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The increased awareness of the role of environmental matrices in enteric disease transmission has resulted in the need for rapid, field-based methods for fecal indicator bacteria and pathogen detection. Evidence of the specificity of β-glucuronidase-based assays for detection of Escherichia coli from environmental matrices relevant to enteric pathogen transmission in developing countries, such as hands, soils, and surfaces, is limited. In this study, we quantify the false-positive rate of a β-glucuronidase-based E. coli detection assay (Colilert) for two environmental reservoirs in Bangladeshi households (hands and soils) and three fecal composite sources (cattle, chicken, and humans). We investigate whether or not the isolation source of E. coli influences phenotypic and genotypic characteristics. Phenotypic characteristics include results of biochemical assays provided by the API-20E test; genotypic characteristics include the Clermont phylogroup and the presence of enteric and/or environmental indicator genes sfmH, rfaI, and fucK. Our findings demonstrate no statistically significant difference in the false-positive rate of Colilert for environmental compared to enteric samples. E. coli isolates from all source types are genetically diverse, representing six of the seven phylogroups, and there is no difference in relative frequency of phylogroups between enteric and environmental samples. We conclude that Colilert, and likely other β-glucuronidase-based assays, is appropriate for detection of E. coli on hands and in soils with low false-positive rates. Furthermore, E. coli isolated from hands and soils in Bangladeshi households are diverse and indistinguishable from cattle, chicken, and human fecal isolates, using traditional biochemical assays and phylogrouping.

The recovery efficiency of human waterborne pathogens and the bioaccumulation, depuration and inactivation rates of these pathogens by commercial market-size Crassostrea ariakensis triploids maintained in water of various salinity levels representing the salinity range of the Chesapeake Bay are determined. Aquacultures of nonnative oysters in the Chesapeake Bay have provided good ecological services in regard to efficient cleaning of human-infectious agents from the estuarine waters.

An immunoassay is described that can detect Norwalk virus and hepatitis A virus in stool samples and oysters. The Norwalk virus is the most common cause of non-bacterial gastroenteritis. The immunoassay can be automated and takes less time than some other methods.

A rapid and simple method for detecting Norwalk-like viruses and hepatitis A virus in food samples is presented. It uses HAV- or NLV-specific primers and reverse transcription PCR.

An immunoaffinity technique efficiently detects waterborne enteric viruses. The method involves indirect antibody capture of intact viruses and release of virion genomic RNA followed by reverse transcriptase PCR amplification and oligoprobe hybridization. The viruses are concentrated from huge volumes of water using 1MDS filters and washed with 1% beef extract-0.05 M glycine (BE/G). The BE/G eluate is concentrated and purified using polyethylene glycol (PEG) precipitation, ProCipitate precipitation, and then another PEG precipitation.

A study is conducted to evaluate the rates of bioaccumulation, retention, and depuration of viruses by Crassostrea virginica and C. ariakensis when the two oyster species are maintained in separate tanks containing synthetic seawater of various salinities at 8, 12, or 20 ppt. The findings have provided guidelines to assess the threat of C. ariakensis as a vehicle for viral pathogens due to the consumption of raw oysters and has validated the role for murine norovirus 1 (MNV-1) as a surrogate for human norovirus (NoV).

The applicability of selected enteric viral surrogates in predicting the persistence of human norovirus (NoV) seeded into surface water and groundwater used as source water for producing potable water is evaluated. Quantitative reverse transcription-PCR (qRT-PCR) assays are developed for each virus and the levels of infections virus and viral nucleic acid are monitored in spiked drinking source water over time.

A person with 30 minutes of occupational or nonoccupational exposure to urban feral pigeons is observed through the cleaning of surfaces contaminated with pigeon excrement. It is demonstrated that a person could inhale approximately 3.5 x [10.sup.3] Enterocytozoon bieneusi spores and a person nearby could inhale 1.3 x [10.sup.3] spores.

Susceptibilities to arsenite, arsenate, and the organoarsenical roxarsone are measured in 251 Campylobacter isolates from conventional and antimicrobial-free retail poultry products. Isolates from conventional poultry products have significantly higher roxarsone MICs (z= 8.22; P < 0.0001).

The detection of norovirus capsid protein is explored using three common mass spectrometry (MS)-based methods that are scanning of intact proteins, peptide mass fingerprinting, and peptide sequencing. This is the first report on MS-based detection of norovirus, accomplished by using structurally identical, noninfective virus-like particles at clinically relevant concentrations.

Research describes the development of a polymerase chain reaction (PCR) amplification and detection method for Toxoplasma gondii oocyst nucleic acids. The method uses uracil-N-glycosylase to prevent false-positives, an internal control to identify false-negatives, and an oligoprobe for the detection of nucleic acids using the PCR-enzyme immunoassay.