Outbreaks of Salmonella Linked to Dairy

More than 2,200 persons in five Midwestern states have become ill in back-to-back outbreaks of salmonella food poisoning, setting off a massive search for the cause and forcing the metropolitan Chicago area’s largest food retailer to pull all milk products except cheese from its shelves.

Jewel Food Stores, which operates 217 supermarkets, shut down its dairy Monday night and announced Tuesday that it will stock milk only from other sources after the two outbreaks were linked to its 2% low-fat milk.

The first salmonella outbreak was detected on March 29, and Illinois and Cook County health authorities are attempting to determine whether the deaths of two persons came as a result.

Evidence of a second outbreak, in another brand of low-fat milk produced by the Jewel dairy, turned up Monday night. Authorities are also trying to determine whether an earlier outbreak--last August--is related.

To avoid a panic, health officials have set up a hot-line in Chicago to answer questions about the food poisoning.

This is believed to be one of the first instances in which food poisoning has been traced to milk that was pasteurized to kill bacteria.

Last February the New England Journal of Medicine reported that a bacterium called Listeria monocytogenes apparently survived the pasteurization process in Massachusetts in 1983. It spawned a rare disease called listeriosis, which killed 14 persons.

In the present case, investigators are trying to determine whether the pasteurization process was somehow faulty or whether contaminants got into the milk after pasteurization.

Law enforcement investigators are exploring the possibility of deliberate contamination, although health authorities say sabotage is an unlikely explanation.

Medical Mystery

The source of the original contamination may be the biggest medical mystery to confront state and federal health officials and Illinois law enforcement personnel since seven persons died in the autumn of 1982 after swallowing cyanide-laced Tylenol that had been contaminated and placed in Chicago-area retail stores.

Milk used in Jewel’s Hillfarm Dairy in suburban Melrose Park, Ill., comes from at least 1,600 dairy farms in Wisconsin, according to federal sources who are searching, with Wisconsin officials, for a possible source of the bacteria.

If medical researchers trace the bacteria involved to specific dairy herds, that could have major ramifications for the nation’s dairy and livestock industries.

For several years, dairy, cattle and hog farmers have added antibiotics to animal feed to spur growth and improve animal health. The practice is controversial, and the Food and Drug Administration is currently considering regulations to severely restrict or ban the routine use of tetracycline and penicillin in animal feed because of fears that the practice may be creating drug-resistant bacteria.

Authorities have identified the strain responsible for the current wave of poisonings as a drug-resistant “salmonella typhimurium.”

“This is an atypical outbreak,” said Dr. Scott D. Holmberg, medical epidemiologist for the Centers for Disease Control in Atlanta. “Pasteurized milk has not been a vehicle for the bacteria.” But the bacteria has turned up in raw milk and in beef, pork and poultry.

Holmberg, who is monitoring results of tests being done in Chicago, headed a team that first traced a drug-resistant strain of salmonella in beef back to a cattle herd in South Dakota that had been fed small doses of antibiotics.