US research shows E. coli present among swine
The pathogen E. coli O157:H7, which is generally associated with
cattle, can also be transmitted through the air among swine, according to
research conducted at Iowa State University.
Nancy Cornick, an ISU associate professor of
veterinary microbiology who previously researched the issue for the Food Safety
Consortium, showed that uninfected pigs sharing pens with infected pigs could
also become infected. In more recent research, it appeared that transmission of
the organism could be accomplished through the air even when infected pigs were
separated from uninfected pigs.
"In this study,
some of the aerosols could be from hosing the pen, although we scrape the pens
first before we hose them," Cornick explained. "One of the air samples was taken
24 hours after the pens had been cleaned." That suggests infectious aerosols may
remain suspended for at least that long or that the pigs themselves may be
creating aerosolised E. coli
"What it says to me is that if the organism is in the
environment with the pig, it's very easily transmitted and the infectious dose
is very low," Cornick said. Cornick had also performed a similar experiment with
sheep and found that E. coli
as easily as in pigs. Other experiments have also shown that E. coli
O157:H7 can establish and maintain a population in
some pigs' intestinal tracts for at least two months, indicating that the
bacterium can colonize swine. The incidence of the pathogen in swine remains
small but worthy of notice.
Cornick noted that one U.S. slaughter facility recovered
O157:H7 in 2% of its pigs, and the bacterium
has also been recovered from healthy swine in Japan, Chile, the Netherlands,
Norway and Sweden.
Cornick seeks to follow up the swine research by
performing the same experiments with cattle, which are considered the major
reservoir of E. coli
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