Cases of human illness caused by Salmonella-tainted dry pet foods, treats and chews have become so common that the U.S. Food and Drug Administration has launched a national effort to collect and test certain pet products for harmful microbes.

In a memorandum published Oct. 24, the FDA’s Center for Veterinary Medicine said it will be analyzing pet products, not including canned pet food, from domestic manufacturers, grocery stores and other retailers, including major chains such as PetSmart, PetCo, WalMart, Costco, Sam’s Club and Target.

The goal of the project, which will run until September 2012, is to discover how prevalent Salmonella is in pet products, to determine the characteristics of the Salmonella strains typically found in the products, to develop surveillance methods to monitor for Salmonella contamination in pet products and to ensure that Salmonella-tainted pet products are removed from commerce.

In 1999, an outbreak of human salmonellosis in Canada was linked to pig-ear dog treats carrying Salmonella Infantis and in 2001 an outbreak in Texas was linked to beefsteak-patty dog treats contaminated with Salmonella Newport. In 2005, illnesses in Canada and the U.S. were caused by pet treats tainted with Salmonella Thompson.

According to the Centers for Disease Control and Prevention, in 2006 and 2007 there were 70 cases of human salmonellosis from Salmonella Schwarzengrund in dry dog foods manufactured by a Pennsylvania company.

Salmonella can make animals sick, and there also is risk to humans who have handled contaminated pet food or treats, especially if they have not thoroughly washed their hands afterward or sanitized any surfaces exposed to these products.

Healthy people infected with Salmonella may experience nausea, vomiting, diarrhea or bloody diarrhea, abdominal cramping and fever. Rarely, salmonellosis can cause more serious complications, including arterial infections, endocarditis, arthritis, muscle pain, eye irritation, and urinary tract symptoms.

Pets with Salmonella infections may be lethargic and have diarrhea or bloody diarrhea, fever, and vomiting. Some pets will have only decreased appetite, fever and abdominal pain. Infected but otherwise healthy pets can be carriers and infect other animals or humans.