In April 2015, Greg Langmo’s five turkey farms teemed with toms, hens and chicks. His family’s decades-old business in Meeker county, Minnesota, was thriving, and the hundreds of thousands of birds he bred and sold each year were healthy.
And then, late one evening, Langmo’s phone rang. Birds in one of his barns, usually active, were sitting, unable to make the short walk to their feeders and waterers. The following morning, he found hundreds of limp, white-feathered bodies. Langmo sent some dead toms to the University of Minnesota’s veterinary diagnostic laboratory. That night, the farmer lay sleepless. Again, his phone rang. It was a vet from the lab: “You got it.”
Langmo’s farms had been hit by the Eurasian/North American H5N2 strain of lethal avian influenza, which – along with another lethal strain, Eurasian H5N8 – rampaged across poultry farms in the American west and midwest between December 2014 and June 2015. A third strain, Eurasian/North American H5N1, was detected in nearly 100 wild birds by US wildlife biologists.
It was the first time a foreign strain of bird flu – H5N8 – had entered North America and mixed with mild bird flu viruses. It’s one of many lethal bird flu outbreaks to kill billions of birds and cost billions of dollars over the past hundred years. Such losses are part of the reality of farming today.
Lethal avian influenza’s advent is strongly linked to the development of modern agriculture, which created a global network of disease incubators – industrial farms in some parts of the world, live animal markets in others – linked by trading routes, movement of labourers and equipment, and migration of wild birds.
Soon after the diagnosis, says Langmo, “the rest of the birds began dying by the bushel”. To stop the spread, Langmo and his employees killed survivors with a swift crack to the back of the head. Within three days, virtually all 11,000 toms in the infected barn were dead.
Then they moved into the other barns. Workers from the US Department of Agriculture’s Animal and Plant Health Inspection Service (USDA-APHIS) arrived and doused any live birds with water-based foam – an asphyxiant used to mass-euthanise poultry in emergencies only. Foam flowed across the floors, bubbling like a choppy sea, the turkeys beneath it gasping for air. Fifteen minutes later, all were dead.
“Only other poultry farmers will know the helpless feeling of losing a great flock of birds,” Langmo reflected. He lost 225,000 turkeys across five farms.
Langmo was one of 211 American commercial poultry farmers who battled bird flu during the 2014–15 outbreak, the worst the $40bn (£31bn) US poultry industry has experienced. Twenty-one flocks on backyard farms were diagnosed and destroyed. Nationwide, more than 50 million chickens and turkeys died from the virus or were killed to control it. American commercial poultry farmers lost about $1.6bn. The US poultry industry lost an estimated $3.3bn.
“This outbreak was … arguably the most significant animal health event in US history,” says Dr Julie Gauthier, assistant director for poultry health at USDA-APHIS.
Lethal bird flu – originally “fowl plague” – was first diagnosed on Italian farms in 1878. While poultry die-offs reported before 1878 may have been bird flu, this was the first time scientists distinguished the virus from bacterial poultry diseases, such as fowl cholera.
Subsequent research revealed that bird flu is an influenza-A virus. These viruses are rarely lethal and often mildly afflict their natural hosts. But lethal influenza-A viruses, which mutate in and emerge from the bodies of domesticated animals, are known to infect and kill not just poultry, but birds, horses, swine, bats, dogs and even humans.
The emergence and coexistence of three hybrid lethal bird flu strains – H5N1, H5N2 and H5N8 – in the US during the 2014–2015 pandemic underscores the ability of influenza-A viruses to rapidly mix, transform, infect and persist.
Lethal bird flu viruses have emerged more frequently as poultry farms have expanded capacities and quickened animal-rearing rates over the past 50 years. In the 37 years from 1959 to 1995, these viruses emerged 14 times globally, about one outbreak every 2.6 years; while in the 13 years from 1996 to 2008, they arose 11 times, about one outbreak every 1.2 years.
These species don’t mix
Scientists and farmers are divided over the best way forward. In terms of prevention, should birds be kept inside, which would reduce potential contact with wild birds? Should large-scale movement of animals (industrial farming depends on the transportation of large populations of birds after breeding and for slaughter) be scaled down? That is one of the key vectors by which the disease may be spread.
Some regions of the world look to good farm hygiene and high levels of biosecurity, where infected birds are confined and killed to eradicate disease; others, particularly in countries with many outdoor industrial farms, struggle with implementing biosecurity and may lack available veterinary care, so they allow diseases to circulate, using vaccines to reduce illness and mortality.
“[Vaccines] do not prevent birds from becoming infected with the avian influenza virus or from producing and shedding the virus into the environment,” says Gauthier, adding that up until now culling birds was the preferred solution in the US.
Gene Baur, president and co-founder of Farm Sanctuary, a US-based animal protection organisation, believes that establishing a network of small farms serving local communities is one powerful possibility, because it reduces the need for transporting animals, farm labourers and equipment. Scientists are recognising the benefits of giving birds more space – research shows chickens stressed by overcrowded living conditions typical to commercial farms have diminished immunity to disease.
After a major avian influenza outbreak in Thailand from 2004 to 2005, experts determined that industrial farms were more likely to be infected than backyard farms. In the Netherlands, after a 2003 outbreak, scientists suggested that thinning commercial flocks could prevent the next epidemic.
“When you confine animals in these filthy, crowded, stressful conditions, just like humans, they become breeding grounds for disease,” says Baur.
After considering his financial losses from the 2014–2015 pandemic, Langmo spent a year rebuilding his business, downsizing from five farms to two. He says he’s boosted biosecurity by cutting cross-traffic, checking birds’ health more frequently and improving sanitation with routine deep-cleanings.
“After a thorough sanitisation, each barn literally needs to be as clean as your kitchen, no feathers, no nothing”, says Langmo. “It’s very expensive.”