Eleven people in Thailand's Phichit province have been tested positive for the Zika virus while 27 others were being monitored, a top official said on Tuesday.
Phichit Governor Wirasak Wichitsaengsi said laboratory test results had confirmed that there were 11 infections and they were all being treated, reports Xinhua news agency.
Health officials have sent special teams to kill mosquitoes in the region to stop the virus from spreading further.
Zika is transmitted by the Aedes aegypti mosquito, which causes birth defects.