Agriculture

Better science increasingly reveals salmonella

Consumers may be worried that no food is safe to eat now that pepper and pistachios are being investigated for salmonella poisonings.

They're right to wonder.

The nuts and spices voluntarily recalled this week join a growing list of foods associated with salmonella outbreaks in the past two years -- tainted peanuts, jalapeño peppers, dry dog food, cantaloupes, puffed wheat cereal and a puffed rice and corn snack mix.

And on Wednesday, mayonnaise sold in Ohio, northern Kentucky and southeast Indiana was voluntarily recalled by the Kroger supermarket chain.

But food-safety experts say the spate of recent outbreaks may be more the result of better scientific tools for finding the germs than an indication of an explosion of the bacteria in processed foods.

Salmonella can survive almost anywhere. The bacteria flourish in soil and water and can survive in a dry environment like that of the sun-baked San Joaquin Valley. They can be on almost any food, and just a few bacteria can make someone ill. Salmonella is the most common cause of foodborne illnesses nationwide.

Yet the presence of salmonella in consumer products -- such as the recently recalled spices from Union City and pistachios from a Terra Bella plant -- is rare. Overall the nation's food supply is safe, food-safety experts say.

"I would hate for consumers to approach the grocery store with trepidation," said Linda Harris, a food-safety microbiologist at the Western Institute for Food Safety and Security at UC Davis.

Most of the food bought in grocery stores has been processed in some way that reduces or eliminates salmonella, she said.

The food industry wants to avoid a food scare. California almond growers, for example, decided to require pasteurization after salmonella outbreaks in 2001 and 2004, Harris said.

And it was a routine industry test -- not a government-required test -- that detected the salmonella-tainted pistachios voluntarily recalled this week by Setton Pistachio of Terra Bella.

Testing by a manufacturer for Kraft Foods Inc. first detected the contamination almost two weeks ago, when workers at a plant in Illinois decided to check roasted nuts going into huge vats of trail mix. Private auditors hired by Kraft later found problems they think caused the contamination at the central California supplier.

Setton has now voluntarily recalled about 2 million pounds of roasted in-shell and shelled pistachios. No illnesses have been reported.

Also this week, Union International Food Company of Union City voluntarily recalled white and black pepper products, including products under the Uncle Chen name. The outbreak has sickened 42 people in four states, including 33 in California. At least one person each in Madera and Merced counties was infected.

But food preparation -- not food processing -- may account for most of the salmonella poisonings, said Mark Sotir, a staff epidemiologist at the federal Centers for Disease Control and Prevention.

One of the big causes of salmonella poisoning is improper handling of raw poultry that allows chicken juices to contaminate vegetables or other foods, Sotir said.

Salmonella bacteria live in the intestines of people and animals, including birds. Raw meat, poultry, milk and dairy products, eggs and seafood are most likely to harbor salmonella bacteria. People become ill when they eat food contaminated by animal feces. The food looks, tastes and smells normal.

Each year, salmonella bacteria cause an estimated 1.4 million cases of foodborne illnesses in the United States -- and 500 deaths, according to the CDC. That's far more cases than those identified as part of nationwide outbreaks. Only about 32,000 illnesses are reported each year through the National Salmonella Surveillance System, a public health laboratory-based system, the CDC reports.

But salmonella outbreaks can sicken hundreds of people at a time, as they have in the past couple of years.

It has become easier for health investigators to recognize a salmonella outbreak in the past 15 years because of advances in DNA technology.

Before that, cases of salmonella poisonings that occurred in different states were hard to connect to a single strain. That made it difficult to trace illnesses back to a single food source or distributor. But molecular DNA fingerprinting now gives microbiologists the ability to do that.

"We have better methods to tease out outbreaks that previously would have gone unrecognized," Harris said.

The sophisticated typing methods also allow growers or food distributors to identify where a problem has occurred and control a salmonella outbreak more quickly, Harris said.

The federal government has invested a lot of money into outbreak surveillance, Harris said.

The CDC takes any salmonella outbreak very seriously, Sotir said. "There are people who get severe illnesses from salmonella," he said.

How ill a person becomes from a salmonella infection depends on the patient's resistance to the germs.

In most cases of salmonella, acids in the stomach kill the bacteria before they can travel into the small intestines, said Dr. Herbert Boro, an infectious disease specialist at Kaiser Permanente Medical Center in Fresno.

But sometimes a few of the germs make it into the colon, where they produce a toxin that causes diarrhea. The whole process can happen quickly -- within six to 24 hours of swallowing the germs -- or as late as three days afterwards, Boro said. Most people recuperate from the infection within a few days without treatment.

Salmonella germs, however, sometimes invade the blood stream, causing blood poisoning that can be life-threatening. The very young, the very elderly and people with weakened immune systems are most at risk, Boro said.

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