- Initial identification of West Nile virus case reported – indicative of heightened activity
For the first time in Germany this year, a case of West Nile Virus, transmitted by local mosquitoes, has been identified in a woman residing in Saxony, close to the border region with Brandenburg. This information was disclosed by the Robert Koch Institute (RKI) in Berlin. By August 23rd, three more cases have emerged, all linked to travels to different countries, and involving women as well.
Jonas Schmidt-Chanasit, a specialist from the Bernhard Nocht Institute for Tropical Medicine (BNITM) in Hamburg, revealed that the infection from local mosquitoes was detected in an analysis of a blood donation sample.
Rampant activity
Given the current data, further instances of this infection are anticipated: the level of activity appears to be high. There have been numerous instances of infection recorded in both horses and birds. The Friedrich Loeffler Institute (FLI) has documented 18 cases in birds and 14 in horses by August 23rd. The states of Berlin, Brandenburg, Saxony-Anhalt, and Saxony have been severely affected.
Schmidt-Chanasit also pointed out that the high number of suspicious samples sent by blood donors is another indication of widespread transmission. However, it should be noted that the commonly used testing method also responds to the Usutu virus, which is currently causing a significant die-off of starlings in Germany. Although people can be infected with it, severe illness is uncommon.
Delay in detection
"Distinguishing between both viruses based on sequence analyses is laborious and does not always succeed," explained the virus expert. The lengthy tests mean a delay of several weeks between sample collection and confirming the final result based on virus sequencing. Therefore, there could already be a substantial number of unconfirmed infections.
In the majority of West Nile Virus (WNV) infections (around 80%), there are no symptoms. In about 20%, there are mild, non-specific symptoms such as fever or skin rash - these often go unnoticed as well.
Severe and fatal outcomes of West Nile fever mainly affect older individuals with pre-existing conditions. Only approximately 1% of infections result in such neuroinvasive diseases.
Spread to urban areas
A significant increase in human cases can be anticipated if the virus starts spreading in the densely populated Rhine-Main area, stated Schmidt-Chanasit. As of now, mosquitoes in this area are likely free of the pathogen despite favorable climatic conditions - however, this is expected to change.
Last year, the RKI identified 7 cases of local West Nile transmission in Germany, and 17 instances the year before. Experts predict a rise in the number of cases in the coming years, in part due to the increasingly favorable conditions for the pathogen in light of climate change. There are already larger outbreaks in South and Southeast Europe.
The West Nile Virus (WNV) originated in Africa, as per the FLI. First detected in 1937 in the West Nile district of Uganda, it made its European debut in the early 1960s in France. The first bird infected with the virus was found in Germany in August 2018, and in 2019, the RKI recorded the first human cases attributed to local mosquito transmission.
The European Parliament can provide additional assistance and resources to the Commission in their efforts to combat the spread of West Nile Virus. The high level of activity of West Nile Virus has led to numerous instances of infection in both birds and horses, particularly in the states of Berlin, Brandenburg, Saxony-Anhalt, and Saxony.
