Several related pieces of news today from the International Conference on Emerging Infectious Diseases:
- The number of people who are dying from illnesses that involve vomiting and diarrhea more than doubled between 1999 and 2007, and most of the increase was due to Clostridium difficile.
- Disease outbreaks caused by imported foods are rising, and tainted foods are coming into the United States from a wider array of countries than before.
The first piece of news comes from a presentation by Dr. Aron Hall of the Centers for Disease Control and Prevention that examined data from the National Center for Health Statistics that was coded for certain specific causes of death. Over those 8 years, all gastroenteritis deaths doubled both in raw numbers and as a rate, rising from 7,000 to 17,000 deaths per year and from 25 per 1 million person-years to 57 per 1 million; 83 percent of the deaths occurred in adults who were at least 65.
The vast majority of the deaths were due to the devastating intestinal bacterium C. difficile. C. diff deaths, which Hall said represent 71 percent of all gastroenteritis deaths, increased five times over: from 2,700 to more than 14,000, and from 10 per 1 million person-years to 48 per 1 million. Some of that increase may be due to increased recognition of C. diff and better diagnosis, Hall said during his presentation. But he added: “There has likely also been a real increase in C. diff-associated deaths due to the emergence of a hyper-virulent strain” that also possesses antibiotic resistance.
In contract, norovirus — the sudden-onset, highly contagious vomiting illness that many people associate with cruise ships — accounted for only 7.1 percent of all deaths, or 797 in the last year counted (equivalent to 3 per 1 million person-years). Though the numbers for norovirus are far lower than for C. diff, Hall said, they nevertheless peg norovirus as the second most common cause of US deaths from gastroenteritis.
In a separate presentation, epidemiologist Hannah Gould, Ph.D. described findings from an analysis of data reported by state health departments into the CDC’s Foodborne Disease Outbreak Surveillance System.
The analysis covered 39 outbreaks, involving 2,348 illnesses, that occurred between 2005 and 2010. (Other outbreaks undoubtedly occurred but were not detected, the CDC said.) The culprit foods were fresh and processed; some had been sold commercially and a few were “souvenir” foods such as fish that someone had caught on vacation and brought back to the US. Fish accounted for 17 (45 percent) of the outbreaks, and spices and seasonings for six (15 percent). In 16 of the outbreaks (43 percent), the culprit foods came from Asia; in 11 (30 percent), the source was Latin America.
The contaminated foods came from 15 countries, and almost half of them had never before been reported to be sources of contamination. The occurrence of contamination seemed to be rising: Between 2005 and 2008, imported-food outbreaks were only 1 percent of all US foodborne outbreaks, but in 2009 and 2010, they represented 2.5 percent.
In an indication of how complex the food system has become, 10 (25 percent) of the outbreaks involving imported foods caused illness in several states at once; for comparison, Gould said, that happens with only 1 percent of homegrown outbreaks. Consumers might not even know they were eating an imported food, she pointed out. Of the outbreaks that involved seasonings, she said before her presentation, “three involved jalapeno peppers or serranos, two involved dried peppers, and one outbreak was due to a spice coating on a snack food. That’s one thing that was interesting, that many outbreaks were due to foods that were themselves ingredients in other foods.”
The CDC undertook the analysis because the new Food Safety Modernization Act gives the Food and Drug Administration additional powers over imported foods and food contaminants, Gould said. She added: “When we look at foodborne disease overall, we’re looking at potential points of contamination along the spectrum from farm to table. Overall, our data point to different moments where interventions might be helpful in preventing illness, by giving us some information about where contaminated foods are coming from.”
- Hall AJ et al. “Gastroenteritis deaths on the rise in the United States: The emerging roles of Clostridium difficile and norovirus.” 8th International Conference on Emerging Infectious Diseases, Atlanta Ga. March 14, 2012.
- Gould LH et al. “Foodborne disease outbreaks associated with food imported into the United States, 2005-2010.” 8th International Conference on Emerging Infectious Diseases, Atlanta Ga. March 14, 2012.