Authorities culled 300 pigs in Vintar, Ilocos Norte after some tested positive for African Swine Fever (ASF).

Strict monitoring is now in place within a 300-meter radius of the affected pig farm.

Officials said four towns in Ilocos Norte are currently classified as "red zones" due to ASF.

Dr. Loida Valenzuela, Ilocos Norte Provincial Veterinarian, said the virus may have been present for about two weeks before the outbreak was detected.

“Well, if you are to look ‘yung course of events, maybe two weeks ago na mayroon na ‘yung virus, and that was also the time [na medyo marami], may cases pa rin sa Laoag,” she said.

“So, we do not know kung may nabili silang karne or may nabili sila o napasyalan ‘yung mga kasama nila, at [posibleng] naiuwi nila ‘yung virus,” she added.

Authorities continue to urge hog raisers to follow biosecurity measures to prevent further spread of the disease.