Initial identification of West Nile virus case reported.
This year, Germany has reported its initial case of the West Nile virus (WNV) infection, acquired locally through mosquito bites. The Robert Koch Institute (RKI) in Berlin shared this information relating to a woman in Saxony. By August 23rd, additional three cases associated with international travel have been recorded, affecting women in these instances as well.
The WNV infection in a woman from the Saxony-Brandenburg border region was detected through an analysis of a blood donation sample, as stated by Jonas Schmidt-Chanasit of the Bernhard Nocht Institute for Tropical Medicine (BNITM) in Hamburg.
Experts anticipate more cases as increased virus activity in the area indicates a potential rise in infections. There have been higher records of infections in both horses and birds compared to the previous years. The Friedrich Loeffler Institute (FLI) recorded 18 cases of the virus in birds and 14 in horses by August 23rd. Areas particularly affected include Berlin, Brandenburg, Saxony-Anhalt, and Saxony.
A high number of blood donor samples containing suspect substances have also been reported, which may suggest many infections yet to be confirmed. However, it is important to consider that the primary screening test may also react to the Usutu virus, which is causing a sudden mass starling die-off in Germany. Although humans can contract the Usutu virus, they seldom fall ill.
Misdiagnosis and Delayed Detection
Distinguishing between the two viruses based on DNA sequence analysis can be challenging and may not always be successful. The time-consuming tests may also result in a delay of several weeks between collecting samples and obtaining the final result through virus sequencing. Therefore, it is possible that there are already numerous undetected infections due to this delay.
Approximately 80% of WNV infections are asymptomatic, and 20% of individuals exhibit mild, non-specific symptoms such as fever or skin rash, these symptoms are often overlooked.
West Nile fever can lead to severe and lethal courses primarily affecting elderly individuals with pre-existing conditions, making up less than 1% of all infections.
Potential Spread in Urban Areas
A significant increase in human case numbers is expected if the virus begins to spread in the densely populated Rhine-Main region, according to experts. While currently, mosquitoes in this area are presumably virus-free despite favorable climatic conditions, it is likely that this situation will change in due time.
Last year, Germany recorded 7 cases of the WNV transmission through local mosquitoes, and 17 cases in the year prior to that. Experts predict an increase in the number of cases in the forthcoming years due to the improving conditions for the virus as a result of climate change, as well as larger outbreaks taking place in Southeast Europe.
The WNV is originally from Africa, as reported by the FLI. It was discovered in the West Nile district of Uganda in 1937 and appeared in Europe for the first time in France in the early 1960s. In Germany, the virus was identified in a bird for the first time in August 2018.
Mosquitoes and birds are capable of transmitting the virus, but neither humans nor other mammals can do so. They are known as 'dead-end hosts'. West Nile fever is one of the few mosquito-borne diseases in Europe. The RKI recorded the first human infections due to local mosquito transmission in 2019.
The potential impact of delayed detection due to distinguishing challenges between WNV and Usutu virus could lead to numerous undetected infections. Increasing the emphasis on education about the symptoms and importance of reporting potential cases could aid in early detection and management.
Moreover, the predicted rise in West Nile virus cases in urban areas, particularly the Rhine-Main region, highlights the need for comprehensive public health education on mosquito-borne diseases and protective measures to mitigate risks.
