FILE - In this Wednesday, Sept. 14, 2016 file photo, a worker from the Ministry of Health sprays mosquito insecticide fog in Kuala Lumpur, Malaysia, a day after two new Zika virus infection cases were detected in the country.
The advisory issued Thursday targets travel to Brunei, Cambodia, East Timor, Indonesia, Laos, Malaysia, the Maldives, Myanmar, the Philippines, Thailand and Vietnam.
The Centers for Disease Control and Prevention said Zika has been in some areas of Southeast Asia for years, and some residents may be immune. But a number of U.S. travelers have become infected there in the last year, so there is a danger to visitors.
Most infected people suffer a mild and temporary illness, at worst. But infection during pregnancy can causes severe brain-related birth defects. The virus is spread primarily by bites from infected mosquitoes.
