To the Editor: On February 1, 2016, the World Health Organization designated the Zika virus disease outbreak in Latin America as a Public Health Emergency of International Concern (1). Genetic and epidemiological data suggest that Zika virus had been present in Southeast Asia since the 1940s (2); however, the disease burden and geographic extent of Zika virus disease in Asia are not clear. Occasional cases in some Asian countries, mostly in returning travelers, have recently been documented (3–5); however, as of February 2016, none were in Vietnam. During December 2015–February 2016, the National Center for Zoonotic Viruses (Tel Hashomer, Israel), diagnosed 8 cases of Zika virus disease in travelers returning to Israel. The Center is part of the Central Virology Laboratory of the Israel Ministry of Health and is the reference laboratory for the diagnosis of Zika, dengue, and chikungunya virus infections in Israel. During the same period, 4 cases of dengue and 1 of chikungunya were also diagnosed. Of the 8 cases of Zika virus disease, 7 were in patients returning from South and Central America and the Caribbean (online Technical Appendix, http://wwwnc. cdc. gov/EID/article/22/8/16-0480-Techapp1. pdf) and 1 was in a patient returning from Vietnam via Hong Kong. We report the patient returning from Vietnam.

The patient was a 61-year-old man from Israel who spent 10 days in Vietnam during December 2015: 3 days in Hội-An, 3 in Hue, and 4 in Ho Chi Minh City. After spending 2 more days in Hong Kong, he returned to Israel. On the third day after his return, he experienced fever, malaise, and headache; he had no rash or conjunctivitis. Laboratory studies showed only lymphopenia and