Map of countries and territories with confirmed cases of Zika Virus.

Interview • Zika infections subside

‘I would travel to South America any time,’ virologist confirms

In Europe, the first baby with Zika-related microcephaly was born in July. The mother had contracted the Zika virus while travelling in America. How dangerous is the virus for Europeans, particularly since many visited Brazil for the Olympic Games in Rio?

Interview: Brigitte Dinkloh

Map of countries and territories with confirmed cases of Zika virus
Source: PAHO/WHO

European Hospital asked Professor Jonas Schmidt-Chanasit , Head of the Immunology and Virology Research Group at Hamburg’s Bernhard Nocht Institute for Tropical Medicine.

Asked, in terms of the Zika virus, whether one should be cautious about visiting South America, Prof. Schmidt-Chanasit responded with little doubt: ‘I would definitely go. The Zika virus has in no way affected the security of travellers – except pregnant women. There are many diseases that are much more problematic than Zika fever, such as dengue or malaria. The only group I would recommend abstaining from a visit to those countries are women during the first three months of pregnancy since there is a low risk of harming the foetus. This fact has caused a lot of concern and received considerable media attention. Generally speaking, however, a Zika virus infection is not a problem for non-pregnant persons. And most people do not get ill. Therefore I would travel to South America anytime.’

Might the disease be sexually transmitted?

Professor Jonas Schmidt-Chanasit , Head of the Immunology and Virology Research Group at Hamburg’s Bernhard Nocht Institute for Tropical Medicine.

‘The main transmission vector is the mosquito. Sexual transmission may happen but it is very rare – a marginal phenomenon. Of all Zika virus infections known in Germany one documented infection was transmitted sexually. If it does happen it’s always transmitted from the male to the female. There is no known case the other way around. Men who are known to carry the virus should always have safe sex with pregnant women. The virus can be detected in sperm for at least three months, maybe even a bit longer – we need further research on this issue. Thus men who were tested positive and have unsafe sex with pregnant women are the only group who pose a problem.’

Could this mean that a virus transmitted to a woman will not cause damage in any of her subsequent pregnancies?

‘There is no indication that the virus will persist in women and cause problems or malformations in later pregnancies.’

How can we protect ourselves from the mosquito?

Sprays, mosquito nets, long-sleeved shirts and air-conditioned environments offer the best protection. The spray should contain diethyltoluamide (DEET) because of its long-lasting effectiveness and because you can spray it on your clothes. Beyond these, there are anti-Zika programmes that need to be organised by public health authorities.

Are people carrying the Zika virus more at risk of developing Guillain-Barré syndrome?

‘This disease also occurs with other infections, such as Campylobacter jejuni. It does not occur more frequently after a Zika virus infection than after any other infection – as was recently shown with regard to the outbreak in French Polynesia. This auto-immune disease is not new to us.’

What about European Zika infections?

‘Since May 1 the infection has to be reported under the German Infection Protection Act, for example. In this country about 100 Zika infections were reported.’

Is there a risk of a pandemic?

The hysteria fired by the media is incomprehensible

Jonas Schmidt-Chanasit

‘No. Today the virus has spread basically all over the world. In many countries it has been endemic for a number of years; in South East Asia it has been known in Thailand for decades. The hysteria fired by the media is incomprehensible. Currently, Europe and Australia are the only non-affected continents, but we do expect imported and locally acquired infections during the summer. But there will not be an outbreak comparable to the one we’ve seen in Brazil. Therefore, there is no reason to worry in Europe.’

Then why was an international health emergency declared?

In February it was still not clear whether there was a connection between microcephaly and the Zika virus. Therefore it was correct to declare the emergency. It triggered an intensification of research efforts and the connection was soon established. Declaring the emergency was the right step. But obviously it is very different from Ebola, which killed 70 percent of the infected persons.’

When will there be a safe vaccine?

‘Unlike with Ebola there was no immediate vaccine candidate for Zika. However, now there is one that’s currently being tested on monkeys. Clinical studies, about to start shortly, will take a few years to complete. Thus any vaccine won’t help in the current situation. However, the epidemic is subsiding in Colombia and Brazil. The vaccine research is an investment in the future, if there is another outbreak in 20 or 30 years. Most people in South America are immune, the so-called herd immunity, thus there is no, or only a low, intensity virus circulation. Consequently the vaccine is not that crucial because it’s too late for the current epidemic.’

Jonas Schmidt-Chanasit MD gained his doctorate at the Charité Berlin Medical School. Still a student, he spent time as a researcher at Kasetsart University in Bangkok. In 2006/2007 he was Research Fellow at the Institute for Medical Virology in Frankfurt am Main, Germany, and then became Head of Virology Central Diagnostics at Bernhard Nocht Institute Hamburg. In 2010 qualified for university professorship in virology at Johann Wolfgang Goethe-University, in Frankfurt am Main, and was appointed professor in arbovirology* at University of Hamburg in 2015.

* Relating to any of numerous viruses that replicate in blood-feeding arthropods, such as mosquitoes and ticks


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