Zika Virus infection is caused by the Zika Virus (ZIKV) belonging to the Flaviviridae family. The virus is primarily transmitted by infected daytime biting female Aedes aegypti and Aedes albopictus mosquitoes which are typically active from dawn to dusk. There is evidence that Zika Virus is also transmitted by other mosquitoes belonging to the Aedes genus. The virus can be transmitted from a pregnant woman to her fetus.
Zika Virus is present in Mexico, Central America, South America, the Caribbean, tropical areas of Southeast Asia, Oceania, and parts of Africa. All travellers are at risk. Long-term travellers and aid or missionary workers going to areas where Zika Virus is endemic are at greater risk.
There is strong scientific consensus that Zika Virus causes neurological complications: Guillain-Barré syndrome (progressive muscle weakness that can lead to temporary paralysis) and microcephaly (decreased head size which may lead to developmental delays) in infants born to pregnant women infected with the virus.
In the majority of cases, Zika Virus infection is asymptomatic – persons do not exhibit symptoms. Those with symptoms usually get ill 3-12 days after being bitten by an infected mosquito. Symptoms include mild fever, headache, muscle and joint pain, nausea, vomiting, and general malaise. The illness is characterised by pink eye (inflammation of the conjunctiva), a skin rash with red spots on the face, neck, trunk, and upper arms which can spread to the palms or soles, and sensitivity to light. Some may also have a lack of appetite, diarrhoea, abdominal pain, constipation, and dizziness. Most people fully recover from the illness within 7 days. Treatment includes supportive care of symptoms. There is no antiviral treatment available.
The Zika Virus is related to Dengue, Yellow Fever, West Nile Virus, and Japanese Encephalitis. It may be misdiagnosed for Dengue and Chikungunya.
Travellers going to areas with Zika Virus should take meticulous measures to prevent mosquito bites during the daytime.
There is currently no preventive medication or vaccine against Zika Virus.
Use a repellent containing 20%-30% DEET or 20% Picaridin on exposed skin. Re-apply according to manufacturer’s directions.
Wear neutral-coloured (beige, light grey) clothing. If possible, wear long-sleeved, breathable garments.
If available, pre-soak or spray outer layer clothing and gear with permethrin.
Get rid of water containers around dwellings and ensure that door and window screens work properly.
Apply sunscreen first followed by the repellent (preferably 20 minutes later).
More details on insect bite prevention.
Pregnancy and Zika Virus
Travellers who are pregnant or considering pregnancy should take special precautions for themselves and their partners.
Pregnant women: If you are pregnant or considering pregnancy, you should postpone travel to areas with Zika Virus transmission.
Travellers with a pregnant partner: Practice safe sex for the duration of the pregnancy after returning from an area with Zika Virus transmission.
Travellers considering pregnancy: After visiting an area at risk of Zika Virus transmission, men should wait 6 months and women should wait 2 months before trying to conceive. If both partners travelled together, they should wait 6 months. (See WHO – Zika Virus for more information)
Practice safe sex or abstinence even if you or your partner do not have symptoms. Most Zika Virus infections are asymptomatic (show no signs or symptoms), but sexual transmission of the virus can still occur.
Women who are pregnant should have regular obstetric ultrasound scans throughout their pregnancy, even if they do not have any symptoms.
‘As a precaution, obstetricians and radiologists have been provided with national guidelines on how to assess pregnant women with possible exposure to the Zika virus. This includes taking a detailed travel history, providing regular ultrasound scans and referral to specialist fetal medicine services if required.’