The bird flu or the avian influenza is caused by a bird influenza virus. The virus is usually carried in the intestines by wild birds traveling for long distances. In most cases the virus does not affect the birds. Though the birds usually do not get sick even if they are carrying the virus, yet the virus is highly contagious and can easily spread from one bird to another. The infected birds secrete contagious saliva, nasal secretions and fecal matters which act as the medium of viral transference to other birds.The bird flu usually causes two main types of influenza. The low pathogenic flu usually goes undetected and the side effects consist of birds having ruffled feathers and a drop in egg laying capacity. The higher pathogenic case is highly contagious and spread rapidly. The internal organs of the infected bird get affected adversely. In most cases the influenza of higher pathogenic is fatal with a mortality rate of 90 % to 100%. To add to the severity of the disease, the infected birds die within 48 hours of in contact with the virus.
There are kinds of A type of virus causing influenza. They differ from one another due different protein compositions, hemagglutinin [HA] and neuraminidase [NA] proteins. Till now16 known HA types and 9 known NA types of influenza has been discovered and all the types are found to quite active in birds.
Bird Flu Human Heath Risks
The virus of the bird flu generally does not infect the humans but since the year 1997 reports of humans being infected by the A type virus have come up. The source of the virus for the humans is the infected birds from the poultry firms. There are mainly three kinds of influenza virus, H1N1, H1N2, and H3N2 that are able to infect the humans. But the A types viruses are rapidly changing and soon they might develop to infect humans.
