Food Protection Connection: Foodborne Illness: Where Do We Stand?

(reprinted from Dietary Manager, June 2008)

With food recalls and illness outbreaks making headlines routinely, you may wonder exactly how we rank today in the battle to stem the tide of foodborne illness (FBI). If so, you’re not alone. The surveillance arm of the Centers for Disease Control (CDC), called FoodNet, is charged with answering that question through ongoing data collection and analysis. On April 11, 2008, FoodNet released its latest report—and concluded that goals for reducing FBI in the US were not met in 2007. Scientists noted, “Although significant declines in the incidence of certain foodborne pathogens have occurred since 1996, these declines all occurred before 2004.” (MMWR Weekly, April 11, 2008.) Here are some highlights.

What’s Up

Cases of FBI from Cryptosporidium are up by 44 percent. Experts say, however, that this bump in the numbers could reflect an increase in diagnostic testing. (Doing more tests means finding more cases.) Cryptosporidium is a protozoan (parasite) that tends to inhabit herd animals such as cows. As few as 10 organisms can cause an infection, which may be totally asymptomatic, or may lead to severe diarrhea, fever, weight loss, and sometimes pulmonary symptoms. The FDA explains, “Cryptosporidium could occur, theoretically, on any food touched by a contaminated food handler. Incidence is higher in child day care centers that serve food. Fertilizing salad vegetables with manure is another possible source of human infection. Large outbreaks are associated with contaminated water supplies.” (FDA. Bad Bug Book)

Cryptosporidium is by no means a new pathogen, but only in the past few decades has it emerged as a cause of human illness. Most of the cases in earlier years were among severely immuno-compromised individuals and patients with AI DS. A majority of early cases led to prolonged diarrhea, and nearly half resulted in death. Some of today’s illnesses trace back to fresh produce, where contamination of fields and/or water with animal manure may contribute to the spread of illness. The organism resists chlorine, so it can be challenging to control fully in drinking water supplies and recreational pools. Handwashing among both foodservice workers and customers is one of the most recommended steps for avoiding the spread of illness.

Cases of Salmonella Newport infection were up as well. FoodNet tracked seven Salmonella strains for 2007. Illness from two declined, and the others were more or less unchanged. Newport is among the newer threats in the Salmonella family, a bug that has emerged as a multi-drug resistant strain, i.e., it stands up against many antibiotics. This new player was first associated with ground beef when an outbreak blasted through five states in 2002 (see Food Protection Connection, Nov./Dec. 2002). Like antibiotic- resistant germs, it is particularly virulent, making people sicker, and is more likely to cause death.

What’s Down

FBI from two strains of Salmonella decreased in 2007. These were Salmonella Typhimurium and Heidelberg. For other pathogens, although FoodNet reported no significant drop in 2007, scientists did note that illness from many bacteria (Yersinia, Listeria, Shigella, Campylobacter, and most Salmonella) has dropped in comparison with rates of illness a decade ago. In other words, improvements in these areas have leveled off for now.

What’s Next

The FoodNet report highlights two areas for attention in coming months. First, from a look at large-scale food contamination leading to outbreaks, FoodNet officials stated, “Outbreaks caused by contaminated peanut butter, frozen pot pies, and a puffed vegetable snack underscore the need to prevent contamination of commercially produced products.”

Reducing contamination of fresh meat is a priority as well, according to the report. Since the USDA launched a Salmonella initiative in 2006, presence of Salmonella contamination in broiler chicken carcasses has dropped from 16.3 percent (2005) to 8.5 percent (2007). Ground beef commands attention, too, as there were 21 beef production recalls due to E. coli contamination in 2007; 10 were linked to outbreaks. The FoodNet report notes this trend is on the upswing.

Tracking trends is important not only to health officials, but to dietary managers as well. In a HACCP-based approach, we can target known areas of risk—such as Cryptosporidium trans-mission through unwashed hands, E. coli transmission through contaminated and undercooked beef, and Salmonella transmission through contaminated and undercooked chicken— and then set control points and critical control points in the flow of food to protect customers.

Inside FoodNet

FoodNet, more officially called the Foodborne Diseases Active Surveillance Network of the CDC, works to determine the extent of foodborne illness in the US, identifying sources of illness, quantifying illness, and identifying patterns and trends. Through data collection and analysis, FoodNet provides the basis for spotting emerging concerns and planning interventions. Its ongoing surveillance system works within 10 states representing 15 percent of the US population. The system is not comprehensive, in that it does not monitor FBI caused by viruses, such as Norwalk or hepatitis. It does cover seven bacteria: Campylobacter, E. coli (STEC), Listeria, Salmonella, Shigella, Vibrio, and Yersinia; and two parasites: Cryptosporidium and Cyclospora.

A crucial aspect to FoodNet is its proactive approach. In its own words, “Current passive surveillance systems rely upon reporting of foodborne diseases by clinical laboratories to state health departments, which in turn report to CDC. Although foodborne diseases are extremely common, only a fraction of these illnesses are routinely reported to CDC via these surveillance systems. This is because a complex chain of events must occur before such a case is reported, and a break at any link along the chain will result in a case not being reported. FoodNet is an active surveillance system, meaning public health officials frequently contact laboratory directors to find new cases of foodborne diseases and report these cases electronically to CDC. In addition, FoodNet is designed to monitor each of the events that occur along the foodborne diseases pyramid, and thereby allow more accurate and precise estimates and interpretation of the burden of foodborne diseases over time.”

Sue Grossbauer, RD, author of several books, and a regular contributor to DIETARY MANAGER magazine.