Morgan E R, Azam D, Pegler K
School of Biological Sciences, University of Bristol, Woodland Road, Bristol BS8 1UG, UK.
Vet Parasitol. 2013 Apr 15;193(4):390-7. doi: 10.1016/j.vetpar.2012.12.034. Epub 2012 Dec 22.
A rich body of work has reported levels of infection with Toxocara species in definitive hosts, and the frequency of eggs in the environment, in many different regions and situations. These have greatly increased our understanding of the relationship between egg excretion from companion and wild animals and the risk of human infection by inadvertent ingestion of eggs from soil and other environmental reservoirs. Nevertheless, it is difficult to compare studies directly because of vagaries in sampling and laboratory methods, a preponderance of prevalence rather than abundance data, and a lack of studies that systematically sample different sympatric definitive host populations. Such comparisons could be instructive, for example to determine the relative contributions of different definitive host populations and categories to environmental contamination in specified areas, and hence guide priorities for control. In this article we use estimates of host density and infection levels in the city of Bristol, UK, as a case study to evaluate the relative contribution of sympatric cats, dogs and foxes to overall environmental contamination with eggs. Results suggest that dogs, especially those less than 12 weeks of age, dominate total egg output, but that this is modified by degree of access to public areas and removal of faeces, such that foxes could take over as the primary source of eggs. Results and conclusions are likely to differ among specific locations. The general aim is to show how an improved quantitative framework for epidemiological studies of Toxocara spp. egg contamination can help to advance understanding and the effectiveness of control strategies in future.
大量研究报告了在许多不同地区和情况下，终末宿主中弓蛔虫属的感染水平以及环境中虫卵的出现频率。这些研究极大地增进了我们对伴侣动物和野生动物排出虫卵与人类因意外摄入土壤及其他环境储库中的虫卵而感染风险之间关系的理解。然而，由于采样和实验室方法的多变性、患病率数据而非丰度数据占主导，以及缺乏对不同同域终末宿主种群进行系统采样的研究，直接比较各项研究存在困难。这样的比较可能具有指导意义，例如确定不同终末宿主种群和类别对特定区域环境污染的相对贡献，从而指导防控重点。在本文中，我们以英国布里斯托尔市宿主密度和感染水平的估计值为例，评估同域的猫、狗和狐狸对环境中虫卵总体污染的相对贡献。结果表明，狗，尤其是12周龄以下的狗，在总产蛋量中占主导，但这会因进入公共区域的程度和粪便清理情况而有所改变，以至于狐狸可能会成为虫卵的主要来源。不同具体地点的结果和结论可能会有所不同。总体目标是展示一个改进后的弓蛔虫属虫卵污染流行病学研究定量框架如何有助于增进未来对防控策略的理解并提高其有效性。
