Bird Flu Is Back in the US. No One Knows What Comes Nexthttps://www.wired.com/story/bird-flu-is-back-in-the-us-no-one-knows-what-comes-next/ampThe fast-moving pathogen, which has already invaded Europe, was found in East Coast ducks. The last outbreak that tore through the US killed 50 million birds.
The flu found in the Carolinas is an H5N1, meaning it is of the subtype that normally infects birds but in the past has sickened people. It is a high-path variety, the kind that can wipe out domesticated flocks. It belongs to a strain related to that first species-crossing jump in 1997. And, to make matters worse, it represents just one instance of a remarkable amount of highly pathogenic H5N1 showing up in the world right now
Last year, the World Organization for Animal Health (known by its French acronym, OIE) estimated that between May 1 and November 1, 41 countries experienced outbreaks of highly pathogenic bird flu, with 16,000 isolations of the virus reported just in October. Fifteen countries also reported outbreaks between October and December
Occasional isolations of avian flu in wild birds are not unusual, but last fall high-path H5N1 began erupting in the United Kingdom with extraordinary intensity. Since October and into this year, the virus has been found in wild species, including swans, geese, shorebirds, and birds of prey. But it has also invaded poultry farms, primarily in Lincolnshire and Yorkshire. By January, more than 1 million chickens and other birds had been destroyed to stop it from spreading. In December, the UK’s chief veterinary officer called the occurrence of bird flu there “phenomenal,” saying the strain had spread to the largest number of farm properties ever seen.
At almost the same moment, Dutch authorities were ordering the slaughter of hundreds of thousands of poultry on farms in the country. In the Czech Republic, more than 100,000 hens died of avian flu on an egg farm, and another 100,000 birds and about 1 million eggs were destroyed to stop the virus from spreading further. In France, farmers feared the virus would invade the duck-raising southwest, the home of foie gras.
Last week, the agriculture ministry ordered 2.5 million birds killed. In Italy, more than 4 million poultry died or were slaughtered between October and December. And the Friedrich Loeffler Institute, the animal-disease research unit of the German government, said at the end of December that Europe was experiencing “the strongest avian influenza epidemic ever,” with cases reaching as far north as the Faroe Islands and as far south as Portugal
Those slaughter numbers should make the case that the flu is not only a threat to animal welfare, but an engine of economic damage as well. Rabobank, a financial services and analysis firm based in the Netherlands, has already predicted that these massive culls, layered on top of pandemic-fueled freight problems and rising feed costs, could inflate food prices this year
For the most part, birds stick to specific north-south migratory pathways and don’t fly laterally around the globe. So to scientists in North America, outbreaks of bird flu in Europe were a cause for worry, but not immediate alarm. But in December and again in January, high-path H5N1 was found in farms in Newfoundland, at the top of the migratory flyway that sweeps down the US coast.
That is the same flyway that crosses over the Carolinas, where the virus-carrying ducks were caught—and also over the more than 1 billion chickens grown each year in Georgia, the most poultry-dense state in the US.
Because this flu is highly pathogenic, the challenge is that there is no time for mitigation once it arrives in a flock. As Midwest turkey producers experienced in 2015, it blows up into a destructive epidemic overnight. That requires poultry farmers to harden their defenses now—and while that seems like an obvious task, it requires precision and cost in an industry that runs on thin margins and speed.
Scientists who monitor wildlife fret that there is something else going on in this wave of flu. Wild waterbirds are accidental transport vehicles for the virus, but rarely victims. They pick it up and transfer it to other birds in ponds and wetlands at the ends of their migration journeys and then carry it with them, unharmed, once they return to the skies.
But in Israel, where more than a half-million poultry have died or been slaughtered, the first sign of trouble was a mass die-off of thousands of wild cranes in a wetland that lies directly under a migration route. The European Food Safety Authority has identified deaths from flu in at least 80 other species of wild birds, leaving scientists to wonder whether bird flu has evolved into a further threat.
“The catastrophic issue economically is poultry,” Stallknecht says. “But we also have to be concerned with wildlife health. And there are some populations of shorebirds that are already not in good shape, so we need to be monitoring them also.”
There’s also evidence these new waves of bird flu have been leaking into humans. In the first week of January, UK health authorities revealed that a man in Devon who kept ducks as pets had the country’s first-ever human case of H5N1 bird flu. The ducks were all slaughtered; the man was reported to be quarantined and surviving the infection but lonely and missing his birds.
In November, the WHO said it has been monitoring a slow surge in human infections in China caused by a known but less common bird flu subtype, H5N6. By the end of 2021, there had been 26 people infected, one of whom died. And in February a year ago, the Russian government revealed that seven poultry farm workers fell ill (and recovered) from yet another subtype, H5N8
Other bird-specific strains have been surging into humans as well. The Chinese government disclosed last June that a man who had no known contact with poultry developed an infection with a flu strain never before seen in humans, H10N3, and that he was hospitalized but recovered. Since 2013, China has recorded more than 1,600 human cases of yet another strain, H7N9.
A further concern lurks behind this bloom of bird flu. Until now, biologists have assumed the danger is seasonal, triggered by the movement of waterbirds as they migrate: If there are no visiting birds overhead, or on shores or in ponds, they can’t spread a virus to local birds or people.
But researchers are beginning to wonder whether climate change is interfering with migration patterns. The typical pattern for bird flu infections has been for them to begin during the fall migrations and then continue through the winter and into spring. But in Germany last year, scientists were able to identify H5 viruses in wild birds throughout the summer, a first.