The Ministry of Public Health has tightened screening criteria for people in eight provinces popular with Chinese tourists after the number of Covid-19 cases in Thailand changed little over the past week.
"Right now, we have reached a point where we are not certain if there are any new patients with Covid-19 or if we are simply unable to find them.
So we have to work in a more aggressive way to identify possible infections as soon as possible," Department of Disease Control deputy director-general Dr Thanarak Plipat told media yesterday.
The new screening measures have been in place for a week. Under them, patients with pneumonia where the cause has not been verified will be automatically referred to Patients under Investigation (PUI) -- the group which tests for Covid-19 -- if they live in Chiang Mai, Chiang Rai, Krabi, Phuket, Prachuap Khiri Khan, Bangkok, Samut Prakan or Chon Buri.
After the new screening was introduced, PUI cases jumped from 957 to 1,151 as of yesterday -- an increase of 194.
On Thursday alone, 99 cases were added to the PUI list. Most of the new cases were found in these eight provinces.
Dr Thanarak told media the new screening method was introduced after the ministry became concerned about the effectiveness of previous screening.
He added the rise in PUI was the result of extending the screening to passengers from South Korea, Japan, Singapore, Hong Kong, Taiwan and Macau, instead of only China.
The number of Covid-19 cases in Thailand has remained unchanged at 35 for the last four days, indicating the contagion rate may have stalled in Thailand.
Meanwhile, Public Health Minister Anutin Charnvirakul yesterday asked the public not to panic over news that the ministry was classifying Covid-19 as a "dangerous" communicable disease, saying that the policy was made to strengthen measures to tackle the outbreak.
On his Facebook page, Mr Anutin said that the new classification would allow health officials to use the law to control transmission instead of relying on screening and quarantines.
Regarding Thais caught up in Japan's Covid-19 outbreak, foreign ministry spokesperson Cherdkiat Atthakor said another Thai crew member of the Diamond Princess tested positive for the virus, bringing the number of Thai cases on the cruise ship to four.
He said the patient has been sent to hospital and all four Thai patients are under close care of Thai officials in Japan.
Two Thai passengers and 23 Thai crew members were registered aboard the cruise ship, which has been docked in Yokohama under quarantine.
The Thai embassy in Tokyo said the remaining Thai crew will be allowed to leave the vessel and return to Thailand if their second test comes back negative.
The Diamond Princess's operator will cover travel expenses.
Also yesterday, Foreign Minister Don Pramudwinai oversaw the presentation of commemorative pins to 14 people who took part in the evacuation by air of 138 Thais from Wuhan in China, where the virus outbreak was first detected.
Meanwhile, Dr Pramote Sathienrat, deputy chief of the Department of Thai Traditional and Alternative medicine, said his department has been working with its partners to test the effectiveness of the herbal remedy Kariyat, known in Thai as Fa Talai Jone, against Covid-19.
The medical trial will be carried out on 10 healthy patients and the results are expected in one month. Fa Talai Jone became well-known after being used to treat infections during the Sars outbreak.
Meanwhile, the Internal Trade Department under the Ministry of Commerce has banned the unauthorised export of face masks.
The move is to ensure the availability of face masks, said Whichai Phochanakij, director-general of the department.
He added that outbound travellers will only be allowed to take a limited number of face masks with them.
Earlier, the department had required exporters to seek permission for the export of 500 masks or more.
Some parties responded by maintaining their export volume but simply shipping fewer than 500 masks in each delivery.