Health officials are urging people to be cautious at agricultural fairs this summer after the Centers for Disease Control and Prevention (CDC) reported an increase in the number of swine flu cases linked to pigs at such fairs in other parts of the country.

The CDC said there were 12 new cases of the H3N2v virus in the past week in Hawaii, Ohio and Indiana, and all were linked to people who attended or exhibited swine at an agricultural fair. Washington-area officials suggest those at high risk for the flu — including children, the elderly, pregnant women and those with weak immune systems — avoid exposure to pigs at county fairs as the annual fair season hits its peak.

“We just want to get ahead of the curve, as these things do tend to spread,” said Peter Beilenson, the health officer for Howard County, Md., which issued an alert Saturday. “We’re not trying to raise hysteria. We’re trying to make sure people avoid getting sick.”

Health officials pay close attention to swine flu cases: Strains of the virus caused a pandemic in 2009 that led to thousands of deaths in the United States, according to the CDC. There were mass vaccinations and shortages of the vaccine.

August is the traditional time of state and county fairs, where attendees can count on fried foods, cotton candy, carnival rides and animal exhibitions. Some Maryland fairs have gotten rid of petting zoos, in part to avoid the spread of animal-carried diseases, especially to young children, who would be most likely to handle the animals.

In Montgomery County, Md., the fair is scheduled to begin Friday, and officials have arranged to have dozens of hand-sanitizing stations, hand-washing stations and portable restrooms with sinks as part of an effort to allow people to keep clean.

Martin Svrcek, executive director of the Montgomery County Agricultural Fair, said safety is his most important priority for the fair.

“As our urbanized society has moved farther from farms, many folks who are city dwellers have not developed the same kind of immunities that farmers or people who have been around farms have,” Svrcek said.

Although swine flu has not been widespread in humans this year — the CDC reports 29 confirmed cases in the United States since August 2011 — health and fair officials recommend that people avoid touching pigs. Typically, pigs contract the virus in their intestines and throats and can pass it easily.

Swine flu symptoms are similar to regular flu symptoms, including fever, coughing and sneezing.

Animals being showcased on fairgrounds have to make the cut before they can be certified for exhibition. In Maryland, such animals must have a veterinary inspection 30 days before the fair, and in some cases they must undergo other testing. Owners also have to sign a self-certification verifying that the animals are not infected. Representatives of the state Department of Agriculture’s Animal Health Division and veterinarians are typically on-site during fairs to conduct spot inspections and make sure animals are not infected.

John Kozenski, president for the Anne Arundel County Fair, said he has been watching news of the swine flu cases closely but is more worried about the possibility of people contracting E. coli. Although fairgoers are not supposed to touch the animals in their pens, it is often possible to reach them, and people do.

“When you’re doing things with the public, it’s hard to get them not to touch to the animals,” Kozenski said. “We try to make sure they don’t get near the animal waste product.”

He also said the jam-packed summer fair schedule can contribute to animal illnesses. Moving stock from barns to fairgrounds means different sources of water, which can affect animals’ stomachs and expose them to illness.

“We all watch what’s happening, where disease outbreaks happen, and we pray they don’t mutate into something else on our fairgrounds,” Kozenski said.