Just in time for the warm summer temperatures and peak mosquito season, West Nile virus has made an impressive comeback in Germany.
Since the beginning of July, the National Reference Laboratory (NRL), in cooperation with the state veterinary offices, has detected the first West Nile virus infections in wild birds and birds kept in zoos. The number of infections increased in August, with the first evidence of infected horses in addition to birds. Currently, the National Reference Laboratory for West Nile Virus Infections at the FLI has confirmed 14 cases in horses and 18 in wild and zoo birds.
The majority of infections have been detected in the German states of Berlin, Brandenburg, Saxony-Anhalt and Saxony, which have been affected in recent years. However, infections have also been detected in a wild bird in the Mannheim area (Baden-Württemberg) and in three zoo birds in northern Mecklenburg-Western Pomerania. In addition, the first cases of infection in two horses have been reported in different districts of Lower Saxony. Suspect wild birds from this federal state are currently being analysed at the NRL. There is also a suspected case in a zoo bird in North Rhine-Westphalia.
As in previous years, further cases in birds and horses and a further regional spread of the infection within Germany are expected. Therefore, a possible infection with West Nile virus should be considered as an important differential diagnosis in the case of neurological symptoms in birds and horses.
According to the recommendations of the Standing Veterinary Vaccination Commission (StIKo Vet) of the Friedrich-Loeffler-Institut (FLI), horses in affected areas and horses moved into affected areas should be vaccinated in advance.
Suspected cases of West Nile virus infection in horses and birds must be investigated. In the case of horses and birds kept in captivity, e.g. in animal parks and zoos, the official veterinarian must be informed in case of suspicion. The initial examination should generally be carried out in the veterinary laboratory of the federal state concerned and the official confirmatory examination in the national reference laboratory at the FLI. The same applies to dead wild birds, which are sent for official testing via the respective veterinary authorities. It is also possible to send dead wild birds directly to the National Reference Laboratory at the FLI for testing.
Information on the current number of human infections is provided by the Robert Koch Institute.
In addition, there is currently increased activity of the Usutu virus (closely related to West Nile virus) in some federal states. In some regions, this is leading to mass die-offs of wild birds, especially blackbirds, as was the case during the 2018 epidemic. More information on Usutu virus disease in birds and an overview of the birds that have died so far and the confirmed cases can be found on the websites of the FLI, the Bernhard Nocht Institute (BNITM) and NABU.
