Avian influenza in the U.S. has spread rapidly in the Upper Midwest, particularly in the states of Minnesota and Iowa. The avian influenza virus was brought to North America by migratory birds, but, while there has been some speculation about airborne spread of the virus, it is likely that movement of people and equipment have played the largest role in spreading the disease.
Dr. John Glisson, director of research, U.S. Poultry & Egg Association, and formerly the department head of Population and Health and Avian Medicine, University of Georgia, said: “People, vehicles, equipment and moving products like eggs are the major vectors. Movement is the major factor. It is sometime hard to swallow that we are the enemy.”
Effective biosecurity requires verification
Dr. Jean-Pierre Vaillancourt, director, Research Group in the Epidemiology of Zoonoses and Public Health, University of Montreal, has been involved in efforts to control infectious disease outbreaks in poultry in the U.S., Canada and Mexico. In research studies aimed at testing how well biosecurity programs are adhered to in the field, he said that it is clear that, without verification and feedback, workers follow the rules less than half of the time.
Vaillancourt said that we shouldn’t be surprised by these results, because unreinforced biosecurity rules are adhered to at about the same rate that patients comply with taking prescriptions as directed. When physicians were asked to predict compliance of their long-term patients, it was no better than chance. Vaillancourt said that many executives for poultry companies have fallen into the same trap -- they think they know how their employees will behave, and they don’t.
Video shows lack of compliance
In a research study, visible video cameras were placed on poultry farms and employees were told that the tapes were being monitored to ensure compliance with biosecurity rules. Vaillancourt said that for the first two weeks the workers were compliant 96 percent of the time, but after six months they were only compliant 60 percent of the time. “Just like reality television, eventually people actually forget they are being recorded,” he said.
So even with cameras in operation, you have to give feedback to employees to ensure compliance. Vaillancourt said that it is also important that you have no exceptions to biosecurity rules. For instance, you can’t have the boss not showering in because he just came from home and wasn’t at another farm. Workers take cues from management as to what rules really matter.
Dr. Ron Prestage, veterinarian, Prestage Farms, former National Turkey Federation Chairman, explained that all of his company’s swine and turkey breeder facilities are shower in and shower out. He said: “All of that goes out the window once someone says, 'I forgot my cigarettes' (and goes back without showering again).”
In the study with video cameras on 24 farms, the farm owners were shown video of all of the people going into the houses at the end of the study. Vaillancourt said that out of 259 people on the videos, the owners could not identify over a dozen people. Are you sure you know who is visiting your farms and that they are following all of the “required” biosecurity practices?
Biosecurity requires a regional perspective
Prestage said that the experience the turkey industry has had with both corona virus and poult enteritis mortality syndrome (PEMS) convinced him that farm biosecurity requires a regional perspective. Because of this, Prestage Farms of South Carolina has regionalized its tom finisher farms into 19 geographic zones. All of the houses within a zone go to market the same week, and this will make any future regional depopulation easier to do.
Vaillancourt said: “In many case you have to suffer enough before producers will do what needs to be done. Other regions need to learn without suffering the losses.”
Avian influenza virus in the environment
Experience with other infectious diseases would suggest that there is more going on in the current avian influenza outbreak than just wild birds contaminating the environment and people tracking the virus into the house, according to Vaillancourt. He looked at infectious laryngotracheitis (ILT) outbreaks in a province of Canada that kept recurring every few years, and he found a couple of significant correlations.
If you used an outside vaccination crew, you were eight times more likely to break with ILT, and if you had someone else come and take litter out of your house, you were 13 times more at risk. Even though these correlations were statistically significant, they didn’t explain all of the outbreaks. When he asked local veterinarians to look at the list of farms that had been infected, they pointed out that the farm owners all went to the same restaurant for morning coffee.
In a North Carolina Mycoplasma gallisepticum (MG) outbreak, Vaillancourt said that one poultry grower was also a barber, and several growers were getting their hair cut at his barber shop. Unfortunately, MG will survive for up to three days on human hair.
Prestage said: “It takes extraordinary biosecurity steps to keep a virus out of your houses if you have it in the environment.” When asked if the only reason we don’t have these viruses in our houses more often is because it usually isn’t present in the environment, Prestage said yes.
Insect control vital for eradication
As soon as the level of heat and humidity in the house changes, insects go to hide or move. Vaillancourt said: “You need to have a priority to treat for the insects as soon as you are depopulating the house and disturbing the litter. You also need to treat again after everything has been removed, cleaned and sanitized.” Darkling beetles and flies can both carry virus on their bodies and take it to other poultry houses. No one really knows how far they can fly, but house flies can travel at least a mile or more.
Litter should be composted
Prestage said that cleaning out houses and spreading litter can actually spread a viral disease around. He explained that this has been shown with ILT in broilers and corona virus in turkeys. For flocks depopulated because of avian influenza, he said that the birds and litter should be composted inside the house to make sure that the virus is destroyed prior to taking the litter out of the house.