Zika belongs to the same family of viruses as dengue, West Nile, yellow fever and Japanese encephalitis, and also to a much larger category (the arboviruses), capable of spreading from one human (or animal host) to another via biting insects.
Since the beginning of 2015, Zika transmission has been reported in 60 countries, mostly in Latin America and the Caribbean. Brazil has seen the largest number of cases, 97% of its cases occurring in the north east of the country. The second highest number of cases has been in Colombia.
Since the Aedes mosquitoes are widely present through hot countries, the major underlying fear is that Zika will spread unchecked to other parts of the world, particularly Asia and Africa (in the same way that two other infections, dengue and chikungunya, have recently done through Latin America and the Caribbean).
After an incubation period of 3 to 14 days following exposure, the commonest Zika virus symptoms are:
Only 20% of people infected with Zika virus develop symptoms. In early stages, the Zika illness is indistinguishable from dengue and chikungunya (two other arbovirus infections that occur in exactly the same parts of the world, and that are currently more frequent than Zika).
No specific anti-viral treatment is available. Most symptoms are mild. People with symptoms of Zika should:
It may be helpful to document infection. RT-PCR blood and urine testing for Zika (and other arboviruses) is available in many of the places where Zika occurs, so seek local medical advice if you think you have been infected. Testing at the time (or shortly after) infection is more likely to yield conclusive results.
Yes, the Fleet Street Clinic can help with Zika blood or urine testing: click here for more information.
Damage to the developing nervous system of the fetus during pregnancy is the greatest concern, especially: microcephaly, calcification, structural abnormalities of grey and white matter, and enlargement of the brain’s ventricles (internal fluid-filled spaces). The risk is highest during the first trimester (three months) of pregnancy and remains present during the middle trimester, and appears to be minimal during the third.
Zika infection has also been associated with Guillain-Barré syndrome, also called GBS. This is a rare autoimmune condition that can follow a variety of viral infections, perhaps weeks later. It consists of weakness, paralysis and a spectrum of neurological complications ranging from mild and transient to life threatening. Despite the increase in cases in Zika-affected countries, GBS remains rare. In the current outbreak, no deaths from GBS been reported.
The virus is spread by bites of mosquitoes from two species: Aedes albopictus and Aedes aegypti which are most active and bite during the day.
Zika can also behave as a blood-borne virus, spread by blood and body fluids. Male-to-female as well as male-to-male sexual transmission can occur. Infectious virus has so far been detected in semen for as long as 69 days following infection.
Bite prevention is the key to personal protection: use insect repellent during daytime hours. Insect repellent containing DEET is most effective and should be used.
Insect bites cannot be avoided completely, but travellers should do everything possible to reduce the numbers of bites.
Public health authorities should take steps to control local mosquito populations and remove stagnant water and other possible breeding sites for mosquitoes.
Any traveller who develops symptoms of Zika infection should contact a GP for advice, Zika testing, and abstain from sex in the meantime.
Couples who are trying to or interested in becoming pregnant after travelling to a country with Zika virus should consider waiting to get pregnant. On returning to the UK, precautionary measures using effective contraception should be taken to reduce the risk of sexual transmission and avoid pregnancy.
The timeframes that men and women can pass Zika through sex are different because Zika virus can stay in semen longer than in other body fluids.
See below recommendations on how long to delay conception:
If both partners travelled: for 3 months after return or last possible Zika virus exposure
For male traveller only: for 3 months after return or last possible Zika virus exposure
For female traveller only: for 2 months after return or last possible Zika virus exposure
Zika virus remains present in the blood of an infected person for about 10 days. There is no evidence that the virus can cause infection in a baby conceived after the virus has been cleared from the blood. Women and their partners who are trying to or are interested in becoming pregnant need to protect themselves from Zika infection.
All travellers to regions with Zika should seek up-to-date, specialist travel health advice before they go.
Fleet Street Clinic is a leading multi-disciplinary medical clinic in London, with particular expertise in Travel Medicine. The clinic has been established for over 20 years and is led by Dr Richard Dawood, an expert in Travel Health and author of bestselling travel health guide: “Travellers’ Health: How to Stay Healthy Abroad”.
For further advice about travel health, to book vaccines or other travel-related appointments, please call us on 020 7353 5678 or email us at info@fleetstreetclinic.com. Alternatively, you can book an appointment through our online booking system here.
Public Health England
World Health Organization
Centers for Disease Control & Prevention
National Travel Health Network & Centre (NATHNAC) UK
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