Progress after one year of a pseudorabies eradication program for large swine herds

Area of Science:

• Veterinary Virology
• Swine Herd Health Management
• Disease Eradication Strategies

Background:

• Pseudorabies virus (PRV) poses a significant threat to swine production.
• Quarantined herds require effective eradication programs to control PRV spread.
• Large-scale swine operations present unique challenges for disease management.

Purpose of the Study:

• To evaluate the efficacy of an intensive PRV eradication program in large commercial swine herds.
• To assess the impact of gene-deleted modified-live virus vaccines on PRV seroprevalence.
• To determine the reduction in PRV antibody prevalence after one year of intervention.

Main Methods:

• Six quarantined farrow-to-finish swine herds participated in the USDA-initiated Large Herd Cleanup Study.
• Intensive program included vaccination with gene-deleted PRV vaccines (gI or gX) and all-in, all-out pig flow.
• Monitoring of PRV antibody prevalence in sows and finishers via serological testing over one year.

Main Results:

• Significant reduction in PRV antibody prevalence observed in sows (median -42%) and finishers (median 4%).
• Post-vaccination PRV antibody prevalence ranged from 7-63% in sows and 0-42% in finishers.
• Decreased seroprevalence in lower parity sows suggested reduced PRV transmission due to vaccination.

Conclusions:

• Intensive PRV eradication programs combining vaccination and improved biosecurity are effective in large swine herds.
• Gene-deleted PRV vaccines contribute to reducing viral circulation and antibody prevalence.
• Further research can optimize strategies for complete PRV elimination in commercial swine populations.