The major economic loss due to infection during the pig rasing period is the nusing and early fattening stages, and the porcine respiratory disease complex and infections of digestic tract are common in these stages, and the porcine circovirus type 2 (PCV2) shows the high prevelance. The single infection of PCV2 results in slight infection, but it's infection combine with other pathogens always exacerbate the infection. Our study intend to visit the north, central and sourthern area in Taiwan and chose where the pig herds is higher condense to perform our studey. We identify the pathogens and do a diagnosis by pathological diagnosis and PCR technique. By this study design, we wish we can realize the prevalance of PCV2 and other pathogens and the shedding pathern of PCV2.