Brazil has declared a six-month animal health emergency after several cases of avian flu were found in wild birds. Seven cases have been reported in Espirito Santo state, with another discovered in Rio de Janeiro state. The emergency declaration makes it easier for the government to now bring in measures to stop the highly infectious H5N1 virus from spreading.

Authorities say the cases were found far away from Brazil's main areas of production in the south of the country. However, outbreaks in commercial flocks elsewhere have sometimes been observed to follow the discovery of avian flu cases in wild birds.

The World Health Organization (WHO) says the further spread of the H5N1 virus will have to be monitored closely to see whether it is mutating into a form that can spread amongst humans. 

The cases that do occur are the result of people coming into close contact with infected birds.