News 497 views last update:Jun 17, 2008

Researchers study antibiotic use in Pig rearing

Ohio State University researchers have warned that pigs raised without antibiotics are more likely to carry bacteria and parasite responsible for food borne illness.

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 drugs.

"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 operations.

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.

They 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 Prevention.

The study is published in a recent issue of the journal Foodborne Pathogens and Disease.

Related Website
• Study Press Release
• Ohio State University

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