In this study, we genotyped parasites from the fecal specimens of sporadic cryptosporidiosis cases in British Columbia from 1995 to 1999. Genotyping was conducted by polymerase chain amplification of the internal transcribed spacer region, a hypervariable region in the 18S rRNA gene and the Cryptosporidium oocyst wall protein gene. Subsequent analysis was by restriction fragment length polymorphism and DNA sequencing. We identified two new Cryptosporidium genotypes in humans. One of these genotypes has been found recently in deer in New York state. The other genotype has not been identified in humans or animals. These results have important implications for drinking water quality strategies, especially for communities that obtain drinking water supplies from surface sources located in forested regions with deer populations.
Cryptosporidium parvum is a protozoan parasite that causes diarrheal illness in a wide range of mammalian hosts, including humans. Characteristic serum immunoglobulin G (IgG) antibody responses to antigens in the 27-and 17-kDa size ranges have been shown to develop after infection, and several enzyme-linked immunosorbent assay (ELISA) and Western blot assay formats have been used to measure these IgG levels in human serum. Using a collection of serial samples from laboratory-confirmed cryptosporidiosis patients, we compared the results obtained by using two new ELISAs with those obtained with two different Western blot assays. When assayed with the large-format Western blot, 97% of the 67 patients had a demonstrable antibody response on at least one occasion. The Cp23 ELISA correctly identified 93% of the samples that had a 27-kDa response by Western blot and 100% of the negative samples. The Triton antigen ELISA detected 77% of the samples that had a 17-kDa response by Western blot and 88% of the negative samples. The sensitivity of the Triton antigen assay was higher for samples collected between 16 and 92 days after the onset of symptoms (96%). The minigel-format Western blot did not compare favorably with the large-format blot for the detection of antibodies to the 27-kDa antigen (71% sensitivity). A half-life of about 12 weeks was estimated for antibodies to both the 27-and 17-kDa antigens. We believe the Cp23 and Triton antigen ELISAs will be useful in epidemiologic studies of the prevalence of Cryptosporidium infection in the population.Cryptosporidium parvum, a protozoan parasite that invades the intestinal epithelium of a wide range of mammalian hosts, causes a self-limiting but sometimes severe diarrheal illness in immunocompetent humans (2). However, in those with compromised immune systems, the disease can be debilitating, chronic, and life threatening (4, 23). Because of its ubiquitous distribution in the environment, its small size, and its resistance to standard chlorination techniques, C. parvum contamination of drinking water may pose a significant public health risk (1,11,12). Numerous outbreaks have been traced to contaminated water, and waterborne outbreaks have even occurred in communities served by state-of-the-art water treatment facilities (3,8,9,15). To conduct epidemiologic studies to assess the risks of C. parvum infection that may be associated with drinking water and other potential sources of exposure, new serologic assays that are rapid, sensitive, and specific are needed.Characteristic serum immunoglobulin G (IgG) antibody responses have been shown to develop in humans after C. parvum infection. As shown by Western blot analysis of serum samples collected from outbreak patients and human volunteers, the antibody response is consistently directed toward two low-molecular-weight antigen families: one in the 27-kDa size range and a second in the 17-kDa size range (16-19, 25, 26).We recently reported the development of two enzyme-linked immunosorbent assays (ELISAs) for the detection ...
Abstract.Isolates from 25 (13 sporadic and 12 outbreak) cryptosporidiosis cases, 24 of which were from British Columbia, Canada, were characterized using nested polymerase chain reaction amplification of the polymorphic internal transcribed spacer 1 locus. Two predominant Cryptosporidium parvum genotypes were found. Twelve (8 sporadic and 4 outbreak) isolates amplified with the cry7/cry21 primer pair and 12 (5 sporadic and 7 outbreak) isolates amplified with the cry7/cryITS1 primer pair. Multi-locus gene analysis using sequence polymorphisms on 3 other loci, i.e., the thrombospondin-related adhesion protein gene, the dihydrofolate reductase gene, and the 18S rRNA gene on 8 (4 outbreak and 4 sporadic) isolates showed non-random association among the human and animal alleles of the 4 different C. parvum gene loci. Associations between these 2 parasite genotypes and different routes of cryptosporidiosis transmission such as zoonotic, anthroponotic, and waterborne transmission were studied using municipal population and agricultural information, as well as detection of C. parvum oocysts in municipal drinking water specimens of the residential communities of sporadic and outbreak cases.Within the last 10 years, several waterborne cryptosporidiosis outbreaks have occurred in North America.
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