SAO PAULO, Brazil (AP) – Authorities ordered the slaughter of 17,000 chickens after 6,000 chickens died from a mysterious respiratory illness in a central western Brazilian state, officials said.

Sanitary authorities do not know what kind of disease the chickens had, but expect to identify it by the end of this week, Gladys Raquel, an animal sanitation manger with the state government of Mato Grosso do Sul state, said Tuesday in a statement.

Raquel and officials with Brazil’s Agriculture Ministry refused to answer questions about the illness, or whether it had similar symptoms to bird flu disease in Asia, saying they want to wait for the test results. “Several diseases have similar symptoms, and as a result, we can’t say which of them is present in the area,” Raquel said.

The regional death toll in Asia’s latest bird flu outbreak stands at 54 people. Vietnam suffered the most deaths with 38.

The Brazilian farm in the town of Jaraguari where the chickens died was surrounded with road blocks.

The Agencia Estado news agency also reported that more than 100 other chicken farms were quarantined in Jaraguari, 20 miles from the Mato Grosso do Sul state capital of Campo Grande. Campo Grande is about 750 miles northwest of Sao Paulo.

Brazil is the world’s largest chicken exporter. Production in South America’s largest country rose 8 percent last year, with exports skyrocketing 26 percent, in part because of the outbreak of bird flu in Asia.