glucosamine sulfate Despite the high concentrations of Giard

Despite the high concentrations of Giardia cysts and Cryptosporidium oocysts recovered in sewage effluent (Table 1), successful genetic characterization was only possible for 33.3% and 50.0% of microscopy-positive samples with Giardia and Cryptosporidium, respectively. These findings can be explained by the poor sensitivity of molecular tests due to empty oocysts and cysts lacking DNA (Smith and Nichols, 2010). On the other hand, IFA methods are known to cross-react with nontarget organisms such as algae (Rodgers et al., 1995) thereby providing false positive microscopy results. Alternatively, false negative PCR amplification may arise due to the inhibitory effects of substances such as humic acids, present in sewage/environmental samples (Mayer and Palmer, 1996). The use of molecular diagnostic tools to characterize species and genotypes of glucosamine sulfate in clinical and environmental samples provides valuable insight into the potential sources of contamination contributing to human infection. Nevertheless, a number of challenges remain. (Monis et al., 2009; Smith and Nichols, 2010; Xiao, 2010). The use of 18S rDNA locus has been recommended as a target for screening Giardia and Cryptosporidium from stool and environmental samples owing to its high copy number within the genome, therefore enhancing detection sensitivity. For example, Giardia has been estimated to have 60 copies of the rDNA repeat (Boothroyd et al., 1987). Compounding the sensitivity of the PCR assays, we were only able to successfully sequence a limited number of samples. Similar results were obtained in other studies conducted in Hungary (Plutzer et al., 2008), Spain (Castro-Hermida et al., 2011) and France (Coupe et al., 2006). Environmental samples are likely to contain multiple mixed assemblages of Giardia and species/genotypes of Cryptosporidium which makes it difficult to identify assemblages/species. Use of second-generation sequencing technologies may assist in overcoming these limitations (Paparini et al., 2015). Despite of the limited number of successful sequences, future studies might aim at targeted amplification and quantification of the zoonotic species and genotypes. Using specific molecular markers/probes will provide a more informative approach to assessing the risk posed by these pathogens from environmental samples. One purpose of this study was to examine the distribution of potentially zoonotic Cryptosporidium isolates. The predominance of C.suis contamination in sewage effluent in this community implicates effluent discharged from cleaning of domestic pigpens as a major source of environmental contamination of Cryptosporidium. Currently, C.suis is recognized as zoonotic and it has been identified in immunocompetent humans (Xiao et al., 2002), however owing to the low proportion of successfully characterized samples, information pertaining to the risk of human transmission of Cryptosporidium remains incomplete. Therefore, effluent used as untreated irrigation water on the open fields can provide a source of potentially zoonotic Cryptosporidium to humans. The majority of water and vegetable samples contaminated with Giardia belonged to assemblage B (6/7) and only one sample of fishpond water was contaminated with livestock-specific assemblage E. Giardia A2 and B3 subgenotypes present in sewage effluent may be a reason for public health concern. Water contaminated with untreated sewage effluent is commonly used for agricultural irrigation purposes and poses a significant source of infection to humans, through the consumption of raw produce. Moreover, farm workers may be placed at direct risk through contact with wastewater during the process of irrigating fields. In this study, the sewage effluent discharged into the irrigation system and Nhue river was mainly of domestic origin sourced from both humans and animals. These findings highlight that both anthroponotic (human) and zoonotic (community dogs, livestock) sources may be responsible for contibuting to the contamination of the environment and in turn may contribute to infection in humans.