湖北省部分规模猪场猪繁殖与呼吸综合征流行病学调查

Epidemiological Investigation on PRRS in Some Intensive Swine Farms in Hubei Province

为探究猪繁殖与呼吸综合征病毒(PRRSV)在规模猪场的流行特征,2021年从湖北省7个规模猪场疑似PRRSV感染猪群以及所有种公猪群中,共收集样品3324份,采用三重巢式RT-PCR法进行PRRSV病原学检测,分析不同养殖类型、不同生长阶段、不同季节及不同感染毒株的流行特点,并将阳性产物进行测序和遗传进化分析。结果显示:3324份样品中共检测出PRRSV阳性样品323份,阳性检出率为9.72%(323/3324)。育种场阳性检出率最低,为2.66%(20/752);商品猪扩繁场与育肥场阳性检出率相近,分别为11.82%(169/1430)与11.73%(134/1142);保育猪群阳性检出率最高,为17.23%(152/882);其余依次为生长育肥猪、哺乳仔猪和母猪,阳性检出率分别为11.30%(121/1071)、5.26%(30/570)和3.24%(20/618);种公猪中未发现PRRSV感染。PRRSV一年四季均可流行,春、夏、秋、冬季的阳性检出率分别为18.16%(148/815)、6.94%(60/864)、6.10%(34/557)、7.44%(81/1088),春季阳性检出率显著高于其他季节(P<0.05),而夏、秋、冬季节间差异不显著(P≥0.05)。3种PRRSV毒株均有流行,类NADC30毒株、经典毒株和高致病性变异毒株的占比分别为49.54%、21.36%、29.10%,类NADC30毒株检出占比显著高于其他类型毒株(P<0.05)。结果表明:PRRSV在所调查的7个规模猪场中流行普遍,尤其是商品猪扩繁场与育肥场;保育猪群PRRSV感染风险较高,种公猪感染风险较低,春季是高发季节,类NADC30毒株为优势流行毒株。结果提示,规模养殖场应根据PRRSV的流行特征,加强免疫和监测,有针对性地制定防控措施。

In order to investigate the epidemiological characteristics of porcine reproductive and respiratory syndrome virus(PRRSV)in intensive swine farms,a total of 3324 samples were collected in 2021 from pigs suspected to be infected with PRRSV and all boars in 7 intensive farms in Hubei Province for pathogenic detection by triple-nested RTPCR to analyze the prevalent situation in different breeding types,growth stages,seasons and strains,followed by sequencing and genetic evolution of positive products.The results showed that 323 positive samples were detected,with the positive rate of 9.72%(323/3324);the lowest positive detection rate was 2.66%(20/752)in breeding farms,similar in commercial propagation farms and fattening farms,which were 11.82%(169/1430)and 11.73%(134/1142)respectively;highest in nursery pigs(17.23%),followed by growing finishing pigs,suckling piglets and sows,with 11.30%(121/1071),5.26%(30/570)and 3.24%(20/618)respectively,no PRRSV infection was found in breeding boars;PRRSV could be prevalent throughout a year,and the positive detection rates in spring,summer,autumn and winter were 18.16%(148/815),6.94%(60/864),6.10%(34/557)and 7.44%(81/1088)respectively;that in spring was significantly higher than those in other seasons(P<0.05),but with slightly difference in summer,autumn and winter(P≥0.05);all three types of strains including NADC30-like strain,classical strain and highly pathogenic variant strain were prevalent,accounting for 49.54%,21.36%and 29.10%,respectively,the proportion of NADC30-like strain was significantly higher than other types of strain(s P<0.05).In conclusion,PRRSV was widely prevalent in the 7 farms,especially in commercial propagation farms and fattening farms;the risk of PRRSV infection was high in nursery pigs,lower in breeding boars;and NADC30 like strain was the dominant epidemic strain,especially in spring.Therefore,immunization and monitoring should be strengthened by the farms according to the prevalent characteristics of PRRSV,and targeted measures for prevention and control should be developed.