Evaluation of Methods for Extraction of Enteric Virus from Louisiana Oysters.

Six techniques were evaluated for recovery of poliovirus from Louisiana oysters. The methods were compared for percent recovery rates, toxicity, ease of extraction, bacterial contamination, and final volume of oyster concentrate. Oyster samples were contaminated with 30-40 plaque forming units of Poliovirus type 1 and processed by six variations of adsorption-elution-precipitation and elution-precipitation methods. The method developed by Ellender et al. (Natural enterovirus and fecal coliform contamination of gulf coast oysters. J. Food Prot. 43:105-110) was judged to be the preferred method for gulf coast oysters.

Detection of Enteroviruses and Bacterial Indicators and Pathogens in Louisiana Oysters and Their Overlying Waters.

Field studies were conducted for 1 year to determine levels of enteroviruses in Louisiana Gulf Coast oysters and their overlying waters. Levels of human enteric viruses were compared with bacterial pathogens ( Salmonella and Vibrio parahaemolyticus ), fecal coliform levels, and physicochemical water parameters (pH, salinity, temperature, and conductivity). Samples of 20-30 oysters and 380 L of overlying water were collected monthly from both "open" and "closed" oyster growing areas. Enteric viruses were found predominantly in January and February. Viruses were isolated only from areas which exceeded the 14 fecal coliforms/100 ml standard for shellfish harvesting waters.