Purpose To investigate the prevalence tendency and co-infection of porcine reproductive and respiratory syndrome virus (PRRSV) in Yunnan Province.
Methods PRRSV nucleic acid was detected in 3112 blood samples from 2013 to 2021 by molecular biology methods, and the prevalence and mixed infection of PRRSV were further analyzed.
Results Among the detected samples, 801 samples were positive for PPRSV, with a positive rate of 25.74%. The double, triple and quadruple mixed infection rates were 41.20%, 12.48% and 1.87%, respectively. The degree of PRRSV infection in pigs at different growth stages varied greatly, and the infection of growing fattening pigs was the most serious (33.24%). Compared with fattening farms and backyard farmers, the infection degree of pig farms was lighter, and the infection rates of the three were 27.94%, 28.94% and 14.29%, respectively. Analysis of different types of strains found that: highly pathogenic strains and classical strains were still the main epidemic strains, accounting for 58.49% and 22.64% of the number of strains, respectively, but the proportion was decreasing year by year. In 2019 and 2021, NADC30-like and NADC34-like strains were found in Yunnan Province, accounting for 15.09% and 3.77% of the number of strains, respectively, and their infection showed a gradual upward trend.
Conclusion Porcine reproductive and respiratory syndrome is still one of the most severe diseases threatening the healthy development of pig industry development in Yunnan Province, and the manifestations are mainly mixed infections with other diseases. With the discovery of new strains, PRRSV genes in Yunnan Province are more diverse, and the prevention and control situation is more complicated.
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