Abstract: The 170 clinic suspected PRRS samples collected in the western region of Henan province from December 2010 to November 2011 were tested by RT-PCR. The PCR was used to detect PCV2 and PRV from the 102 HP-PRRS positive samples. The detection results showed that the total mixed infection rate was 58.52%, the double mixed infection rate was 39.21%, and the triple mixed infection rate was 19.61%. The PRRSV/PCV mixed infection rate was the highest, which was 33.33%.In spring and summer, autumn and winter season, the mixed infection rates were 48.57% and 81.25% respectively. The mixed infection was more serious in the autumn and winter than in the spring and summer whether the double or the triple mixed infection. Especially the triple mixed infection rates about PRRSV/PCV2/PRV were 11.43% and 37.50% in spring and summer, autumn and winter. There were mixed infection from suckling to fattening period, the mixed infection rates of PRRS were 42.10%, 50.00% and 100.00%. There was different mixed infection at different stages of swine. The chief mixed infection at suckling period was PRRSV/PCV2 (42.10%), the chief mixed infection at nursery period was PRRSV/PCV2 or PRRSV/PCV2/PRV(22.73%, 22.73%), and the chief mixed infection at fattening period was PRRSV/PCV2/PRV(50.00%).This research reflected the situation and the rule of the mixed infection (PRRSV, PCV2 and PRV),and provided theoretical basis and guidance for clinical diagnosis and treatment of mixed infection and regional prevention in western region of Henan province.

Key words: the western region of Henan province; PRRSV; PCV2; PRV; mixed infection