What is Bird Flu

Bird Flu, more properly called avian influenza, is an infectious disease that primarily affects birds but can also infect several kinds of mammal, including pigs and humans.

Many species of wild bird – particularly migratory waterfowl, and, especially, ducks - seem able to carry bird flu without coming to any apparent harm, but infection with avian influenza causes other species, including domestic chickens, turkeys and geese, to become seriously ill. In poultry, the sickness caused by bird flu comes in two different types, one mild, widespread and barely noticeable, the other uncommon, deadly and very difficult to overlook.

In the first, very common, form of bird flu, the only indications of sickness in the infected bird may be ruffled feathers, reduced egg production or minor respiratory problems. Unless a regular screening program is in place, it is possible that the outbreak may be so mild as to go entirely undetected.

The second, lethal, kind of bird flu causes birds to become very ill extremely quickly and, because it is highly contagious, spreads rapidly to surrounding birds. It affects the birds’ respiratory tract, and attacks multiple organs and tissues, leading to massive internal haemorrhaging. So deadly is this form of bird flu that almost 100% of infected birds may die within 48 hours of contracting the disease.

As well as spreading naturally between birds in the same immediate vicinity, bird flu can easily be spread from one location to another, such as farms and marketplaces, by the transportation of infected birds and contaminated people, vehicles or other equipment. This happens because birds infected with avian influenza shed the virus that causes the disease in their droppings, feathers, saliva and nasal secretions, which then contaminate the birds’ cages, food and the shoes and clothing of people living and working around the birds. To make matters worse, bird flu can survive in this way for long periods of time, particularly in low temperatures. It has been known to survive in faeces from infected birds for up to 35 days at a temperature of up to 4 degrees Celsius, and for up to 6 days at temperatures of 37 degrees Celsius.

Because bird flu spreads so quickly, and is so deadly, radical methods are needed to attempt to control the disease. Where an outbreak is confirmed, it is recommended that all infected birds, and those that have been exposed to avian influenza but are not yet sick, be swiftly destroyed and their carcasses disposed of. Strict quarantine procedures should be introduced, and property thoroughly disinfected to reduce the risk of bird flu recurring. It may also be necessary to impose restrictions on the movements of live poultry within and between countries.

As yet, it is difficult, although not impossible, for humans to catch bird flu. All of the reported cases so far, with the exception of a very small number, occurred in people who had been in close contact with infected birds and had caught avian influenza from them. Bird flu has not yet learned how to spread from human to human in the same way that it spreads from bird to bird. However, as the number of humans infected by birds increases, so do the opportunities for bird flu to adapt. It is widely feared that it is only a matter of time before bird flu crosses the boundary between species and unleashes a wave of sickness and death upon the human race.