The woman was bitten by mosquitoes in Vietnam, then experienced a headache and rash on the body before arriving in Japan on September 8.
After experiencing other symptoms such pain in joints and red eyes, the woman sought medical attention at a hospital in Tokyo on September 9, two days later she was diagnosed with Zika virus.
Prof. Dr. Tran Dac Phu, Head of the General Department of Preventive Medicine, said the department is contacting Japan’s health agency for information on the woman’s address in Vietnam.
The woman is the 11th Zika-infected case in Japan since 2013 but she is the first in Tokyo since the Japanese government raised the Zika virus warning to Level IV in February, 2016.
On September 13, the General Department spread messages on Zika virus control and issued guidelines on how to avoid contracting Zika and how to kill mosquitoes carrying the virus.