This year West Nile fever also reached Germany and aroused many fears. Because the virus responsible is insidiously transmitted to humans by mosquitoes. But how dangerous is it? And can you protect yourself from it? FITBOOK asked an expert about this.
According to the Robert Koch Institute, the West Nile Virus (WNV) was first found in birds and two horses in Germany in 2018. The Bavarian State Office for Health and Food Safety only reported in October 2018 on a veterinarian who contracted the virus and became ill. He was most likely infected during the autopsy of a bird in the Ebersberg district through contact with its bodily fluids.
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This raises the question of how high the risk is for German citizens of also being infected with the WNV. We answer these and other questions about the virus.
Where does West Nile fever come from?
In 1937, the virus was discovered in a woman in the West Nile province of the African state of Uganda who was suffering from an unexplained fever – hence the disease’s name.
The disease became known worldwide through an epidemic that was probably caused by a mosquito in the USA in 1999. This probably got to New York on a plane from Tel Aviv. By 2016, more than 46,000 people in the United States were said to have contracted the fever, with 2,000 deaths.
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It is particularly widespread in Africa, especially in Uganda and Mozambique. Other danger areas are Egypt, India, Southeast Asia and the Middle East. For several years, cases in southern Europe (Italy, Greece, France), central Europe (Czech Republic, Hungary, Serbia, Austria) and the Black Sea countries (Bulgaria, Romania, Moldova, Ukraine, southern Russia) have increased significantly.
How is the virus transmitted?
The virus is mainly transmitted by mosquitoes and has so far been detected in 43 different species. Wild birds serve as the main host. This is how the virus can get from birds to humans through mosquitoes. Mammals such as horses can also get the virus, but are not themselves a source of the virus.
Another risk of becoming infected is during organ transplants, blood transfusions, during pregnancy and when breastfeeding infants. For example, blood donors who were in a risk area are «blocked» for four weeks after their return.
How is the disease progressing?
The incubation period after infection is about two to 14 days. “Around 80 percent of those infected show no major symptoms. The remaining 20 percent develop a flu-like illness with fever, chills and body aches,» says Dr. Maximilian Gertler, specialist in internal medicine and tropical medicine from the Tropical Institute of the Berlin Charité. In addition, about half of those affected get a rash all over their body. The symptoms subside after about three to six days.
dr Maximilian Gertler, specialist in internal medicine and tropical medicine from the Tropical Institute of the Berlin CharitéPhoto: Sebastian Bolesch / Doctors Without Borders
According to the Robert Koch Institute, the disease develops severely in about every 150th infected person. «This is especially the case in older people and those with a weakened immune system,» explains Dr. Gertler. This can also be cancer and HIV patients.
In these cases, meningitis – usually benign – can occur, which heals without permanent damage. In rare cases, it leads to encephalitis, which usually leaves long-term effects or ends in death. «Unfortunately, in this case, the encephalitis is difficult to treat, only symptoms such as fever and pain can be alleviated,» says Dr. Gertler from the Tropical Institute in Berlin.
How do you diagnose West Nile Virus?
Most people are unaware of their infection and even if it is flu-like, the virus is not suspected to be behind it. «That’s exactly what’s perfidious, it’s not that easy to diagnose. Most doctors do not suspect it to be behind a flu-like illness. In addition, the diagnostic methods are not very common and an explicit blood test for the virus is expensive,» explains Dr. Gertler.
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So it may be that although there are no proven cases in Germany apart from the veterinarian from Bavaria who was infected in October, there are unreported cases of people infected with WNV.
How can I protect myself?
There is still no vaccine or medication against West Nile Virus. This means that you can generally only protect yourself against mosquito bites – which is possible with sprays, clothing and mosquito nets. This is particularly advisable in the particularly endangered regions that we have listed above.
In addition, the Bavarian State Office for Health and Food Safety recommends not to touch dead birds and to contact the veterinary office in the event of accumulations of dead birds.
Is Germany threatened with an epidemic like in the USA in 1999?
“It is not unlikely that the virus will spread more in Germany in the future. In the German winter, the risk of transmission by mosquitoes is very low, but it increases again with the warm season,” says the expert from the Tropical Institute at the Charité. It is currently not possible to say with certainty whether the frequency will also increase due to longer and warmer summers.
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So there is no all-clear for West Nile fever in Germany, but the likelihood of getting seriously ill is very low so far.
More security for blood donations demanded
In view of the spread of the West Nile virus in Germany, tropical medicine specialist Jonas Schmidt-Chanasit advocates a new discussion about the safety of blood supplies. «Blood donation services will have to deal with this more in the future,» said the expert from Hamburg’s Bernhard Nocht Institute for Tropical Medicine (BNITM). Only a few services tested the blood bags for the viruses by default. Others deferred four weeks for donors who have been in certain countries. «One should consider whether that still makes sense.»
So far, only a few services have tested banked blood for West Nile virus and the closely related Usutu virus by default, Schmidt-Chanasit said. So far, services that don’t test have had to hold back blood donors who’ve been in North America and some European countries where West Nile virus is rampant for a period of time. «One should consider whether that still makes sense.» There are therefore no regulations for the closely related Usutu virus.
The spread of West Nile fever 2018
In 2018, West Nile fever sickened or killed a particularly large number of people in Europe. According to the EU health authority ECDC, there were over 1,460 reported infections in the EU member states by the end of October.
At least 170 people died from the virus across Europe, most of them in the south of the continent. For comparison: In the entire previous year there were only a good 200 reported infections in the EU. At that time, the authority counted 25 deaths in all European countries. Even from the previous years, none stands out as much as 2018. The number of unreported cases is likely to be even higher in all years, since the virus often causes no or only mild symptoms.
There were particularly many deaths in Europe in 2018 in Italy (44), Greece (42), Romania (42) and Serbia (35). Deaths from infections are rare. Around 80 percent of those infected have no symptoms, around 20 percent get a feverish, flu-like illness. Only about every 150th person – usually older patients with previous illnesses – becomes seriously ill with high fever and meningitis. Cold weather towards the end of the year is helping to reduce the number of pathogens, which are mainly transmitted by mosquitoes.