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4 bacteria strains suspected in outbreak


Saturday, August 7, 2004

The salmonellosis outbreak that sickened at least 416 people in five states might have been caused by four bacterial strains, an unusual occurrence, health officials said Friday.

Investigators suspect that all strains were found on contaminated Roma tomatoes served at convenience stores owned by Altoona-based Sheetz, according to the Pennsylvania Department of Health and the U.S. Centers for Disease Control and Prevention. Officials said they believe the tainted tomatoes have been removed from the market and are no longer infecting people.

"Logically, it is possible that outlets other than Sheetz served tainted tomatoes obtained from a common source, but thus far no alternate outlets have been linked to human cases," Dr. Calvin Johnson, Pennsylvania Secretary of Health, said in a health update issued yesterday to hospitals and doctors.

"The full extent of this outbreak will not become clear until vast amounts of epidemiologic and laboratory data are analyzed and the FDA investigations are completed," he wrote.

Salmonella's Javiana strain has infected 324 of the 330 people with confirmed salmonellosis cases in Pennsylvania, state Health Department spokesman Richard McGarvey said. Health officials in Ohio, West Virginia, Maryland and Virginia have confirmed 86 salmonellosis cases linked to the outbreak, and are investigating at least 51 others.

A second, rare strain, Anatum, is the only one found on the more than 260 samples of food the Pennsylvania Department of Agriculture has tested. Four people who ate at a Sheetz were sickened by that strain, which was matched genetically to the salmonella in an unopened bag of tomatoes taken from a Franklin County Sheetz. A fifth person infected with that strain is still being investigated for a potential link.

The health update sent to medical professionals said "another rare salmonella" strain, which it did not identify, might be involved in the outbreak. McGarvey identified that strain as Thompson. About a dozen people who ate at Sheetz have been infected with that strain, but are not yet counted among the Pennsylvania's 330 confirmed cases, he said.

The update was an edited version of a slightly more detailed report sent earlier this week to other agencies involved in the investigation, including health departments in other states. The report said the Thompson strain and a fourth variant, Muenchen, each infected about one dozen people, potentially from tomatoes served at Sheetz in early July.

Finding multiple strains of salmonella in a single outbreak is unusual, but it has happened several times, said Jennifer Morcone, CDC spokeswoman. Three strains of salmonella were found in beef jerky that sickened 93 people in New Mexico in 1995, and two salmonella strains were associated with orange juice that sickened people in Florida.

An animal could carry more than one strain and contaminate food growing in the field, the CDC said.

The symptoms of salmonellosis are diarrhea, abdominal cramps and fever. They usually strike 12 to 72 hours after infection and can last up to 10 days.

Karen Roebuck can be reached at or (412) 320-7939.

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