Porcine respiratory disease complex: Dynamics of polymicrobial infections and management strategies after the introduction of the African swine fever

Abstract

A few decades ago, porcine respiratory disease complex (PRDC) exerted a major economic impact on the global swine industry, particularly due to the adoption of intensive farming by the latter during the 1980's. Since then, the emerging of porcine reproductive and respiratory syndrome virus (PRRSV) and of porcine circovirus type 2 (PCV2) as major immunosuppressive viruses led to an interaction with other endemic pathogens (e.g., Mycoplasma hyopneumoniae, Actinobacillus pleuropneumoniae, Streptococcus suis, etc.) in swine farms, thereby exacerbating the endemic clinical diseases. We herein, review and discuss various dynamic polymicrobial infections among selected swine pathogens. Traditional biosecurity management strategies through multisite production, parity segregation, batch production, the adoption of all-in all-out production systems, specific vaccination and medication protocols for the prevention and control (or even eradication) of swine diseases are also recommended. After the introduction of the African swine fever (ASF), particularly in Asian countries, new normal management strategies minimizing pig contact by employing automatic feeding systems, artificial intelligence, and robotic farming and reducing the numbers of vaccines are suggested. Re-emergence of existing swine pathogens such as PRRSV or PCV2, or elimination of some pathogens may occur after the ASF-induced depopulation. ASF-associated repopulating strategies are, therefore, essential for the establishment of food security. The “repopulate swine farm” policy and the strict biosecurity management (without the use of ASF vaccines) are, herein, discussed for the sustainable management of small-to-medium pig farms, as these happen to be the most potential sources of an ASF re-occurrence. Finally, the ASF disruption has caused the swine industry to rapidly transform itself. Artificial intelligence and smart farming have gained tremendous attention as promising tools capable of resolving challenges in intensive swine farming and enhancing the farms' productivity and efficiency without compromising the strict biosecurity required during the ongoing ASF era.

The scene of lung pathology during PRRSV-1 infection

“…The disturbance of the physical barriers and immune response by several viruses, such as PRRSV, PCV2 or SIV, and Mycoplasma hyopneumoniae , among others, which are primary agents of the porcine respiratory disease complex (PRDC), is plausible to play a role in the coinfection with secondary endemic bacteria ( Pasteurella multocida , Bordetella bronchiseptica , Gläesserella parasuis , etc.) ( 41 , 42 ) or the proliferation of lung commensal microorganisms. Thus, further studies should address a proper characterisation of the pathogenic bacteria involved in the pathogenesis of the bronchopneumonia that is frequently observed concomitantly in virulent PRRSV-1 infections under experimental and field conditions.…”

Establishment and Application of a Quadruplex Real-Time Reverse-Transcription Polymerase Chain Reaction Assay for Differentiation of Porcine Reproductive and Respiratory Syndrome Virus, Porcine Circovirus Type 2, Porcine Circovirus Type 3, and Streptococcus suis

“…Porcine respiratory disease complex (PRDC) is a significant challenge in the swine industry worldwide [ 1 ]. Four common and important respiratory pathogens in swine production include Porcine Reproductive and Respiratory Syndrome Virus (PRRSV), Porcine Circovirus Type 2 (PCV2), Porcine Circovirus Type 3 (PCV3) and Streptococcus suis ( SS ) [ 2 , 3 , 4 ].…”

Simultaneous co-infection with swine influenza A and porcine reproductive and respiratory syndrome viruses potentiates adaptive immune responses

“…Porcine respiratory disease is a major cause of economic losses in the global pig industry, hampering growth and production ( 1 ). The etiology of this disease is often multifactorial, leading to its description as the porcine respiratory disease complex (PRDC) ( 2 ). The pathogens involved in the PRDC include both bacteria and viruses, and co-infections are identified in over 80% of cases ( 3 ).…”