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Zika virus Infection

Key facts about Zika virus (from the World Health Organisation)

Zika virus disease is caused by a virus transmitted primarily by Aedes mosquitoes.

Zika is a flavivirus spread by mosquitoes, usually causing a mild illness. It was first isolated from a monkey in the Zika forest in Uganda in 1947 and is sustained by non-human primates worldwide.

People with Zika virus disease can have symptoms including mild fever, skin rash, conjunctivitis, muscle and joint pain, malaise or headache. These symptoms normally last for 2-7 days

There is scientific consensus that Zika virus is a cause of birth defects and Guillain-Barré syndrome. Links to other neurological complications are also being investigated.

From 1947 to 2007 it circulated in Africa and Asia, with outbreaks being rare. In 2007, the first Zika outbreak reported outside Africa and Asia occurred on Yap Island in the Federated States of Micronesia in 2007, caused by the Asian strain of the virus. There were subsequent outbreaks caused by the Asian strain in French Polynesia in 2013-14, followed by outbreaks in South and Central America in 2015 and in India, 2016-18.

Zika is now circulating across a large part of the world, with the Americas, South East Asia and some Pacific islands being particularly affected since 2013.

Transmission (how Zika spreads)

The virus is transmitted by the bite of an infected female Aedes mosquito, most commonly Aedes aegypti. Other species of Aedes mosquitoes, may have the potential to transmit this virus. The Aedes aegypti mosquito is not present in the UK and is unlikely to establish in the near future as the UK temperature is not consistently high enough for it to breed. 

Zika can also be transmitted via sexual contact (male to female or female to male), but this is much rarer than spread via mosquitoes.

Possible complications

Infection with Zika virus usually causes only mild symptoms or no noticeable disease. However, following the outbreaks in 2013-16 it was found to be associated with some more serious problems, including:

Neurodevelopmental defects (mainly microcephaly) in children born to infected mothers

Guillain-Barré syndrome (a neurological condition causing paralysis)

WHO declared the association with neurodevelopmental defects a Public Health Emergency of International Concern (PHEIC) in 2016, and has set out a longer-term response in their Zika Strategic Response Plan.

The World Health Organization (WHO) declared the association with neurodevelopmental defects a Public Health Emergency of International Concern (PHEIC) in 2016, and has set out a longer-term response in their Zika strategic Response Plan.

Risk assessment

The risk to people in Wales from Zika virus is currently very low.

  • The Aedes mosquito that transmits Zika is not currently found in the UK
  • The risk of sexual transmission is low

However, travellers to areas where Zika is circulating may become infected and become ill. The main concern is infection in pregnant women, due to the possibility of effects on the unborn child.

Advice for the public

(NB this is not comprehensive: please consult PHE links for full advice).

All travellers, especially pregnant women and couples planning pregnancy, who are travelling to an area where Zika virus cases are being reported, should ensure they seek travel health advice from their GP or a travel clinic well in advance (at least 4 to 6 weeks) of their trip; and obtain adequate health insurance, covering pregnancy if appropriate. Travellers can consult the Fit for Travel website for advice. 

Travel advice regarding Zika virus infection should be tailored to the individual and will be based on the Zika risk in the country of travel and whether they or their sexual partner is perceived as being at increased risk from complications of Zika virus infection. 

As the greatest risk from Zika is to the developing foetus, it is very important that pregnant women and couples planning pregnancy take enhanced measures to avoid exposure to Zika virus, including during sexual contact. Find out more.

A list of countries/territories with their associated risk of Zika virus can be found here.

Countries or areas with current or past Zika virus transmission are rated as either “risk” or “very low risk” based on Zika virus epidemiology and risk to UK travellers.

For travel advice specifically, use this link.

The full PHE advice is available through this link.

Further general advice:
  • Medical attention must be sought quickly for any feverish illness experienced whilst travelling or on return
  • Avoid insect bites during travel (see below)

Insect bite avoidance

As there is neither vaccine nor specific treatment for Zika, mosquito bite avoidance, through insect repellents and appropriate clothing, is the main means of prevention. Find out more.

To prevent mosquito bites, it is recommended that people in areas where there are cases of the disease, including as travellers and especially pregnant women should:  

  • Cover exposed skin with long-sleeved shirts, trousers, and hats.
  • Insecticide-impregnated bed nets and air conditioning should be used in bedrooms.
  • The mosquitoes that transmit ZIKV are particularly persistent and aggressive biters. DEET-based insect repellents are recommended. If DEET is unsuitable then another, proven alternative should be used.
  • If you need sunscreen, apply repellent after sunscreen.
  •  Reduction of mosquito breeding sites around homes is advised for longer-term stays.

Advice for Professionals

Clinicians should consider Zika virus in patients returning from affected regions (or whose partners have travelled) who present with a febrile illness. Find out more.

For testing, advice and risk assessment, clinicians should contact their local infectious diseases or microbiology consultant. Maternity services should ask women about recent travel to affected regions. The UK obstetric surveillance scheme and the British Paediatric Surveillance Unit are undertaking surveillance for the possible effects of Zika virus in pregnancy and birth. Find out more.

Public health advice on Zika virus is also available via the all Wales Health Protection service: 0300 00 300 32

Further information on Zika Virus: