Monster Seminar JAM - The distinctive ecology and population structure of Vibrio parahaemolyticus in the Pacific Northwest: Implications for Risk Assessment and Early Warning Systems
Dr Rohinee Paranjpye, Northwest Fisheries Science Center, NOAA Fisheries
Vibrio parahaemolyticus is responsible for nearly 50% of Vibrio-related infections in the United States. The majority of infections are acquired by ingestion of raw or undercooked shellfish such as oysters that harbor the bacterium, resulting in a severe but self-limiting gastroenteritis. Over the past decade there have been significant increases in Vibrio parahaemolyticus-related illnesses in some years from consumption of raw oysters harvested from shellfish growing areas in Washington State. Current risk assessment models are based on the presence or absence of two potential virulence genes, tdh (encoding the thermostable-direct hemolysin) and trh (encoding the thermostable-related hemolysin). However, extensive monitoring and analyses of oysters by the Washington State Department of Health (WDOH), along with modifications in post-harvest handling of oysters by shellfish growers, has shown little or no correlation of illnesses with the presence or concentrations of tdh+/trh+ V. parahaemolyticus in oysters harvested from the Pacific Northwest.
We are investigating the influence of environmental variables on concentrations of potentially pathogenic and avirulent strains of V. parahaemolyticus in oysters as well as in water and plankton, focusing on harvest areas with historically higher incidences of the bacteria. In addition we are examining the association of V. parahaemolyticus with co-isolated phytoplankton species. Finally we are comparing the genetic diversity of environmental and illness-associated V. parahaemolyticus strains from the Pacific Northwest to a strain representative of the pandemic complex as well as strains from other geographic regions. Through this work, we hope to gain a better understanding of the spatial, temporal, environmental, and bacterial genetic relationships that promote the selection of strains responsible for clinical V. parahaemolyticus infections, which may assist in the improvement of risk assessment strategies, early warning systems, and mitigation tools to prevent disease outbreaks.
Date and Time:
May 6, 2010,
11:00 am - 12:00 pm