The patient was a seafood vendor, aged 48. She had visited a seafood market in Samut Sakhon province, where hundreds of cases had been found recently, for purchasing products to sell in her stall.
In addition to the closure, the market was sterilised. Local officials have set up barriers to prevent people from entering the high-risk area.
The market will be reopened if the situation in the province gets better, governor Phol Damtham said. More than 200 people were considered at risk for infection from contacts with the seafood seller. The results of their tests will be announced on Tuesday.
Meanwhile, Uttaradit Primary Educational Service Area Office 1 has closed child development centres located near the market. Some schools have temporarily closed for the safety of students and staff.