Seasonal Variation in Prevalence of Mycoplasma hyopneumoniae and Other Respiratory Pathogens in Peri-Weaned, Post-Weaned, and Fattening Pigs with Clinical Signs of Respiratory Diseases in Belgian and Dutch Pig Herds, Using a Tracheobronchial Swab Sampling Technique, and Their Associations with Local Weather Conditions

Abstract

Besides Mycoplasma hyopneumoniae (M. hyopneumoniae), many other viruses and bacteria can concurrently be present in pigs. These pathogens can provoke clinical signs, known as porcine respiratory disease complex (PRDC). A sampling technique on live animals, namely tracheobronchial swab (TBS) sampling, was applied to detect different PRDC pathogens in pigs using PCR. The objective was to determine prevalence of different PRDC pathogens and their variations during different seasons, including correlations with local weather conditions. A total of 974 pig farms and 22,266 pigs were sampled using TBS over a 5-year period. TBS samples were analyzed using mPCR and results were categorized and analyzed according to the season of sampling and local weather data. In samples of peri-weaned and post-weaned piglets, influenza A virus in swine (IAV-S), porcine reproductive and respiratory syndrome virus—European strain (PRRSV1), and M. hyopneumoniae were found as predominant pathogens. In fattening pigs, M. hyopneumoniae, porcine circovirus type 2 (PCV-2) and PRRSV1 were predominant pathogens. Pathogen prevalence in post-weaned and finishing pigs was highest during winter, except for IAV-S and A. pleuropneumoniae, which were more prevalent during autumn. Associations between prevalence of several PRDC pathogens, i.e., M. hyopneumoniae, PCV-2 and PRRSV, and specific weather conditions could be demonstrated. In conclusion, the present study showed that many respiratory pathogens are present during the peri-weaning, post-weaning, and fattening periods, which may complicate the clinical picture of respiratory diseases. Interactions between PRDC pathogens and local weather conditions over the 5-year study period were demonstrated.

Viral and Bacterial Profiles in Endemic Influenza A Virus Infected Swine Herds Using Nanopore Metagenomic Sequencing on Tracheobronchial Swabs

“…Furthermore, the swIAV viral loads were the highest at the nursery stage, suggesting that swIAV is present at an early age. This was confirmed in recent studies in Europe ( 16 , 28 ). Hence, swIAV might significantly impact the further clinical course of other pathogens ( 10 , 32 , 33 ).…”

“…However, this does not imply that PCV-2 infections do not contribute to respiratory disease and/or PRDC. In addition, its identification is thought to be age-dependent, as an increase from 11% (6- to 11-week-old pigs) to 27% (12- to 25-week-old pigs) was observed in Belgian TBS samples ( 16 ). To ensure its relevance, lymph nodes and/or lung tissues of pigs should be collected to determine PCV-2 infections via immunohistochemistry and qPCR.…”

“…Multiplex qPCR approaches may help to bundle polyetiological diagnostic approaches, and such assays have been designed for the bovine respiratory disease complex (BRDC), which has a similar polymicrobial etiology; however, they are often incomplete, are sensitive to primer mismatching due to viral evolution, and come with a higher cost ( 15 ). Comparable multiplexing alternatives in porcine respiratory disease and PRDC have been generated, but they are not widely used in routine diagnostic laboratories ( 16 ). With the increased availability of new sequencing technologies, the costs associated with sequencing could be significantly reduced.…”

Prevalence and phylogenetic analysis of porcine circovirus type 2 (PCV2) and type 3 (PCV3) in the Southwest of China during 2020–2022

“…The reason of the lower growth rate for 2021–2022 might be attributed to the lower sample size in 2022 as only the first half of the year was tested. Also, since PCVs prevalence is the highest mainly in winter after weaning ( 36 ), the incidence rate in spring 2022 cannot fully reflect the infection rate in that region. In addition, some studies have reported higher rates of infection and more pronounced clinical symptoms of PCV3 when other viruses are present, including PCV2, porcine parvovirus (PPV), and PRRSV ( 37 , 38 ).…”

Detection of Porcine Circovirus Type 2a and Pasteurella multocida Capsular Serotype D in Growing Pigs Suffering from Respiratory Disease

“…bronchiseptica are frequently detected in cases of PRDC [ 12 , 14 , 15 , 16 , 17 ]. However, the type of combinations and kind of associated infectious agents vary with local weather conditions, region, and breeding conditions, which generally complicates the severity, prevention, and control of the disease [ 18 ]. P. multocida is one of the most common bacterial agents isolated from respiratory clinical cases worldwide and often is a secondary or opportunistic pathogen of PRDC [ 19 , 20 ].…”