Investigators from the US Centers for Disease Control and Prevention (CDC) presented major findings last week at the International Conference on Emerging Infectious Diseases (ICEID) showing the number of US gastroenteritis deaths has more than doubled in 8 years. Clostridium difficile and norovirus are the leading causes.

CDC scientists used data from the National Center for Health Statistics to identify gastroenteritis-associated deaths from 1999 to 2007 among all age groups in the United States. Over the eight-year period, gastroenteritis-associated deaths from all causes increased from nearly 7,000 to more than 17,000 per year. Adults over 65 years old accounted for 83 percent of deaths.

C. difficile, which cause diarrhea, accounted for two-thirds of the deaths. Much of the recent increase in the incidence and mortality of these bacteria is attributed to the emergence and spread of a hypervirulent, resistant strain of C. difficile.

The highly contagious Noroviruses are the most common cause of gastroenteritis in the United States and the leading cause of infection outbreaks in U.S. hospitals. The study associated about 800 deaths annually, with more deaths in peak years experiencing a new virus strain. The CDC estimates more than 20 million cases of acute gastroenteritis are caused by Noroviruses each year. That translates to about 1 in every 15 Americans getting the illness annually.

“While C. difficile continues to be the leading contributor to gastroenteritis-associated deaths, this study shows for the first time that norovirus is likely the second leading infectious cause,” said lead author Aron Hall, D.V.M., M.S.P.H., of the CDC’s Division of Viral Diseases. “Our findings highlight the need for effective measures to prevent, diagnose, and manage gastroenteritis, especially for C. difficile and norovirus among the elderly.”