A German tourist may have contracted Japan’s first case of dengue fever in more than 60 years, the health ministry said Friday.

The Health, Labor and Welfare Ministry is asking the public to be on alert for the dangerous disease after a German woman was diagnosed with it upon returning from a trip to Japan last August.

The woman, 51, visited several mainland areas from Aug. 19 to 31 last year. She was diagnosed with dengue fever in Germany after developing a high fever, nausea and other symptoms starting Sept. 3.

According to the ministry, the woman recovered after a week of hospitalization. She is said to have complained about being bitten by a mosquito in Japan.

In East Asia, dengue fever is transmitted by the tiger mosquito. Those bitten by an infected mosquito often develop a sudden fever around three to seven days after transmission, accompanied by head and muscle pains and a rash.

Most people will develop mild symptoms, but a small number might go into shock, which can be life-threatening.

Around 250 Japanese a year suffer dengue fever symptoms after returning from overseas travel.

The ministry said it is possible a mosquito picked up the virus from a Japanese person infected overseas before it bit the woman.

Some mosquitoes in Japan may carry the virus, but the risk of a dengue fever outbreak in the country is very low, epidemiology expert Atsuo Hamada at Tokyo Medical University said.