The public health significance of Giardia lamblia cysts in raw water sources is unclear because few studies have attempted to characterize the organism in water. Recent results from molecular epidemiological studies have suggested that not all G. lamblia isolates infect humans. In fact, it has been proposed that G. lamblia be re-classified into seven distinct species based on host specificity and molecular genetics. Identifying the existence of Giardia species and genotypes in environmental water will enhance our current understanding of the potential threat of contamination that multiple host sources (I.e., livestock, wildlife, pets and humans) have on human health. This study will focus on genotyping G. lamblia cysts recovered from slides prepared from spiked raw water using the U.S. Environmental Protection Agency Method 1623 method with a seminested PCR-DNA sequencing approach. Successful amplification and detection sensitivities were enhanced when multiple copy SSU rRNA genes were targeted compared to the single copy gdh gene. Preliminary results indicate the presence of single and multiple species/genotypes present in raw water but further study is required. The present study represents a preliminary model for source tracking G. lamblia in environmental waters.
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