During the study, the pigs raised outdoors without antibiotics had higher
rates of three food-borne pathogens than did pigs on conventional farms, which
remain indoor, and receive preventive doses of antimicrobial
"Animal-friendly, outdoor farms
tend to have a higher occurrence of Salmonella, as well as higher rates of
parasitic disease," said lead study author Wondwossen Gebreyes, associate
professor of veterinary preventive medicine at Ohio State University.
The researchers found that more than half of the pigs on antibiotic-free
farms tested positive for Salmonella, compared to 39 percent of conventionally
raised pigs infected with the bacterial pathogen.
The presence of the
Toxoplasma gondii parasite was detected in 6.8 percent of antibiotic-free pigs,
compared to 1.1 percent of conventionally raised pigs. Moreover, two naturally
raised pigs of the total 616 sampled tested positive for Trichinella spiralis, a
parasite considered virtually eradicated from conventional U.S. pork
Human health risk
As long as pork is
cooked thoroughly, the presence of these infectious agents in should pose no
risk to human health.
Antibiotics are added to their feed to promote
growth and protect against infections, followed by a withdrawal period before
slaughter to ensure the meat doesn't contain any antibiotic residue.
are given antibiotics only for treatment against active infections, and once
sick pigs are treated, they are separated from the herds and no longer marketed
as naturally raised pork.
The infection resulting from Trichinella
parasite has historically been associated with undercooked pork, but in the
recent past, the parasite has been associated mostly with wild mammals.
People with this infection typically
experience diarrhoea, vomiting, fatigue and fever first, followed by headaches,
cough, and aching joints and muscle pains. The symptoms can last for months, and
severe cases can be fatal, according to the Centers for Disease Control and
The study is published in a recent issue of the journal
Foodborne Pathogens and Disease.
â€¢ Study Press Release
â€¢ Ohio State University
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