The results of genetic tests suggested that Brazil's first outbreak of bird flu on a commercial poultry farm in the state of Rio Grande do Sul shares the strain with cases in zoo animals in the same state,

SAO PAULO (Reuters) - A suspected case of bird flu in a farm worker in the Brazilian city of Montenegro came back negative, the health ministry of Rio Grande do Sul, the country's southernmost state, said in a statement on Tuesday.

Brazil is still analyzing a new suspected case of bird flu on a commercial poultry farm, raising concerns the deadly virus may be spreading in the world’s largest chicken exporter.