The outbreak of Zika virus disease first reported in the December 2015 edition of Epi-Insight, has continued to spread to further countries in the Americas and the Caribbean, emerging in countries previously unaffected by the virus (Volume 16 Issue 12). Autochthonous Zika cases have been reported in the Pacific region since the beginning of 2014 and in Brazil since April 2015. Since then, Zika virus infections have spread to 36 countries or territories.
Countries affected
Countries reporting local transmission of confirmed Zika virus infections in past nine months:
American Samoa, Aruba, Barbados, Bolivia, Bonaire, Brazil, Cape Verde, Colombia, Costa Rica, Curacao, Dominican Republic, Ecuador, El Salvador, Fiji, French Guiana, Guadeloupe, Guatemala, Guyana, Haiti, Honduras, Jamaica, Maldives, Marshall Islands, Martinique, Mexico, New Caledonia, Nicaragua, Panama, Paraguay, Puerto Rico, Saint Martin, Samoa, Solomon Islands, St Croix US Virgin Islands, Suriname, Thailand, Tonga, Trinidad and Tobago, Venezuela. A full list of affected countries and their territories can be found on the ECDC website.
Link to congenital malformations of the CNS
Possible links between Zika virus infection in pregnancy and microcephaly of the foetus have been under investigation since October 2015, when the Brazilian Ministry of Health reported an unusual increase in cases of microcephaly following the Zika virus outbreak in the north-eastern area of the country. This followed on from French Polynesia’s reporting of an excess of central nervous system malformations during 2014–2015 following a Zika virus outbreak on the islands between September 2013 and March 2014. On February 17, Brazil’s Ministry of Health announced a joint case control study was being undertaken with CDC, to determine the risk of microcephaly in mothers with confirmed Zika infection. In addition, a possible association between ZVD and Guillain-Barré syndrome (GBS) is also being investigated.
On February 1st 2016, the World Health Organization (WHO) declared the Zika outbreak to be a Public Health Emergency of International Concern (PHEIC), following the first meeting of the Emergency Committee convened by the Director-General under International Health Regulations (IHR).
Since 2015, three cases of imported Zika virus disease have been identified in Ireland.
ECDC’s most recent Rapid Risk Assessment (February 9th 2016) outlines the current situation, documenting the numbers of CNS malformation and GBS from the affected countries.
The Scientific Advisory Committee of the Health Protection Surveillance Centre has established a Zika Virus Disease Subcommittee with relevant, microbiological, infectious disease, obstetrics, paediatric, public health and environmental health experts to monitor the situation and oversee the development of guidance relevant to this outbreak.
Communication strategies and messages have been developed to minimise the potential for infection in Irish citizens travelling to affected countries. The key risk groups are pregnant women or women at risk of becoming pregnant.
The primary transmission pathway for Zika virus disease is through bites from, infected mosquitoes so advice on minimising the likelihood of being bitten is available on the HPSC website.
Sexual transmission
Zika virus has been shown to be transmitted sexually via semen, especially if the male partner developed symptoms of Zika virus disease. As a precaution, women are being advised to practise safe sex with a partner who has recently returned from an affected area:
A sexual partner who has not had any symptoms of Zika:
- Practise safe sex (by wearing a condom) for a period of 1 month after return from a Zika affected area.
A sexual partner who developed symptoms that could be due to Zika (fever, headache, aches, pains, rash, sore eyes):
- Practise safe sex (by wearing a condom) for 6 months following start of his symptoms.
Transmission through blood donation
ECDC has noted (1) that viraemic asymptomatic travellers returning from affected areas could potentially transmit Zika virus disease through blood donation and that EU Blood Authorities should consider a temporary deferral from blood donation of persons with a travel history to the affected areas. Under current rules of donation, the Irish Blood Transfusion Service already prohibits those who have travelled to a tropical region from donating for a period of three months. If, additionally, the area visited is a malarious area, the period of deferral is extended to 12 months. Furthermore, if any person is confirmed as having Zika virus disease, donation will be deferred for a period of six months.
