Every summer, the news reports on a bacterium called Vibrio vulnificus found in warm saltwater that causes people to get sick, or die, after they eat raw tainted shellfish or when an open wound comes in contact with seawater. People with a weakened immune system, chronic liver disease or iron overload disease are most at risk for severe illness. Vibrio vulnificus infections in high-risk individuals are fatal 50 percent of the time. Now, researchers at UCLA have figured out why those with iron overload disease are so vulnerable. People with the common genetic iron overload disease called hereditary hemochromatosis have a deficiency of the iron-regulating hormone hepcidin and thus develop excess iron in their blood and tissue, providing prime growth conditions for Vibrio vulnificus.