Shore residents more like to be infected; microbiologists look for links
PRINCESS ANNE (Sept. 9, 2012) — Eastern Shore residents are three times more likely to get sickened by salmonella than the rest of Maryland, and the area’s poultry industry may be at least partly to blame, experts say.
The nine counties stretching from Cecil to Worcester averaged about 41 cases per 100,000 people in 2011, according to a Daily Times analysis of Maryland Department of Health and Mental Hygiene data. In all other Maryland counties, the average was 14 per 100,000.
Last year was no fluke. Annual rates vary little from year to year. Last year was no fluke. Annual rates vary little from year to year.
Last year was no fluke. Annual rates vary little from year to year.
To some extent, the difference can be explained by the Shore’s smaller population, said Lucy Wilson, a state epidemiologist. It doesn’t take as many cases to significantly boost the rate in a smaller county.
For example, last year, rural Somerset County saw 13 cases, which yielded a rate of 49 per 100,000. Meanwhile, the 103 reports in Prince George’s County, where there’s far less elbow room, led to a rate of just 11.
Still, Wilson said, the higher rates on the Shore can’t be accounted for by math alone.
“Are there differences in risk in different places? We don’t have an answer for that,” she said. But “there are environmental factors that may be related that aren’t completely understood.”
One of the most common causes of food poisoning, salmonella is a nasty bug that triggers diarrhea, fever and abdominal cramps within 12 to 72 hours after exposure and lasting for up to a week. Nationwide, it’s blamed for 1.4 million illnesses and 500 deaths a year.
The bacteria’s preferred home is in animal digestive tracts.
It can spread to just about anything, though. Recent national outbreaks have been traced to a variety of tainted sources, such as mangoes, cantaloupe and even hedgehogs.
The biggest cause of illnesses is eating foods contaminated with animal feces. And the type of salmonella that causes the most human illnesses, the variant known by the scientific name enteritidis, is most commonly found on laced chicken, according to the Centers for Disease Control and Prevention.
“You have a lot of people who are exposed through occupational exposure,” he said.
They may come into contact through touching chicken feces directly or breathing it in, Oscar said. Then, those workers may bring salmonella home to their families on their clothes and bodies.
Bill Satterfield, executive director of the Delmarva Poultry Industry Inc., said it is “irresponsible to try and make a correlation to the chicken industry.” The state disease-tracking reports, he noted, don’t identify what types of salmonella are getting people sick or what happened leading up the onset of their symptoms — crucial clues in determining the cause.
A scientist with the U.S. Poultry and Egg Association, who reviewed the Maryland data, agreed.
“From these data, to infer that the cases are connected to any particular source, including poultry, would not be scientifically valid,” John R. Glisson said in a statement.
To be sure, many factors may influence a disease’s reported frequency. Salmonella’s symptoms mimic many other ailments, and doctors in one area may be more attuned to suspect it than those in other areas. An area’s prevalence of doctors and medical facilities also may play a role.
Such factors may account for the high salmonella rates in Baltimore City, said Ellen Silbergeld, a Johns Hopkins University researcher who has studied the link between poultry production on the Eastern Shore and human health. Indeed, the actual illness counts in Caroline, Kent and Somerset counties are so low that they “cast some doubt about the stability of the measurement,” she said in an email.
But the population of Wicomico is large enough and its salmonella rate high enough to warrant further examination, wrote Silbergeld, who is in Italy working on a book about industrial food animal production.
“I would not make any other conclusions,” she said.
Carole Morison, a Pocomoke City chicken farmer whose plight was documented in the 2008 documentary “Food Inc.,” said she has never been diagnosed with salmonella. But she claims to have developed a severe allergy to antibiotics from years of working closely with chickens.
She wouldn’t be surprised if the salmonella rates were tied to the industry. Chicken houses are “nasty” places, she said.
“The only thing you could do is wear a dusk mask and frequent washing of hands,” Morison said. “But everything is floating in the air. You go to scratch your nose and don’t realize what you’re doing. Anytime you’re in there, you’re bound to pick up something.”
Morison gave up her houses four years ago in favor of a pasture. And she has felt better ever since, she added.
Microbiologists play detective
Could the salmonella hot spot on the Shore be tied to another abundance: the many chicken houses and processing plants that dot its landscape?
Salina Parveen, a food and microbiology researcher at the University of Maryland Eastern Shore, has studied the link between salmonella and human contact for years. While no one has ever directly studied the possibility of a link between the region’s plateau of salmonella rates and the poultry industry, she said she believes it’s the “main reason.”
Four of the Top 50 broiler chicken producing counties in the United States are on the Eastern Shore.
Parveen said her studies of salmonella-laced chickens suggest that where the fowl are raised and processed could be a lot cleaner. The only reason that a chicken carcass would have salmonella bacteria on it is if it somehow comes into contact with bacteria from its gut during the butchering process.
“It looks like they’re not meeting good manufacturing processes at the processing plant,” she said. “Proper care was not taken raising them on the farm.”
Poultry industry critics have long decried the practice of raising chickens by the tens of thousands in cramped chicken houses and the routine use of antibiotics in their brief lives. Parveen’s studies lend some scientific weight to those concerns.
In a study conducted in 2004 and 2005 at a Wicomico County plant, Parveen and her colleagues found salmonella on four out of five chicken carcasses. And the vast majority of types of salmonella she found were resistant to at least one kind of antibiotic.
Later research showed that the amount of salmonella on chickens bought at a supermarket was very low, usually no more than one to five cells. Most was on the right drumstick, likely owing to the way the intestine’s are placed during the butchering process, the UMES study found.
But the mere presence on the chickens means that the people who work with them at plants and farms are probably getting exposed, too, said Thomas Oscar, a U.S. Department of Agriculture scientist who works in the same lab as Parveen and has served as her co-author on several studies.
This article and accompanying photo appeared in The (Salisbury, MD) Daily Times and is reproduced with the newspaper's permission.