F. Le Guyader

Fecal Contamination in Coastal Areas: An Engineering Approach

Introduction : The occurrence of pathogenic microorganisms in seawater or in shellfish could exist anytime sewage from human or animal origin would be discharged to the coast (Metcalf, 1982). According to the diseases occurring in the human population or in animals, pathogens might be present in recreational waters or in shellfish. Thus, the presence of human enteric viruses (norovirus, astrovirus, rotavirus, hepatitisAvirus (HAV)) and pathogenic bacteria (Salmonella, Listeria monocytogenes, Shiga-toxin-producing Escherichia coli (STEC), Vibrio cholerae, Vibrio parahaemolyticus, etc.) has been reported in coastal areas for a long time (Colwell, 1978; Metcalf, 1978; Melnick et al., 1979; Grimes, 1991; Bosch et al., 2001;Kong et al., 2002). These microorganisms have been implicated in gastrointestinal and respiratory illnesses and other infections (skin, eyes, etc.), (Griffin et al., 2003). Using risk-assessment models for viruses, maximum risks were estimated to be 1.3 infections per 100 swimmers (Colwell et al., 1996). To evaluate the risk due to the presence of these pathogens in the environment, certain criteria have to be determined. Among them, the infectious dosewould be of a greatest importance (Table 14.1). Even if the infectious dose vary with the strains, the age of the patient, or other parameters, some pathogens are highly dangerous for men even at low concentrations (HAV, E. coli O157:H7, V. cholerae), whereas others have to be ingested in high concentrations to be harmful (V. parahaemolyticus) or are highly infectious but not very dangerous (norovirus). Thus, for some pathogens, a low contamination in seafood, for example, is not acceptable, based on risk-assessment models (Colwell et al., 1996). Among bacteria, the Vibrio family plays an important role in infections, waterborne or seafood diseases, especially in countries surrounded by warm marine waters. Toxigenic V...

Detection of human enteric viruses in shellfish collected in Tunisia

Aims:  The aim of this study was to detect the main pathogenic human RNA enteric viruses able to persist in the environment such as astrovirus, enterovirus, norovirus and hepatitis A virus (HAV) in shellfish collected from two locations in northern Tunisia.

An improved method for the detection of Norwalk-like caliciviruses in environmental samples.

An original magnetic beads RNA capture was developed for the detection of Norwalk‐like virus by RT‐PCR. The same oligonucleotide was used both for capture and reverse transcription of the viral RNA. The optimization studies showed that the most important parameter for sensitivity is the biotin‐binding capacity of the beads. This method was found to be efficient for eliminating inhibitors in sewage samples compared with the classic RT‐PCR. Moreover, the sensitivity was greatly enhanced, allowing the detection of 42% positive sample after gel electrophoresis, which is fourfold greater than classic RT‐PCR (11%). Beads‐RT‐PCR sensitivity is the same as classic RT‐PCR and hybridization. Thus, this method, which is easy to perform, should be of particular interest for developing quantitative RT‐PCR and sequencing.

A norovirus oyster-related outbreak in a nursing home in France, January 2012

The presence of norovirus in shellfish is a public health concern in Europe. Here, we report the results of an investigation into a norovirus gastroenteritis outbreak following a festive lunch which affected 84 (57%) residents and staff members of a nursing home in January 2012 in France. Individuals who had eaten oysters had a significantly higher risk of developing symptoms in the following 2·5 days than those who had not, the risk increasing with the amount eaten [relative risk 2·2 (1·0-4·6) and 3·3 (1·6-6·6) for 3-4 and 5-12 oysters, respectively]. In healthy individuals during those days, 29 (32%) subsequently became ill, most of whom were staff members performing activities in close contact with residents. Genogroup II noroviruses were detected in faecal samples, in a sample of uneaten oysters and in oysters from the production area. Identifying a noroviruss infectious dose may facilitate the health-related management of contaminated shellfish.

Comparative study of the behaviour of poliovirus in sterile seawater using RT-PCR and cell culture

Abstract Survival of poliovirus 1 was determined in sterile seawater at different salinity levels by detection of viral RNA by RT-PCR and comparison with tissue culture infectivity assay. Salinity appeared to have little influence on the behaviour of infectious particles: times necessary to obtain negative results by cell culture were not statistically different for the three salinities tested. Viral RNA was always detected by RT-PCR showing that in sterile medium viral particles can persist in a noninfectious form.

Detection of hepatitis a virus in wild shellfish

Twenty-two mussel and cockle samples were collected after a hepatitis A outbreak on the Atlantic coast, in France. Detection of hepatitis A virus (HAV) antigen by radioimmunoassay and HAV RNA by hybridization were negative. However, HAV RNA was detected by reverse transcription and semi-nested polymerase chain reaction in 16 samples, and replication in cell culture was observed with four of them.

Monitoring viral contamination in shellfish growing areas

Human and animal fecal wastes and urine contain a large number of different viruses that can enter the environment through the discharge of waste materials from infected individuals. Despite the high diversity of viruses that are introduced into the environment by human fecal pollution, only a few have been recognized to cause disease in association with consumption of contaminated shellfish. Viruses are present in shellfish in very low numbers. Nevertheless, they are present in sufficient quantities to pose a health risk as presented. This low level of contamination has made it necessary to develop highly sensitive viral extraction methods to ensure virus recovery from shellfish tissues. The most common route for accidental contamination is after heavy rainfall, leading to overflow and release of untreated sewage into the aquatic environment. To limit shellfish contamination the most desirable and effective option is to reduce the viral input.

Adsorption of norovirus and ostreid herpesvirus type 1 to polymer membranes for the development of passive samplers

This study was performed to develop a passive sampling methodology for the detection of two viruses in seawater in the area of shellfish production, the norovirus (NoV), a human pathogen implicated in gastroenteritis outbreaks linked to oyster consumption and the ostreid herpesvirus type 1 (OsHV‐1), a virus associated with mass mortalities of Pacific oysters.

Faecal contamination of echinoderms: first report of heavy Escherichia coli loading of sea urchins from a natural growing area.

Although little evidence existed to support that view, European countries and in particular France, have regarded echinoderms, including sea urchins, as low risk in terms of feacal contamination. It is hypothesized that the sea urchins mode of feeding, which is based on grazing and differs from bivalve molluscs, would prevent it from concentrating high levels of Escherichia coli. Here, we monitored E. coli levels in sea urchins (Paracentrotus lividus) and in filter‐feeder mussels (Mytillus galloprovincialis), collected concurrently from the same natural area over a 1‐year period to verify this assumption. Sea urchins were collected on the seafloor, whereas mussels were collected from the water column at a depth of 4 m. Our results showed heavy bacterial loading of sea urchins in a natural growing environment. Moreover, we highlighted that E. coli contamination of sea urchins could, in certain conditions, be higher than those detected in filter‐feeding mussels collected at the same location. Finally, the results showed a significant correlation between rainfall and E. coli concentrations in sea urchins, suggesting that the bacterial safety of sea urchin could be linked to the quality of the surrounding water.