Tak provincial officials stepped up security at three camps for Burmese refugees after a coronavirus-infected Myanmar man was found living at the Umpiem complex this week.
Gov. Pongrat Piromrat on Wednesday ordered administrative officials to screen everyone entering and leaving the Umpiem, Ban Nupo and Mae La refugee camps which are home to about 50,000 people who fled ethnic unrest in Myanmar.
Disease-prevention measures have been enforced inside the camps and nearby villages.
All 100 people at the Umpiem camp underwent coronavirus testing but no one else tested positive for Covid-19.
The infected migrant crossed the border through a natural pass. Soldiers and local officials have increased patrols in border areas and parts of the Moei River, which have dried up.
Barbed-wire fences at borders were strengthened and more officials and volunteers have been deployed to prevent illegal border crossings.
Meanwhile, the Center for Covid-19 Situation Administration on Wednesday reported four new coronavirus cases in quarantine over a 24-hour period.
The latest patients include three Thai nationals from Mozambique, Philippines and Russia, and one Indian from India.
The case from Mozambique was a 41-year-old Thai laborer. The second case was a 32-year-old Thai employee of a private firm who arrived from the Philippines.
The third case was a 55-year-old Thai laborer. She arrived from Russia on Nov. 23 and tested positive that day.
The fourth case from India was a 46-year-old Indian laborer who arrived on the same flight as five previously confirmed cases.
Most of them were asymptomatic, except for the Thai woman from Russia.
Of the 3,926 people diagnosed with Covid-19, 3,780 have recovered, including eight discharged from hospitals over the past 24 hours, and 86 people remain in hospitals. The death toll remained at 60.