The Zika virus is a flavivirus. It is transmitted by mosquitoes of the genus Aedes or rarely via sexual intercourse. A Zika virus infection is asymptomatic in 60% to 80% of cases. In the remaining 20% to 40% of cases, moderate symptoms may occur such as slight fever, skin rash with red spots, headache, joint and muscle pain. Sometimes it leads to a non-purulent conjunctivitis and in rare cases, vomiting. Since October 2015, several countries in Central and South America, and several islands in the Caribbean, but also in the South Pacific, have reported that cases of the Zika infection have multiplied. An increase of cases of microcephaly and other deformities of the skull and brain in newborn babies has been found in some parts of Brazil, as well as in French Polynesia, where early cases of Zika virus infections occurred. Neurological (Guillain-Barré Syndrome) and immunological complications were also reported in the infected persons. Women who are pregnant or planning to become pregnant are advised not to travel to the affected countries. Women of a childbearing age are recommended to avoid pregnancy for at least 3 menstrual cycles after travelling to these countries. The Zika virus can survive in sperm and there is a risk of infection during unprotected sexual intercourse. Men who have visited a region with active Zika virus transmission should use condoms for up to 3 months (or longer) after their return, and if their partner is pregnant, until the end of the pregnancy. (Source: BAG)
Clarification: It must be considered that other infectious diseases in the affected regions lead to similar clinical syndromes and can cause serological cross-reactions. We therefore recommend testing for the dengue and chikungunya viruses when performing serological tests. See also "Zika virus clarification diagram".