September 4, 2008
Ocean Springs, MS - Not all killers in the ocean have razor sharp teeth or venomous poison. In fact, some are so small that even under a microscope they would never appear intimidating.
Such is the case with Vibrio parahaemolyticus (Vp), naturally occurring bacteria found in oysters. Oysters are prized for their taste and health benefits, but they can also come with significant risk to certain consumers.
If oysters containing Vp are harvested and not kept on ice, the Vp levels can increase. If Vp levels reach high enough densities, they can cause serious illness in consumers, especially those with preexisting heath conditions such as diabetes, liver disease, or immune system deficiencies. In some cases Vp can even cause death. Recreational swimming, fishing, or other water activities in Vp infected water can also pose a threat. In the wake of Hurricane Katrina, there were 22 vibrio wound infections reported, 3 of which were caused by Vp, and 2 of these led to death.
In order to assuage the risks of Vp, the U.S. Food and Drug Administration (FDA) developed an experimental prediction model that uses water temperature and salinity to estimate Vp densities. While this effort was a good start, it wasn’t enough.
In 2003, the Gulf Coast Research Lab at The University of Southern Mississippi began taking the prediction methods a step further. The vision was to provide real-time data about the risks of Vp, with the ability of displaying the risk areas on a map. Dr. Jay Grimes, a professor in the Department of Coastal Sciences at the GCRL, is leading the efforts of this project. Grimes received his PhD in microbiology, and has long been involved in the study of marine bacteria.
Through collaboration with federal and state agencies, GCRL is utilizing water temperature and other data provided by satellites, to map the risk conditions for Vp. Measuring the water temperature data remotely brings significant benefit in that vital information can still be obtained when conditions (e.g., weather, remoteness) prohibit sending boats and people out to physically monitor the water conditions. The data provided by satellite is physically compared to conventional thermometer measurements to ensure its accuracy. By verifying the integrity of the satellite data, GCRL is able to ensure a continuous stream of precise data in oyster-harvesting waters.
So how does it work? GCRL researchers take data points from NASA’s MODerate resolution Imaging Spectroradiometer (MODIS). They then factor these MODIS data points into the risk model (equation) developed by the FDA. When combined, this information makes incredibly useful maps illustrating water temperature color grids, which can then be used to plot the Vp risk levels on a second map.
GCRL scientists are also working to understand the characteristics of Vp better. How do humans contract the bacteria? What about these natural marine organisms cause them to enter the human body? How does Vp fit in with the overall food chain of the gulf, and how do they interact with their environment? These are just some of the questions Grimes and the GCRL scientists work hard at answering.
The ultimate goals of the Vp research project are to better understand the risk conditions of Vp infection, and to increase public awareness of how to avoid it. “Our objective is to provide a service to the public regarding water safety in the gulf coast,” said Dr. Jay Grimes. “We are all proud of the Gulf of Mexico and its bountiful resources, and anything we can do to remove people from risks such as Vp in the gulf is a good thing.”
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