Postweaning Multisystemic Wasting Syndrome (PMWS)

Postweaning multisystemic wasting syndrome (PMWS) represents a viral ailment of significant impact, particularly on weaned piglets. This syndrome manifests through a series of symptoms, including progressive weight reduction, pallid or jaundiced dermis, and respiratory difficulties. Notably, in recent times, PMWS has inflicted substantial financial repercussions upon nations boasting advanced pig industries, emerging as a foremost threat to sustained pig production.

Cause and Effect

PMWS is caused by porcine circovirus type 2 (PCV2) infection. The disease occurs throughout the United States and often causes clinical symptoms in piglets 6-16 weeks of age. PCV2 is a member of the Circoviridae family and the Circovirus genus, a single-stranded circular DNA virus, and one of the smallest known animal viruses. PCV2 infection leads to immune system dysregulation and subsequent development of PMWS. The exact mechanism by which PCV2 causes the syndrome is not fully understood. However, PCV2 is believed to replicate and spread in pigs, targeting immune cells and disrupting normal immune responses. This immune dysregulation results in the characteristic wasting syndrome observed in affected pigs.

Fig.1 Hosts and transmission routes of PCV2.^1,2

Signs and Symptoms of PMWS

PMWS is characterized by a spectrum of clinical symptoms of varying severity. There are six basic aspects of performance, as shown below.

Diagnosis of PMWS

The disease is easily confused with PRRS, porcine pseudorabies, and other diseases. An accurate diagnosis should be based on a combination of clinical examination, laboratory tests, and histopathological evaluation. BioVenic provides advanced laboratory diagnostic solutions including PCR, immunology, and histopathology for tissue samples.

• PCR: Detection of PCV2-specific DNA using quantitative PCR is the most sensitive detection method.
• Immunodiagnostics: Indirect immunofluorescence assay or competitive ELISA methods can be used to detect PCV2-specific antigens or antibodies.
• Electron microscopy: A large number of non-enveloped virus particles accumulate in the spleen, lymph nodes, and other tissues of sick pigs.

Treatment of PMWS

There is currently no specific treatment for PMWS. Symptomatic treatment, such as fluid therapy and administration of antibiotics, may be required to control secondary infection and provide supportive care.

Fig.2 Schematic of the PCV2 replication cycle.^3.4

Prevention and Control of PMWS

Given the potential for PMWS to lead to elevated piglet mortality rates, its effective management has emerged as a pressing challenge in pig production. At BioVenic, we specialize in tailoring personalized prevention and control strategies to address the unique requirements of our clients. The following measures, when diligently applied, have demonstrated effectiveness in the management of PMWS.

• Improve feeding methods. Avoid feeding pigs of different ages in mixed groups to reduce the chance of PCV2 contact infection among pig groups.
• Establish a complete biosecurity system for pig farms. Minimize the contamination of pathogenic microorganisms in pig farms.
• Improve the nutritional level of pig herds. Since PCV2 infection can lead to a decline in the immune function of pigs, nutrition is an important factor affecting PMWS.
• Reduce the stress factors of pigs and strengthen their feeding and management.
• A complete drug prevention program should be implemented to control secondary bacterial infections in pigs.
• Get the parvovirus (PPV) vaccine. Develop an appropriate vaccination schedule based on the PMWS prevalence in the area.

BioVenic primarily provides cutting-edge diagnostic solutions designed to accurately identify PCV2. In addition, we provide custom vaccine development services to our customers to prevent this disease. Our team of experienced experts works closely with veterinary researchers to develop customized management programs to improve the well-being and productivity of your pig herds. If this offer piques your interest, we invite you to contact us immediately for further discussion.

References

1. Zhai, Shao-Lun, et al. "Porcine circovirus type 2 in China: an update on and insights to its prevalence and control." Virology journal11.1 (2014): 1-13.
2. Image retrieved from Figure 7 "Possible infection and cross-species transmission routes of PCV in pigs." Zhai, Shao-Lun, et al., 2014, used under [CC BY 2.0], the image title was changed to "Hosts and transmission routes of PCV2."
3. Niu, Guyu, et al. "Advances in crosstalk between porcine circoviruses and host." Viruses14.7 (2022): 1419.
4. Image retrieved from Figure 2 "Model of PCV lifecycle."Niu, Guyu, et al., 2022, used under [CC BY 4.0], the image title was changed to "Schematic of the PCV2 replication cycle."