Cross-sectional study of seropositivity, lung lesions and associated risk factors of the main pathogens of Porcine Respiratory Diseases Complex (PRDC) in Goiás, Brazil

Abstract

Background The objective of the study was to evaluate the occurrence and severity of Porcine Respiratory Diseases Complex (PRDC) pathogens in the Goiás State, Brazil. Were assessed the serological antibodies occurrency of Mycoplasma hyopneumoniae, Actinobacillus pleuropneumoniae and swine influenza virus (SIV), as well as the evaluation of pulmonary Mycoplasma-like lung lesions, pleuritis, histopathological lesions and diseases occurrence associated with risk factors, such as management, housing and productive indexes. We conveniently selected 2536 animals for serology testing, and 900 lungs at slaughtering of animals from 30 multisite herds in Goiás State, Brazil. Results For M. hyopneumoniae, all herds presented seropositive animals at some stage of production. Even though most herds (29/30) vaccinated against this pathogen, 90.0% (27/30) of the herds presented at least 50.0% of seropositive animals in finishing and slaughter. Overall, antibodies against A. pleuropneumoniae were present in lower occurrence, varying from 22.4% of the animals in the nursery phase to 1.3% of the animals at slaughter. Conversely, SIV circulated in most herds, with 29 seropositive herds without vaccination. The occurrence of anti-SIV antibodies was higher at slaughter (74.5% of the animals) than nursery (41.8% of the animals), and at slaughter, 23 herds (76.7%) presented at least 50.0% of seropositive animals. All herds presented animals with pulmonary Mycoplasma-like lung lesions, and of the 900 lungs evaluated in the slaughterhouse, 665 (73.9%) presented an average Mycoplasma-like lung lesions of 7.3%. Evaluations of the pneumonia index (PI) showed that 73.3% of the herds were strongly affected by a pathology that manifested itself in different presentation forms. Microscopically, there was a predominance of bronchopneumonia lesions (74.6% of affected lungs), with a high occurrence of the chronic form (57.1%), and there was a moderate to marked proliferation of bronchial associated lymphoid tissue (BALT) in 64.1% of the affected lungs. Pleuritis were observed in 13.5% of the animals. Conclusion Serological tests evidenced that antibodies against App and SIV were present in the Goiás State herds, and high occurrence of M. hyopneumoniae antibodies in finishing phases and slaughter may be influenced by pathogen circulation in vaccinated herds, leading to respiratory lesions at slaughter. Additionally, swine influenza virus was broadly disseminated in technified herds in Goiás State.

Prevalence of mycoplasma-like lung lesions in pigs from commercial farms from Spain and Portugal

“…However, to a certain extent, it agrees with our observations, since most of the deaths were consequence of an acute process of fibrinous and suppurative bronchopneumonia. A recent study carried out in Brazil by Galdeano et al [ 15 ] also found the characteristic lesions of M. hyopneumoniae infection as the most prevalent one, being detected in 63.75 % of the lungs examined microscopically, but different to our study, the second most frequent lesion was chronic bronchopneumonia (57.14 %) whereas other lung lesions common in our study such as suppurative bronchopneumonia, interstitial pneumonia or fibrinous bronchopneumonia, were observed in a lesser extent (15.63 %, 3.61 % and 0.15 %, respectively). Nevertheless, it must be taken into account that porcine reproductive and respiratory syndrome virus (PRRSV) has never been detected in Brazil [ 33 ], thus, one of the main primary agents involved in the PRDC [ 5 ], alone or in combination with other pathogens, is not taken place in those farms.…”

“…Prevalence and severity of lung lesions, identification of the possible etiology and herd risk factors associated with these lesions, as well as the impact of the lesions on performance indicators and carcass and meat quality have been the subject of many studies [ 9 – 16 ]. Thus, a high variation among countries in the prevalence of mycoplasma-like lesions (MLL) at abattoir, ranging from 23.85 % in Belgium to 72.60 % in Germany, has been reported [ 9 , 11 , 12 , 15 , 17 – 20 ].…”

Prevalence of Mycoplasma-like Lung Lesions in Pigs From Commercial Farms From Spain and Portugal

“…However, to a certain extent, it agrees with our observations since most of the deaths were consequence of an acute process of brinous and suppurative bronchopneumonia. The recent study carried out in Brazil by Galdeano et al [13], also found the characteristic lesions of M. hyopneumoniae infection as the most prevalent ones, which were detected in 63.75% of the lungs examined microscopically, but different to our study, the following observed lesion was chronic bronchopneumonia (57.14%) and other lung lesions common in our study such as suppurative bronchopneumonia, interstitial pneumonia or brinous bronchopneumonia, were observed in a lesser extent (15.63%, 3.61% and 0.15%, respectively). Nevertheless, it must be taken into account that in Brazil porcine reproductive and respiratory syndrome virus (PRRSV) has never been detected [31], then the effect of one of the main primary agents involved in the PRDC [5], alone or in combination with other pathogens, is not taken place in those farms.…”

“…At abattoir, the post-mortem inspection is a truly common and useful practice in many countries to gather information about the herd health status and to monitor those changes in management or treatment which have been implemented in the farms. There are many studies carried out to evaluate the presence and severity of lung lesions and to identify the possible etiology and herd risk factors associated with these lesions, as well as the impact of the lesions on the carcass and meat quality [8,9,10,11,12,13].…”

“…Thus, it is reported that the prevalence of mycoplasma-like lesions (MLL) at abattoir raging from 23.85% in Belgium to 72.60% in Germany, with a high variation among countries [9,10,13,14,15,16,17].…”