The infection of seven Russian farmworkers by a virus that is lethal among birds underscores the need for close monitoring to avert another disaster, a new study says.
(CN) — With the world’s attention focused on Covid-19, scientists are urging vigilance to prevent a subtype of bird flu that has infected wildfowl and poultry in 46 countries and a small group of Russian farmworkers from triggering the next pandemic.
After 101,000 hens died at a farm in far southwest Russia in early December, tests quickly found the culprit: the H5N8 strain of avian influenza virus.
A vigorous containment effort followed in which employees of the farm culled thousands of hens, disposed of their eggs and bedding and applied disinfectants across the sprawling property.
Virologists took nose swabs and blood samples of the workers and learned seven had been infected, marking the first known cases of bird-to-human transmission of H5N8, though none of them showed any symptoms and they did not transmit the virus to any of their family members nor close contacts.
“The virus can be transmitted from birds to humans, it has overcome the interspecies barrier,” Anna Popova, a Russian public health official, announced on Feb. 20.
“As of today, this variant of the influenza virus is not being transmitted from person to person. Only time will tell how quickly future mutations will allow it to overcome this barrier,” she added.
In a report published Thursday in the journal Science called “Emerging H5N8 avian influenza viruses,” Chinese immunologist George Gao, director of the Chinese Center for Disease Control and Prevention, and Weifing Shi, a scholar at Shandong First Medical University, note H5N8 was first found in a sample taken from a domestic duck at a wet market in Jiangsu, China, in 2010.
By 2014, they say, it had caused outbreaks in domestic and wild birds in South Korea and Japan. By 2016, it had also been found in birds in Europe, Russia, India, Mongolia, the United States and Canada.
Scientists believe it reached North America from migratory birds entering from the Bering Strait Flyway, according to the report.
Just last year, continuous outbreaks of the virus in both poultry and wild birds in Taiwan, South Africa, Europe, Israel, Japan and South Korea, led to the slaughter of thousands of birds, the report states.
H5N8 has “clearly displayed a propensity for rapid global spread in migratory birds” and an ability to bind to human cells as its swaps gene segments with other bird flu subtypes in a process called reassortment, Shi and Gao say.
They advise surveillance should be restored at poultry farms, live poultry markets and on wild birds to the level before the Covid-19 pandemic or higher.
They also suggest moving away from raising fowl on family farms will help reduce the spread of the virus.
“Education and outreach are also important, including enhanced personal protection measures during the influenza season, keeping away from wild birds, and avoiding hunting and eating wild birds,” the researchers conclude.
Like Covid-19, bird flu is a zoonotic disease, one that can spread between humans and animals.
While the exact source of the coronavirus outbreak is unknown, the U.S. Centers for Disease Control and Prevention says it came from an animal, probably a bat.
Gao and Shi did not respond to emailed questions about their report.