An outbreak of highly pathogenic avian influenza (HPAI) in chicken and turkey flocks has spread to 24 US states since it was first detected in Indiana on February 8, 2022. Known as bird flu, avian influenza is a family of highly contagious viruses. which are not harmful to wild birds that transmit it, but are fatal to domesticated birds. By early April, the outbreak had killed about 23 million birds from Maine to Wyoming. Yuko Sato, an associate professor of veterinary medicine who works with poultry producers, explains why so many birds are getting sick and whether the outbreak is a threat to human health.
Why is avian influenza so deadly to domesticated birds but not to wild birds that carry it?
Avian influenza (AI) is a contagious virus that affects all birds. There are two groups of AI viruses that cause disease in chickens: the highly pathogenic AI and the less pathogenic AI.
HPAI viruses cause high mortality in poultry and sometimes in some wild birds. LPAI can cause mild to moderate disease in poultry, and there are usually little or no clinical signs of disease in wild birds.
The primary natural hosts and reservoirs of AI virus are wild waterfowl, such as ducks and geese. This means that the virus is well adapted to them, and these birds usually do not get sick if infected with it. But when domesticated poultry, such as chickens and turkeys, come into direct or indirect contact with the feces of infected wild birds, they become infected and begin to show symptoms such as depression, coughing and sneezing, and sudden death.
There are several types of avian influenza. What is this outbreak like, and is it dangerous to humans?
The virus of concern in this outbreak is a Eurasian H5N1 HPAI virus that causes high mortality and severe clinical signs in domesticated poultry. Scientists monitoring wild bird flocks have also detected a reseller virus that contains genes from both the Eurasian H5 and the less pathogenic North American virus. This is when multiple strains of the virus circulating in bird populations exchange genes to create a new strain of the virus, just as new strains of COVID-19 such as Omicron and Delta have been exposed to the ongoing pandemic. emerged during
According to the US Centers for Disease Control and Prevention, the risk to public health from this outbreak is low. No human disease has been associated with the virus in North America. The same was true of previous H5N1 outbreaks in the US in 2014 and 2015.
Should people avoid poultry products until this outbreak is over?
no, it’s not necessary. Infected poultry or eggs do not enter the food supply chain.
To detect AI, the US Department of Agriculture oversees routine testing of flocks conducted by farmers and a federal inspection program to ensure that eggs and birds are safe and free of viruses. When H5N1 is diagnosed in a farm or backyard flock, state and federal officials will quarantine the site and remove all birds in the infected flock. The site is then disinfected.
After the new virus has not been detected for several weeks, the area needs to test negative to be free of infection. We call this process the Four D’s of outbreak control: diagnosis, deportation, disposal, and decontamination.
Avian influenza is not transmitted by eating properly prepared and cooked poultry, so eggs and poultry are safe to eat. The USDA recommends cooking eggs and poultry to an internal temperature of 165 degrees Fahrenheit (74 Celsius).
Are avian influenza outbreaks happening more frequently around the world, or do we hear about them more than we did 20 or 30 years ago?
The dynamics of the spread of avian influenza viruses is very complex. HPAI is a transboundary disease, which means it is highly contagious and spreads rapidly across national borders.
Some research indicates that the detection of HPAI virus in wild birds has become more common. Reports are seasonal, with a peak in February and a low point in September. HPAI outbreaks in wild birds continue to occur in Asia, Europe and Africa. Many migratory bird species travel thousands of miles between continents, posing a risk of AI virus transmission.
In addition, we have better diagnostic tests for more rapid and better detection of avian influenza than we did 20 to 30 years ago, using molecular diagnostics such as polymerase chain reaction (PCR) tests – the same methodology. Use laboratories to detect COVID-19 infections. ,
Farmers can take steps to make their flocks more biosafe, such as preventing the birds and their feed from coming into contact with wild birds.
What are the chances of developing a vaccine for poultry that could reduce the economic damage caused by the outbreak?
Several factors have to be weighed before adopting vaccination as a strategy to control HPAI. At this time, the Department of Agriculture has not approved the use of vaccination in the US to protect birds from avian influenza.
One reason for this is that the use of vaccines will have a potential impact on international trade and poultry exports. Importers would not be able to separate vaccinated birds from infected birds based on routine testing, so they could ban all US poultry exports.
Vaccination can also delay outbreak detection, as it can potentially hide non-obvious infections in infected birds. And if infections go unnoticed, they can spread to other farms before farmers can take control measures.
Avian influenza vaccines can reduce clinical symptoms, illness, and mortality in domestic poultry, but they will not prevent birds from becoming infected with the virus. Ultimately, the USDA aims to eliminate HPAI as soon as it is detected. However, vaccines can be used to help control outbreaks, and are an option the agency is currently investigating.
This article is republished from The Conversation under a Creative Commons license. Read the original article.
