The fever of the chickens is produced by a subtype of so called virus of the flu H5N1, at first it has characteristics similar to other viruses of the flu but it was not possible to have demonstrated that it is possible to transmit from person person.

The contagion route is proceeding from the chickens and there are evidences that also her the pigs and the ducks can transmit.

Since it is a virus vine to the what one the persons have not been exposed, and it is very virulent, the symptoms are very intense with affectation respiratory and a high mortality.

The countries where cases have been described from 1997 are:

• Hong Kong
• Vietnam
• South Korea
• Japan