An outbreak of avian flu has affected a record number of poultry birds in the United States. More than 58 million poultry birds in 47 states have either died from avian influenza or been culled (killed) due to exposure to infected birds, according to the U.S. Centers for Disease Control and Prevention. It’s one of the reasons the price of eggs is so high. There are increasing reports that the virus has spread to mammals such as sea lions, foxes, and minks. So should we, as humans, be concerned that we could be next? Yale School of Public Health epidemiologist Dr. Sten Vermund answers your questions.
What is avian flu, and why is the current outbreak causing so much concern?
S.V.: Avian flu or avian influenza (H5N1) is part of a family of viruses known as Influenza A, which are the only influenza viruses known to cause global flu pandemics in humans. Avian flu refers to bird, duck, and goose hosts. Other Influenza A viruses have been found in pigs (Swine flu or H1N1), horses (Equine Influenza), whales, and even cats.
Avian influenza is known as a zoonotic disease, which means it is an infection that can transmit from animals to people.
The most common way people get infected with Influenza A is through a respiratory route or by coming into contact with infected areas or surfaces. Avian flu exposure is often the result of people handling infected animals.The good news is all of these animal viruses are separate from human influenza viruses and are not easily transmitted between humans.
Why are health officials worried that the current avian flu virus has been found in mammals?
S.V.: Simply put, the jump from birds to mammals increases the risk of humans becoming infected through a process known as “reassortment.” This happens when two influenza viruses -one human-adapted strain and one animal strain from birds or pigs, most often- infect the same host at the same time and swap genetic information.
Viruses live to propagate. So, the more a virus spreads, the more opportunities it has to multiply in a host and for reassortment to occur. These genetic changes can occur suddenly, potentially making the virus more infectious to humans who have little or no immunity to this new virus. That is what health officials are most concerned about.
What can people do now to avoid possible infection with avian flu?
S.V.: The threat of avian flu to humans is still very low. If people are unfortunate enough to become infected with avian flu, most experience only minor flu-like symptoms, sometimes pneumonia. Death is extremely rare.
However, to provide some protection against a novel reassortment virus, everyone should at least be vaccinated with this year’s flu vaccine, as well as the new human flu vaccine available every fall.
Avoiding direct contact with wild birds and dead birds is advised. As is frequent handwashing, particularly after touching a bird feeder or after being around animals. It is safe to eat poultry and eggs as long as they are properly handled and cooked to 165 degrees F. That temperature kills bacteria and viruses, including bird flu.
Additional information about avian flu, its causes and treatment can be found here, here, and here.