Exploratory study on the influence of climatological parameters on Mycoplasma hyopneumoniae infection dynamics

Determinants of farms' antibiotic consumption - A longitudinal study of pig fattening farms in Germany

As high consumption of antibiotics in livestock production poses risks to public health, Germany has implemented a monitoring system to decrease their administration to farm animals. Data from 1,984 German pig farms are used to describe prescription trends for different antibiotic subclasses between Autumn 2017 and Autumn 2019. A panel Tobit model with control function approach is implemented to identify determinants of antibiotic consumption, where variables studied include farm, farmer, and county characteristics as well as weather variables. The overall quantity of prescribed antibiotics has been stable but with seasonal fluctuations and a shift away from critically important antibiotics used. Biosecurity factors such as livestock farm density in a county and pigs per farm are shown to be important drivers of antibiotic consumption. In addition, the number of cold days within a season increases antibiotic consumption but precipitation and the number of hot days have no significant effect.

Influence of parity and reproductive stage on the prevalence of Mycoplasma hyopneumoniae in breeding animals in belgian farrow-to-finish pig herds

Background

Dam-to-piglet transmission plays an important role in the epidemiology of enzootic pneumonia on farms. Although Mycoplasma hyopneumoniae (M. hyopneumoniae) infections in breeding animals are often subclinical, their control could have a positive effect on M. hyopneumoniae infection levels in fattening pigs. This study investigated the presence of M. hyopneumoniae in the breeding population of ten Belgian farrow-to-finish farms suspected by the herd veterinarian to be M. hyopneumoniae infected. Gilt vaccination against M. hyopneumoniae prior to first insemination was practiced on nine of the ten farms. At four different time points in the reproductive cycle 20 animals were sampled on each farm, namely 30–40 days of gestation, 75–85 days of gestation, 3–5 days after farrowing, and 1–3 days after weaning. In total, tracheobronchial swabs and blood samples were collected from 344 gilts and 456 sows (n = 80/farm). Swabs were analysed for the presence of M. hyopneumoniae DNA using nested PCR and M. hyopneumoniae-specific antibodies were detected in serum with a commercial ELISA. Generalized linear mixed models with farm as random factor were used to test the effect of time point in the reproductive cycle and parity on M. hyopneumoniae PCR prevalence and seroprevalence.

Results

M. hyopneumoniae PCR prevalence ranged between 0% and 43.8% at the farm level and the seroprevalence between 32.5% and 93.8%. Gilts were significantly more M. hyopneumoniae PCR positive than sows at the 2-4th parity (P = 0.02) and > 4th parity (P = 0.02). At 30–40 days of gestation, significantly more breeding animals were PCR positive as compared to 75–85 days of gestation (P = 0.04), 3–5 days after farrowing (P = 0.02) and 1–3 days after weaning (P = 0.02). Gilts had significantly more often M. hyopneumoniae-specific antibodies than sows (P = 0.03).

Conclusions

M. hyopneumoniae PCR prevalence varied a lot between farms and due to gilt vaccination the number of animals with M. hyopneumoniae-specific antibodies was high on most farms. Gilts were more often M. hyopneumoniae PCR positive than sows and positive animals were mostly found at 30–40 days of gestation. This emphasizes the importance of a sufficiently long quarantine period and proper gilt acclimation practices before introducing gilts to the sow herd.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40813-022-00267-w.

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

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.

Prevalence of porcine respiratory pathogens in slaughterhouses in Shanxi Province, China

Background

Porcine respiratory diseases remain the biggest challenge in pig‐based food production and are a public health concern. Despite control measures, persistent outbreaks have been reported worldwide.

Objective

To establish an early detection mechanism for pig farm disease outbreaks based on slaughterhouse risk and environmental assessment.

Methods

We investigated the prevalence and risk factors of porcine respiratory disease‐causing pathogens including Mycoplasma hyopneumoniae (MHP), porcine circovirus type 2 (PCV2), porcine reproductive and respiratory syndrome virus (PRRSV) and Haemophilus parasuis (HPS). Polymerase chain reaction (PCR) was used to analyse the lungs of 491 pigs from 19 slaughterhouses across 11 cities in Shanxi Province, China.

Results

PCR detected MHP, PCV2, PPRSV and HPS in 76.99%, 67.00%, 11.82% and 19.55% of the samples, respectively; 10.12% were negative for all four pathogens. Co‐positivity rates for two and three pathogens were identified. The results confirmed significant correlations between PCV2 and MHP (p = .001, p < .05), HPS and PCV2 (p = .01, p < .05) and MHP and PRRSV (p = .01, p < .05). No significant correlation was observed between HPS and MHP (p = .067, p > .05). Positive MHP and PCV2 rates were low in areas with high vegetation coverage. The overall pathogen positivity rate was higher in both lower and higher temperature environments.

Conclusions

Interactions among pathogens may increase disease severity. Furthermore, environmental assessment and pathogen surveillance within pig slaughterhouses can be an effective approach for early detection and mitigation of new disease threats before broad dissemination occurs among a herd.

Environment-, health-, performance- and welfare-related parameters in pig barns with natural and mechanical ventilation

A multifactorial approach using environmental, performance, health and welfare parameters was used to investigate the numerous associations of ventilation throughout three consecutive fattening batches (08/2015 to 12/2016) in a farrow-to-finish commercial pig farm in Belgium. Two fattening pig units were used, unit A (1256 pigs) with mechanical ventilation and unit B (1264 pigs) with natural ventilation. Animal genetics, nutrition, stocking density and health management were the same for both units. Key environmental indicators were monitored in real-time (temperature, humidity, CO2 and NH3) and the daily prevalence of respiratory disease cases was recorded to monitor the temporal expression of disease over time within a farm environment. The welfare status of the animals was assessed twice per production round (batch) with a simplified version of the Welfare quality® protocol. Serological tests for the most prevalent respiratory infectious agents (Mycoplasma hyopneumonniae, swine influenza virus (subtypes H1N1, H1N2 and H3N2), Actinobacillus pleuropneumoniae serotypes 1-2-9-11 and porcine circovirus type 2) were performed during the first, second and final third of each fattening period. Finally, key performance parameters were calculated (average daily growth, feed conversion ratio) and upon slaughter lungs from pigs from unit A (n: 782) and from unit B (n: 544) were assessed for the presence of lung lesions, pleurisy and fissures. To identify the associations of ventilation on the aforementioned parameters, statistical models were run that also included other factors (when applicable) namely production batch, season, age and sampling. Overall, the use of natural ventilation was associated with a less optimal environment with regards to thermal comfort (p < 0.001), CO₂ (p < 0.001) and NH₃ (p < 0.001). A higher daily prevalence of respiratory disease cases was seen in the naturally-ventilated unit (p < 0.001). Concerning the sero-prevalence of the infectious agents tested, the odds to have a positive H1N1 sample were 3.17 higher in the naturally-ventilated unit (p = 0.003). From the visual assessment of the lungs no statistically significant associations were seen between ventilation type and the presence of lesions, fissures or pleuritis. Yet, the lung lesion score was expected to be lower in the naturally-ventilated unit (p = 0.010). Regarding performance parameters, feed conversion ratio and average daily gain were overall better in the mechanically-ventilated unit (descriptive results). Finally, a better welfare score was seen in the mechanically-ventilated unit in all three production batches (descriptive results). In conclusion, the mechanically-ventilated farm was associated with better environmental conditions for the fattening pigs. Yet, further research is needed to reach definite causal claims.

Objective pathogen monitoring in nursery and finisher pigs by monthly laboratory diagnostic testing

Background

Infectious diseases are of great economic importance in commercial pig production, causing both clinical and subclinical disease, with influence on welfare, productivity, and antibiotic use. The causes of these diseases are often multifactorial and laboratory diagnostics are seldom routinely performed. The aim of the present study was to explore the benefits of monthly pathogen monitoring in nursery and finisher herds and to examine association between laboratory results and observed clinical signs, including coughing and diarrhoea. Three monthly samplings were conducted in three different age groups in six nursery and four finisher production units. For each unit, two pens were randomly selected in each age group and evaluated for coughing and diarrhoea events. Furthermore, faecal sock and oral fluid samples were collected in the selected pens and analysed for 18 respiratory and enteric viral and bacterial pathogens using the high-throughput real-time PCR BioMark HD platform (Fluidigm, South San Francisco, USA).

Results

In total, 174 pens were sampled in which eight coughing events and 77 diarrhoeic events were observed. The overall findings showed that swine influenza A virus, porcine circovirus 2, porcine cytomegalovirus, Brachyspira pilosicoli, Lawsonia intracellularis, Escherichia coli fimbria types F4 and F18 were found to be prevalent in several of the herds. Association between coughing events and the presence of swine influenza A virus, porcine cytomegalovirus (Cq ≤ 20) or a combination of these were found. Furthermore, an association between diarrhoeic events and the presence of L. intracellularis (Cq ≤ 24) or B. pilosicoli (Cq ≤ 26) was found.

Conclusions

The use of high-throughput real-time PCR analysis for continuous monitoring of pathogens and thereby dynamics of infections in a pig herd, provided the veterinarian and farmer with an objective knowledge on the distribution of pathogens in the herd. In addition, the use of a high-throughput method in combination with information about clinical signs, productivity, health status and antibiotic consumption, presents a new and innovative way of diagnosing and monitoring pig herds and even to a lower cost than the traditional method.

Effects of pre-farrowing sow vaccination against Mycoplasma hyopneumoniae on offspring colonisation and lung lesions

This study investigated Mycoplasma hyopneumoniae colonisation and lung lesions at slaughter in pigs from vaccinated (V) and non-vaccinated (NV) sows, in two herds (A and B). In each herd, two sow batches were V against M. hyopneumoniae with a commercial bacterin at six and three weeks before farrowing and two sow batches remained NV. From each sow batch, laryngeal swabs were collected from the litters of five primiparous sows at weaning and seven days post-weaning. All samples were tested for M. hyopneumoniae by nested PCR. In total, 488 piglets were sampled. At slaughter, the extent of Mycoplasma-like pneumonia lesions (lung lesion score (LLS)) was assessed. The colonisation rates with M. hyopneumoniae at weaning and seven days post-weaning were (V-A=14.2, NV-A=20.0 (P=0.225); V-B=0.9, NV-B=0.8 (P=0.948)) and (V-A=0.8, NV-A=7.0 (P=0.039); V-B=1.8, NV-B=2.5 (P=0.738)), respectively. The average LLS (in per cent) was V-A=15.5, NV-A=26.4 (P=0.021); V-B=9.7, NV-B=8.4 (P=0.541). In conclusion, in herd A, with a substantially higher level of piglet colonisation at weaning than herd B, offspring from V sows had a significantly lower colonisation rate seven days post-weaning and a significantly lower LLS at slaughter compared with the offspring of the NV sows. This implies that sow vaccination might be useful for control of M. hyopneumoniae infections, although significant results may not be achieved at all times (such as in herd B).

Increased Mycoplasma hyopneumoniae Disease Prevalence in Domestic Hybrids Among Free-Living Wild Boar

Wildlife immune genes are subject to natural selection exerted by pathogens. In contrast, domestic immune genes are largely protected from pathogen selection by veterinary care. Introgression of domestic alleles into the wild could lead to increased disease susceptibility, but observations are scarce due to low introgression rates, low disease prevalence and reduced survival of domestic hybrids. Here we report the first observation of a deleterious effect of domestic introgression on disease prevalence in a free-living large mammal. A fraction of 462 randomly sampled free-living European wild boar (Sus scrofa) was genetically identified as recent wild boar-domestic pig hybrids based on 351 SNP data. Analysis of antibody prevalence against the bacterial pathogen Mycoplasma hyopneumoniae (Mhyo) showed an increased Mhyo prevalence in wild-domestic hybrids. We argue that the most likely mechanism explaining the observed association between domestic hybrid status and Mhyo antibody prevalence would be introgression of deleterious domestic alleles. We hypothesise that large-scale use of antibiotics in the swine breeding sector may have played a role in shaping the relatively deleterious properties of domestic swine immune genes and that domestic introgression may also lead to increased wildlife disease susceptibility in the case of other species.

Mycoplasma hyopneumoniae infections in peri-weaned and post-weaned pigs in Belgium and The Netherlands: Prevalence and associations with climatic conditions

Mycoplasma hyopneumoniae (M. hyo) is an important pathogen in modern intensive pig farming in Europe. The objectives of the present study were (1) to use the tracheobronchial swab (TBS) technique to obtain data on the distribution of M. hyo infections in recently weaned pigs in Belgium and The Netherlands, and (2) to look for associations between infection prevalence and specific climatic conditions. One hundred and seventy-six pig herds were randomly selected and 30 piglets sampled on each farm: 18 at 3-5 weeks of age and 12 at 6-11 weeks. Mucus collected from the tracheobronchial bifurcation and suspended in saline was subjected to PCR analysis for M. hyo. In 27% of herds (n= 44) at least one piglet tested positive for M. hyo at 3-5 weeks of age, and 29% (n= 47) at 6-11 weeks of age. The individual animal prevalence at the two ages was 7.1% and 10.9%, respectively. The probability of 3-5 week old piglets being M. hyo-positive was negatively associated with the precipitation rate (odds ratio [OR] = 0.971) during the week preceding the sampling. In the older post-weaning group, the odds of being M. hyo-positive at piglet level were significantly affected by season (OR of detection during autumn compared to summer 20.9). Thus, under Belgian and Dutch field conditions, piglets may be infected with M. hyo very early in life, with prevalence increasing further during the post-weaning period.

Intra-farm risk factors for Mycoplasma hyopneumoniae colonization at weaning age

The objective of this study was to identify intra-farm risk factors that affected the colonization with Mycoplasma hyopneumoniae at weaning age. Three farrow-to-wean farms were visited at least 5 times each. An average of 54 piglets were sampled at each visit and assayed by means of real-time PCR in nasal swabs. The proportion of PCR positive piglets was evaluated as a response to several variables including dam's PCR status, piglet serological status, and local climatic conditions during the lactation period, as well as other factors. All piglets at weaning age were negative to M. hyopneumoniae in 2 of the 3 farms. M. hyopneumoniae positive piglets were demonstrated in 5 of 7 weaning groups in 1 farm. The proportion of M. hyopneumoniae positive piglets in each weaning group at the positive farm was correlated with the proportion of positive dams in the group. The prevalence of M. hyopneumoniae at weaning increased with the piglet's age in the groups where at least one dam was positive. These results highlight the influence of the sow in the sow-to-piglet colonization process, as previously reported, and contribute to a more comprehensive understanding of the epidemiology of M. hyopneumoniae infections.