Link to zoo critter is tough to trace
By SARAH AVERY, Staff Writer
November 2, 2004
The number of people suspected of being infected with E. coli bacteria has risen to 16 -- 12 cases confirmed -- as state health investigators try to figure out whether the common link is a petting zoo at the N.C. State Fair.
Nine of the 16 cases under scrutiny had some ties to the fair's petting zoo, state health officials reported Monday. But the State Fair hypothesis remains in question, because two people infected in Mecklenburg County got sick in early October, well before the fair opened Oct. 15.
"It's going to be tough" to trace the source, said Dr. Jeffrey Engel, state epidemiologist. He said the Mecklenburg County cases might be coincidental; the county has, on average, six E. coli incidents a year.
The victims are mostly children from across the state: Chatham, Cleveland, Durham, Harnett, Lee, Mecklenburg, Wake, Wilson and Union counties.
But tracing the root of the bacteria is more complicated. Early on, three Wake County cases turned up a link at the petting zoo, which featured goats and sheep. Those animals, along with cattle, are common sources of E. coli. The bacteria live in their intestines and cause them no harm. Some studies indicate that up to 10 percent of ruminant animals carry E. coli.
The animals pass the bug to humans through their feces. Although petting zoos have been the source of outbreaks in Pennsylvania and Washington, most infections occur when meat is exposed to animal feces during slaughter and packing.
"Quite a bit of sampling is done on ground beef, but as far as trying to isolate it from an animal, that would be difficult," said Dr. David Marshall, state veterinarian with the N.C. Department of Agriculture.
To test the petting zoo animals, Marshall said, a stool sample would need to be collected from each animal. The sample would then be cultivated for E. coli. If the bacteria grew, they would need to be DNA-tested to determine a genetic link to the strain that infected people in North Carolina.
Even animals that carry the bacteria might not be found, however, because they may not have been shedding bacteria at the time testing began, Marshall said.
"It would take an extensive amount of lab testing to find the animal," Marshall said.
Testing on the animals has not occurred, because the link to the petting zoos has not been confirmed.
Petting zoos notified
Agriculture Department officials said they have contacted the two companies that ran the petting zoos during the 10-day fair. One company, Commerford and Sons, has headed to its next show, in South Carolina. The other, Crossroads Farms, does a few shows a year.
"I'm not sure what actions they are taking," said Brian Long, an Agriculture Department spokesman. "They are aware that there are cases in North Carolina, and that the State Fair is a commonality in some of those cases. We're waiting to hear some determination from public health at this point."
It's unclear what actions the state would take if the cases were linked to one of the petting zoos.
Long said agriculture officials are aware of the risks of E. coli exposure at the fair, where thousands of people come in contact with livestock. For that reason, he said, hand-washing stations are posted near all livestock exhibits, especially the petting zoos.
Hand washing is the best way to avoid the bacteria. State health leaders said they want to convey that message now, since any future E. coli infections would likely stem from person-to-person contact.
"You hear the hand-washing message every time, no matter what it is," Engel said. "Flu, wash your hands. E. coli, wash your hands."
The most recent major outbreak in North Carolina happened in 2001, when more than 200 people in Robeson County, most of them schoolchildren, got sick from a batch of butter that was being churned during a school presentation. Five of them suffered kidney damage, Engel said.
Of the North Carolina patients, most have been hospitalized over the course of their illness. One youngster at UNC Hospitals was described by a Wake County health official as "a bit more ill, but stable."
EFFECTS OF E. COLI
E. coli causes severe abdominal cramping, vomiting and watery diarrhea that can then become bloody. The bacteria produce toxins that damage the lining of blood vessels and can lead to permanent kidney damage, sometimes death. There is no treatment, and sometimes antibiotics increase the risk of developing the kidney disease. North Carolina reported 38 cases in 2003.
State officials have sent the stricken families a 14-page survey, asking where the victims had been, what they had eaten and with whom they had come in contact in the days before becoming sick. After officials get the surveys back, the medical sleuthing begins.
Already, scientists at the state laboratory are running DNA tests of the bacteria that infected the victims. That will determine whether the cases are actually related. Results might be available later this week.
Staff writer Sarah Avery can be reached at 829-4882 or firstname.lastname@example.org.