FAQ – Zika virus

Last update: 6 February 2018

More information on Zika

What is the Zika virus (Zika)?

Zika is an illness caused by the Zika virus. Zika, along with dengue, belongs to the flavivirus family.

Areas with Zika?

The Zika virus was discovered for the first time in 1947 in Uganda, Africa. In 2015 the outbreak started in South America, Central America, the Caribbean and a few pacific islands. Zika also occurs in several countries in Asia and Africa. For an overview of the countries with zika outbreak, view the complete list of affected countries (we advise pregnant women to avoid the regions of category 1 & 2).

What are the symptoms of Zika?

Those who contract the virus may suffer the following symptoms 2-7 days after infection:

  • Fatigue
  • Fever
  • Joint and muscle pains
  • Skin rash
  • Conjunctivitis (red eyes)

These flu-like symptoms only last about a week. After being cured the person will probably have gained long-term immunity to the virus.

How is Zika transmitted?

Zika is transmitted primarily through the bite of an infected Aedes mosquito, the same mosquito that spreads dengue and chikungunya viruses. Pregnant women can transmit the virus to their unborn baby. Some cases of sexual transmission have also been reported. Transmission of Zika through blood transfusion is also possible.

Can Zika be sexually transmitted?

Although the Zika virus is transmitted primarily by mosquitoes, sexual transmission between man and woman or between man and man is also possible. The virus can remain present in semen longer than in blood, but it is unclear how much longer. Until now, the virus has been detected in sperm up to 6 months after infection. Sexual transmission has been confirmed 44 days after the onset of symptoms. The number of confirmed cases is very limited at the moment, so we have to remain careful with the interpretation of the data.

The use of a condom or sexual abstinence can prevent transmission of the Zika virus. If you are worried about sexual transmission, please seek advice, a risk assessment and prompt medical attention from a specialized centre. We recommend the use of a condom while awaiting the results of the medical. This applies in particular to couples where the woman is pregnant or planning to become pregnant in a near future.

Who is at risk of infection?

Anybody living in or traveling to areas where the Zika virus is endemic and who has not been infected by the virus previously, can contract the disease. Infection is also possible through sexual contact with an infected person, regardless whether this person shows symptoms or not. If you have been affected previously, you have gained long-term immunity.

What is the risk for pregnant women?

When a pregnant woman contracts Zika, she can transmit the virus to her unborn child resulting in growth retardation, visual disorders, hearing impairment, arthrogryposis (joint deformity), brain defects with psychomotor retardation or microcephaly (underdeveloped skull), and miscarriage.

What is ITM's advice to pregnant women or women of child-bearing age?

The Institute of Tropical Medicine advises pregnant women or women trying to become pregnant during or after their stay abroad, to postpone non-essential travel to areas where the Zika virus is present (on the WHO list: avoid the regions of category 1 & 2).

If the trip cannot be postponed, we advise pregnant women to protect themselves as much as possible against mosquitoes that bite during the day.

  • Cover exposed skin by wearing long sleeved shirts and pants.
  • Stay in air-conditioned rooms.
  • Avoid visiting tropical gardens during daytime.
  • Wear insect repellent at all times.
  • We advise the sexual partner of pregnant women or women wishing to become pregnant to have themselves tested and use a condom while awaiting test results.

How long do women returning from risk areas have to postpone their pregnancy?

Couples with an urgent pregnancy wish can be tested to determine whether they contracted the virus. If you are or were ill, we advise to have yourself tested as quickly as possible. If you had no symptoms, the best moment to have yourself tested is three weeks after your return. (After three weeks, it is very likely that the test establishes correctly whether you were infected or not.) Contact your general practitioner, an infectious diseases department or travel clinic for more information. If you have no urgent pregnancy wish and you were not tested, we advise men to wait a minimum of 6 months and women a minimum of 2 months before planning conception.

What are the adverse effects of a Zika infection for women who are not pregnant?

After a Zika infection, people can present neurological complications such as the Guilllain-Barré disorder which causes temporary muscle weakness and paralysis as a result of an immune dysfunction. This can be cured when treated correctly and sometimes after revalidation. These symptoms are not specific to Zika but occur in various other infectious diseases as well.

Can I be tested?

You can be tested if you have been ill, preferably as soon as possible. If you are not pregnant and have no symptoms, there is little point to having yourself tested, and we discourage it.

How can I protect myself against Zika?

Zika infection can be avoided by taking preventive measures against mosquito bites during the day, such as wearing long pants and long-sleeved clothing and regularly applying insect repellents to protect exposed skin. However, these precautions are not foolproof. Sexual transmission can be avoided by using a condom or by practicing abstinence.  

There is as yet no treatment or vaccine against Zika.

How is Zika treated?

Currently the treatment is purely symptomatic.

Zika in Europe?

Zika is transmitted by the Aedes mosquitoes. The Aedes aegypti mosquito is not present in Europe but the Aedes albopictus mosquitoe has been detected in Southern European countries in the summer. Local outbreaks of Zika virus could therefore happen in Southern Europe if a person with Zika infection returns and would consequently be bitten by the Aedes albopictus mosquito. This is similar to import cases of dengue and chikungunya.

What if symptoms occur?

Patients who develop flu-like symptoms after a trip to an area where Zika, dengue or chikungunya are endemic, are advised to consult a physician at a specialized centre. Doctors can contact the National Reference Centre for arboviruses of the ITM for advice on the diagnosis.