Old Pathogens, New Threats: Re-Emerging Diseases in Modern Poultry Farms

Old Pathogens, New Threats: Re-Emerging Diseases in Modern Poultry Farms

Dr. K. Bhargava Jyothi^* 

^*Assistant Professor, Department of Veterinary Pathology, School of Veterinary and Animal Sciences, Centurion University of Technology and Management, Paralakemundi, Odisha.

In many places around the world, poultry farms are noisier, more biosecure, and better managed than ever before. Yet paradoxically, some old enemies—viruses, bacteria, and parasites once thought under control—are making comebacks. These re-emerging diseases threaten flock health, farm profitability, food safety, and even human health. What’s driving this resurgence? And how can farmers, veterinarians, and public health authorities respond?

What Does “Re-Emerging Disease” Mean?

A re-emerging disease is one that was previously decreasing or well-controlled, but which has renewed incidence, geographic spread, or increased virulence. Sometimes such diseases mutate; sometimes changing farming practices, environment, climate, trade, or lapses in control allow them to gain a new foothold.

Key Players: Which Pathogens Are Back — and Why They Matter

Here are several examples of old pathogens that are resurfacing, or new forms of them, especially in modern poultry settings:

Recent Case Studies: Lessons Learned

• Brazil, 2025 — HPAI Outbreak in Breeder Farm
  In May 2025, a commercial breeder farm in Rio Grande do Sul, Brazil, experienced its first HPAI outbreak. Mortality was about 92%, with ~15,650 birds lost. By modeling different detection delay scenarios, it was shown that even a 3-day delay multiplied the risk of spread to neighboring farms substantially. Early detection and fast action (culling, movement restrictions) helped contain the outbreak (arXiv).
• China — Central Province Flocks
  From 2020 to 2022, there were outbreaks in chicken flocks involving immunosuppressive and neoplastic diseases. MDV rates were higher than ALV/REV; co-infections observed. Suggests that old tumor viruses are not under adequate control (PMC).
• Tamil Nadu & Andhra Pradesh, India — Antimicrobial Resistance Traces
  A study collecting litter and groundwater samples from several poultry farms found the presence of ARGs that confer resistance to antibiotics including glycopeptides, carbapenems, macrolides, etc. Raises concerns as these are critical drugs in human medicine (dtnext).

Why This Matters: Beyond the Flock

• Economic Losses: Mortality, reduced productivity (growth, egg yield), increased costs (vaccination, biosecurity), trade impacts.
• Food Security: Poultry is a primary source of affordable protein globally. Disruptions in supply due to disease hit consumers, especially the poor.
• Human Health Risks: Zoonoses, foodborne pathogens, and AMR are bridges between animal disease and public health.
• Animal Welfare: Disease outbreaks are crisis points for welfare; sick flocks endure suffering; culling also raises ethical concerns.

What Can Be Done: Prevention, Preparedness, and Policy

Here are strategies for mitigating the threat of re-emerging poultry diseases:

1. Strengthen Biosecurity at All Levels

• Secure perimeters, control traffic (people, vehicles, materials).
• Clean/disinfect equipment, footwear, feed/water sources.
• Separation between wild birds and poultry houses.
  2. Better Surveillance & Early Detection
• Regular health monitoring, necropsy of dead birds.
• Molecular diagnostics (PCR, next-generation sequencing) to detect newer strains.
• Integration of farm-level surveillance with wildlife and environmental surveillance (One Health).
  3. Vaccination & Matching Vaccines to Circulating Strains
• Update vaccine strains when mismatches are found.
• Ensure proper vaccine handling (cold chain, booster schedules).
  4. Responsible Antibiotic Use
• Stewardship programs: use antibiotics only when needed, under veterinary supervision.
• Alternative measures: probiotics, improved nutrition, hygiene to reduce disease pressure.
  5. Education & Capacity Building
• Train farm workers, veterinarians in disease recognition, biosecurity.
• Raise awareness about zoonotic risks and AMR.
  6. Policy, Regulation & International Collaboration
• Stronger regulations for reporting, managing disease outbreaks.
• Cross-border cooperation in disease tracking, trade oversight.
• Incentives or subsidies for small‐scale farmers to maintain biosecurity.

Conclusion

The battle against poultry disease is not over. Old pathogens, in new forms or with new opportunities, are asserting themselves again. But the tools to fight back are better than ever—if they are used well. Modern diagnostics, stronger biosecurity, thoughtful vaccination, and awareness can keep these threats under control. For farmers, veterinarians, scientists, and governments, the message is clear: vigilance is not optional—it’s essential.

References

1. First highly pathogenic avian influenza outbreak in a commercial farm in Brazil: Outbreak Timeline, Control Actions, Risk Analysis, and Transmission Modeling.Cárdenas et al., 2025. arXiv
2. The role of wild birds in the global highly pathogenic avian influenza H5 panzootic.Couty, Guinat et al., 2025. arXiv
3. Current Epidemiology and Co-Infections of Avian Immunosuppressive and Neoplastic Diseases in Chicken Flocks in Central China.PMC article. PMC
4. Emerging and re-emerging diseases of poultry (viral & bacterial) reviews.SR Publications summary. SR Publications
5. High levels of antimicrobial resistance in the environment of poultry farms, Tamil Nadu & Andhra Pradesh, India.Toxics Link / World Animal Protection study. dtnext

Please follow and like us: