Not your great-grandmother’s botulism

My bedside reading this week was Emerging Pathogens in Meat and Poultry, a new study from the Pew Charitable Trusts that tries to capture just where we are in the eternal battle between people and the bacteria, viruses, parasites, and prions that infest the food we eat.

The title may suggest a simple laundry list of foodborne bad guys that you’ve never heard of (and there are certainly a few of them in there), but the report itself is far subtler. “Emerging,” it turns out, is a fairly complicated idea.

For me, the biggest surprise in the report was how slowly our knowledge of foodborne pathogens has evolved. We’re so used to thinking about the major foodborne pathogens—salmonella, listeria, E. coli—that it’s easy to forget that their role in human disease is a relatively recent discovery, in many cases dating back only to the 1960s and 1970s.

The prototypical example: It was 1975 when scientists first isolated the strain of E. coli known as O15:H7, but it wasn’t until seven years later, in 1982, that the Centers for Disease Control and Prevention (CDC), responding to a pair of outbreaks associated with ground beef, identified the strain as a foodborne pathogen. You know the rest of the story: In 1993, O15:H7 in undercooked hamburgers at the Jack in the Box restaurant chain sickened more than 500 people, and four children died. The government finally took decisive action, declaring the pathogen an adulterant (which meant that meat found to contain the bug couldn’t be sold) and instituting the Hazard Analysis and Critical Control Point (HACCP) system of food safety, which transformed U.S. food production.

The report is filled with stories of slowly emerging understanding. This is the most striking: “In A.D. 900,” the authors explain, “Byzantium’s Emperor Leo VI forbade—under threat of exile and loss of all possessions—the making and eating of blood sausage, prepared in pigs’ stomachs and then smoked. It was believed that miasmas, or infectious vapors, emitted from the sausages would result in a paralytic infection. This disease was called ‘botulism,’ after ‘botulus,’ the Latin word for sausage. Botulism’s true cause, a toxin produced by a bacterium named Clostridium botulinum, would not be discovered until 1895, when Emile Pierre van Ermengem at the University of Ghent in Belgium studied an outbreak associated with smoked ham.” A thousand years to figure out a known pathogen. Thank God we are a bit more nimble today.

But we shouldn’t be complacent: O15:H7 is what’s known as a Shiga toxin-producing E. coli (STEC), and it’s far from the only one. More than 100 strains of STEC are known, and outbreaks linked to non-O15:H17 strains of STEC have been rising sharply over the past ten years—probably at least in part because of increased attention on the part of food safety agencies. In 2011 USDA added six additional strains of STEC to its list of adulterants, including O111, a strain that is linked with hemolytic uremic syndrome, a disease marked by destruction of red blood cells and acute kidney failure. More are undoubtedly on the way, both because scientists will discover new pathogenic strains (or will link known ones to diseases they cause), and because strains will evolve to become more pathogenic, more virulent, or more drug resistant.

And new links between pathogens and disease continue to be made.