Rat Hepatitis E Virus in Norway Rats, Ontario, Canada, 2018-2021

Abstract

We tested liver samples from 372 Norway rats (Rattus norvegicus) from southern Ontario, Canada, during 2018-2021 to investigate presence of hepatitis E virus infection. Overall, 21 (5.6%) rats tested positive for the virus. Sequence analysis demonstrated all infections to be rat hepatitis E virus (Rocahepevirus ratti genotype C1).

Keywords: Canada; Norway rats; Rattus norvegicus; Rocahepevirus ratti; hepatitis E virus; public health; rats; zoonoses.

Figure 1

Sites of collection and HEV PCR status of rats submitted by pest control professionals in southern Ontario, Canada, during November 2018–June 2021. Geographic administrative boundaries of the cities of Windsor, Hamilton, and Toronto are displayed. Inset map indicates the location of southern Ontario within Canada. HEV, hepatitis E virus.

Figure 2

Phylogenetic tree based on the nucleotide alignment of hepatitis E virus (HEV) sequences from rats submitted by pest control professionals in southern Ontario, Canada, during November 2018–June 2021 (black dots), and select reference sequences from other studies in GenBank (accession numbers provided). Maximum-likelihood analysis of a 283-nt fragment of the RNA dependent RNA polymerase of open reading frame 1 was performed by the general time reversible plus gamma plus invariant sites substitution model as determined for the alignment by Smart Model Selection (12). Tree construction was optimized by nearest neighbor interchange and subtree pruning and regrafting with branch support computed by the approximate likelihood-ratio test based on a Shimodaira-Hasegawa-like procedure (13). Only bootstrap values >70% are shown. Scale bar indicates the number of nucleotide substitutions per site. DRC, Democratic Republic of the Congo.