The epidemiological investigation of co‐infection of major respiratory bacteria with pseudorabies virus in intensive pig farms in China

Abstract

Porcine respiratory disease complex (PRDC), a respiratory disease caused by a variety of factors, is one of the most common problems in the intensive pig farms. To investigate the mixed infection incidence of wild‐type pseudorabies virus (WT PRV) and respiratory bacteria, a total of 1,293 clinical samples were collected from pigs with typical respiratory signs from 14 different provinces of China from September 2016 to February 2018. The WT PRV was detected by ELISA targeting gE antibody while the bacteria were detected by bacterial isolation and serotyping by PCR. The results revealed that the detection rate of A. pleuropneumoniae and B. bronchiseptica infection associated with WT PRV infection were 6.30% and 15.99%, respectively, which were significantly higher than those without WT PRV infection (3.41% and 4.41%) at the farm level (p < .05). There were no significant differences in the detection rate of H. parasuis, S. suis or P. multocida between WT PRV positive and negative farms (p > .05). However, the detection rate of attenuated H. parasuis and S. suis strains were 68.19% and 64.75%, respectively, in WT PRV infected farms, which were significantly higher than those (41.56% and 52.25%) in WT PRV free farms (p < .05). The prevalent serotypes of H. parasuis‐5/12 and S. suis‐2 were also investigated by multiplex PCR. These results indicated that the presence of WT PRV increased the chance of bacterial infection and the number of pathogenic strains in the respiratory system of pigs. Therefore, the eradication of pseudorabies is an effective approach to prevent and control the bacterial respiratory diseases in the intensive pig farms in China.

Investigation and analysis of etiology associated with porcine respiratory disease complex in China from 2017 to 2021

“…After introducing a new method, serotypes 1 and 14, 2, and 1/2 were re-investigated, and serotype 1/2 infection was found in China as early as 2018. Between 2017 and 2021, the detection rates of most serotypes were relatively stable, but the detection rate of serotype 9 decreased dramatically, which was considerably different from the latest survey results (17,41,42), suggesting a new change in the epidemic situation of S. suis in China. For G. parasuis, a similar phenomenon occurred in different serotypes.…”

“…Over the past 5 years, the detection rate of serotype 1 has shown a gradual increase, particularly in 2021, and the proportion increased significantly. In contrast, the detection rate of serotype 5, which was the highest proportion in the past, decreased annually, which undoubtedly showed that the serotype trend of G. parasuis in China is changing (17,42,43). For P. multimedia, the results showed that the most prevalent strains in China were still the capsular serogroups D strains, followed by the capsular serogroups A, which was consistent with the previous research results (44,45).…”

“…This could be related to the ventilation frequency and the air quality of the pig house. Environmental and management conditions have been shown to be of major importance in the modulation of bacterial infection ( 17 , 42 ).…”

“…At present, numerous studies have reported the interaction between viruses and bacteria such as PRRSV and S. suis ( 9 , 10 ), PRRSV and G. parasuis ( 11 ), and PRV and A. pleuropneumoniae ( 12 ), indicating that immunosuppressive pathogens can extremely increase the susceptibility to bacterial infection, and coinfection can significantly increase the pathogenicity of bacteria in pigs ( 5 ). However, little scientific and clinical evidence exist to support this conclusion at the clinical level ( 7 , 16 , 17 ). Therefore, there is an urgent requirement to investigate and understand the correlation between immunosuppressive viruses and respiratory bacteria at the clinical level.…”

Conception of the 'feed’s chain' for porcine circovirus-bacterial infections in piggery

“…Метою досліджень було застосування QMRA-моделювання [5,6] для вивчення впливу бактерійного забруднення ячменю з власних кормових угідь господарств, ензоотично неблагополучних vs. умовно благополучних, на рушійні сили епізоотичного процесу цирковірусасоційованих синдромокомплексівпроліферативно-некротизуючої пневмонії (PNP) та комплексу респіраторних хвороб свиней (PRDC). За даними літератури в етіології PNP активну участь приймають актинобацили плевропневмонії свиней та гемофіли, а PRDC, крім ЦВС-2, часто спричиняє вірус хвороби Ауєскі у асоціації з бактеріями родини пастерел [7][8][9][10].…”