Hunter Paul R, Thompson R C Andrew
School of Medicine, Health Policy and Practice, University of East Anglia, Norwich NR4 7TJ, UK.
Int J Parasitol. 2005 Oct;35(11-12):1181-90. doi: 10.1016/j.ijpara.2005.07.009.
The molecular characterisation of Giardia and Cryptosporidium has given rise to a more epidemiological meaningful and robust taxonomy. Importantly, molecular tools are now available for 'typing' isolates of the parasites directly from clinical and environmental samples. As a consequence, information on zoonotic potential has been obtained although the frequency of zoonotic transmission is still poorly understood. Analysis of outbreaks and case-control studies, especially when coupled with genotyping data, is slowly providing information on the public health significance of zoonotic transmission. Such studies support the hypothesis that Cryptosporidium hominis is spread only between humans but that the major reservoir for Cryptosporidium parvum is domestic livestock, predominantly cattle, and that direct contact with infected cattle is a major transmission pathway along with indirect transmission through drinking water. The situation is less clearcut for Giardia duodenalis but the evidence does not, in general, support zoonotic transmission as a major risk for human infections. However, for both parasites there is a need for molecular epidemiological studies to be undertaken in well-defined foci of transmission in order to fully determine the frequency and importance of zoonotic transmission.
贾第虫属和隐孢子虫属的分子特征促成了一种在流行病学上更具意义且更为可靠的分类法。重要的是，现在已有分子工具可直接从临床和环境样本中对寄生虫分离株进行“分型”。因此，尽管人畜共患病传播的频率仍知之甚少，但已获得了有关人畜共患病潜力的信息。对疫情爆发的分析以及病例对照研究，尤其是结合基因分型数据时，正在慢慢提供有关人畜共患病传播对公共卫生意义的信息。此类研究支持以下假设：人隐孢子虫仅在人与人之间传播，但微小隐孢子虫的主要储存宿主是家畜，主要是牛，并且与受感染牛的直接接触是主要传播途径之一，同时还存在通过饮用水的间接传播。对于十二指肠贾第虫，情况不太明确，但总体而言，证据并不支持人畜共患病传播是人类感染的主要风险。然而，对于这两种寄生虫，都需要在明确界定的传播疫源地开展分子流行病学研究，以便充分确定人畜共患病传播的频率和重要性。
