Covid-19 cases linked to bars, pubs and clubs have spread to 71 provinces so far this month, according to the Centre for Covid-19 Situation Administration (CCSA).
CCSA spokesman Taweesilp Visanuyothin said on Tuesday there were 6,020 cases to date in this month linked to entertainment venues, most of them (3,432) in the 20-29 age group.
Bangkok alone logged 1,583 such cases, or 40% of all this month's infections, while in other provinces, cases linked to nightspots comprised 25% of all their Covid-19 cases.
Only six provinces remained free of cases linked to entertainment venues this month: Chai Nat, Pattani, Narathiwat, Yala, Satun and Ranong.
Dr Taweesilp said investigating these infections was especially difficult because 27% of people in cases linked to entertainment places withheld information. The others cooperated, and included 1,157 visitors to entertainment places, 364 staff and 348 people in close contact with infected people.
Ten new coronavirus cases have been confirmed in Nakhon Phanom, most linked to local entertainment venues where more than 1,500 customers have now been tested.
Governor Kaisorn Kongchalard and senior health officials announced the 10 new infections on Tuesday, raising the total number in the northeastern province to 43.
They were from a cluster in the Muang municipality, where a pub employee was believed to have been infected with the virus by visitors from at-risk provinces. The disease spread quickly, the governor said.
People who visited entertainment venues between April 4 and 12 are asked to give a Covid-19 swab at the provincial hall, where a testing station will remain open until tomorrow. To date, more than 1,500 people had given samples, he said. Results were expected this week.
All entertainment venues in Muang district have been ordered closed for 14 days and are being disinfected. Popular tourist spots in 12 districts have also been temporarily closed to the public. They include Wat Phrathat Phanom Voramahaviharn in That Phanom district and Lan Phaya Srisatta Nakharat, also known as the Naga monument, in Muang district.
People arriving from any of 18 provinces declared red zones must report to authorities and self-quarantine. Field hospitals in the province's 12 districts have more than 300 beds, enough for infected people, the governor said.
Fourteen more infections were confirmed in Ayutthaya, including a 44-year-old American in Wang Noi district who had contact with three previously confirmed cases, raising the total to 203. The Ayutthaya public health office reported the new infections on Tuesday, most were family members of previously confirmed cases.
Of Ayutthaya's 203 cases, 62 have already recovered and been discharged, while 141 remain at hospitals.
In April, 143 people have so far been confirmed as infected.