As of yesterday, the U.S. Food and Drug Administration announced that there have been 183 cases of food borne illness caused by exposure to the noxious bacterium E. coli O157:H7. So far, 95 people have been hospitalized, 29 of whom are suffering from Hemolytic Uremic Syndrome (HUS). One person has died from the illness. The outbreak has been traced to pre-washed spinach from a packing plant of California produce grower Natural Selection Foods which markets the Earthbound brand. In this case, Natural Selection packed the spinach for the Dole food company.
The first outbreak of the O157:H7 strain that came to national attention was traced to two McDonald's restaurants in February, 1982 in Medford, Oregon. Twenty-six diners fell ill after eating McD's burgers. Three months later 21 patrons at a McDonald's in Traverse City, Michigan became ill. Before those outbreaks, only one case of O157:H7 had been identified, in 1975. Since then there have been nineteen outbreaks that have come to the attention of media and regulators. Most notorious was the outbreak in 1993 in which 600 people fell ill from eating undercooked hamburgers at Jack-in-the-Box restaurants in Washington State. Four children died in that case. The most recent incident occurred in October of last year when nearly two dozen people apparently became infected with E. coli O157:H7 from eating pre-packaged salads from Dole. All in all—the most recent outbreak would be the fifth traced to produce grown in the Salinas Valley since July 2002. The sources of the O157:H7 bacteria were never found in those prior instances.
In the current case, initial suspicion fell on organic spinach since it is often fertilized using cow manure. Cow manure needs to be composted for nearly a year before being applied in fields, to ensure that the deadly microbes are destroyed. However, the suspect spinach was grown using conventional fertilizers. One plausible scenario suggests that cow manure somehow contaminated water used to irrigate the spinach.
Cows naturally harbor the bacteria. Tests show that it is likely that 100 percent of all cattle herds have been exposed to O157:H7. Some critics argue that grain-fed as opposed to grass-fed cattle are more susceptible to the pathogenic version of E. coli. (This claim is often cited by boosters of organic agriculture who are against raising cows in feedlots.) Evidence for this contention is found in a study done by Cornell University scientists in 1998. However, a year later researchers at the University of Idaho found the opposite. The science on this issue is far from settled.
All the speculation may be moot because the contamination may well have not taken place in the field. So far all of the bags of spinach appear to have been processed during the same shift on August 15 at a Natural Selection Foods plant in San Juan Bautista, Calif. The outbreak could be the result of something as simple as a mildly infected worker failing to wash his or her hands after using the bathroom.
So how big a problem is foodborne illness? In 2000, researchers at the U.S. Centers for Disease Control and Prevention (CDC) estimated that "foodborne diseases cause approximately 76 million illnesses, 325,000 hospitalizations, and 5,000 deaths in the United States each year." That sounds pretty bad. But let's give those numbers a bit of context. In 1900, six years before Upton Sinclair wrote his great muckraking book, The Jungle, about the filthy conditions in the meatpacking industry, the death rate from gastritis, duodentitis, enteritis, and colitis was 142.7 people per 100,000. It is likely that most people experienced bouts of intestinal distress several times a year. Today, accepting CDC calculations of 5000 deaths per year implies a hundred-fold reduction, to just 1.4 deaths per 100,000 people. Additional good news is that the incidence of many foodborne illnesses continues to decline according to the CDC's FoodNet surveillance network established in 1996. In its 2005 report, the CDC found that the incidence of O157:H76 infections had fallen by 29 percent from the 1996-98 level.
Efforts to reduce the incidence of foodborne illnesses began almost as soon as Louis Pasteur nailed down the germ theory of disease. Consider that New York City was supplied with milk from 40,000 different dairies at the end of the 19th century and their standards of hygiene were not high. So in 1893 New York City philanthropist Nathan Straus established "milk depots" that offered low-priced pasteurized milk to city residents. Straus' milk depots dramatically reduced the death rates from typhoid and tuberculosis in the city's children. The public health movement took off as well and food safety regulations were widely adopted. Prior to the 20th century, most food was produced on small family farms and sold by individual grocers and butchers in local markets.
Critics decry modern outbreaks of foodborne illness as the alleged consequence of "factory farming." However, the demise of small family farms over the past century has coincided with a substantial reduction in foodborne illnesses. In 1900, 30 million farmers (nearly 42 percent of the country's population) lived on 5.7 million farms. By 2002, only 1.9 million (less than 1 percent of the population) Americans described farming as their primary occupation and they worked on 2.1 million farms, half of which are under 100 acres in size. Also during the 20th century, the rise of national and regional grocery chains and industrial food processors saw dramatic improvements in overall food safety. Such companies had a lot more to lose if urban dwelling consumers believed that the companies were poisoning them. Natural Selection Foods is learning this lesson now. And it must be said that more centralized food production and distribution also enabled more effective regulatory oversight.
What about the future? I suspect that new tracking technologies such as radio frequency identification tags will enable faster identification of problematic foodstuffs and thus permit more targeted warnings and recalls. Finding that a few bags of spinach or carrots or whatever are contaminated will not mean that every bag has to be tossed into the garbage. In addition, it may be possible to control E. coli O157:H7 by vaccinating cows so that they shed less of the bacteria. Or perhaps not. It is not much comfort to the scores of people suffering through this latest outbreak, but most evidence indicates that our food supply is becoming safer, not more dangerous. In other words, don't panic, but be sure to cook that spinach and those hamburgers well.
Disclosure: I grew up on a family dairy farm (dairy farms = prisons without walls) and I own no stock in any food companies, but I do eat too much sometimes. I also had a bout with Norwalk virus picked up a salad bar in Montana a couple of years ago.