Fayer R, Trout J M, Lewis E J, Santin M, Zhou L, Lal A A, Xiao L
Animal Waste Pathogen Laboratory, Agricultural Research Service, USDA, Beltsville, MD 20705, USA.
Parasitol Res. 2003 Jan;89(2):141-5. doi: 10.1007/s00436-002-0734-0. Epub 2002 Oct 1.
Shellfish (oysters and/or clams) were obtained from 37 commercial harvesting sites in 13 Atlantic coast states from Maine to Florida and one site in New Brunswick, Canada. Gill washings from each of 25 shellfish at each site were examined by immunofluorescence microscopy (IFA) for oocysts of Cryptosporidium. Gill washings from another 25 shellfish at each site were grouped into five pools of five shellfish each. DNA from each pool was utilized for PCR and genotyping. Oocysts were found in 3.7% of 925 oysters and clams examined by IFA in shellfish from New Brunswick and 11 of 13 states. Cryptosporidium DNA was detected by PCR in 35.2% of 185 pools. Cryptosporidium parvum genotypes 1 and 2, and Cryptosporidium meleagridis,all of which have been identified in infected humans, were identified at 37.8% of the sites. Gill washings from every site were tested for the presence of infectious oocysts by biological assay in neonatal BALB/c mice but no mice were found infected, suggesting that either the oocysts were no longer infectious or infections in mice were below the level of detection. Collectively, these findings indicate that Cryptosporidium species, indicative of pollution from human and animal feces and potentially infectious for humans, were found in commercial shellfish from 64.9% of sites examined along the Atlantic coast by either microscopy or molecular testing. Previous reports link periods of high rainfall with the elevated numbers of pathogen contaminated shellfish. Because shellfish in the present study were examined during a period of exceptionally low precipitation, the data are thought to underestimate the number of Cryptosporidium contaminated shellfish likely to be found during periods of normal or above normal precipitation.
贝类（牡蛎和/或蛤）取自从缅因州到佛罗里达州的13个大西洋沿岸州的37个商业捕捞点以及加拿大新不伦瑞克省的一个捕捞点。对每个捕捞点的25只贝类的鳃冲洗液进行免疫荧光显微镜检查（IFA），以检测隐孢子虫的卵囊。每个捕捞点的另外25只贝类的鳃冲洗液被分成5组，每组5只贝类。每组的DNA用于PCR和基因分型。在新不伦瑞克省和13个州中的11个州的贝类中，通过IFA检查的925只牡蛎和蛤中，有3.7%发现了卵囊。在185组中的35.2%通过PCR检测到隐孢子虫DNA。在37.8%的地点鉴定出了已在受感染人类中发现的微小隐孢子虫基因型1和2以及火鸡隐孢子虫。通过新生BALB/c小鼠的生物学检测对每个捕捞点的鳃冲洗液进行传染性卵囊检测，但未发现小鼠感染，这表明要么卵囊不再具有传染性，要么小鼠中的感染低于检测水平。总体而言，这些发现表明，通过显微镜检查或分子检测，在大西洋沿岸64.9%的检测地点的商业贝类中发现了隐孢子虫物种，这表明存在来自人类和动物粪便的污染，并且可能对人类具有传染性。先前的报告将降雨量大的时期与受病原体污染的贝类数量增加联系起来。由于本研究中的贝类是在降水量异常低的时期进行检查的，因此这些数据被认为低估了在正常或高于正常降水量时期可能发现的受隐孢子虫污染的贝类数量。
