WEDNESDAY, March 14 (HealthDay News) -- In recent years, deaths resulting from the common stomach and intestinal illness known as gastroenteritis have more than doubled in the United States, a new report reveals.

Infections involving one of two germs in particular -- C. difficile or norovirus -- seem to be driving the trend.

Researchers at the U.S. Centers for Disease Control and Prevention (CDC) report that between 1999 and 2007 the total number of deaths resulting from the vomiting and diarrhea that characterizes the illness rose from about 7,000 to more than 17,000.

"The message here is that clearly this is not just a problem in the developing world," noted study lead author Aron Hall, an Atlanta-based epidemiologist in the CDC's division of viral diseases. "Diarrhea is an important problem in the U.S., particularly among the elderly, and it seems to be worsening in recent years."

According to the study, 83 percent of all observed deaths from gastroenteritis in the United States now occur among adults over the age of 65.

Using data gleaned from the National Center for Health Statistics, the team found that most such deaths are now attributable to two types of bacteria: Clostridium difficile( C. difficile) and norovirus.

C. difficile is particularly troubling, the authors said, because deaths attributed to this germ rose by a factor of five over the course of the study period -- C. difficile infections led to 2,700 deaths in 1999 but by 2007 that figure had risen to 14,500.

By 2007, C. difficile infections made up two-thirds of all fatalities from gastroenteritis, with the highest incidence of related deaths occurring during the spring (March to May).

The observation builds on concerns raised just last week, when experts speaking at a CDC news conference warned that patients being treated at a variety of clinical settings -- hospitals, nursing homes, doctors' offices, and/or clinics -- are at a "historically high" risk for infection with C. difficile.

But Hall and colleagues also found another culprit in the rising death rate, norovirus, which was linked to roughly 800 deaths per year.

What's more, the number of gastroenteritis fatalities tended to climb much higher during years in which new strains of norovirus led to outbreaks.

And while C. difficile infections are more deadly, the team pointed out that the highly contagious norovirus is a major year-round public health threat in its own right. It is easily spread via contaminated food, water, surfaces and person-to-person contact, and has become especially notorious because of outbreaks on cruise ships. As a result, norovirus is now the number one cause of gastroenteritis illness (but not deaths) in the United States, with over 20 million infections thought to occur each year, the researchers said

What accounts for these worrisome trends? "It's in part due to the emergence of new, virulent strains," Hall believes. "And also an increased recognition on the part of doctors, who have come to recognize this is an important issue. So as a result we're getting more diagnoses," he added.

"But now that we've identified C. difficile and norovirus as the most common causes for gastroenteritis, we know that when an elderly person has diarrhea those are the bugs to be concerned about," he continued.

To minimize your infection risk, "hand hygiene is important," Hall said, "along with environmental disinfection. And in hospitals, the use of cleaning services and bleaching products is critical."

Dr. Philip Tierno, director of clinical microbiology and immunology at New York University Medical Center in New York City, agreed.

"Hygiene is the most important preventive measure," he said. "That means good food hygiene, with cutting boards and countertops being sanitized properly. And good home hygiene, by cleaning toilets and sinks. And also personal hygiene: the best thing you can do is wash your hands with soap and water. For C. difficile it doesn't kill the organism, but it allows it to fall off your hands into the sink if you've contaminated yourself by going to a medical facility. And you should always wash your hands before touching your face, or before eating or drinking," Tierno stressed.

"That is the triplet of hygiene," said Tierno. "And that will certainly help lower risk."

The study findings are slated for presentation Wednesday at the International Conference on Emerging Infectious Diseases in Atlanta. Research presented at medical meetings should be viewed as preliminary until published in a peer-reviewed journal.

More information

Find out more on gastroenteritis at the U.S. National Library of Medicine.