Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 7, Utrecht, 3584 CL, The Netherlands.
Vet Res. 2013 Apr 26;44(1):28. doi: 10.1186/1297-9716-44-28.
Between 2007 and 2009, the largest human Q fever epidemic ever described occurred in the Netherlands. The source was traced back to dairy goat farms, where abortion storms had been observed since 2005. Since one putative cause of these abortion storms is the intensive husbandry systems in which the goats are kept, the objective of this study was to assess whether these could be explained by herd size, reproductive pattern and other demographic aspects of Dutch dairy goat herds alone. We adapted an existing, fully parameterized simulation model for Q fever transmission in French dairy cattle herds to represent the demographics typical for Dutch dairy goat herds. The original model represents the infection dynamics in a herd of 50 dairy cows after introduction of a single infected animal; the adapted model has 770 dairy goats. For a full comparison, herds of 770 cows and 50 goats were also modeled. The effects of herd size and goat versus cattle demographics on the probability of and time to extinction of the infection, environmental bacterial load and abortion rate were studied by simulation. The abortion storms could not be fully explained by demographics alone. Adequate data were lacking at the moment to attribute the difference to characteristics of the pathogen, host, within-herd environment, or a combination thereof. The probability of extinction was higher in goat herds than in cattle herds of the same size. The environmental contamination was highest within cattle herds, which may be taken into account when enlarging cattle farming systems.
2007 年至 2009 年期间，荷兰发生了有史以来最大的人类 Q 热疫情。源头可追溯到奶牛场，自 2005 年以来，这些奶牛场一直出现流产潮。由于这些流产潮的一个潜在原因是山羊的集约化饲养方式，因此本研究的目的是评估这些因素是否可以仅通过荷兰奶牛场羊群的规模、繁殖模式和其他人口统计方面来解释。我们对现有的法国奶牛 Q 热传播的全参数模拟模型进行了改编，以代表荷兰奶牛场羊群的典型人口统计学特征。原始模型代表了在引入一只受感染动物后，一个由 50 头奶牛组成的畜群中的感染动态；改编后的模型则代表了一个由 770 头山羊组成的畜群。为了进行全面比较，还对 770 头奶牛和 50 头山羊的畜群进行了建模。通过模拟研究了羊群规模和山羊与奶牛的人口统计学特征对感染的灭绝概率和时间、环境细菌负荷和流产率的影响。仅通过人口统计学特征无法完全解释流产潮。目前缺乏充分的数据来将差异归因于病原体、宿主、畜群内环境或其组合的特征。与同等规模的牛群相比，羊群的灭绝概率更高。在牛群中，环境污染最为严重，这在扩大牛养殖系统时需要考虑到。
