 |
| Centers for Disease Control and Prevention graphic |
In Pennsylvania, "207 poultry flocks in eastern Lancaster County and western Chester County that supply live bird markets" have been quarantined, reports Philip Gruber of Lancaster Farming. "A wave of farms in the live market system have tested positive for avian influenza, and others have tried to manage sick birds on the farm without reporting them to the state, State Veterinarian Kevin Brightbill told industry members. Brightbill said, “That is the kind of misguided thinking that can result in, frankly, a massive outbreak in Lancaster County and loss of all of our flocks."
 |
| Lancaster County (Wikipedia) |
In November, "Arizona, Mississippi, and South Carolina reported their first highly pathogenic avian flu outbreaks in poultry flocks, part of expanding activity involving the Eurasian H5N1 strain that has now affected poultry in 46 states, with poultry losses soon to pass a record set in 2015," reports Lisa Schnirring for the University of Minnesota's Center for Infectious Disease Research and Policy. "The Arizona Department of Agriculture said that officials have quarantined the affected locations, where depopulation is under way. The virus had been previously detected a few times in waterfowl found dead in Arizona."
Scientists are watching how H5N1 mutates to gauge its threat to humans. In Colorado, Sawyer and her collegaues Emma Worden-Sapper and Sharon Wu did a Q and A; here's an edited summary:
1. Is this virus a serious threat to humans? The virus is highly pathogenic to birds, meaning that infections often cause extreme symptoms, including death. But its impact on humans is complicated. There have been relatively few human infections detected – fewer than 900 documented globally over several decades – but about half of those infected individuals have died. The good news about H5N1 for humans is that it currently doesn’t spread well between people. Most people who have contracted H5N1 have gotten it directly from interacting with infected poultry – specifically chickens, turkeys, ducks and geese, which often are raised in close quarters on large commercial farms.
2. Why is this outbreak suddenly getting so much attention? H5N1 is causing the largest “bird pandemic” ever recorded. A certain viral variant that arose in 2020, called H5N1 2.3.4.4b, is driving this outbreak. In agricultural poultry flocks, if a few birds test positive for H5N1, the whole flock is killed regardless of symptoms or infection status. The Biden administration is considering vaccinating farmed poultry flocks, but the logistics could be quite complicated.
The second reason for increased attention is that H5N1 is now infecting more bird and mammalian species than ever before. The virus has been detected in a broad array of wild birds and in diverse mammals, including badgers, black bears, bobcats, coyotes, ferrets, fisher cats, foxes, leopards, opossums, pigs, skunks and sea lions.
The third and most worrisome reason that this virus is getting so much press is that H5N1 now seems to be transmitting well between individuals of at least one mammalian species. In late 2022, mammal-to-mammal spread occurred in Spain in farmed minks. H5N1 spread very efficiently between the minks and caused clinical signs of illness and death in the mink populations where it was detected.
3. Here’s the key question: If H5N1 can achieve spread in minks, why not humans? We are also mammals. It is true that the farmed minks were confined in close quarters, like chickens on a poultry farm, so that may have contributed. But humans also live in high densities in many cities around the world, providing the virus similar tinder should a human-compatible variant arise.
4. Why don’t we make a vaccine just in case? With avian influenza viruses, it is not possible to make effective human vaccines in advance, because we don’t know exactly what the genetics of the virus will be if it starts to spread well in humans. . . . Right now, the best way people can protect themselves from H5N1 is to avoid contact with infected birds. For more information about prevention, especially for people who keep domesticated birds or are bird-watching hobbyists, the Centers for Disease Control and Prevention has a list of guidelines for avoiding H5N1 and other bird flu viruses.
Scientists are watching how H5N1 mutates to gauge its threat to humans. In Colorado, Sawyer and her collegaues Emma Worden-Sapper and Sharon Wu did a Q and A; here's an edited summary:
1. Is this virus a serious threat to humans? The virus is highly pathogenic to birds, meaning that infections often cause extreme symptoms, including death. But its impact on humans is complicated. There have been relatively few human infections detected – fewer than 900 documented globally over several decades – but about half of those infected individuals have died. The good news about H5N1 for humans is that it currently doesn’t spread well between people. Most people who have contracted H5N1 have gotten it directly from interacting with infected poultry – specifically chickens, turkeys, ducks and geese, which often are raised in close quarters on large commercial farms.
 |
| Photo via Lancaster Farming |
The second reason for increased attention is that H5N1 is now infecting more bird and mammalian species than ever before. The virus has been detected in a broad array of wild birds and in diverse mammals, including badgers, black bears, bobcats, coyotes, ferrets, fisher cats, foxes, leopards, opossums, pigs, skunks and sea lions.
The third and most worrisome reason that this virus is getting so much press is that H5N1 now seems to be transmitting well between individuals of at least one mammalian species. In late 2022, mammal-to-mammal spread occurred in Spain in farmed minks. H5N1 spread very efficiently between the minks and caused clinical signs of illness and death in the mink populations where it was detected.
3. Here’s the key question: If H5N1 can achieve spread in minks, why not humans? We are also mammals. It is true that the farmed minks were confined in close quarters, like chickens on a poultry farm, so that may have contributed. But humans also live in high densities in many cities around the world, providing the virus similar tinder should a human-compatible variant arise.
4. Why don’t we make a vaccine just in case? With avian influenza viruses, it is not possible to make effective human vaccines in advance, because we don’t know exactly what the genetics of the virus will be if it starts to spread well in humans. . . . Right now, the best way people can protect themselves from H5N1 is to avoid contact with infected birds. For more information about prevention, especially for people who keep domesticated birds or are bird-watching hobbyists, the Centers for Disease Control and Prevention has a list of guidelines for avoiding H5N1 and other bird flu viruses.
No comments:
Post a Comment