Zika Virus Infection
Zika infection is caused by the Zika virus (ZIKV).
Infection is spread by the bites of the Aedes species of mosquitoes. These mosquitoes predominantly bite during the day, and can also transmit dengue fever, chikungunya fever and yellow fever.
Rarely ZIKV can be transmitted sexually.
Infection during pregnancy can lead to congenital zika syndrome, with severe consequences for the baby.
ZIKV was first discovered in Africa and has been occasionally noted in countries in Africa and Asia since then. The first outbreaks of ZIKV occurred in the Pacific islands. In 2015/2016 the largest known outbreak affected the whole of Central/South America, the Caribbean and some parts of North America.
Most people infected with ZIKV will have only very mild, or no symptoms. Symptoms usually start 3-14 days after the bite of an infected mosquito and last for 2-7 days. They include: rash, itch, mild fever, headache, red eyes, muscle and joint pains. Other less common symptoms include: loss of appetite, diarrhoea, constipation, abdominal pain and dizziness.
There is no specific treatment for ZIKV infection available. Most people will get better without any treatment. Symptoms like headache and fever can be treated symptomatically. Hospital care is indicated in severe illnesses or if complications arise.
There is no medicine or vaccine currently available that prevents ZIKV infection.
Travellers are advised to seek travel advice from a health care provider at least 6-8 weeks in advance of travel, but particularly important if you are pregnant or planning pregnancy.
All travellers to countries with a risk of ZIKV transmission must consider:
- Mosquito Bite Avoidance measures.
- Travel Insurance.
- Any additional travel recommendations for pregnant travellers, those planning pregnancy and for preventing onward sexual transmission.
Mosquito Bite Avoidance
Strict Bite avoidance measures are recommended for all travellers, especially pregnant women. Aedes mosquitoes are particularly persistent and aggressive biters from dawn until dusk.
- 50% DEET- based insect repellents should be applied regularly (according to manufacturers instructions).
- DEET is appropriate for use in pregnancy.
- If DEET is unsuitable then another, proven alternative should be used.(detailed on Mosquito Bite Avoidance page).
- Wearing loose, cover-up clothing is recommended.
- Clothing can be impregnated or sprayed with the insecticide permethrin.
- Insecticide-impregnated bed nets and air conditioning should be used in bedrooms.
- Reduction of mosquito breeding sites around hotel rooms/homes is advised for longer-term stays.
Travellers should be strongly advised not to travel without adequate insurance.
- Pregnant women should check with their travel insurance company that they are covered under the policy before booking their trip.
Pregnant women should be aware that the risk of ZIKV in any country may change during the time between planning the trip and travelling.
Additional Travel Recommendations
These are based on the risk of transmission of ZIKV in a country or area and full details are listed under 'Noticeboard' on specific country pages.
Countries or areas with a risk of ZIKV transmission.
Depending on the level of risk within a country or area you will be advised to:
- postpone non essential travel
- consider postponing non essential travel
Men/women planning pregnancy or where there is a risk of pregnancy should avoid the risk of ZIKV in pregnancy and sexual transmission of ZIKV by the use of contraception and condoms during travel and for:
- 2 months afterwards if female
- 3 months afterwards if male
If you are pregnant and considering travel to a country or area with a risk of ZIKV transmission you should discuss the risk of ZIKV with your healthcare provider so you can make a fully informed decision regarding your travel plans. You should:
- Remember that malaria and other travel related hazards may pose a risk during pregnancy
- Use condoms to prevent sexual transmission of ZIKV during travel and throughout the pregnancy.
- On return, seek early obstetric review, even if well.
Medical attention must be sought quickly for any feverish illness experienced whilst travelling or on return home. Remember that other travel related hazards, including malaria, may be present in ZIKV affected countries, and can be serious, particularly if you are pregnant.
Travellers returning from countries or areas with a risk of ZIKV transmission, or who have been diagnosed with ZIKV should use contraception and follow guidelines for reducing sexual transmission as detailed above.
Travellers returning from countries affected by ZIKV cannot donate blood for 4 weeks after return if they have had no symptoms, or 6 months if they have had symptoms of ZIKV infection. UK Blood Transfusion Services have a policy of 28 day deferral for donors who have visited Zika affected countries, and also for sexual partners of anyone who has been diagnosed with ZIKV infection (in the six months before sexual contact). This is a precautionary measure to protect the blood supply, particularly in relation to pregnant women.
- For answers to commonly asked questions see NHS Choices Zika Virus: Your Questions Answered.
- Mosquito Bite Avoidance leaflet for travellers
- Public Health England Leaflet - Health advice for women returning from areas with high or moderate risk of Zika virus transmission. (updated February 2019)