<p><br> Here's a pearl of wisdom: Sniff after you shuck, and swallow only when you're certain. Of the riskiest foods regulated by the U.S. Food and Drug Administration, raw oysters rank high for their outbreak-causing potential. The two pathogens wreaking the most havoc are Norovirus (which can cause gastroenteritis) and Vibrio, a bacterium related to cholera that can cause fever, septic shock, blistering skin lesions, and even fatal septicemia.</p>