Zika virus disease is mainly spread by mosquitoes. For most people it is a very mild infection and isn't harmful.
However, it may be more serious for pregnant women, as there's evidence it causes birth defects – in particular, abnormally small heads (microcephaly).
Zika does not naturally occur in the UK. Zika outbreaks have been reported in the Pacific region, and the virus has now spread to South and Central America and the Caribbean.
Experts predict that Zika virus will spread to all countries in the Americas (including the Caribbean), with the exception of Chile and Canada.
People travelling to affected areas should seek travel health advice before their trip. You can use this A to Z guide to check if the country you are visiting has a high risk, medium risk or low risk for Zika virus transmission.
It is recommended that pregnant women postpone non-essential travel to areas with active Zika virus transmission. These are areas where cases of Zika virus disease have been acquired locally, through mosquito bites, and reported by health authorities within the last three months.
If you travel to an affected area, you can reduce your risk of catching the virus by using insect repellent and wearing loose clothing that covers your arms and legs.
Symptoms of Zika virus infection
Most people don't have any symptoms. If symptoms do occur, they are usually mild and last around two to seven days.
Commonly reported symptoms include:
- itching all over the body
- joint pain (with possible swelling, mainly in the smaller joints of the hands and feet)
- muscle pain
- conjunctivitis (red eyes)
- lower back pain
- pain behind the eyes
How you catch Zika virus infection
Most cases of Zika virus disease are spread by infected mosquitoes biting humans. Unlike the mosquitoes that spread malaria, affected mosquitoes (the Aedes mosquito) are most active during the day, especially during mid-morning, then late-afternoon to dusk.
There have been a small number of reports of Zika virus being passed on through sexual intercourse, although the risk is thought to be low.
Reducing your risk of Zika virus infection
Before travelling, seek travel health advice from your GP/practice nurse or a travel clinic ideally four to six weeks before you go. Detailed travel health advice for your destination is also available from the National Travel Health Network and Centre (NaTHNaC) website or the Scottish travel health service fitfortravel.
To reduce your risk of infection, you should avoid being bitten by an Aedes mosquito. The most effective bite prevention methods, which should be used during daytime and night-time hours, include:
- Using insect repellent that contains DEET (N, N-diethyl-meta-toluamide) on exposed skin, after sunscreen has been applied. DEET can be used by pregnant or breastfeeding women in concentrations up to 50%, and in infants and children older than two months. It should not be used on babies younger than two months.
- Wearing loose clothing that covers your arms and legs.
- Sleeping under a mosquito net in areas where malaria is also a risk.
Advice for pregnant women
Scientists believe that there is enough evidence to show that Zika virus infection is a cause of birth defects, including microcephaly (this means the baby will have an abnormally small head and can be associated with abnormal brain development). This is also known as congenital Zika syndrome.
It is therefore recommended that pregnant women postpone non-essential travel to areas with active Zika transmission until after pregnancy.
Discuss your travel plans with your GP, practice nurse or a travel clinic. If travel is unavoidable, then you should take extra care to avoid being bitten by mosquitoes.
Public Health England (PHE) provides regular updates about the current spread of the disease.
If you and your partner are currently in an area with active Zika virus transmission, make sure you use condoms during vaginal, anal and oral sex while travelling and for the duration of your pregnancy.
If you are pregnant and have recently returned from an area with active Zika virus transmission, see your GP or midwife and mention where you have been, even if you have not been unwell. Your midwife or hospital doctor will discuss the risk with you and can arrange an ultrasound scan of your baby to monitor growth.
If there are any issues, you will be referred to a specialist foetal medicine service for further monitoring.
Zika virus is most likely to be detected by currently available tests when symptoms are present. If you are currently experiencing Zika symptoms, contact your GP, who will decide whether investigations are necessary. Investigations might include a blood test and/or an ultrasound test if you are pregnant.
Advice for women trying to get pregnant
If you are trying to get pregnant, discuss your travel plans with your GP, practice nurse or travel clinic. You should take extra care to avoid being bitten by mosquitoes.
It is recommended that you avoid becoming pregnant while travelling to an area with active Zika virus transmission, and for eight weeks after you return home. It is also recommended that you take folic acid supplements for 28 days before trying to get pregnant.
If you have experienced Zika symptoms within two weeks of returning home, it is recommended that you wait at least eight weeks after full recovery before you try to get pregnant.
If your partner has travelled to an area with active Zika virus transmission, you should use effective contraception to prevent pregnancy and condoms during vaginal, anal and oral sex to reduce the risk of sexual transmission. These measures should be taken during travel and:
- for eight weeks after his return home, even if he has no Zika symptoms
- for six months following the start of his symptoms, if he does experience Zika symptoms or a Zika virus infection has been confirmed by a doctor
How Zika virus infection is treated
There is no specific treatment for Zika virus symptoms.
Drinking plenty of water and taking paracetamol may help relieve symptoms.
If you feel unwell after returning from a country that has malaria as well as active transmission of Zika virus, you should seek urgent (same day) advice to help rule out a malaria diagnosis.
If you remain unwell and malaria has been shown not to be the cause, seek medical advice.
What if I'm worried that my baby has been affected by Zika?
Speak to your midwife or doctor for advice. If you are still concerned after receiving assurances from your healthcare professional and feel anxious or stressed more than usual, you can ask your GP or midwife for referral to further counselling.
Zika virus and blood donation
As a precaution, the NHS Blood and Transplant service has recommended that people who have travelled to areas with active Zika virus transmission wait 28 days before donating blood.
If you want to know whether any recent foreign travel temporarily bars you from giving blood, you can call their National Contact Centre on 0300 123 23 23.
Zika virus and Guillain-Barré syndrome
Scientists now believe that Zika virus is a cause of Guillain-Barré syndrome (GBS), a serious condition of the nervous system.
The risk of developing GBS following a Zika virus infection is currently unknown, but thought to be very low.
Information about you
If you have been infected with Zika virus, your clinical team will pass information about you on to the National Congenital Anomaly and Rare Diseases Registration Service (NCARDRS).
This helps scientists look for better ways to prevent and treat this condition. You can opt out of the register at any time.
Find out more about the register.
Public Health England. Zika virus: travel advice for pregnant women.
Royal College of Obstetricians and Gynaecologists. Q&As on Zika and pregnancy.
World Health Organization. Zika virus fact sheet.
Travel Health Pro. Zika virus – update and advice for travellers including pregnant women.
European Center for Disease Prevention and Control (ECDC). Countries with active Zika virus transmission.
Best use of medicines in pregnancy. Zika virus.