Health and city officials in Thailand downplayed risks from rising infections from the mosquito-borne Zika virus, which is linked to serious birth defects, and expressed concern that disclosing information would damage its tourism industry.
On Friday the European Centre for Disease Prevention and Control (ECDPC) warned of the increasing spread in Thailand of Zika, which can cause microcephaly in unborn children.
Thailand is combating the risk by misting and spraying mosquito-infested areas, said Anuttarasakdi Ratchatatat, epidemiologist at the health ministry's Bureau of Vector Borne Disease.
It has not changed or updated its Zika prevention plan since Singapore, which has a more extensive prevention campaign, began reporting a spike in cases from late August.
Twenty-two new cases were confirmed on Sunday in the upmarket Sathorn area of Bangkok, part of the city's Central Business District, including a pregnant woman who later gave birth with no complications.
"It's concerning because I live just around the corner," said Dietrich Neu, a Canadian who works in publishing.
"It's different in Canada; the government would be all over it. There would be a center where people can get treated and leaflets about what the symptoms are."
The health ministry on Monday urged Thais not to panic as it said the virus was not deadly or contagious - though in fact it can be passed on sexually - and ministry epidemiologist Anuttarasakdi added that it did not want to deter tourists.
"The information on Zika is quite sensitive because if we say which province has infections then attention will turn on that province, and if that province is popular with tourists it will have an impact on tourism," he said.
"We don't want people to be too alarmed."
Health authorities in Thailand are not treating Zika as seriously as dengue, which is much more widespread in the country, said Assistant Professor Watcharee Chokejindachai from the Faculty of Tropical Medicine at Mahidol University in Bangkok, because of a perception that Zika is less dangerous.
"Dengue is perceived as more serious; it can lead to death. That's why they pay more attention to dengue than Zika," Watcharee told Reuters.
"Diagnosing Zika is also more expensive than dengue because it takes time - up to eight hours - whereas with dengue we have a rapid test which takes 15 minutes."
There have been more than 31,000 dengue cases in Thailand this year to Aug. 19, including 25 fatalities, according to the International Society for Infectious Diseases.
Several countries in Southeast Asia have reported a rising number of Zika cases, but Thailand has one of the highest number in the region, with more than 100 confirmed since January.
A total of 30 pregnant Thai women with the virus are being monitored, the health ministry said. Six have given birth with no complications, so far.
A map showing countries with active local transmission of Zika from the ECDPC updated on Friday shows Thailand with "increasing or widespread transmission".
Singapore, where homes have been inspected and communities blanketed with information leaflets, reported its first locally infected Zika patient on Aug. 27, and the number of reported infections has since swelled to more than 300.
People there risk fines if they have even a flower pot with old water in it.
Samlee Pliangbangchang, Regional Director of the World Health Organization's Southeast Asia Region from 2004 to 2014, said Thailand should be more transparent in reporting the Zika threat to the public and should look to Singapore as an example.
"The Ministry of Public Health don't want people to be afraid, so they say they have it under control," Samlee told Reuters.
"The truth is we don't know the extent of the Zika spread in Thailand," he added.
"Singapore has an open policy to inform the public about what is going on so that the public can take precautions. Maybe we should do that, too."