Getting sick from pathogens in food

Surveillance is one of the least sexy and most vulnerable of public health functions. It has only a small constituency and its voice is only faintly heard in the clamor that ensues when budgets for essential services are cut. But surveillance is also one of the most important functions in public health, alerting us to new threats and serving as a benchmark for existing efforts. If we had better surveillance we would know much more about influenza than we do now. What you don't know, can hurt you, as everyone knows.

We also have remarkably little knowledge of foodborne and waterborne disease incidence in the US. It's a difficult problem, of course. How many people see a doctor when they have diarrhea, cramps or a couple of hours of queasiness? They go to the drugstore and buy over-the-counter medications. If they do call a health care provider, that's what they are told to do anyway. But usually they only seek medical care if they are seriously ill or sick for an unusually long time. For diarrhea, that might mean having it for weeks or months. When they seek care, it is treated symptomatically and if that doesn't succeed, perhaps a stool culture ordered. Unless specific directions are given (look for ova and parasites or look specifically for cryptosporidium, say) important food or waterborne agents will be missed. It is estimated that less than 1% of possible cases of food or water related disease receives a diagnostic work-up. Of these, only a fraction identify specific organisms. Of these, even if part of a large outbreak, only some identify a source.

FoodNet is one of the few examples of an active foodborne disease surveillance system. FoodNet collects population-based data on laboratory-confirmed diagnoses of a handful of organisms important in foodborne illness. It began in 1996 and now incorporates a network of clinical laboratories and hospitals whose diagnostic services cover about a 5% of the US population. It recently released preliminary data for 2005.

In 2005, FoodNet sites reported 205 foodborne disease outbreaks to the national Electronic Foodborne Outbreak Reporting System; 121 (59%) were associated with restaurants. Etiology [causal organism] was reported for 159 (78%) outbreaks; the most common etiologies were norovirus (49%) and Salmonella (18%). (CDC)

If you multiply the numbers by twenty you'll get a rough estimate of the number of detected outbreaks for the country as a whole. However there is a bias toward larger and more serious outbreaks, since they are more likely to come to the attention of public health officials. Thus we are just seeing the tip of the iceberg. In addition, it is generally thought that considerable foodborne illness also occurs from food prepared at home. Modern methods of industrial agricultural production provide us with abundant, but not necessarily pathogen free, food. Our food safety system, after an initial improvement in the late 1990s, began moving backward again in 2001. From the CDC report:

In 2005, compared with the 1996--1998 baseline period, significant declines occurred in the estimated incidence of Campylobacter, Listeria, Salmonella, Shigella, STEC O157, and Yersinia infections. Several important food safety initiatives might have contributed to the declines, indicating progress toward meeting the national health objectives. However, most progress occurred before 2005. Most of the decline in Campylobacter incidence occurred by 2001, with continued small decreases since then. The incidence of Listeria infections in 2005 is higher than its lowest point in 2002. Of the five most common Salmonella serotypes, only Typhimurium has declined, with most of the decline occurring by 2001. Most of the decline in STEC O157 [E. coli "Jack in the Box" organism] incidence occurred during 2003 and 2004. The observed sustained increase in Vibrio incidence indicates that additional efforts are needed to prevent Vibrio infections. Oysters are the most important source of human Vibrio infections, and most human infections can be prevented by not eating raw or undercooked oysters. Measures that reduce Vibrio contamination of oysters also prevent illness.

Food animals are the most important source of human Salmonella infections. Transmission of Salmonella to humans can occur via various food vehicles, including eggs, meat, poultry, and produce, and via direct contact with animals and their environments. Testing by the U.S. Department of Agriculture, Food Safety and Inspection Service (FSIS) at slaughter and processing plants has demonstrated declines in Salmonella contamination of ground beef since 1998 (4). However FSIS recently announced a sustained increase in chicken-broiler carcasses testing positive for Salmonella during 2002--2005 and subsequently launched an initiative to reduce Salmonella in raw meat and poultry products.

Since the diversion of time, effort, energy and money to other matters, food safety has declined. It's not just a choice between Guns and Butter. Butter is a luxury item. We also lose the necessities. Clean food, water and air.

Guns or clean food. You choose.