Antibodies against Actinobacillus pleuropneumoniae, Mycoplasma hyopneumoniae and influenza virus and their relationships with risk factors, clinical signs and lung lesions in pig farms with one-site production systems in Brazil

Abstract

A study was conducted on 21 pig herds using one-site production system in the southeast region of Brazil to assess the relationships among serological results for primary pathogens involved in respiratory diseases (Actinobacillus pleuropneumoniae, App; Mycoplasma hyopneumoniae, Mhyo; and swine influenza virus, SIV), cough index, pneumonia index, pleuritis and herd characteristics. The prevalence of antibodies against Mhyo and SIV increased throughout the raising phases, with the highest prevalence in slaughtered pigs (> 40%), while pigs in 65% (14/21) of nurseries demonstrated marked seroprevalence of App that decreased until the day of slaughter. Pleuritis and pulmonary consolidations were recorded in 9.0 and 72.4%, respectively, of the 908 evaluated lungs. Histopathological analysis of the lung lesions revealed suppurative bronchopneumonia in almost half of the lungs (48.9%). Regression analyses were conducted to identify risk factors associated with the cough index; pleuritis; pulmonary consolidation; and App, Mhyo and SIV serological results. All-in-all-out management in nursery buildings reduced the seroprevalence of Mhyo in herds. App seroprevalence was associated with pleuritis, and the presence of cough episodes in growing pigs was associated with SIV seropositivity in nursery pigs.

Current Swine Respiratory Diseases Morphology in Intensive Swine Production in Serbia

“…However, vaccine protection against clinical pneumonia is incomplete because a commercial vaccine does not prevent colonization. The number of seropositive pigs gradually increased until end of the fi nishing period, indicating that M. hyopneumoniae may continue the circulation in vaccinated animals and cause active infection [8]. Poor management and safety measures are important factors that may cause secondary infections with other pathogens, resulting in further economic losses [12,13].…”

“…It is well known that the respiratory diseases of swine have multifactorial causes resulting from interactions among different etiological agents, environmental conditions and management practices [4,7,8]. The list of infectious agents that cause respiratory diseases in swine is extensive and includes both, bacterial and viral pathogens [9][10][11].…”

Associations between animal and herd management factors, serological response to three respiratory pathogens and pluck lesions in finisher pigs on farrow-to-finish farms

“…Lateral transmission occurs by pig-to-pig contact between infected and susceptible animals. An effective way to reduce disease spread is the implementation of strict all-in/all-out (AIAO) management practices [24,25]. In true AIAO systems, pigs are closely matched by age and move forward through the production stages in the same groups.…”

“…However, implementation of strict AIAO practices is di cult in farrow-to-nish farms as the majority lack facilities exclusively dedicated to pull outs (i.e. slow-growing and/or sick pigs) and pigs are often regrouped at various times according to their body weight [3], in an effort to achieve uniformity in slaughter weight [24]. This results in creating, perhaps inadvertently, several "production ows" increasing the likelihood of disease transmission between pigs of different age groups [3] with mixed immune status [27], within and between ows and extending to subsequent farrowing batches.…”

Associations between animal and herd management factors, serological response to three respiratory pathogens and pluck lesions in finisher pigs on a farrow-to-finish farm

“…slow-growing and/or sick pigs). Pigs are often regrouped at various times according to their body weight [2], in an effort to achieve uniformity in slaughter weight [16]. This results in creating, perhaps inadvertently, several "production ows" increasing the likelihood of disease transmission between pigs of different age groups [2] with mixed immune status [19], within and between ows and extending to subsequent farrowing batches.…”