Worawit said two Thai-Karen people who worked in Myanmar were infected and one later died in Myanmar while the other died in Ban Jor Kua of Tambon Mae Chan in Umphang.
While there have been no reported outbreaks in Thailand, he has urged Thais living in the border area to be careful.
He said the outbreak in Myanmar began in May.
The hospital sent a medical team to Myanmar to help treat patients and provide advice to locals on how the best protect themselves from the disease.