SEOUL — South Korea raised its avian flu alert to orange Wednesday, the second highest level in its four-tier alert system, after more outbreaks were found this week at poultry farms across the country.

The first outbreak of the virus was reported earlier this month at a farm near Kunsan Air Base. The new cases include outbreaks at farms near Camp Humphreys, Kunsan Air Base and the city of Kwangju.

The closest outbreak to a U.S. facility was one about eight miles from Humphreys — about 40 miles south of Seoul.

“The 2008 outbreak is clearly heading towards rivaling the 2003-2004 outbreak for the number of farms that end up positive for the virus,” Col. James Jolissaint, commander of the 121st Combat Support Hospital, said in a message posted on the U.S. Forces Korea Web site.

No cases of avian flu have been reported in people, the message said.

To avoid avian flu, don’t eat undercooked chicken or runny eggs bought off post, visit local poultry farms or be present during the slaughter of poultry or water fowl, Jolissaint said.

According to an 8th Army news release, all poultry products sold at the Army and Air Force Exchange Service and the Defense Commissary Agency — including most eggs — come from the United States and are safe.

Any eggs bought locally for resale on base are heat-treated and also safe, the release said.

Avian flu outbreaks typically happen when geese, ducks and other large birds migrate and leave feces in rice paddies. From there, the virus can spread to nearby farms.