[Global spread of Zika virus epidemic: current knowledges and uncertainties].

Zika virus (ZIKV) is an enveloped RNA virus that belongs to the Flaviviridae family. Although more than 60 years have passed since the discovery and first reported human cases of the virus, only a small number (< 10) of cases had been encountered in the literature until the last 10 years. Zika virus was known as a virus which caused sporadic infections and was confined to Africa and Asia along a narrow equatorial line. In 2007, however, the first major outbreak of ZIKV occurred in Yap Island (Micronesia), and so it was reported for the first time outside of Africa and Asia. Between the years of 2007 and 2014, ZIKV spreaded to island groups located in Southeast Asia and the Pacific Ocean, and in 2015-2016, it has spread to South and Central America and the Caribbean. Today, travel-related imported cases is still been reported in Europe, North America, and other countries in the Far East. According to the data from the World Health Organization and the Centers for Disease Control and Prevention, as of March 2016, ZIKV infections have already spread locally in more than 30 countries, and travel alerts have been issued for the countries where the virus is present. Zika virus infections are generally asymptomatic or may present with a moderate clinical picture (e.g. acute onset of fever, maculopapular rash, arthralgia, and nonpurulent conjunctivitis). Although no deaths were attributed to ZIKV infection over the past 60 years, as of November 2015, it has been suggested that three deaths in Brazil, including the death of a newborn with microcephaly, may be attributed to ZIKV infection. In addition, concurrent with outbreaks in 2013 in French Polynesia and in 2015 in Brazil, there have been significant rises reported in the incidence of some autoimmune and neurodevelopmental disorders, including Guillain-Barre syndrome and microcephaly; these reports have caused considerable international concern. There are many points that are still unclear about ZIKV, including: (1) intrauterine transmission risk, frequency, and effects of the infection on fetal development; (2) the probability of perinatal transmission and if so the possible risks; (3) association with autoimmune and neurological diseases, and presence of long-term sequelae risks after infection; (4) possible routes of transmission other than mosquito bites, such as sexual contact, blood transfusion, and other body fluids (saliva, semen, or urine); (5) presence of reservoir(s) and different mosquito vectors; (6) diagnostic difficulties including cross reactivity in serological tests and standardization of testing procedures; (7) severity of the infection in immunocompromised patients; and (8) the potential effectiveness of antiviral therapy or preventive vaccines. In this review, updated information and recommendations regarding ZIKV outbreaks and risks, and the epidemiology, diagnosis and characteristics of ZIKV infections, are summarized in light of the most recent literature.