What is the Avian Bird Flu?
- Infectious disease of birds caused by type A strains of the influenza virus.
- All birds are thought to be at risk of catching the avian influenza infection, though some are more resistant to infection than others
- Symptoms in birds range from mild illness to a highly contagious & rapid fatal disease that can result in severe epidemics.
- Worst care scenario, known as highly pathogenic avian influenza, is characterized by sudden onset, severe illness & rapid death. The mortality rate can approach 100%.
- 15 subtypes of the Avian bird flu are known to infect birds, and all outbreaks of the highly pathogenic form have been caused by influenza A viruses of subtypes H5 & H7.
What birds are most vulnerable?
- Migratory waterfowl, particularly wild ducks, are the natural reservoir of avian influenza viruses. However, these birds are the most resistant to infection.
- Noted for being particularly susceptible to epidemics of rapid fatal influenza is domestic poultry; which includes chicken and turkey.
- Direct or indirect contact of domestic flocks with wild migratory waterfowl. Live bird markets are also at risks.
Spreading of the disease?
- The normal procedure for controlling potential exposed flock is the quarantining of infected farms & destruction of infected or potentially exposed flock.
- Apart from being highly contagious, avian influenza viruses are readily transmitted from farm to farm by mechanical means, including contaminated equipment, vehicles, feed, cages, or personal clothing.
- Highly pathogenic viruses can survive for long periods of time in the environment, especially when temperatures are low. This time of the year is between the months of November and March.
Public Health Concern
- Influenza A viruses, including subtypes from different species, can swap or reassort genetic materials and merge. Known as antigenic shift, results in a novel subtype different from both parent viruses. As populations will have no immunity to the new subtype, and as no existing vaccines can confer protection, antigenic shift has historically resulted in highly LETHAL pandemics.
- For this to occur, the novel subtype needs to have genes from human influenza viruses that make it readily transmissible from person to person for a sustainable period
- The antigenic shift has long been thought to involve humans living closely to domestic poultry and/or pigs. Pigs are at risk of the infection with both avian and mammalian viruses, including human strains, they may serve as a mixing vessel of the genetic material from human and avian viruses, making the novel subtype
How are humans infected?
- Direct contact with infected poultry, or surfaces contaminated by their feces, is the main route of human infection.
- Most human cases have occurred in rural areas where many households keep small poultry flocks that roam freely, have direct contact with small children, or enter the house.
- Many families sell or slaughter and consume birds when signs of illness appear.
- The virus does not spread easily from birds to humans.
- Though rare, instances of limited human-to-human transmission of H5N1 (most infected and dangerous subtype of the avian virus) and other avian viruses have occurred in association with outbreaks in poultry and should not be a cause for alarm.
- There is no evidence that properly cooked poultry and turkey carry the virus. Another words, it is still safe to eat poultry right now.
