TAIPEI (Taiwan News) – The Centers for Disease Control are warning visitors and business people returning from Vietnam to look out for measles symptoms, reports said Tuesday.

Individuals experiencing symptoms such as breathing difficulties or rashes should immediately contact a doctor and reveal their travel history, according to the CDC. Of the more than 40,000 suspected cases of measles recorded in Vietnam since the start of the year, 3,400 were confirmed, Radio Taiwan International reported.

The total was double the number during the same period last year.  Only about 40% of the Vietnamese population has been vaccinated against measles.

People visiting crowded places in the Southeast Asian country should wear masks and wash their hands, said CDC Spokesperson Tseng Shu-hui (曾淑慧). The best prevention is vaccination against measles before travel.

The CDC raised its travel alert for Vietnam to the second-highest level in February. Vietnamese officials warned that the measles problem is growing across the country.