The 27-year-old Indonesian found to have been infected by the Zika virus and to display a mild form of the disease is from Jambi, Central Sumatra, about 320km south of Singapore.
The man was found to have been infected with the Zika virus last year during an outbreak of dengue fever that hit Jambi province, from December 2014 to April last year, Eijkman Institute for Molecular Biology deputy director Herawati Sudoyo was quoted as saying by The Jakarta Post.
"It started during the dengue fever outbreak in Jambi. We were ordered to examine samples of blood from 103 patients. In one patient, we found the Zika virus in a sample of his blood," said Dr Herawati.
The Zika virus has been spreading fast in South and Central America. In South-east Asia, Thailand is the worst-hit country, with seven Zika cases uncovered between 2012 and 2014 across its provinces. The Philippines, Cambodia, Indonesia and Malaysia each have had one Zika-related case since 2010.
The Jambi resident was diagnosed with a mild case of Zika and was hospitalised for only a day before he was sent home, Ms Andi Pada, head of Jambi's health department, told Kompas TV.
Dr Oscar Primadi, head of the Health Ministry's communications and public health service department, confirmed the Jambi case, but dismissed reports that a woman in her 60s who lived outside Jakarta had died of Zika last month.
He said Indonesia has only two laboratories that have the equipment to test for the Zika virus - one at the Health Ministry headquarters and the other at the Eijkman Institute for Molecular Biology.
"There is no confirmed case of anyone infected with Zika in 2016," Dr Oscar said in a statement on the health ministry's website.
In the statement, he appealed to the public to step up preventive measures by regularly cleaning their refrigerator trays, emptying all water-filled containers, and covering all water buckets.
Indonesians have also been asked to use mosquito nets when sleeping, to keep their homes well-lit and avoid hanging wet clothing indoors as it can be home to the Aedes aegypti mosquito, the carrier of dengue, chikungunya and Zika viruses.
World Health Organisation officials say the disease is likely to have spread far more widely in South-east Asia than the number of cases suggests.
This is partly because detection of the Zika virus is often delayed, its symptoms being similar to those of other mosquito-borne viruses such as that of dengue and chikungunya.
Thailand's most recent case was discovered last month after a Thai man was stopped at a fever screening station at Taiwan's Taoyuan International Airport.
Hong Kong's top health officials and medical experts are meeting today amid a heightened alert over the fast-spreading Zika virus.