At every step along the way, some of those chickens were infected with salmonella, a pathogen that lives in the intestinal tracts of birds and other animals and can easily spread. Invisible, tasteless and odorless, it doesn’t make the chickens sick. But transferred to humans, it can lead to salmonellosis — an infection that causes diarrhea, fever and stomach cramps, and, in severe cases, can spread from the intestines to the bloodstream.
It sickens an estimated 1 million people annually, and is the most commonly reported foodborne illness. The incidence of salmonella infection has remained stubbornly high even as foodborne illnesses have been dropping over the past 15 years. Included among those that have declined is listeria, although that pathogen has been implicated in the current deadly outbreak of infections from cantaloupe traced to a farm in Colorado. More than 70 people in 18 states have gotten ill so far, and at least 15 have died.
A look at how the nation’s food safety system operates in the case of salmonella-infected poultry shows how a combination of industry practices and gaps in government oversight results in a fractured effort that leaves the ultimate responsibility for safe food with the consumer.
Food safety experts and poultry scientists say that salmonella control must start on the farm, but federal food safety inspectors never set foot there. The Agriculture Department’s Food Safety and Inspection Service lacks the legal authority to test for salmonella on farms or to require farmers to have a food safety plan.
As a result, attempts to prevent salmonella are done voluntarily by farmers or because poultry processing companies ask them to — leading to a patchwork of efforts, some of which work better than others.
For instance, vaccinating the hens used in breeding can reduce — but not eliminate — the incidence of salmonella in their offspring, researchers found by testing chickens before slaughter.
While vaccination has been on the rise over the past two years, the practice has not been widely embraced by the poultry industry, largely because of its cost and varied efficacy. Among those breeding operations that do vaccinate their birds, the number of doses given and the strains of salmonella that are targeted vary widely.
Live birds are almost never tested for salmonella. And because the bacteria do not make the birds sick, they show no signs of being infected.
As a result, farmers don’t know whether their chicks have salmonella — and, if they do, how widespread the infection is — or whether their interventions have been effective.
This moves the onus of killing the pathogen later down the line.