostrum-deprived lambs. A total of 22 flocks lost accreditation due to detection of 36 seropositives. These positives and their progeny were culled, and all flocks regained accreditation after passing the two negative flock tests required. In a total of seven flocks, an unusual course of events during the pre-accreditation stage was observed; this was mainly attributed to late seroconversions and uncommon degrees of horizontal transmission. The results indicate that this certification yields a substantial guarantee of freedom from maedi-visna virus and they indirectly show that the basic design of the program has been adequate.
本文介绍了荷兰国家自愿性梅迪-维斯纳病控制计划前四年（该计划于1982年1月1日启动）的实施结果。在观察期结束时，1711个繁殖群参与其中，占注册繁殖群的70%。该计划基于对繁殖群的认证，即繁殖群需通过连续两次血清学检测，两次检测间隔为六个月，且认证后每12个月进行一次检测。这些繁殖群必须符合一系列特定规定。从这些繁殖群出售的绵羊会获得一份证书，证明其来源已获认证。共有1212个繁殖群获得认证。在这些繁殖群中，29.5%从一开始就没有感染，35.6%是通过全部更换原有种群建立的，19.6%采用了对阳性个体进行反复检测和扑杀的方法，15.3%是通过人工饲养初乳剥夺羔羊建立的。共有22个繁殖群因检测出36个血清阳性个体而失去认证。这些阳性个体及其后代被扑杀，所有繁殖群在通过所需的两次阴性群体检测后重新获得认证。在总共七个繁殖群中，观察到认证前阶段出现了异常情况；这主要归因于血清转化延迟和水平传播程度异常。结果表明，这种认证为无梅迪-维斯纳病毒提供了实质性保证，并且间接表明该计划的基本设计是充分的。
