Zika virus

Zika virus disease is mainly spread by mosquitoes. For most people it's a very mild infection and isn't harmful.

But it may be more serious for pregnant women, as there's evidence it causes birth defects – in particular, abnormally small heads (microcephaly).

Zika doesn't naturally occur in the UK. Zika outbreaks have been reported in the Pacific Islands, South and Central America, the Caribbean, Africa, and parts of south and southeast Asia.

If you plan to travel to an affected area, seek travel health advice before your trip. Travel advice is tailored to you and based on the level of risk (high, moderate or low) for the country you're travelling to.

It's recommended that pregnant women should:

• postpone non-essential travel to areas at high risk of Zika virus transmission
• consider postponing non-essential travel to areas at moderate risk of Zika virus transmission until after pregnancy

High-risk areas are where there are current outbreaks of Zika virus, or where there's been an increase in the number of cases acquired locally, through mosquito bites.

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're usually mild and last around 2 to 7 days.

Commonly reported symptoms include:

• a rash
• itching all over the body
• fever
• headache
• 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 4 to 6 weeks before you go.

You can use this A to Z guide to check if the country you're visiting has a high, moderate or low risk for Zika virus transmission.

Detailed travel health advice for your destination is also available from the TravelHealthPro 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 2 months. It should not be used on babies younger than 2 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 have concluded that there's enough evidence to show that Zika virus infection is a cause of birth defects, including microcephaly.

Microcephaly 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's therefore recommended that pregnant women should:

• postpone non-essential travel to areas at high risk of Zika virus transmission
• consider postponing non-essential travel to areas at moderate risk of Zika virus transmission until after pregnancy

Discuss your travel plans with your GP, practice nurse or a travel clinic. If travel is unavoidable, you should take extra care to avoid being bitten by mosquitoes.

If you and your partner are currently in an area with a high or moderate risk of 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're pregnant and have recently returned from an area with a high or moderate risk of Zika virus transmission, see your GP or midwife and mention where you have been, even if you haven't 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'll be referred to a specialist foetal medicine service for further monitoring.

Zika virus is most likely to be detected by the tests currently available when symptoms are present.

If you're currently experiencing Zika symptoms, contact your GP, who will decide whether investigations are necessary.

Investigations might include a blood test and an ultrasound test if you're pregnant.

Screening tests for Zika for those without symptoms aren't available.

Advice for women trying to get pregnant

If you're 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's recommended that you avoid becoming pregnant while travelling to an area with a high or moderate risk of Zika virus transmission, and for 8 weeks after you return home.

It's also recommended that you take folic acid supplements for 28 days before trying to get pregnant.

If you have experienced Zika symptoms within 2 weeks of returning home, it's recommended that you wait 8 weeks after full recovery before you try to get pregnant.

If your male partner has travelled to an area with a high or moderate risk of Zika virus transmission, you should use effective contraception to prevent pregnancy.

Use condoms during vaginal, anal and oral sex to reduce the risk of sexual transmission.

These measures should be taken during travel and for 6 months:

• after the start of symptoms (if he does experience Zika symptoms or a Zika virus infection has been confirmed by a doctor)
• after his return home (if he has no Zika symptoms)

Detailed advice on preventing infection by sexual transmission is available from Public Health England.

How Zika virus infection is treated

There's 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 having a high or moderate risk of Zika virus transmission, 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're 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 a high or moderate risk of 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 after a Zika virus infection is currently unknown, but thought to be very low.

Further reading

Public Health England – Zika virus: clinical and travel guidance

Royal College of Obstetricians and Gynaecologists – Q&As on Zika and pregnancy

World Health Organization – Zika virus fact sheet

TravelHealthPro – Zika virus: update and advice for travellers including pregnant women

Best use of medicines in pregnancy – Zika virus