Pileri Emanuela, Martín-Valls Gerard E, Díaz Ivan, Allepuz Alberto, Simon-Grifé Meritxell, García-Saenz Ariadna, Casal Jordi, Mateu Enric
IRTA, Centre de Recerca en Sanitat Animal (CReSA, IRTA-UAB), Campus de la Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain,; Departament de Sanitat i d'Anatomia Animals, Universitat Autònoma de Barcelona, 08193 Bellaterra (Cerdanyola del Vallès), Spain.
IRTA, Centre de Recerca en Sanitat Animal (CReSA, IRTA-UAB), Campus de la Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain,; Departament de Sanitat i d'Anatomia Animals, Universitat Autònoma de Barcelona, 08193 Bellaterra (Cerdanyola del Vallès), Spain.
Prev Vet Med. 2017 Mar 1;138:147-155. doi: 10.1016/j.prevetmed.2017.01.008. Epub 2017 Jan 18.
In the present study, the transmission parameters of swine influenza virus (SIV) and porcine reproductive and respiratory virus (PRRSV) have been calculated using the basic reproductive rate (R) parameter in two commercial pig farms (F1 and F2). In order to do this, a serological (PRRSV genotype 1 and SIV) and virological (SIV) follow-up of a batch of animals was carried out weekly from 3 weeks of age until the age of slaughter on each farm. Results of the analysis for SIV and PRRSV showed different transmission profiles depending on the farm, the pathogen, and time of transmission. In F1, transmission of both viruses was detected throughout the sampling. The R (R for a given period of time) value for SIV ranged from 1.5 [0.9-2.3] to 3.6 [2.3-4.9] from farrowing to the beginning of the fattening period, and the R value for PRRSV was 3.3 [2.9-4.3] to 3.5 [2.8-4.1] from farrowing until the slaughter age. These results indicated that both viruses were transmitted enzootically in that farm for these periods of time. A different transmission pattern with a higher incidence was also observed during the fattening period in F1 (after 15 weeks of age) for SIV, coinciding with the entrance of a new subtype. In this case, R value for SIV reached 3.3 [1.65-4.9]. On the other hand, in F2, SIV and PRRSV seemed to be restricted to the fattening period. R reached a value of 6.4 [4.1-8.8] for SIV and 7.1 [3.5-10.6] for PRRSV. These findings suggest a different origin of the virus, as well as a more epidemic circulation, especially for SIV, where most of the new cases were observed in a one week period. In conclusion, the present study offers a reliable estimation of the range of R values for SIV and genotype 1 PRRSV transmission under field conditions, suggesting that enzootic circulations of both viruses are similar in terms of transmission, probably higher for PRRSV, but also that transmission of SIV is more efficient (or epidemic) than transmission of a genotype 1 PRRSV isolate in naïve animals given the new cases observed in only in F2.
在本研究中，已使用基本繁殖率（R）参数计算了两个商业猪场（F1和F2）中猪流感病毒（SIV）和猪繁殖与呼吸综合征病毒（PRRSV）的传播参数。为此，在每个猪场从3周龄到屠宰年龄每周对一批动物进行血清学（PRRSV 1型和SIV）和病毒学（SIV）跟踪监测。SIV和PRRSV的分析结果显示，传播情况因猪场、病原体和传播时间而异。在F1猪场，整个采样期间均检测到两种病毒的传播。从产仔到育肥期开始，SIV的R（给定时间段内的R）值范围为1.5[0.9 - 2.3]至3.6[2.3 - 4.9]，PRRSV从产仔到屠宰年龄的R值为3.3[2.9 - 4.3]至3.5[2.8 - 4.1]。这些结果表明，在该时间段内这两种病毒在该猪场呈地方流行性传播。在F1猪场育肥期（15周龄后）还观察到SIV的另一种传播模式，发病率更高，这与一种新亚型的引入相吻合。在这种情况下，SIV的R值达到3.3[1.65 - 4.9]。另一方面，在F2猪场，SIV和PRRSV似乎仅限于育肥期传播。SIV的R值达到6.4[4.1 - 8.8]，PRRSV的R值达到7.1[3.5 - 10.6]。这些发现表明病毒的来源不同，且传播更具流行性，尤其是SIV，其中大多数新病例在一周内被观察到。总之，本研究提供了在田间条件下SIV和1型PRRSV传播的R值范围的可靠估计，表明两种病毒的地方流行性传播在传播方面相似，PRRSV可能更高，但鉴于仅在F2猪场观察到新病例，SIV的传播比1型PRRSV分离株在未接触过该病毒动物中的传播更有效（或更具流行性）。
