As most of you I’m sure are aware, there has been a new strain of avian influenza infecting birds in Europe and has recently moved to Wales. I composed some questions that I wanted responses to and did some research into the answers. In the veterinary profession our vets work to ensure human health is taken into account when working towards good animal health.
Where has this originated from?
According to ‘Reuters’ and ‘Fox News’ the first case of the H5N8 strain of avian flu was detected in Denmark on a poultry farm. About one-third of 30 ducks at a farm north of Copenhagen were killed by the same virus that had been found in Denmark in wild birds.
How is it spread between birds?
Infected birds can shed avian influenza A viruses in their saliva, nasal secretions, and feces. Susceptible birds become infected when they have contact with the virus as it is shed by infected birds. They also can become infected through contact with surfaces that are contaminated with virus from infected birds. Domesticated birds (chickens, turkeys, etc.) may become infected with avian influenza A viruses through direct contact with infected waterfowl or other infected poultry.
How are these strains changing so quickly?
As well as the mutations we are familiar with such as bases being substituted, there is another type of mutation; viruses exchange information with one another. These mutations can occur when different kinds of viruses come into contact with one another in a single host. Hypothetically, for example, a virus that is easily spread from person to person could exchange genetic information with a highly pathogenic strain of avian flu virus, creating a new strain that can be transmitted easily among humans.
The potential for this type of mutation to occur is greatest when there are many opportunities for the virus to multiply—in large flocks with many infected birds. The virus can spread more quickly in crowded conditions, and birds in high-density flocks may be more susceptible to the disease because the stressful conditions may weaken their immune systems.
Viruses have more opportunities to exchange information where these flocks are in close contact with humans or other domestic animals, raising the potential for a human or a pig, for example, to serve as a host for two flu viruses that can exchange genetic information and become more harmful to humans.
Will this put human lives at risk?
WHO write “Human infection with the H5N8 virus cannot be excluded, although the likelihood is low, based on the limited information obtained to date. It should be noted that human infection with H5N6 of related clade 18.104.22.168 has already occurred. WHO will re-assess the risk associated with the virus when more information is available.”
In the past:
- Humans can be infected with avian and other zoonotic influenza viruses, such as avian influenza virus subtypes A(H5N1), A(H7N9), and A(H9N2)
- Human infections are primarily acquired through direct contact with infected animals or contaminated environments
- Avian infections in humans may cause disease ranging from mild conjunctivitis to severe pneumonia and even death.
- The majority of human cases of A(H5N1) and A(H7N9) infection have been associated with direct or indirect contact with infected live or dead poultry. Controlling the disease in the animal source is critical to decrease risk to humans.
Why are people so concerned if the disease infects domesticated birds?
- the potential for low pathogenic viruses to evolve into highly pathogenic viruses (we do know that this virus, is in fact, highly pathogenic)
- the potential for rapid spread and significant illness and death among poultry during outbreaks of highly pathogenic avian influenza
- the economic impact and trade restrictions from a highly pathogenic avian influenza outbreak
- the possibility that avian influenza A viruses could be transmitted to humans