Written by Nicole Scholz
The rapid spread of the Zika virus, and especially its suspected link with an observed increase in congenital malformations and other neurological complications, has created worries. The response strategy globally, including in the EU, is taking shape. Where do we stand?
Zika virus disease
The Zika virus is named after the Ugandan forest (Zika forest) where it was identified among monkeys in 1947. It was detected in humans five years later. There had only been sporadic cases of people infected with the virus until the first outbreaks were reported in 2007 and 2013 in the Pacific (Yap and French Polynesia respectively), and in 2015 in the Americas (Brazil and Colombia) and Africa (Cape Verde). The ongoing current epidemic started in Brazil in May 2015 and has since spread to 40 countries or territories. Zika is mainly transmitted through the bite of an infected female mosquito of the Aedes genus, primarily Aedes aegypti, which is also a vector for dengue and yellow fever. Transmission has also been documented from mother to child during pregnancy, and through blood transfusion and laboratory exposure. In addition, there have been two confirmed sexually transmitted cases.
Symptoms and suspected link with microcephaly and Guillain-Barré syndrome
Zika virus disease can cause mild symptoms including fever, rash and conjunctivitis, while 80% of cases are asymptomatic. Although there is currently no scientific proof, evidence is mounting that Zika infection during pregnancy could lead to babies being born with microcephaly, a birth defect involving incomplete head and brain development. Since October 2015, Brazil has reported a sharp increase in the number of suspected cases of microcephaly, with 5 640 cases notified to date. As of 23 February 2016, 583 had been confirmed, while 4 107 remain under investigation. In some Latin American countries where the Zika virus is present, there has also been an observed increase in Guillain-Barré syndrome, a rare autoimmune disease of the nervous system.
Prevention and control
No specific treatment or vaccine is currently available. Prevention is based on personal protection measures to avoid mosquito bites, especially in pregnant women, and controlling the vector mosquito population through removal of breeding sites. Brazil has mobilised 220 000 soldiers, accompanied by community health agents and mosquito control teams, for a nationwide door-to-door information campaign. The World Health Organization (WHO) is currently discussing the use of three tools to help combat the spread of Zika: the mass release of male mosquitoes sterilised by low doses of radiation; a biological method that uses male mosquitoes carrying naturally occurring Wolbachia bacteria; and a technique to genetically modify Aedes aegypti. The potential use of the latter technology, in particular, which could drive the vector species to extinction, has raised concerns over unforeseen ecological consequences.
WHO guidance and global response to the Zika outbreak
On 1 February 2016, WHO Director Margaret Chan declared a Public Health Emergency of International Concern, prompted by ‘the recent cluster of microcephaly cases and other neurological disorders reported in Brazil, following a similar cluster in French Polynesia in 2014’. The WHO’s six-month Strategic Response Framework and Joint Operations Plan in response to the spread of Zika was launched on 16 February. Its implementation, which will require US$56 million in funding, includes enhanced surveillance and improved vector control; risk communication; guidance and protection measures for those affected; and fast-tracking research and development of vaccines, diagnostics and therapeutics. After a call to interested stakeholders, the WHO is currently mapping existing research and development to prioritise suitable products and approaches. It also issued guidance on blood donation, in which it recommends that donors with Zika virus infection, or presenting the symptoms associated with it, should not give blood less than 28 days after symptoms have gone.
European Union action for preparedness and risk recommendations
In accordance with Decision No 1082/2013/EU on serious cross-border threats, the EU’s Early Warning and Response System for medical emergencies has been activated, and the Health Security Committee (HSC), bringing together EU Member States and the European Commission, will meet regularly to coordinate Zika virus prevention and readiness. On 15 February, the European Medical Corps, which can mobilise staff and equipment for health emergencies inside and outside the EU, was launched. So far, it has been joined by nine Member States. Moreover, the Commission has made €10 million available for urgent research into the Zika virus and is addressing broader issue of vaccines, vector control and infectious diseases through several ongoing project calls for research under the Seventh Framework Programme and Horizon 2020 with a budget of over €50 million.
The European Medicines Agency (EMA) has set up a task force of experts specialising in vaccines and infectious diseases to provide pharmaceutical companies with scientific and regulatory advice on the development of medicines or vaccines against the virus. According to the risk assessments provided by the European Centre for Disease Prevention and Control (ECDC), no local transmissions have been recorded in Europe, while 10 Member States have notified imported cases. The ECDC judges the risk of transmission of Zika virus infection to be ‘extremely low’ in the EU currently because of the climatic conditions in the winter season. As a mitigation measure, the ECDC recommends that pregnant women (and women trying to become pregnant) that plan to travel to Zika-affected areas consider postponing their trip. Males returning from an affected area are advised to wear a condom during intercourse with a pregnant female partner, for a 28-day period after their return, if they have not had any symptoms of a Zika virus infection, or if symptoms were observed, for six months following recovery.
Further dimensions to the Zika debate
The World Bank has provided US$150 million to support countries in Latin America and the Caribbean affected by the Zika virus outbreak. Beyond the economic impact, there have been calls for a holistic approach to Zika and consideration of women’s health and reproductive rights. In this context, Pope Francis has been said to condone the use of artificial contraception by women exposed to the virus.
At EU level, the question has also been raised of whether the infection might spread to the Mediterranean region, where Aedes albopictus (the Asian tiger mosquito) has established itself, and scientists are gathering data as they prepare for a potential outbreak in southern Europe.
On 23 February, the European Parliament’s Committee on the Environment, Public Health and Food Safety (ENVI) voted to put forward an oral question to the Commission on emergency measures to prevent the Zika virus spreading in Europe, and also discussed a draft motion for a resolution. It wants to see a debate on this question scheduled for a forthcoming plenary session.
Read the full At a Glance on ‘Zika virus: Stepping up preparedness‘ in PDF.