Information on the Zika Virus

The geographical spread and distribution of the Zika-virus (ZIKV) can quickly and dynamically change (for detailed information see ECDC).

According to the European Center of Disease Control (ECDC) there is a high risk of ZIKV transmission in red and red-hatched areas of the ECDC map, while it is moderate in yellow, and low in gray/blue marked areas. For further Information, please click here.

The Expert Committee of Travel Medicine (ECTM) of Switzerland recommends the following

  • For all travellers: Travellers visiting countries with risk of ZIKV transmission should be informed about the ongoing outbreak, the possibility of sexual ZKV transmission and the risk of ZIKV infection of the foetus during pregnancy. Counselling on safer sex practice and on contraceptive methods is recommended. Protection against mosquito bites (indoors and outdoors) during daytime, evening and early night time hours (especially in the mid-morning and late afternoon to dusk) by using repellents (DEET), wearing long-sleeved shirts and long pants of light colours that should be impregnated or sprayed with an insecticide, sleeping under mosquito bed nets or in air conditioned rooms.
  • Pregnant women: For the risk assessment of possible neonatal malformation while infected by ZIKV during pregnancy
    • All pregnant women (regardless of pregnancy trimester) or women who cannot rule out a pregnancy should be advised not to travel to areas with ZIKV transmission. If travel cannot be avoided, special pre-travel advice is necessary including advice of strict protection against mosquito bites.
    • Safer sex practice for the whole duration of pregnancy, if the partner had a ZIKV exposure* 
  • Couples and women who are planning a pregnancy should avoid becoming pregnant while travelling in an area with high risk of ZIKV transmission. As per current knowledge, to avoid sexual transmission following timeframes** after potential ZIKV exposure* are advised before trying to conceive (safer sex practice during theses timeframes):
    • Women: at least 8 weeks after symptoms onset (if symptomatic) or after last ZIKV exposure* (if asymptomatic)
    • Men: at least 6 months after symptoms onset (if symptomatic) or after last ZIKV exposure* (if asymptomatic)
    • Discuss with their healthcare provider the period for deferring conception/pregnancy in relation to individual exposure characteristics and availability of test results.
  • Patients with underlying immune disease and/or severe chronic diseases should take maximal protection against mosquitos.

Of note

  • * Definition of a ZIKV exposure: a) History of travel/residence in an area with high risk of ZIKV transmission and/or b) unprotected sexual contact (without a condom) with a woman within 8 weeks and/or with a man within 6 months after their return from an area with high risk of ZIKV transmission. irrespectively whether she/he had ZIKV symptoms or not.
  • **as proposed by WHO it can be considered to prolong the timeframes up to 6 months for both women and men, after potential ZIKV exposure.
  • With regard to testing after ZIKV exposure, please see below section ZIKV diagnostics on Zika information file.   
  • For countries with moderate ZIKV transmission risk in Central and South America, Caribbean and Oceania the Swiss ECTM recommends to take the same prevention measures as for countries with high risk of ZIKV transmission (red marked countries). Travel to other areas with moderate or low risk reported ZIKV transmission (Asia, Africa): women who are planning to get pregnant should consider postponing travel. To the current knowledge, in countries of Asia and Africa not mentioned under “high risk ZIKV transmission areas” (see section “incidence”) or areas with sporadic ZIKV transmission, the risk of an infection or even damage to the unborn child cannot be excluded but is estimated to be very low. Pregnant women are advised not to travel to any ZIKV endemic countries.
  • How long to wait with reproduction after potential exposure? Is it possible to shorten the time from 6 months to a shorter interval after last ZIKV exposure? Some experts consider serology testing after a minimum of 4 weeks after return (potential last exposure*). In a review on 25 symptomatic patients with exact dates of exposure and symptom onset, all infected persons had a positive serology by 28 days (Lessler et al). Negative tests would then allow to proceed with having unprotected (condom) sex. However, serological data are best known for symptomatic patients, data on asymptomatic ZIKV infections are scare. In addition, data on sensitivity and specificity are only available from small series. If a traveller is demanding a serological examination for ZIKV infection, he/she should be informed on the currently limited data available and a second serological test should be offered about one month later. Until all serology results are available however, use of condoms or abstinence from sex is recommended.
  • Travellers with clinical suspicion of ZIKV infection within 3 weeks of their return from a ZIKV endemic area should seek a physician and should mention their travel destination.
  • In case of travel to/ or stay in a ZIKV endemic area during pregnancy, women (asymptomatic or symptomatic) should inform their gynaecologist for further follow up.
  • Pregnant women should discuss their sex partner’s possible history of having been in areas with active ZIKV transmission and history of illness consistent with ZIKV disease


  • Safe Travel: link
  • Centre for Disease Control CDC: link
  • WHO / Pan American Health Organization: link 
  • European Centre for Prevention and Disease Control: link