Brazilian authorities say they've now confirmed 47 cases of yellow fever, and 25 deaths.
The Health Ministry also says it's investigating more than 160 other suspected cases of the mosquito-borne disease.
The outbreak is centered in the east-central state of Minas Gerais, whose governor declared a 180-state of emergency this month after an initial report of eight deaths.
The government says it's sent 2 million extra doses of vaccine against the disease to Minas Gerais. And it says hundreds of thousands of other doses will be sent there and to nearby Espirito Santo this week.
Last year, Brazil registered just seven confirmed yellow fever cases.
The U.S. Centers for Disease Control and Prevention says the disease can cause fever, chills, severe headache, pain, nausea and vomiting.
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