It has been the worst yellow fever outbreak in Brazil since 2000, killing at least 40 people in just two months. The authorities have confirmed 70 cases, while 300 more are being investigated.

Yellow fever is carried by monkeys and can be transmitted to humans by mosquito bites. The disease causes shivers, aches, vomiting and jaundice, but in severe cases can result in kidney and liver failure and hemorrhages.

Brazil's Ministry of Health has ordered 11.5 million vaccines to fight the outbreak. Around 5.5 million doses have been sent to five states that have confirmed yellow fever cases or are at risk, while six million more will arrive soon, according to health officials.

"We are in a state of alert, but there is no cause for panic," Eduardo Hage, chief of the health ministry's infectious diseases department, told the AFP news agency.

The current yellow fever outbreak has hit the southeastern state of Minas Gerais. Officials have also confirmed cases in the states of Sao Paulo and Espirito Santo.

'Unusual'

"It's unusual," Jimmy Whitworth, a professor at the London School of Hygiene and Tropical Medicine, said of the outbreak, according to the Associated Press. "The more cases you have, the more chances that it's going to light up and take off in urban areas."

Whitworth praised the Brazilian authorities for taking the situation seriously and stockpiling vaccines.

The South American country is recovering from an outbreak of the Zika virus that caused brain damage in thousands of newborn babies over the past year.

shs/blc (AFP, AP)