Spread of Zika Outbreak Likely to Cross Ocean

In a new review, infectious disease experts provide recommendations and information about current risks posed by the Zika virus, and predict that the outbreak will shortly spread from the Americas into Africa and Southern Europe.

Experts at the European Society of Clinical Microbiology & Infectious Diseases (ESCMID; Basel Switzerland) and its study group on Travelers & Migrants (ESGITM) are conducting research to gather more solid data to better assess risks associated with infection. They point to the need to find evidence on how the Zika virus affects the body, why it is spreading rapidly in the Americas, how else it can be transmitted apart from mosquito bites, and whether it is linked with congenital defects in babies and nervous system diseases.

The researchers discussed the threat posed, particularly to residents of Brazil and attendees of the upcoming 2016 Rio Olympics. They are also preparing for a possible outbreak in Europe and a return of the virus to the African continent where it was first isolated – Zika Forest, Uganda, 1947.

An international team led by Prof. Eskild Petersen from Aarhus University (Denmark) and Prof. Alimuddin Zumla, University College London (UK), published the review that concludes: “Molecular analyses of the virus are most urgently needed to understand whether a change in the virus can explain the rapid spread and the association with microcephaly in babies exposed to the virus during pregnancy.” Research is underway into treatments, vaccines, and better diagnostics, which will improve surveillance and assessment of risks.

“The emergence of Zika virus soon after the Ebola outbreak is yet another reminder for the urgent need for a coordinated global effort to have sufficiently resourced rapid-response groups for proactive surveillance and conduct of priority-research in emergency situations,” said Prof. Petersen.

Prof. Hakan Leblebicioglu, ESGITM chairperson, added: "Emerging and re-emerging infections usually arise from resource-limited countries and since the infrastructure for diagnostics is not well-established, the timely diagnosis and control of outbreaks are usually late. For this reason, an international collaboration for capacity-building of the laboratories and technology-transfer is essential."

ESGITM board member Dr. Nick Beeching, from Liverpool School of Tropical Medicine, notes that Aedes mosquitoes are widespread and already responsible for epidemics due to dengue and chikungunya viruses. It is not known whether other types of mosquito that are more common in Europe can act as vectors for Zika virus and research on this is urgently needed.

Only 1 in 5 people infected with the virus show any symptoms, so that many people will be unaware that they have been infected. There is infection risk for travel to affected countries, unprotected sexual contact with someone who has recently returned from an affected area, and from transfusion of blood donated by those recently infected.

One of the main questions to be answered is why the virus was able to spread so rapidly now and why such huge outbreaks did not occur before. Also, until the Zika virus RNA sequence is analyzed (months) we will not know if it is a mutation or other factors that play a role in the apparent increased occurrence of microcephaly and Guillain-Barré syndrome in affected regions.

“Even in Brazil 25% of the cases of microcephaly showed no symptoms of Zika,” said Dr. Rogelio López-Vélez, from the Spanish national referral center of the Hospital Ramón y Cajal (Madrid), “we urgently need rapid diagnostic tests and more information on how long the risk of microcephaly exists after infection. For now however, particularly among female migrants from South America or Europeans visiting Latin America, we need to ensure they remain vigilant when travelling.”

The paper was published February 4, 2016, in the International Journal of Infectious Diseases.

Related Links:
European Society of Clinical Microbiology and Infectious Diseases (ESCMID)
ESCMID Study Group on Infections in Travellers and Migrants (ESGITM)
Published review on Zika virus