When the Oregon State Fair opens next week, the pigs will be kept behind an elaborate configuration of plastic and ribbon barriers, taller-than-usual fences and off-limits walkways.

The state veterinarian is also urging visitors to stay 6 feet away.

The worry? The spread of swine flu, but with a twist: state officials hope to protect the pigs from sick people.

“;Help us protect the piggies,”; signs at the fair will read in pink.

The recent H1N1 flu strain, which has raised fears worldwide despite having had relatively mild effects on most people so far, is turning upside down traditional health concerns at agricultural exhibitions and state and county fairs around the country.

At the state fair in Iowa, visitors are barred from holding piglets, and in North Carolina, the state veterinarian, David T. Marshall, has advised fair visitors to wash their hands upon leaving — and entering — pig barns.

“;The whole idea of the animals getting sick from people is a foreign concept to people, but that's what we're looking at here,”; said Marshall, whose state is one of several where E. coli outbreaks linked to fairs and petting zoos sickened dozens of people several years ago.

The flu discovered this spring includes genetic parts of human, swine and avian flus. Although its genetic structure technically makes the new strain a “;swine flu,”; experts say, it has not been found in pigs in this country or most elsewhere, aside from a few herds in Canada, Argentina and Australia. In those cases, epidemiologists suspect that people working on farms may have infected the pigs around them.

The virus is not believed to be particularly deadly to pigs, scientists say, nor, according to the U.S. Department of Agriculture's chief veterinary officer and others, can it cause any risk for people eating pork. But scientists still hope to keep it from spreading in pigs, which can act as “;mixing vessels”; for human and avian flus, possibly leading to a more dangerous strain.

And there is the worry of public relations: Would a report of an infected pig at a fair harm the pork industry, already wrestling with economic misery in part because of people's unfounded fears about what the flu might mean for their dinner?

Those matters have left health authorities, fair organizers and those in the swine business wrestling with how best to balance risks of the flu with rural rites of summer. The result is a patchwork of rules on the matter of pigs and people.

Many local fair leaders said their existing safety measures — like isolating livestock after fairs until a typical flu incubation period had passed — already offered enough protection, and some questioned the scientific basis of strict guidelines elsewhere.

At the state fair in Wisconsin, where a young woman crowned “;Fairest of the Fair”; stood inside a pen where prize pigs were auctioned, pig owners scoffed at the suggestion that tested practices might need refinement.

“;We had no thought of not coming,”; said Debbie Schoenbeck, whose family owns pigs.

Schoenbeck stood beside the swine barn's center walkway, used on one recent afternoon by large, grunting pigs and by people, including a girl who caressed one pig's snout. (The Wisconsin fair's agricultural director, Brian Bolan, said that on most days visitors were discouraged from walking on thoroughfares when pigs were passing through and that more hand-washing stations were added this year.) Still, some fair veterinarians said they were visiting pig barns more often for signs of respiratory illness among the animals.

To keep illness from spreading back to home farms, some fairs discourage farmers from showing any animals that are not “;terminal,”; due to be slaughtered right after the fair.

The different approaches have caused tension between some fair leaders and veterinarians. Don Hansen, Oregon's veterinarian, said he was contacted by lawyers for some county fairs and lampooned in cartoons for his relatively rigorous suggestions (the 6-foot rule was not to “;be written in stone,”; he says now), adding that he had “;never seen a reaction as immediate and profound before on anything.”;

The issue has also created stress, according to some involved, between the interests of the biggest pork producers, who harvest about 109 million pigs a year, and those who mostly compete in pig shows, a group that shows an estimated 1 million pigs each year.

Darrell D. Anderson, the chief executive of the National Swine Registry, representing those who raise purebred pigs, said some large pork producers had initially pushed to cancel the World Pork Expo in Des Moines in June.

“;If you take those big opportunities away, it would have been devastating to the show-pig industry and the breeding industry,”; said Anderson, who, along with others from all sides of the pig world reached a consensus on appropriate rules for exhibitions and shows.

Among new provisions at this year's Des Moines expo was a requirement that exhibitors sign an affidavit attesting that they, their families and their animals had been healthy for at least the last seven days, and that they would remove their animals if show officials deemed it necessary.

Still, for some who raise pigs to sell to commercial producers, the possibility of a show pig's falling ill at a county fair sounded like one more needless horror in a crushing year.

Others wondered if mere talk of safety measures at fairs' swine barns actually scared people more than the measures would spare pigs: Might reminders to keep pigs safe just plant new, irrational fears about pork in some people's minds?

Given all of it, any decision about what should come of the summer fairs felt fraught.

“;There were those who said you should be on the side of canceling these shows, and there were others saying the shows have to go on,”; said Paul Sundberg, the vice president of science and technology for the National Pork Board, a group representing the industry. “;It was dancing on the head of a pin.”;