No 47 - 2020

Outbreak of avian influenza in wild birds and poultry in Denmark – no apparent risk for human infections

The variant of avian influenza detected in Danish birds this autumn has never been observed to transmit to humans.

The avian influenza virus detected in various wild birds and now also in a commercial chicken holding is of type A, subtype H5N8. In addition to H5N8, a single case of H5N5 was detected in a peregrine falcon. These subtypes are avian influenza viruses exclusively, i.e. transmission of these subtypes to humans has not been observed (Avian Influenza Overview, August 2020, ECDC). It is therefore not likely that humans may become infected with the avian influenza viruses in question, cases of which have also been observed in birds in several other European countries.

Statens Serum Institut (SSI) monitors the prevalence and development of influenza virus in humans and birds very closely. The SSI influenza laboratory is the National WHO Influenza Reference Laboratory. Here, the influenza viruses that affect Danes are mapped every year. The viruses are characterised in detail to the genetic material level. If a new virus, e.g. H5N8, suddenly occurs in humans, this can be diagnosed at the SSI. The influenza laboratory is also the National Reference Laboratory for avian influenza and, as such, performs laboratory examinations of birds as part of the Danish contingency for avian influenza.

Do not touch dead birds

In the past few weeks, avian influenza has been detected in dead wild birds at several locations in Denmark. It is recommended to avoid touching dead and sick wild birds. Instead, contact the Danish Veterinary and Food Administration who will make sure that relevant birds are submitted for examination. For further information, please see the website of the Danish Veterinary and Food Administration.

Special measures for humans with close contact to sick birds

In 2006, the Danish Health Authority prepared a guideline on prophylactic measures in humans in the event of avian influenza outbreaks (in Danish language). The Danish Health Authority recommends that people with close contact to birds with avian influenza, e.g. in connection with the destruction of bird flocks, use personal protection gear and are recommended treatment with medication to prevent influenza. Furthermore, any affected persons are subsequently recommended to contact their GP with a view to sampling for influenza analysis in case influenza symptoms arise.

Suspicion of human infection with avian influenza virus is notifiable to the authorities. The examining doctor is to notify the authorities, and samples for laboratory diagnostics are sent to the SSI in accordance with the instructions in Diagnostic Handbook (In Danish language: Diagnostisk håndbog). Human cases of avian influenza are notifiable by phone to the Danish Patient Safety Authority and in writing on Form 1515 to the Danish Patient Safety Authority and the Department of Infectious Disease Epidemiology and Prevention, SSI.

(R. Trebbien, C.K. Hjulsager, Department for Virus and Microbiological Special Diagnostics, L.S. Vestergaard, Department of Infectious Disease Epidemiology and Prevention)