Bird flu ‘an urgent warning to move away from factory farming’ | Bird flu

Catastrophic declines in the numbers of birds and other wildlife are likely if countries do not act urgently to change the way animals are housed, wildlife health scientists have warned.

The unprecedented die-off of seabirds from highly pathogenic avian influenza (HPAI) witnessed in breeding colonies across Europe, North America and Africa has been traced to a commercial goose farm in southern China, where a relatively mild bird disease mutated into a killer in 1996.

After spreading into wild bird populations in 2007, HPAI has spread across the world, killing millions of birds and showing no sign of stopping.

Disease outbreaks between livestock and wildlife have increased as intensive agriculture has escalated to feed growing wealthier human populations demanding cheap meat.

In the past 50 years, the global poultry population has multiplied sixfold, from 5.7 to nearly 36 billion; the number of pigs has almost doubled, from 547.2 to 952.6 million; and the number of cattle has grown from 1.1 to 1.5 billion.

Dutch vet searches for chickens infected with bird flu on a farm
A Dutch veterinarian checks for chickens infected with bird flu after an outbreak on a farm. Photo: Michael Kooren/Reuters

But the risk of spillovers and new pathogens arising from larger herds and herds of commercial animals has also grown as intensive livestock farming has been normalized.

“These large livestock populations, which are linked by trade, form reservoirs where infectious diseases can evolve and spill over into the wild, sometimes with devastating consequences,” wrote Thijs Kuiken, professor in the department of viroscience at the Erasmus University Medical Center. Rotterdam, and lead author of the editorial published this week in the journal Science.

Kuiken goes on to describe the HPAI outbreak in seabirds as “a warning, with devastating consequences if not heeded”.

Seabirds washed up on shore in suspected avian flu die off in Newfoundland, Canada.
Seabirds wash up on shore in suspected avian flu die-off in Newfoundland, Canada. Photo: Greg Locke/Reuters

Farm animals are “transmitting more and more diseases to wildlife,” said co-author Ruth Cromie, wildlife health adviser for the Convention on the Conservation of Migratory Species. She highlights the spread of African swine fever across Europe and Asia through the trade in pigs and pork products, which translates into wild boars and endangered species of wild south (pigs) in Southeast Asia.

Other spillovers mentioned by the authors included Mycoplasma gallisepticum bacteria from poultry to finches and other songbirds in North America.

The authors argue that governments should protect wildlife from diseases linked to human activities. They propose reducing livestock herd size and density on farms, limiting the transport of livestock from farm to farm, and limiting contact between farmed animals and related wild species. In middle- and high-income countries, they say people should switch from animal- to plant-based proteins.

Sam Sheppard, professor of microbial genomics and evolution at the University of Oxford, who was not involved in the editorial, said that only a move away from intensive livestock farming would reduce the risk of disease.

“Due to the large size of these host niches with many millions of individual animals, viruses and bacteria inevitably spill over into the environment and into wild animal species. This can have serious consequences, as with bird flu.

“However, this is only part of the problem. The larger the herd, [or group of animals] the greater the number of pathogens and the faster they develop. Farms can reduce spillover with biosecurity, but that doesn’t stop pathogens from developing. You can change the speed at which pathogens evolve just by farming in a different way,” he said.