Swine in Minnesota

M.hyopneumoniae: knowledge gaps for improved disease control

Enzootic pneumoniae is a chronic respiratory disease caused by Mycoplasma hyopneumoniae in pigs. It has been present in the industry for decades and causes significant economic losses. Yet, control methods like vaccination have not been able to contain the disease. Why is that? What information are we missing to design more effective control methods? This is the goal of the review paper co-authored by Dr. Maria Pieters from the University of Minnesota.

Focusing on various aspects of the disease like epidemiology, pathogenicity, diagnostics, and control measures, this publication regroups all the knowledge we currently have of Mycoplasma hyopneumoniae and identifies what we need to investigate to improve disease control.

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Abstract:

Mycoplasma hyopneumoniae (M. hyopneumoniae) is the primary pathogen of enzootic pneumonia, a chronic respiratory disease in pigs. Infections occur worldwide and cause major economic losses to the pig industry. The present paper reviews the current knowledge on M. hyopneumoniae infections, with emphasis on identification and analysis of knowledge gaps for optimizing control of the disease. Close contact between infected and susceptible pigs is the main route of M. hyopneumoniae transmission. Management and housing conditions predisposing for infection or disease are known, but further research is needed to better understand M. hyopneumoniae transmission patterns in modern pig production systems, and to assess the importance of the breeding population for downstream disease control. The organism is primarily found on the mucosal surface of the trachea, bronchi and bronchioles. Different adhesins and lipoproteins are involved in the adherence process. However, a clear picture of the virulence and pathogenicity of M. hyopneumoniae is still missing. The role of glycerol metabolism, myoinositol metabolism and the Mycoplasma Ig binding protein—Mycoplasma Ig protease system should be further investigated for their contribution to virulence. The destruction of the mucociliary apparatus, together with modulating the immune response, enhances the susceptibility of infected pigs to secondary pathogens. Clinical signs and severity of lesions depend on different factors, such as management, environmental conditions and likely also M. hyopneumoniae strain. The potential impact of strain variability on disease severity is not well defined. Diagnostics could be improved by developing tests that may detect virulent strains, by improving sampling in live animals and by designing ELISAs allowing discrimination between infected and vaccinated pigs. The currently available vaccines are often cost-efficient, but the ongoing research on developing new vaccines that confer protective immunity and reduce transmission should be continued, as well as optimization of protocols to eliminate M. hyopneumoniae from pig herds.

Science page: Are patterns of spatiotemporal clustering of PRRSv consistent across years?

This is our Friday rubric: every week a new Science Page from the Bob Morrison’s Swine Health Monitoring Project. The previous editions of the science page are available on our website.

This week, we studied a subset of MSHMP participants located in the Midwest to test if some location/time combinations are more prominent during certain seasons across the years. Data from 358 farms in 10 management systems from 2011 to 2015 was compiled to look for clusters.

The clusters found by the SaTScanTM software are represented below. The red circles represent clusters identified in the time period from January to June, whereas blue ones are July to December. We can note that clusters were identified every year but that they varied with time.

Significant PRRS spatial cluster midwest — Significant spatial clusters for PRRSV in the Midwest between 2011 and 2015.

Key points

PRRS cases are recognized to be seasonal and aggregated by geographical space.
However, spatiotemporal patterns of PRRS clustering were not consistent across years.
Drivers of infection spread may vary over the years.

Future uses for this model can be found in the entire report

What are the acclimation practices for Mycoplasma hyopneumoniae accross the EU?

This new publication in the Porcine Health Management journal is the result of a collaboration between the University of Barcelona in Spain, PIC (Pig improvement Company) and the MycoLab at the University of Minnesota.

321 farms were surveyed across Europe and Russia regarding their practices for gilt acclimation especially in the context of Mycoplasma hyopneumoniae. The farms are spread over 18 countries and this is reflected in the strong variation of the measures taken to acclimate the incoming gilt population.

Among the questions asked, the type of farm as well as the size of the herd were recorded. Regarding the gilts, the researchers took into account receiving schedule as well as origin and age in addition to the acclimation measures.

In the table below, you can see the summary of the measures taken to acclimate the gilts to Mycoplasma hyopneumoniae. The vast majority of the herds (77%) used vaccination either as a single intervention or coupled with exposure to sows about to be culled. Another popular option (22.4%) was no intervention at all.

Acclimation methods for Mycoplasma hyopneumoniae across the EU — Number of farms (%)according to the methods used for replacement gilt acclimation in terms of *M. hyopneumoniae*

Click on the table above to see the full open-access publication.

Abstract

Gilts are considered to play a key role in Mycoplasma hyopneumoniae (M.hyopneumoniae) transmission and control. An effective gilt acclimation program should ideally reduce M. hyopneumoniae shedding at first farrowing, decreasing pre-weaning colonization prevalence and potential respiratory problems in fatteners. However, information on gilt acclimation practices is scarce in Europe. The aim of this study was to identify current acclimation strategies for M. hyopneumoniae in Europe using a questionnaire designed to assess 15 questions focused on gilt replacement status,

acclimation strategies and methods used to ascertain its effect. A total of 321 questionnaires (representing 321 farms) were voluntarily completed by 108 veterinarians (from 18 European countries). From these farms, 280 out of 321 (87.2%) were aware of the health status of gilts on arrival. From these 280 farms, 161 (57.5%) introduced M. hyopneumoniae positive replacements. In addition, 249 out of 321 (77.6%) farms applied an acclimation process using different strategies, being M. hyopneumoniae vaccination (145 out of 249, 58.2%) and the combination of vaccine and

exposure to sows selected for slaughter (53 out of 249, 21.3%) the most commonly used. Notwithstanding, only 53 out of 224 (23.6%) farms, knowing the M. hyopneumoniae initial status and performing acclimation strategies against it, verified the effect of the acclimation by ELISA (22 out of 53, 41.5%), PCR (4 out of 53, 7.5%) or both (27 out of 53, 50.9%). This study showed that three fourths of the farms represented in this European survey have M. hyopneumoniae acclimation strategies for gilts, and one fifth of them verify to some extent the effect of the process. Taking into account that the assessment of acclimation efficacy could help in optimizing replacement gilt introduction into the breeding herd, it seems these practices for M. hyopneumoniae are still poorly developed in Europe.

Link to the full open-access publication

Science page: Evaluation of biosecurity measures to prevent indirect transmission of PEDV

This is our Friday rubric: every week a new Science Page from the Bob Morrison’s Swine Health Monitoring Project. The previous editions of the science page are available on our website.

The objective of the study presented today was to evaluate the efficacy of of biosecurity procedures directed at minimizing transmission via personnel following different protocols in controlled experimental settings.

Four (4) groups were housed in different rooms:

INF: Pigs infected with PEDV
LB: Naive pigs which were exposed to personnel coming from the INF room without changing PPE at all
MB: Naive pigs which were exposed to personnel coming from the INF room after washing their hands and face as well as changing footwear and clothing.
HB: Naive pigs which were exposed to personnel coming from the INF room after showering as well as changing clothing and footwear.

Results are shown in the figure below. Naive pigs were exposed to personnel from 44h after the pigs in the INF group were infected with PEDV until 10 days post infection.

PEDV indirect transmission biosecurity measures — Viral shedding of pigs. Movements were terminated at 10 dpi. Data presented are average values of viral RNA copies (± SD) of infected (INF), low biosecurity (LB), medium biosecurity (MB) and high biosecurity (HB) groups

Key points:

PEDV transmission is likely to occur with contaminated fomites in low biosecurity scenarios.
Indirect contact transmission of PEDV can happen very rapidly. Transmission was detected 24h after personnel moved from infected to low biosecurity rooms (no change in clothes, boots or washing hands)
Changing PPE (personal protective equipment) and washing skin exposed areas is beneficial to decrease the risk of PEDV transmission.

Link to the facilities diagram explaining the experiment setup as well as the results on PEDV indirect transmission in this study.

Bioaerosol sampling for airborne virus surveillance in swine facilities

Bioaerosol sampling refers to the methods by which one is able to collect the particles of biological origin (microbial, animal, or plant) in the air. This is useful information in swine production because many economically important pathogens can be transmitted by air from one farm to the next. 73 scientific reports were included in this review published in the journal Frontiers in Veterinary Science. The information regarding the presence of viruses in the air around swine settings is limited but their findings has been compiled in the figure below. Overall, bioaerosol sampling could be a promising way to conduct non-invasive viral surveillance among swine farms.

Viruses detected in radisuses around farms — Influenza A, PRRSV, PEDV detection downwind from farms with infected source populations

Abstract

Modern swine production facilities typically house dense populations of pigs and may harbor a variety of potentially zoonotic viruses that can pass from one pig generation to another and periodically infect human caretakers. Bioaerosol sampling is a common technique that has been used to conduct microbial risk assessments in swine production, and other similar settings, for a number of years. However, much of this work seems to have been focused on the detection of non-viral microbial agents (i.e., bacteria, fungi, endotoxins, etc.), and efforts to detect viral aerosols in pig farms seem sparse. Data generated by such studies would be particularly useful for assessments of virus transmission and ecology. Here, we summarize the results of a literature review conducted to identify published articles related to bioaerosol generation and detection within swine production facilities, with a focus on airborne viruses. We identified 73 scientific reports, published between 1991 and 2017, which were included in this review. Of these, 19 (26.7%) used sampling methodology for the detection of viruses. Our findings show that bioaerosol sampling methodologies in swine production settings have predominately focused on the detection of bacteria and fungi, with no apparent standardization between different approaches. Information, specifically regarding virus aerosol burden in swine production settings, appears to be limited. However, the number of viral aerosol studies has markedly increased in the past 5 years. With the advent of new sampling technologies and improved diagnostics, viral bioaerosol sampling could be a promising way to conduct non-invasive viral surveillance among swine farms.