Cano Lourdes, de Lucio Aida, Bailo Begoña, Cardona Guillermo A, Muadica Aly Salimo Omar, Lobo Luis, Carmena David
Parasitology Service, National Centre for Microbiology, Carlos III Health Institute, Ctra. Majadahonda-Pozuelo Km 2, 28220 Majadahonda, Madrid, Spain.
Livestock Laboratory, Regional Government of Álava, Ctra. de Azua 4, 01520 Vitoria-Gasteiz, Spain.
Vet Parasitol. 2016 May 15;221:144-8. doi: 10.1016/j.vetpar.2016.03.026. Epub 2016 Apr 1.
Aquatic birds are known to be suitable hosts for a number of avian-specific species and genotypes of the enteric protozoan parasites Giardia and Cryptosporidium. Waterbirds have also been reported as sporadic carriers of species of both pathogens from human or domestic animal origin via environmental contamination. Because aquatic birds can shed substantial amounts of infective Giardia and Cryptosporidium (oo)cysts to the environment including surface waters intended for human consumption, this situation may pose a potential risk of waterborne zoonotic disease. A total of 265 waterbird faecal samples were collected from May 2014 to June 2015 at Salburua (Álava), one of the most valued continental wetlands in northern Spain. The detection of Giardia oocyst and Cryptosporidium oocysts was carried out by direct fluorescence microscopy and molecular (PCR and sequence analysis) methods targeting the small subunit ribosomal RNA gene of the parasites. Typing of Giardia duodenalis isolates at the sub-assemblage level was based on the specific amplification and sequencing of a partial fragment of the glutamate dehydrogenase gene. Overall, Giardia cysts and Cryptosporidium oocysts were detected in 22 (8.3%) and 6 (2.3%), respectively, of the 265 faecal samples analysed. The two only Giardia isolates characterized (one novel, one known) were assigned to the sub-assemblage BIV of G. duodenalis, none of them previously reported in Spanish human isolates. This finding raises doubts about the actual origin of the infection and whether waterbirds may serve as potential source of infective Giardia cysts to humans via waterborne transmission or through direct contact. The six Cryptosporidium isolates obtained were characterized as avian genotype III (n=4), duck genotype b (n=1), and goose genotype Id (n=1), all considered avian-specific and therefore of negligible risk of zoonotic infection.
已知水鸟是多种肠道原生动物寄生虫贾第虫和隐孢子虫的特定鸟类宿主物种和基因型的适宜宿主。也有报道称水鸟是这两种病原体的散在携带者，这些病原体通过环境污染来自人类或家畜。由于水鸟可向环境中大量排放感染性贾第虫和隐孢子虫（卵）囊，包括排放到供人类食用的地表水中，这种情况可能构成水源性人畜共患病的潜在风险。2014年5月至2015年6月，在西班牙北部最受重视的大陆湿地之一萨尔布鲁阿（阿拉瓦省）采集了265份水鸟粪便样本。通过直接荧光显微镜检查以及针对寄生虫小亚基核糖体RNA基因的分子（聚合酶链反应和序列分析）方法检测贾第虫卵囊和隐孢子虫卵囊。十二指肠贾第虫分离株的亚群分型基于谷氨酸脱氢酶基因部分片段的特异性扩增和测序。总体而言，在分析的265份粪便样本中，分别有22份（8.3%）和6份（2.3%）检测到贾第虫囊肿和隐孢子虫卵囊。仅有的两株特征明确的贾第虫分离株（一株为新发现的，一株为已知的）被归为十二指肠贾第虫的BIV亚群，此前西班牙人类分离株中均未报告过。这一发现引发了对感染实际来源的质疑，以及水鸟是否可能通过水传播或直接接触成为人类感染性贾第虫囊肿的潜在来源。获得的六株隐孢子虫分离株被鉴定为鸟类基因型III（n = 4）、鸭基因型b（n = 1）和鹅基因型Id（n = 1），所有这些都被认为是鸟类特有的，因此人畜共患感染风险可忽略不计。
