Robertson L J, Forberg T, Gjerde B K
Parasitology Laboratory, Department of Food Safety and Infection Biology, Norwegian School of Veterinary Science, Oslo, Norway.
J Appl Microbiol. 2008 Apr;104(4):1147-52. doi: 10.1111/j.1365-2672.2007.03630.x. Epub 2007 Nov 1.
In autumn/winter 2004, a large outbreak of waterborne giardiasis occurred in Bergen, Norway. Over 1 year later, the concentrations and genotypes of Giardia cysts occurring in sewage influent were studied to investigate the impact of the outbreak event on Giardia infections in the community.
Sewage influent samples from four sewage treatment works (STW) serving Bergen were analysed for Giardia cysts on four occasions between 15 and 23 months after the outbreak. Cysts genotypes were investigated at one to three genes. Data from influent analysis from one of the STW before the outbreak, and from patient faecal samples analysed during the outbreak, provided baseline comparative data. Relatively high concentrations of Giardia cysts of diverse genotypes, both from Assemblages A and B, were detected at all STW.
Comparison of data suggests that although Giardia cyst concentrations in sewage influent returned to pre-outbreak levels within 18 months after the outbreak peak, the genetic composition of the isolates remained significantly influenced by the Assemblage B isolate associated with the outbreak.
Genotypes associated with an extensive outbreak of giardiasis continued to occur in Giardia infections in Bergen's population many months after the outbreak was considered to be over.
2004年秋冬，挪威卑尔根市发生了大规模水源性贾第虫病疫情。1年多后，对污水进水口中贾第虫包囊的浓度和基因型进行了研究，以调查疫情事件对社区中贾第虫感染的影响。
在疫情爆发后15至23个月期间，对为卑尔根市服务的4个污水处理厂的污水进水样本进行了4次贾第虫包囊分析。对包囊基因型进行了1至3个基因的研究。爆发前其中一个污水处理厂的进水分析数据以及爆发期间分析的患者粪便样本数据提供了基线对比数据。在所有污水处理厂均检测到来自A群和B群的相对高浓度的多种基因型贾第虫包囊。
数据比较表明，尽管污水进水口中贾第虫包囊浓度在疫情高峰后18个月内恢复到爆发前水平，但分离株的基因组成仍受到与疫情相关的B群分离株的显著影响。
在疫情被认为结束后的许多个月里，与大规模贾第虫病疫情相关的基因型仍在卑尔根市人群的贾第虫感染中出现。
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