March 16, 2012 -- The number of Americans who died from gastroenteritis, most commonly caused by stomach bugs, more than doubled between 1999 and 2007, a new study from the CDC shows.

Researchers found that people aged 65 and older were the hardest hit: They accounted for 83% of all deaths from gastroenteritis.

Gastroenteritis refers to an inflammation of the stomach and intestines. Symptoms include cramps, nausea, vomiting, and diarrhea. It's a common illness that usually lasts just a few days, but it can leave people feeling weak and miserable.

Infection with a stomach "bug" may lead to severe dehydration, and can sometimes be serious in children, the elderly, and people with other health conditions.

For the study, researchers looked at data from the National Center for Health Statistics to determine the number of deaths linked with gastroenteritis over an eight-year period in the U.S. During this time, the number of deaths more than doubled, jumping from nearly 7,000 a year at the beginning of the study to more than 17,000 a year by 2007.

These findings were recently presented at the International Conference on Emerging Infectious Diseases 2012 in Atlanta.
2 Common Culprits

Clostridium difficile , a type of bacterium also known as C. diff, was the most common cause of gastroenteritis deaths over the eight-year period. Those deaths most frequently occurred between March and May.

Deaths from C. diff increased fivefold, from roughly 2,700 a year to 14,500 annually. Researchers suspect this large jump is due to the emergence and spread of highly resistant strains of the bacterium.

Norovirus, sometimes described as the "cruise ship virus," claimed an average of nearly 800 lives a year. Those deaths peaked in the winter between December and February.

Whether on the high seas or on land, this highly contagious virus can spread rapidly from person to person in crowded, confined places. Norovirus outbreaks can also occur in close-contact settings, such as day care centers, college dorms, long-term care facilities, and hospitals. It's transmitted by having contact with an infected person or by drinking or eating contaminated foods and liquids.

"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," says Aron Hall, DVM, an epidemiologist in the CDC Division of Viral Diseases, in a news release.

"By knowing the causes of gastroenteritis-associated deaths and who's at risk, we can develop better treatments and help health care providers prevent people from getting sick," he says.

These findings were presented at a medical conference. They should be considered preliminary as they have not yet undergone the "peer review" process, in which outside experts scrutinize the data prior to publication in a medical journal.