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Avian Influenza or Bird Flu is a virus that infects the respiratory, digestive, or nervous system of birds both domestic and wild. Some birds are carriers but not as likely to show the symptoms or even be affected by the virus while other birds succumb quickly to the disease. Of most concern is the infection of chickens, turkeys and guineas.
The first reported avian influenza case showed up in Italy in 1878 and the first case showed up in poultry in the U.S. around 1924 and a second epidemic in poultry in 1929 but both times the virus was eradicated quickly. The next big epidemic was in 1983 and it took a couple of years to get under control and cost tens of millions of dollars with around 17 million birds destroyed. In the late 90’s cases turned up in Pennsylvania and nine commercial flocks were destroyed and an area of 75 square miles was quarantined to poultry or poultry products. Some states have begun to require the registration of backyard poultry flocks as they view them as one of the prime threats to the commercial poultry industry. Reading the press releases from the states it is obvious that several states are ready to destroy backyard flocks that are located within the quarantine radius of any infected flocks. Other states are looking at forcing backyard poultry producers to keep a list of birds for three years including where the birds were sent or sold. Some states offer free registration of backyard flocks and charge for commercial flocks
The disease can strike so rapidly that there are no real observable symptoms other than dying birds. Like most other viral disease the mortality depends upon the strength of the virus strain. The main infection vector is wild birds that carry the virus without appearing sick, indeed they might not be sick.
Signs or symptoms include ruffled feathers, depression or listlessness, a drop in egg production, soft shelled eggs, poor appetite, purple coloring on the wattles and comb, swelling of the head, eyelids, combs, wattles, and feet, diarrhea, bloody discharge from nostrils, inability to walk or stand, bleeding feet or leg shanks, respiratory symptoms, and large numbers of seemingly healthy birds dying.
The virus will mutate, sometimes getting milder as it spreads between flocks, sometimes becoming more virulent. Chickens are not the preferred host for Avian Influenza so the virus has to mutate to survive and in that process it can become quite lethal and contagious. Infected birds spread the virus in their feces and from nasal discharges that can contaminate feeders and waterers. Once infected the chickens are carriers for life. The virus can survive in the water and mud where infected wild ducks are present and can remain outside a host for long times and are not harmed by freezing temperatures. People and contaminated equipment can also spread the virus so nothing should be moved into your flock without through disinfection and cleaning.
Besides the wild birds and wild ducks acting as carriers, rodents and insects can spread the virus. Once again we see the value of a good treadle feeder to prevent vermin from bringing in deadly diseases. The virus can be transmitted into eggs but the infected eggs don’t usually hatch.
There is no treatment for bird flu other than broad spectrum antibiotics to control any secondary infections. Any surviving birds will continue to shed the virus for life.
If your flock gets infected the birds should be culled and the bodies burned or buried deep in the ground. Clean and disinfect the coop and surrounding area and any litter should be thoroughly composted before spreading on the land. Mild strains of bird flu can be controlled by vaccination of uninfected birds and quarantine but the lethal strains of bird flu require the culling of the entire flock
The poultry industry considers backyard flocks as the greatest threat to their industry. There is little to no biosecurity in home based flocks and they have much greater risk of becoming infected and people tend to not think about buying a new bird and bringing it into their flock. Commercial poultry usually is brought in and removed in an all in/all out fashion with much tighter controls on biosecurity and the genetics of the brood stock.
Free range birds will be nearly impossible to provide biosecurity but cooped birds should have the cooped bird tight, have all feed in treadle feeders, and use the nipple style water dispensers hung out of reach of wild birds. As the virus is easily spread through fecal matter allowing wild birds to congregate is enough to contaminate your flock. However, most wild birds have to work hard and long to feed themselves so keeping the feed away from the wild birds in a wild bird proof chicken feeder will mean very few birds will stick around long enough to leave droppings behind.