HANOI, July 18 (Xinhua) -- "Blue ear" disease, or Porcine Reproductive and Respiratory Syndrome (PRRS), has hit Vietnam's northern Hai Duong province, raising the total number of affected localities in the country to 12, according to a local veterinary agency on Friday.

    Since July 15, the disease has killed 20 pigs and sickened 51 others in Thanh Ha district, said the Department of Animal Health under the Ministry of Agriculture and Rural Development.

    Now, PRRS is striking 12 Vietnamese provinces, including Hai Duong, Quang Ninh and Lao Cai in the northern region, Thua Thien Hue, Quang Tri, Binh Dinh, Phu Yen and Quang Nam in the central region, and Vinh Long, Bac Lieu, Soc Trang and Ba Ria Vung Tau in the southern region, the department said.

    PRRS was first recognized in the United States in the mid-1980s and is now present in most pig-producing countries. The symptoms include reproductive failure, pneumonia and increased susceptibility to secondary bacterial infection.