02 March 2016 - PRESS RELEASE

Zika virus: which concerns are justified?

Infections with Zika viruses are usually harmless. However, in Brazil, reports about a potential link between an infection with the virus and brain malformations (microcephaly) in newborns have recently been increasing. The World Health Organisation (WHO) has declared a global public health emergency, but sees no cause for panic. The Federal Foreign Office advises pregnant women to avoid travelling to the risk regions if possible. These reports give rise to uncertainty. An expert from the German Center for Infection Research (DZIF), Prof Jonas Schmidt-Chanasit, Bernhard Nocht Institute for Tropical Medicine in Hamburg, assesses the current situation.


A first study has confirmed the presence of the virus in brain tissue of a newborn with microcephaly. Does this confirm a link between Zika infections and malformations like this in newborns?

J. Schmidt-Chanasit: This first study has been published in the renowned journal New England Journal of Medicine. It proves that Zika viruses can cause damage to foetal brains. It is assumed that the first trimester of pregnancy is particularly risky. However, it has not yet been verified whether the virus is the sole factor causing microcephaly in the affected newborns in Brazil. We also have to cautiously say: this publication does not yet prove that the increase in the number of microcephaly cases in Brazil is due to Zika viruses. We need more publications.

Can pregnant women currently travel to South America? And what advice do you give to pregnant women returning from South America?

J. Schmidt-Chanasit: There are clear recommendations for this provided by, for example, the Robert Koch Institute and the European Centre for Disease Prevention and Control. Amongst other things, they advise pregnant women to avoid Zika virus outbreak regions if possible. There are also clear recommendations for pregnant women returning from Brazil: we have developed guidelines which clarify who should get tested, as well as how and when. They also describe the type of samples needed for the investigations, for example blood or urine. You can find these guidelines on the Bernhard Nocht Institute website www.bnitm.de in the "News" section under "Communication".

Do particular precautionary measures need to be taken for the upcoming summer Olympic Games in Brazil in August?

J. Schmidt-Chanasit: It is to our advantage that it will be wintertime Brazil during the Olympic Games. This means that temperatures will, in part, only reach 12 to 15 degrees and mosquitos will not be in high season. Besides this, measures are already being implemented: mosquito breeding sites are being destroyed in order to reduce the number of insects. The athletes also need to protect themselves, for which they have clear guidelines. At the DZIF partner site Hamburg-Lübeck-Borstel, a project investigating which areas in Rio de Janeiro have the most mosquitos that transmit Zika, dengue and chikungunya viruses has been ongoing since 2013. Based on these results, control measures will be initiated early on to protect guests, athletes and locals from these infectious diseases.

How high is the likelihood of contracting a Zika infection in Germany?

J. Schmidt-Chanasit: Unlikely, but it cannot be ruled out, of course. We simply know too little about the Zika virus to be sure. We need further studies to enable us to better estimate the risks for Germany as well. And this is exactly what we are working on: for example, at the Bernhard Nocht Institute we are infecting native mosquitos with the Zika virus to then test under laboratory conditions whether they are able to transmit the virus. Besides this, Germany also has the advantage of having a real winter which the mosquitos cannot survive.

How is a Zika infection actually confirmed?

J. Schmidt-Chanasit: Two possibilities exist for diagnosing Zika infections: in the first days after infection the virus can be directly confirmed by so-called polymerase chain reaction (PCR). After this, the infection can be verified serologically through antibodies in the blood. You will also find more information on this on the BNITM website.

What research is already being conducted in Germany?

J. Schmidt-Chanasit: In 2013, the first case of imported Zika virus infection to Europe was confirmed in Hamburg. Since then, the location has become an important establishment for Zika virus research in Germany. There are a range of long-term projects in various fields: for example in diagnostics where the first commercial serological and molecular diagnostic tests have been developed in collaboration with two industrial partners. In regions where Zika infections occur more frequently, laboratories have been set up to enable further studies. These studies concentrate on both researching virus ecology and examining the course of severe Zika infections in humans more closely. Additionally, experiments with native mosquitos and mosquitos brought in from other countries are being conducted to elucidate if they transfer Zika to humans.

Will a vaccine be developed if the link to microcephaly is confirmed?

J. Schmidt-Chanasit: One this is sure, a vaccine will definitely be developed. However, we are very much further away from developing a vaccine that we were with Ebola, where we already had available a candidate vaccine during the last epidemic. However, I do expect that it will be possible to develop a vaccine against Zika viruses, because we already have some against other flaviviruses, such as ESME and yellow fever. Once we have a vaccine, immunisation will probably be conducted similarly to rubella: children will be vaccinated which will result in “herd immunity”, meaning that the pathogen can no longer cause epidemics. However, getting to such a stage will take several years.

Background information

Virus research at the DZIF

The DZIF research field “Emerging Infections” has put in place an excellent foundation to enable rapid development of diagnostic agents and vaccines in the event of novel virus outbreaks, and to prevent further spreading of outbreaks. Arboviruses, like the Zika virus and dengue virus, are being intensively researched at the Bernhard Nocht Institute for Tropical Medicine. A research team led by Christian Drosten in Bonn has already developed a standard test for the MERS pathogen which is being used globally. DZIF scientists in Marburg and Hamburg are involved in Ebola research.

The Robert Koch Institute answers further questions about the Zika virus (in German). Click here.


Prof Schmidt-Chanasit
DZIF research field “Emerging Infections”
Bernhard Nocht Institute for Tropical Medicine
T + 49 40/428 18-546

DZIF Press Office
Karola Neubert and Janna Schmidt
T + 49 531/6181-1170 and -1154

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