Peanut butter, black pepper and cookie morsels are disparate food items with something in common — each has been at the center of a prominent recall that involved contamination with the pathogen Salmonella. The hardy pathogen has been the culprit in several high-profile food recalls, and while there have been fewer food recalls related to Salmonella so far during fiscal 2010 compared to fiscal 2009, the pathogen was involved in more than half the 2010 recalls.

There are several factors at play: Salmonella is able to survive in a wide range of conditions; the U.S. food chain is becoming increasingly complex; regulatory requirements are becoming more stringent; and food companies are getting better at detecting the pathogen.

A joint industry report released in May found that the number of product recalls more than doubled since 1999, with the greatest increases linked to Salmonella and undeclared allergens. Salmonella-related product recalls increased most notably, from 25 in 2007 to 240 in 2008, according to the report “Recall Execution Effectiveness: Collaborative Approaches to Improving Consumer Safety and Confidence,” which was published jointly by the Food Marketing Institute and the Grocery Manufacturers Association.

The incidence of Salmonella-related recalls and illnesses has remained problematic throughout most of this decade. According to data from the Food and Drug Administration, the agency recorded 613 food recalls so far in fiscal year 2010, of which 339 were related to Salmonella. Total recalls for fiscal 2009 were 518, of which 330 were related to Salmonella. The Centers for Disease Control and Prevention in Atlanta said that in 2006, Salmonella and Norovirus were the leading causes of outbreaks that year. There were 1,270 reported foodborne illness outbreaks resulting in 27,634 illnesses and 11 deaths. According to the C.D.C., Salmonella caused 18% of the illnesses. And, finally, the C.D.C.’s Foodborne Diseases Active Surveillance Network (FoodNet) reported that incidents of foodborne illnesses held steady in 2007. However, incidents involving Salmonella and several other foodborne pathogens hadn’t declined significantly in that year.

The costs of foodborne illness outbreaks are high. The Produce Safety Project, an initiative of the Pew Charitable Trusts at Georgetown University, found that foodborne illnesses cost an estimated $152 billion annually in health care, workplace and other economic losses compared with $35 billion reported by the U.S. Department of Agriculture in 1997. The joint F.M.I., G.M.A. industry report found that the average cost of a recall to food companies is $10 million in addition to brand damage and lost sales.

“Because Salmonella has the ability to survive in a wide range of conditions, it has been associated with a variety of products — toasted cereal, black pepper, fresh peppers, tomatoes, eggs, poultry, peanut butter, frozen meals and more,” said Marisa Bunning, assistant professor in the Department of Food Science and Human Nutrition at Colorado State University, Fort Collins.

Dr. Bunning said the pathogen has been the cause of outbreaks ranging from municipal water to dry, shelf stable snack products.

“As consumers, we have access to a huge selection of products from different regions, so there are many opportunities for exposure to Salmonella,” Dr. Bunning said.

Elaine Scallan, an assistant professor in the Epidemiology Department of the Colorado School of Public Health, said there are some geographic variations in infection rates.

“Overall, rates in FoodNet sites vary from 10 to 25 (infections) per 100,000,” she said. “These differences are not fully understood. There are differences in the incidence of some common Salmonella serotypes.

“For example, Salmonella Javiana is thought to have its reservoir in amphibians and is more prevalent in the southeastern U.S.”

Dr. Bunning said exploring regional trends in Salmonella infections is difficult because there are more than 2,400 serovars of Salmonella. (Serovars are a group of closely related microorganisms with a common set of antigens).

“For example, Salmonella Newport has been associated with tomatoes grown on the East coast of the U.S.,” she said. “The location and types of food products involved in Salmonella outbreaks are factors to consider in the distribution of cases for any given year, and the wide distribution of products — peanut products, for example — complicate the issue.”

In the case of peanut products, contamination was traced to production facilities in two regions of the United States, but the cases of infections were widely distributed, Dr. Bunning said.

“There may be trends, but considering all the factors that influence case distribution makes it difficult to identify regional variations,” she said.

Although improved detection methods have had an impact on food companies’ ability to detect the pathogen before it reaches consumers, it is unclear what impact reporting vehicles such as the Reportable Food Registry have had on the number of food product recalls.

“As awareness and familiarity with the registry increases, it has potential to be a useful tool for facilitating the recall process and possibly limiting the extent of some foodborne illness outbreaks,” Dr. Bunning said.

Salmonella outbreaks – A recent history

Jan. 21. 2009
The Food and Drug Administration confirms that the Blakely, Ga., facility owned by Peanut Corporation of America is at the center of a Salmonella Typhimurium outbreak that sickened hundreds and was linked to at least five deaths. The investigation into the recall became a criminal matter after F.D.A. investigators found records showing that after the P.C.A. received test results showing a positive sample for Salmonella, the company would conduct a follow-up test but ship product before receiving results for the second test. By early February, the recall included more than 1,700 varieties of products manufactured by numerous companies.

April 9, 2009
Setton Pistachio of Terra Bella, Inc. expands its recall to include all lots of roasted in-shell pistachios and roasted shelled pistachios that were produced from the company’s 2008 crop. According to F.D.A. investigators Salmonella had been found in “critical areas” of the Terra Bella facility that may have led to cross-contamination of product.

Jan. 23, 2010
Daniele International, Inc., a Rhode Island-based meat processor, recalled more than 1 million lbs of ready-to-eat Italian-style meat products. The F.D.A. identified black pepper as the source of a foodborne illness outbreak caused by Salmonella Montevideo.

Feb. 26, 2010
Wholesome Spice of Brooklyn recalled all lots of its 25 lb boxes of crushed red pepper. According to the F.D.A., samples of product tested positive for Salmonella, and may be related to the Daniele Italian sausage recall.

March 4, 2010
The F.D.A. identifies Salmonella Tennessee in hydrolized vegetable protein (HVP). Basic Food Flavors, Las Vegas, manufactured the HVP involved in the recall. No illnesses were linked to the pathogen, but the recall involved an extensive list of products.

April 29, 2010
Nestle USA confirms that it received a single positive test for Salmonella on one sample of morsels at the company’s Burlington, Wis., facility. Nestle shut down the facility on April 29 for a thorough cleaning. No product was shipped to consumers. This was the second positive test for Salmonella at the Burlington facility. The first came in mid-February.