On July 15, 2016, the US Centers for Disease Control and Prevention (US CDC) reported the first known case of female-to-male sexual transmission of Zika virus in the male partner of a female Zika patient who returned from a country with ongoing Zika transmission. Hence, the Taiwan Centers for Disease Control (Taiwan CDC) reminds travelers to follow the “2226 Principle” after leaving Zika-affected areas to prevent Zika transmission. The “2226 Principle” specifies that female travelers are urged to postpone pregnancy 2 months after their return regardless whether they develop suspected Zika symptoms, and male travelers, if they do not develop suspected Zika symptoms, are urged to avoid sex or use condoms correctly for 2 months after their return from an affected-area, and if they develop suspected Zika symptoms, they are urged to avoid sex or use condoms correctly for 6 months after their return.

The man had not traveled to any region where Zika is active, had not had mosquito bites, and had not had any other sex partner besides the female patient. Additionally, a July 11 letter published in The Lancet described the first time Zika virus was detected in the female genital tract. 3 days after the onset of symptoms, the patient’s genital swab, endocervical swab, and cervical mucus sample were all positive for Zika virus. 11 days after the onset of symptoms, the patient’s blood and urinary samples tested negative, whereas her cervical mucus still tested positive for Zika virus. The presence of the virus in the female genital tract implies that sexual transmission of Zika virus is not only possible from men to women and from men to men, but also from women to men. It also means that vertical transmission from mother to fetus might be possibleAs a result, Taiwan CDC will continue to evaluate all available evidence and to update recommendations as new information becomes available.

Current scientific evidence has proved that Zika virus infection is usually mild in adults and suggested the occurrence of congenital microcephaly and even deaths in babies of mothers who were infected with Zika virus while pregnant. In addition, pregnant women during their first trimester are at higher risk of contracting the virus. Therefore, pregnant women and women planning pregnancy are advised to postpone all unnecessary travels to Zika-affected areas and follow the “2226 Principle” after leaving the Zika-affected area. If symptoms develop within two weeks of their return, please seek immediate medical attention and inform the physician of their travel history. For more information, please visit the Taiwan CDC website at http://www.cdc.gov.tw or call the toll-free Communicable Disease Reporting and Consultation Hotline, 1922 (or 0800-001922).

Thus far, at least 62 countries, areas and/or territories worldwide, primarily in Latin America and the Caribbean region, have reported local outbreaks of Zika virus infection. Taiwan CDC has issued a travel notice of Level 2: Alert for Zika virus for 52 countries and territories, including 4 countries in Asia: Thailand, the Philippines, Vietnam, and Indonesia. On the other hand, as no Zika cases have been reported in Maldives, Papua New Guinea, New Caledonia, and Vanuatu within the past 3 to 12 months, Taiwan CDC has lowered the travel notice for these countries to Level 1: Watch for Zika virus along with 5 other countries that have been issued the same level of travel notice, including Cambodia, Malaysia, Laos, Bangladesh, and Gabon in Africa.