Why all the recalls, illnesses and even deaths around the country over the past few months linked to a microscopic organism-Listeria monocytogenes-that normally gets little attention?
As of March 20, 21 people had died nationwide and about 100 had been sickened by listeriosis associated with certain batches of hot dogs and deli meats produced by Bil Mar Foods, a Michigan subsidiary of Sara Lee Corp.
(A federal grand jury in Grand Rapids, Mich., has started an investigation of Bil Mar, a Sara Lee spokeswoman said March 19. The U.S. Department of Agriculture’s Inspector General also has launched an investigation of the outbreak’s origins. The agency’s Food Safety and Inspection Service already is examining the Zeeland, Mich., plant.)
Other recent listeria-linked recalls have involved a Washington brand of franks and knockwurst, a national brand of chicken burritos, another company’s meat and poultry products and some milk, though except for one case, no illnesses have been connected to them.
A microbe many people never heard of suddenly seems to be invading more of our food supply. Is this really the case? Or are we just getting smarter about detecting and reporting it?
“We don’t know.”
That answer came up several times when we asked experts why we’re seeing more listeria.
“It could just be coincidence,” said Washington state epidemiologist John Kobayashi. Also, the illness detection and reporting systems-including high-tech DNA “fingerprinting”-are improving, he said. But the possibility that listeria really is on the rise, or that inspection systems are falling short, can’t be ruled out.
Listeriosis can be dangerous to the elderly, infants, pregnant women and people with impaired immune systems, and can cause miscarriages, stillbirths and meningitis.
If you’re a healthy adult and not in one of those groups, you probably wouldn’t be hit with more than temporary flu-like symptoms. If you are in a high-risk group, or care for somebody who is, there are precautions you can take.
Animals carry the listeria bacteria, which can be transferred to meat and cheese products and occasionally to vegetables and fruit.
Because the deli meats and other products involved in the recent recalls were heat-treated, any listeria in them should have been killed. It’s possible some were inadequately cooked, but more likely they were contaminated after cooking and before packaging, said a spokeswoman for the U.S. Department of Agriculture.
For example, a worker could have inadvertently carried the bacteria from the raw-meat area to the cooked-meat area. Officials are investigating the possible sources of contamination.
Listeria first gained widespread notoriety in the mid-1980s, when several people died and others were sickened after eating (the now-defunct) Jalisco-brand soft cheese. Since then, listeria has only occasionally made the news.
Virtually any contaminant can have a vast effect, given today’s nationwide distribution of countless food products. In the days when most of what we ate was grown or manufactured close to home, far fewer people could get sick from a single product. Now, food distribution is more complicated, and so is the job of tracking down the source of a food-borne illness.
But listeriosis can trick both victims and doctors into thinking it’s just the flu, so in many cases a stool test confirming listeria is never done. This means an outbreak can be well under way before it’s noticed and traced.
Complicating things is listeria’s long incubation period: up to 70 days. By the time victims feel symptoms, they often can’t remember where or what they ate that might have made them sick.
Not so long ago, the only way authorities could trace the source of a listeria outbreak was to interview victims, searching for foods that all had eaten within a certain time frame.
“This has been a very frustrating disease to work with because we haven’t had adequate laboratory tools,” Kobayashi says. “You might get a cluster of cases, but you couldn’t prove the source.”
Victim interviews are still important, but now authorities can quickly confirm a suspected source with DNA tests, which reveal whether the listeria strain in a victim’s stool sample matches the strain in a suspect food.
Another new boon to listeria sleuthing is a program pooling the forces of the federal Centers for Disease Control and Prevention and several states. State authorities contact physicians and conduct lab tests to collect listeria data, including DNA results, then pass them on to the CDC. The data help reveal if an outbreak is under way.
But there are holes in the listeria net. So far, for instance, only a few states are involved in the CDC-connected listeria-tracking program.
Also, critics contend the USDA’s recall policies don’t help as much as they could. The USDA doesn’t announce recalls until it can test and confirm listeria in food from a sealed package.
In the Bil Mar case, that meant the company’s hot-dog recall in December went for nine days without the publicity boost of a government announcement. Critics say this kept some consumers in the dark and left them more likely to eat contaminated products. The USDA is looking into changing that policy.
(Federal investigators have so far been unable to determine how hot dogs and deli meats produced by Bil Mar Foods could have become contaminated. The focus so far has been on summer maintenance work done on an air-conditioning unit that may have spread dust onto food-processing equipment.)
The USDA also is backing a U.S. Senate bill that would carry even greater weight by giving the government the authority on recalls, which are now only voluntary actions on the part of food companies.
Yet another criticism of the government’s role is that although USDA inspectors check the sanitation of plants, they don’t routinely do lab tests for listeria.
Defenders say such tests wouldn’t help much because it’s impossible to test every piece of meat that goes through a plant, so contaminated items could easily be missed. Still, the USDA is reassessing its procedures, a spokeswoman said.
Even with the system’s shortcomings, improvements are encouraging, says Kobayashi.
For instance, most of the recent recalls occurred not because anyone got sick from the products in question-apparently only one did, outside of the Bil Mar cases-but because inspections uncovered listeria in the foods. That beats having people get sick, even if the explanation for the contamination remains a mystery for now.
Protecting yourself
You can take steps to avoid illnesses caused by listeria. This is especially important for infants, the elderly, pregnant women and people with impaired immune systems, for whom listeriosis can be life-threatening.
Listeria has been found at times in hot dogs, deli meats, processed-poultry products, soft cheeses and, occasionally, fresh produce.
Listeria can survive freezing or refrigeration, but thorough cooking kills it.
The U.S. Department of Agriculture recommends that members of at-risk groups reheat deli-style meat and poultry products such as hot dogs, lunch meats, cold cuts, fermented and dry sausages, such as summer sausage, until they are steaming hot.
Some experts go further, recommending that those individuals avoid all such products, as well as soft cheeses.
All produce should be thoroughly washed, though there are no guarantees that washing will remove every trace of listeria. Consider peeling hard fruits.
