A black-necked swan died from the disease in a locality in the department of San José, west of here.
The area is a nature reserve with abundant wild birds.
This is the eighth outbreak in Uruguay, in the departments of Canelones, Flores, Maldonado, Montevideo, Tacuarembó and now San José.
So far, avian influenza has been detected in wild and backyard birds.
Last week, the government announced the imminent start of 100 percent vaccination of laying and breeding hens in poultry farms.