Out of 2384 samples, 1115 and 1361 were positive forPRRSV and TTSuV1, respectively. From the geographicaldistribution, PRRSV and TTSuV1 were detected from all 6provinces, the prevalence rate was very high. This indicatesthat the two viruses are widely distributed in China, and itmight reach the distribution equilibrium to some extent.TTSuV1 detection rate in PRRSV-positive samples was>60% in 4 provinces: Jiangxi was the highest (69.5%) andShanghai the lowest (51.9%). In PRRSV-negative samples, the rate was >50% in 3 provinces: Jiangxi was the highest(55.1%) and Shanghai the lowest (33.6%). Among these, theoverall prevalence of TTSuV1 in PRRSV positive/negativesamples was 65.3% and 47.2%, respectively, and the formerrate was higher than the latter. Table 1 shows that exceptShandong province, the phenomenon of the prevalencerate of TTSuV1 in PRRSV-positive was higher than negative existed in each province. The results indicate that PRRSVand TTSuV1 are widely distributed in swine in China andTTSuV1 is mostly likely to have a synergistic effect with PRRSV.