"Wherever you see Myanmar people, shoot them down," read one Thai comment on YouTube after a surge of coronavirus cases among workers from Myanmar.
The outbreak, first detected at a seafood market near Bangkok, has prompted a flare-up of such online hate speech as well as questions over the treatment of millions of migrant workers.
"Myanmar people are being labelled for spreading Covid-19, but the virus doesn't discriminate," said Sompong Srakaew of the Labor Protection Network, a Thai group helping migrant workers.
Shifting sentiment had real consequences, he said, with workers from Myanmar, previously known as Burma, being barred from buses, motorcycle taxis and offices.
One of the many incendiary comments on social media seen by Reuters called for infected migrant workers to remain untreated and punishment for people that brought them into the country.
The rhetoric reflects a global pattern since the start of the pandemic of foreigners being blamed for spreading the virus.
The independent Social Media Monitoring for Peace group said it found hundreds of comments classified as hate speech on YouTube, Facebook and Twitter.
"The comments included racist language aimed at triggering discrimination and promoting nationalism," said the group's Saijai Liangpunsakul.
After Reuters flagged some posts, Facebook said it had removed several for violating hate speech policies. Twitter said it was looking into the issue. YouTube did not respond to requests for comment.
Not all the social media traffic has been negative, with some Thais defending the Myanmar workers.
The outbreak was first detected last week at a shrimp market at Samut Sakhon, barely 35 kilometres from central Bangkok.
Since then nearly 1,300 infections linked to the market have been found while thousands of people have been quarantined.
"We feel really sad that we Myanmar workers are being blamed," said Nay Lin Thu, a 35-year-old worker from Myanmar who has now volunteered to help others.
"We are told 'this happened because of you Myanmar'. Mostly we do not respond but some of us couldn't contain their anger."
Officially, Thailand has nearly 1.6 million Myanmar workers, but the real figure is higher because of illegal immigration. Most migrants are labourers or work in service industries.
"Thai people won't take the jobs they are doing," Taweesilp Visanuyothin, of the Covid-19 taskforce, said as he pleaded for tolerance in a televised broadcast. "Today they are our family... Both Myanmar and Thai people are Buddhists."
A video clip of a Myanmar migrant worker wiping his tears while listening to Dr Taweesilp went viral on social media.
Thailand has traditionally been seen as tolerant of foreigners, but a historic enmity has been revived on social media with references to the 18th-century destruction by Burmese forces of Ayutthaya, capital of what was then known as Siam.
Myanmar has suffered a much more severe coronavirus outbreak, with over 2,500 dead from nearly 120,000 confirmed cases compared with 60 fatalities from over 5,800 cases in Thailand.
How the new cases first appeared in Thailand is unclear.
Panpimol Wipulakorn, director-general of the Department of Mental Health, urged Thais to give migrant workers moral support and not blame them for the new wave of infections in the kingdom. Cooperation will help curb the virus, he said.
A Myanmar woman in a clip circulated online said no one knew who imported the virus into the kingdom, adding her compatriots love Thailand as much as Thais.