HANOI, April 17 (Xinhua) -- Porcine Reproductive and Respiratory Syndrome (PRRS), known as "blue ear" disease, has recently hit Vietnam's northern Thai Binh province, bringing the total number of affected localities to seven, according to local newspaper Young People on Thursday.

    PRRS has stricken 470 communes and wards of 36 districts and towns of the seven provinces of Thanh Hoa, Ha Tinh, Nghe An, Quang Nam, Lam Dong and Thua Thien Hue in the central and central highlands regions and Thai Binh, leading to the death and the forced culling of nearly 171,300 pigs since early this year, said the country's Department of Animal Health.

    Thanh Hoa alone has 357 communes and wards hit by the disease with a total of over 146,700 affected pigs.

    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.