In wake of the avian flu pandemic last year, a U.S. expert examines failures in disease management and possible solutions
KANSAS CITY, Mo. — Biosecurity breaches probably caused one of the worst animal disease crises in the United States.
Fast moving outbreaks of highly pathogenic avian influenza in 21 states resulted in the destruction of 50 million turkeys and chickens last year. More cases affecting 400,000 birds were reported in Indiana at the beginning of this year.
The rapid spread of the disease showed increased vulnerability in the animal population, said John Clifford, chief trade adviser for the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service.
As well, porcine epidemic diarrhea and porcine delta corona virus had previously entered the U.S., killing millions of pigs.
The viral roots of these deadly diseases are in Asia, but no one is sure how they got to North America, Clifford said at the National Institute of Animal Agriculture’s April 3-7 annual meeting in Kansas City.
“Did we have good biosecurity? I don’t think so,” Clifford said.
“If we don’t have good biosecurity and we don’t have good traceability in all sectors of the livestock population, we are vulnerable to these types of events.”
Biosecurity and disease management plans need to be updated regularly to deal with known and future issues.
Biosecurity is expensive and inconvenient, said James Roth, director of Iowa State University’s Center for Food Security and Public Health.
Food secure plans have been in the works since 2007 to detect, control and contain a foreign animal disease as soon as possible. The intention is to avoid interruptions in animal movement from farms with no evidence of infection and provide consumers with safe eggs, milk, poultry, beef and pork.
Government, universities and commodity groups test the plans and regularly update them to figure out how to establish quarantine zones and control movement.
Biosecurity is essential to the success of these plans.
“Everyone has to have confidence that producers have sufficient biosecurity to protect their herds or flocks from becoming infected,” Roth said.
Outbreaks of porcine epidemic diarrhea and Seneca Valley virus in pigs and avian influenza in poultry have shaken public confidence in farmers’ ability to keep out serious diseases.
In the case of avian influenza, many feared that backyard flocks would present the greatest risk because they could be exposed to wild birds and other contaminants.
However, most of the outbreaks were on large commercial farms with millions of birds in one facility.
“There was something about the biosecurity of those commercial sites that had a really big vulnerability,” Roth said.
Producers have realized their biosecurity deficiencies the hard way.
“A routine level of biosecurity is not sufficient to protect from a newly introduced, highly contagious disease,” he said.
The recent outbreaks have shown that the original biosecurity plans were based on current best practices and did not account for the increased rigour needed for a new contagion.
“Biosecurity only works if everyone on the production site understands the importance of biosecurity and follows it all the time,” he said.
Epidemiology investigations of infected sites checked weather conditions to see if the virus was carried on the wind, but there was no evidence of that, said Brian McCluskey of APHIS.
Commitment to biosecurity plans likely had more to do with disease spread.
“It is difficult to prove which biosecurity practices work best to keep out serious disease,” he said.
A research project that evaluated 81 infected turkey farms in five Midwest states for biosecurity found that most farm sites were free of debris and trash. Workers wore rubber boots, and most had coveralls to be worn exclusively in the barn.
Less than half washed and sprayed vehicles, even though rendering and garbage trucks were more likely to be infected.
Less than half monitored farm visitors or asked them to change clothes.
Less than half of the affected farms did biosecurity audits of any kind. Almost all shared expensive farm equipment.
Most said their poultry houses were bird proof, but investigators routinely saw sparrows and starlings on site.
Other risks included disposing of dead birds within 30 metres of the barns. Proximity to dead bird disposal and litter compost areas are proven risk factors.
This practice was seen during this outbreak and needs to be ad-dressed, said McCluskey.
Biosecurity and the practice of maintaining hazard analysis critical control points programs have a lot in common. Identifying hazards at every site and figuring out controls is something producers can do on their own.
The USDA posted a voluntary biosecurity self-assessment checklist in September that included 12 points to monitor. Biosecurity training material for the poultry industry was published in English and Spanish.
The same approach is coming for dairy, beef and pork.