MADISON, Wis. (AP) -- Tests of Clark County swine herds for pseudorabies in a final quarantine area came out negative, and officials say that should clear the way for the state to retain its status as free of the disease despite an outbreak in two herds.

The herds that tested negative are being released immediately from the quarantine aimed at preventing any spread of the viral illness, which causes respiratory symptoms in healthy adult hogs but can kill newborn pigs and cause abortion or stillbirth in sows.

Both herds where the disease was found, one with 300 pigs near Greenwood and the other with 27 near Loyal, were destroyed last Friday.

The Greenwood cases were the first confirmed in a commercial herd nationally since 2003.