Until a couple of years ago, the Zika virus was considered an obscure mosquito borne illness thought to be milder than both dengue and chikungunya, self-limiting, and of little immediate concern to Europe or the Americas. Our perceptions began to change after an outbreak in French Polynesia in 2014 (see Zika, Dengue & Unusual Rates Of Guillain Barre Syndrome In French Polynesia) began to produce some unusual neurological side effects.
Recently, a study published by researchers from Brazil and Senegal (see Zika Adaptations To Humans Helped Spark Global Spread) has suggested that the virus underwent genetic changes in recent years to make it replicate better in human hosts.
The virus made its first appearance in the Americas in 2014, but only began to spread in earnest last spring in Brazil. In the past couple of months it has turned up in at least 9 South and Central American countries. Concurrent with its appearance and spread in their Northeastern states, Brazil has reported a 25-fold increase in microcephalic birth defects.
While Brazil’s MOH has tentatively linked maternal infection with the Zika virus to these birth defects – and a smaller but noticeable rise in Guillain-Barré Syndrome – the evidence for causation has yet to be established. Doing so may take several more months.
Today the ECDC has updated their Rapid Risk Assessment on the Zika virus to reflect recent events, and as always provides some of the best background information, charts, and graphs available.
Conclusions and options for mitigation
The Zika virus outbreak in the Americas and the South Pacific is evolving rapidly, and its spread is likely to continue as the vector species Aedes aegypti and Aedes albopictus are widely distributed there. While a significant increase in the number of newborns presenting with a low head circumference seems established in the north-eastern states of Brazil, the magnitude of the increase cannot be precisely estimated. Similarly, a link with Zika virus infection cannot be confirmed until the ongoing investigations are completed.
In the light of the current disease trend – and the possible association with severe complications – public health authorities in EU/EEA Member States should consider the following mitigation options:
- Enhance vigilance towards the detection of imported cases of Zika virus infection in EU Member States, EU Overseas Countries and Territories, and EU Outermost Regions, in particular where vectors or potential vectors are present, in order to reduce the risk of autochthonous transmission.
- Strengthen laboratory capacity to confirm suspected Zika virus infections in the European region in order to differentiate Zika virus infections from other arboviral infections (e.g. dengue, chikungunya).
- Blood safety authorities should consider the deferral of donors with a relevant travel history to areas with active Zika virus transmission, in line with measures defined for dengue virus.
- Increase awareness of clinicians and travel health clinics about the evolution of the Zika virus outbreak and the endemic areas so that they can include Zika virus infection in their differential diagnosis for travellers from those areas. Fever and/or macular or papular rash not attributable to dengue or chikungunya infection among travellers returning from areas currently experiencing a Zika virus outbreak should be considered indications for further investigation of Zika virus infection.
- Avise residents and travellers visiting affected areas, particularly pregnant women, to take individual protective measures to prevent mosquito bites all day round as Zika virus disease, chikungunya and dengue are transmitted by a daytime-biting mosquito. Consequently, protective measures should be taken, especially during the day.
- Ensure that Zika virus-infected patients in areas with Aedes mosquitoes avoid getting bitten during the first week of illness (mosquito net, screened doors and windows as recommended by WHO/PAHO).
- Increase awareness among health professionals who provide prenatal care of the possible association of Zika virus and microcephaly and adapt prenatal monitoring in accordance with the level of exposure to the vector.
Information for travellers to areas with circulation of Zika Virus
- Travellers visiting countries where Zika virus is circulating should be made aware of the ongoing outbreak of Zika virus infection.
- Travellers visiting these countries should use personal preventive measures based on protection against mosquito bites. As Aedes mosquitoes bite during the day, both indoors and outdoors, personal protection measures should be applied all day long, especially during the hours of highest mosquito activity (mid-morning, late afternoon to dusk).
- Personal protection measures to avoid mosquito bites should include the following:
− Using mosquito repellents in accordance with the instructions indicated on the product label. DEET*-based repellent use is not recommended in children under three months of age but can be used in concentrations up to 50% in pregnant women.
− Wearing long-sleeved shirts and long pants, especially during the hours of highest mosquito activity.
− Using insecticide-treated mosquito nets is essential if accommodations are not adequately screened or air conditioned.
- Travellers that are pregnant, have immune disorders or severe chronic illnesses, or are accompanied by young children should consult their doctor or seek advice from a travel clinic before travelling in order to receive recommendations on the use of repellents and other preventive measures.
- Travellers showing symptoms compatible with dengue, chikungunya or Zika virus disease within three weeks after returning from an affected area should contact their healthcare provider.
- Pregnant women who have travelled to areas with Zika virus transmission should mention their travel during antenatal visits in order to be assessed and monitored appropriately.