South Korea has announced its fourth Zika case who is a woman just returning from a trip in Vietnam.
The Korea Times reported Saturday that the 25-year-old woman was diagnosed with the virus on May 4 when she visited a hospital after having rash and joint pain.
She worked in Ho Chi Minh City between April 10-30 and came back to South Korea on May 1, the report cited a statement from the Korea Centers for Disease Control and Prevention.
The agency suspected she might have received mosquito bites in Vietnam. Aedes aegypti mosquito, which has been identified as the main vector of the virus, is very common in Vietnam. It is also known for carrying the dengue, yellow fever and Chikungunya viruses.
Korean health authorities said the woman is in stable condition. They are also examining a person who met with the patient in Vietnam between April 13 and 17.
Local health ministry is also following the case.
Vietnam has raised Zika alerts after an Australian tourist tested positive after leaving the country on March 6.
The country announced its first two Zika patients last month, who were a 64-year-old woman in Nha Trang and a 33-year-old woman in Ho Chi Minh City. The latter was then pregnant at eight weeks but has had an abortion, reportedly after the ultrasound scan did not detect the fetal heartbeat.
No further infections in their neighborhoods have been reported since.
Zika was first detected in Africa in 1947 when it was considered a relatively mild disease until the current outbreak started in Brazil in May 2015.
The virus has since spread to more than 60 countries and territories, including many in the region such as Indonesia, Laos, Malaysia, the Philippines, Thailand and South Korea.
Brazil, Venezuela and Columbia each has linked three deaths to the Zika virus.
Brazil has registered nearly 5,000 confirmed and suspected cases of microcephaly associated with Zika, Reuters reported.