Later, he drove a fuel truck, which paid less money but offered a more stable income.

Five months ago, with tourism booming, Mr. Thongsuk decided to go back into the taxi business, sharing a green and yellow cab with a friend.

“I must have bad karma to have gotten sick so soon after I began driving again,” said Mr. Thongsuk, a Buddhist, like most Thais.

About 10 percent of Thailand’s gross domestic product derives from tourism, and Chinese people are by far the biggest group of visitors. Thailand is one of relatively few countries Chinese tourists can visit without a visa. More than one million visited Thailand last month, before the epidemic fully hit.

“I didn’t think to protect myself when I picked up tourists because I thought the government screened them before they came into the country,” Mr. Thongsuk said.

Most flights between Thailand and China have been canceled, although not all. And Thailand is now dealing with Thais bringing the virus home from trips abroad to countries where it is spreading. The Ministry of Public Health announced on Wednesday that a Thai man who had returned from Hokkaido, Japan’s northernmost island and a popular skiing destination, had contracted the virus, along with his wife.

Their 8-year-old grandson, who had not been to Japan, has also come down with the virus.