The bird flu outbreak affecting poultry farms across the U.S. is not yet a cause for concern, but disease surveillance specialists are doing their best to stop the spread and prevent any human cases, experts said.
During this outbreak of highly pathogenic bird flu (HPAI) H5N1, the first outbreak in a commercial herd occurred among turkeys in Indiana in early February, and since then, 18 states have reported infections in commercial herds, according to the U.S. Department of Agriculture (USDA). .
HPAI was previously detected on January 14 in a wild bird in South Carolina. Prior to that, HPAI had not been detected in the U.S. since 2016, according to the USDA.
“With the arrival of this virus on our doorstep, we need to be on high alert to quickly detect and respond to outbreaks in our poultry herds,” said Jack Shere, DVM, PhD, co-administrator of USDA’s Animal and Plant Health Inspection Service, during a January webinar.
In discussing the last major outbreak of HPAI in the US, in 2015, Shere said: “We do not want to relive that event. More than 50 million birds have died or had to be culled as a result of that virus. Producers lost $ 1.6 billion and the overall impact on the US economy is thought to have exceeded $ 3 billion. “
Denise Derrer Spears, director of public information for the Indiana State Board of Animal Health, said MedPage Today that the state had to exterminate some 171,000 birds from six swarms affected, but conditions have improved significantly since those early cases in February.
“We are making good progress. We have been able to release all six control areas,” she said, referring to the six sites with HPAI cases and the surrounding 10km radius.
“Any time there is a case, there is a substantial response to eradicate it,” she added.
Spears said the 2015 outbreak did not affect Indiana farms as badly as other parts of the country, but the state did suffer a much worse outbreak in January 2016. This year’s outbreak in her state does not appear to be as severe as it seems. is for other places. South Dakota is currently being hit particularly hard, she noted.
HPAI H5N1 is a flu-type A virus that first appeared in southern China and led to major poultry outbreaks in Hong Kong in 1997, leading to 18 human infections, according to the CDC . The virus was controlled but not eradicated, and re-emerged in 2003 and spread widely among birds throughout Asia and later in Africa, Europe and the Middle East.
The first time the virus was detected in North America was in 2014, and it caused widespread poultry outbreaks and deaths of wild birds in the U.S. and Canada before disappearing in 2016, the CDC noted.
Worldwide, there have been more than 860 human infections since 2003, with a significant mortality rate of about 53%, according to the CDC.
CDC spokesman Nick Spinelli said MedPage Today by email that the outbreak “remains primarily an animal health issue at this time,” and confirmed that no cases have been detected among people exposed to infected birds at U.S. poultry farms. The agency also maintained that the “health risk to the general public is low.”
“CDC compared the characteristics of current and previous H5N1 bird flu viruses, and found that the H5N1 bird flu viruses detected in the US in late 2021 and 2022 differ from the H5N1 bird flu viruses that were present in a large proportion of the world circulated., “he said.
“So far, current H5N1 bird flu viruses do not have changes seen in the past that have been associated with bird flu viruses that spread easily among poultry, infect humans more easily and cause serious diseases in humans,” Spinelli added. “However, we are taking routine precautions to be prepared in case of human infections with these viruses, and will continue to assess the risk posed by these viruses, including performing additional laboratory work to further characterize current H5N1 bird flu viruses.”
Concern stems from the fact that any influenza A viruses that circulate among poultry have the potential to recombine with human influenza A viruses and increase transmission among humans. If these bird viruses develop to transmit effectively among humans, the world could face a pandemic with “potentially high numbers of diseases and deaths worldwide,” according to the CDC.
This is why the scientific community was in arms a decade ago when two researchers reported that they changed bird H5N1 to spread among ferrets. Critics were concerned that any action that could improve the virus’ transmission capacity could pose a pandemic risk, especially if it had accidentally or maliciously found its way into the world.