First detection of European bat lyssavirus type 2 (EBLV-2) in Norway

Abstract

Background: In Europe, bat rabies is primarily attributed to European bat lyssavirus type 1 (EBLV-1) and European bat lyssavirus type 2 (EBLV-2) which are both strongly host-specific. Approximately thirty cases of infection with EBLV-2 in Daubenton's bats (Myotis daubentonii) and pond bats (M. dasycneme) have been reported. Two human cases of rabies caused by EBLV-2 have also been confirmed during the last thirty years, while natural spill-over to other non-flying mammals has never been reported. Rabies has never been diagnosed in mainland Norway previously.

Case presentation: In late September 2015, a subadult male Daubenton's bat was found in a poor condition 800 m above sea level in the southern part of Norway. The bat was brought to the national Bat Care Centre where it eventually displayed signs of neurological disease and died after two days. EBLV-2 was detected in brain tissues by polymerase chain reaction (PCR) followed by sequencing of a part of the nucleoprotein gene, and lyssavirus was isolated in neuroblastoma cells.

Conclusions: The detection of EBLV-2 in a bat in Norway broadens the knowledge on the occurrence of this zoonotic agent. Since Norway is considered free of rabies, adequate information to the general public regarding the possibility of human cases of bat-associated rabies should be given. No extensive surveillance of lyssavirus infections in bats has been conducted in the country, and a passive surveillance network to assess rabies prevalence and bat epidemiology is highly desired.

Keywords: Daubenton’s bat (Myotis daubentonii); European bat lyssavirus type 2 (EBLV-2); Rabies; fluorescent antibody test (FAT); polymerase chain reaction (PCR); rabies tissue culture infection test (RTCIT).

Fig. 1

The bat was identified as a subadult male Daubenton’s bat based on external characteristics. Photographer: Jeroen van der Kooij

Fig. 2

Phylogenetic relationship between the Norwegian EBLV-2 sequence and other EBLV-2 sequences based on 391 nucleotides from the nucleoprotein gene. The tree was constructed with the Maximum Likelihood algorithm with 1000 bootstrap replicates and the Tamura-Nei substitution model. The number at each branch of the phylogenetic tree represents the likelihood in percentage that the sequences cluster together. RABV from an Arctic fox is used as outgroup . The country and year of collection, host species and GenBank accession number for sequences are given