[This article is written by Adelaida Sarukhan and Antoni Trilla and it has been published in Spanish in El País - Planeta Futuro]
Zika virus infection has caused a major stir in the media over the past few weeks. The magnitude of the epidemic and the rise in the incidence of foetal malformations in Brazil have generated alarm even in places where the risk is very low. Objectively, is there cause for alarm?
In Europa, the likelihood of an outbreak or epidemic with a relatively large number of cases is extremely low
First of all, the situation in Latin America is different from what we are seeing in Europe today. The Zika virus has spread throughout the Americas in just over a year because it is a newcomer to the region and the entire population is susceptible because no one has been previously exposed. Furthermore, the vectors that transmit the virus -mosquitoes of the genus Aedes- are widely distributed throughout the region and also transmit other viral diseases, including dengue and chikungunya.
Europe is, for the moment, the only continent where no local transmission of the virus has been reported, although the mosquito vector Aedes albopictus (the tiger mosquito) is found along the entire Mediterranean coast. However, although occasional cases of local transmission can be expected and we may even see a few small outbreaks, the likelihood of an outbreak or epidemic with a relatively large number of cases is extremely low. Local transmission is most likely to occur between May and October because the presence of the vector falls to nearly undetectable levels in the winter. Moreover, the conditions of European domestic life (air-conditioning, windows, etc.) and health care (access to the health system, diagnostic capacity) are different from those of Latin America. Still, it makes sense to take precautions, primarily by trying to minimise the presence of the Aedes mosquito in our communities (eradication appears to be impossible). Fewer mosquitoes means a lower risk of transmission.
Now is the time to encourage pregnant women to avoid travelling to areas with active Zika virus transmission and to take measures to protect themselves from mosquito bites
The alarm raised in recent weeks about Zika is reminiscent of what happened with chikungunya several months ago. In fact, the two diseases have many points in common: both are transmitted by the same vector, both cause similar symptoms, and both have caused major epidemics in Latin America that have led to reports of imported cases in Europe. The figures for chikungunya -which has been in Europe longer- can be taken as a reference: in just over a decade, out of the millions of cases worldwide, there have only been a few cases of local transmission and three minor outbreaks in Europe (fewer than 220 cases in 10 years).
Further studies are urgently needed to confirm the link between Zika infection during pregnancy and microcephaly and to determine whether the virus is linked to another neurological condition -Guillain-Barré syndrome- which has affected a few adults. Commercial tests need to be developed to facilitate serologic diagnosis of Zika infection -a process that is currently quite complex. A safe, effective vaccine is also needed. Sadly, history seems to be repeating itself: no such vaccine currently exists, nor are there any plans to develop one in the next few years. Still, there is no reason to panic. Now is the time to step up epidemiologic monitoring and encourage pregnant women to avoid travelling to areas with active Zika virus transmission and to take measures to protect themselves from mosquito bites.
We must dedicate resources and effort to the surveillance, prevention and control of many emerging diseases
Today, in Europe we need to be alert but not alarmed. This epidemic, like so many before it, reminds us that we have a strong health care system and that, in today’s globalised world, we must dedicate resources and effort to the surveillance, prevention and control of many emerging diseases. It is essential to encourage collaboration between veterinary surveillance and vector control systems, the systems of epidemiologic monitoring in humans, and health care services (especially primary and specialised care).
We need to pay special attention to keeping both health professionals and the general public informed about the rapidly evolving situation, which is relatively new and uncertain. In the sphere of public health, we must always concentrate on communicating to others what we know, what we believe to be true, and what we can demonstrate.
Over the coming months, we will have to deal with the Zika virus, whether by following the situation in the Americas or by providing advice to international travellers. And whenever we see a patient who has a fever, we should ask the fundamental question: Where have you come from?
Zika virus: 10 key questions and answers