WEDNESDAY, Nov. 1, 2006 (HealthDay News) -- U.S. health officials said Tuesday that a nationwide outbreak of salmonella that sickened 171 people in 19 states may essentially be over.
Although officials are still trying to pinpoint the source of the contamination, they believe it will ultimately be traced to some form of produce.
"That is the 64-million-dollar question," said Dave Daigle, a spokesman for the U.S. Centers for Disease Control and Prevention, said. "We believe it's going to be a produce item, but we haven't narrowed it down."
Reports of the illness peaked in late September, according to David Acheson, chief medical officer of the U.S. Food and Drug Administration. That suggests the outbreak is over, and there is no continuing public health risk, he added.
"Whatever was contaminated that caused the illness, it has either been consumed, destroyed or thrown out. So the suggestion there is a need to put out a consumer warning about produce on the shelf is unwarranted. It seems to be past," Acheson told the Associated Press.
Earlier reports had speculated that the bacteria may possibly have spread through tomatoes. But the CDC said Tuesday the outbreak, which left 11 people hospitalized, has yet to be linked to any specific food, food-distribution chain, restaurants or supermarkets.
Currently, Daigle said, state and local health officials are using a standardized questionnaire to interview people who have fallen ill in an effort to trace the source of the outbreak, which apparently started in September.
"We are doing the interviews, and we hope to have [the source] very soon," he told HealthDay. "We hope it won't take too long."
The outbreak, which caused no fatalities, was announced late Monday night. It follows last month's outbreak of E. coli contamination in fresh, packaged spinach that killed three people and sickened more than 200 in 26 states and one Canadian province.
CDC officials said they first noticed a problem two weeks ago through a national computer lab system that looks for patterns and matches in reports of food-borne illness. The U.S. Food and Drug Administration has joined the investigation and will try to help trace the outbreak to its origin, the AP reported.
The states involved are Arkansas, Connecticut, Georgia, Indiana, Kentucky, Maine, Massachusetts, Michigan, Minnesota, North Carolina, New Hampshire, Ohio, Pennsylvania, Rhode Island, Tennessee, Virginia, Vermont, Washington and Wisconsin.
Most of the cases are in adults, and more than 60 percent are women, CDC epidemiologist Dr. Chris Braden told the AP.
The Boston Globe reported that Massachusetts had 51 of the cases in September, and that there have been no new cases there since the end of that month.
"It's still too early to say what the cause is," Dr. Alfred DeMaria Jr., assistant commissioner at the Massachusetts Department of Public Health, told HealthDay. "We're doing a case-control study where we compare exposures of people with salmonella to people without salmonella to try to figure out how do they differ. It's going to take some time."
In addition, the Louisville Courier-Journal reported 15 cases in Kentucky, all in September. The Pennsylvania Health Department was probing at least five cases in five counties in that state; Arkansas was investigating four.
Salmonella is a germ that causes a bacterial disease called salmonellosis. The typical symptoms included diarrhea, fever and stomach pain, which can start up to three days after people become infected. The symptoms usually go away after one week. But some victims do see a doctor or end up in hospital, because the diarrhea is severe or the infection has affected other organs, according to the CDC.
There are about 2,500 types of salmonella. The type in the new outbreak -- salmonella typhimurium -- is one of the most common, Braden said.
According to the CDC, people can get salmonellosis by eating contaminated food, such as chicken, eggs or produce.
"Most people think it's meat and eggs, but you can see it with produce as well," Daigle said.
Animals can carry salmonella and pass it in their feces. Therefore, people can also get salmonellosis if they don't wash their hands after touching the feces of animals. Reptiles (such as lizards, snakes and turtles), baby chicks, and ducklings are especially likely to pass salmonellosis to people. Dogs, cats, birds (including pet birds), horses and farm animals can also pass salmonella in their feces.
The process appears similar to what has recently been tracked in the tainted spinach cases. U.S. and California health officials narrowed the search for the source to a ranch in California's Salinas Valley, where it is now believed that wild boar may have carried the bacteria from cattle feces to nearby spinach fields.
To learn more about salmonella, visit the CDC.