# Serological Evidence of Highly Pathogenic Avian Influenza (H5N1) in Invasive Wild Pigs in Western Canada

## TL;DR

Wild pigs in Alberta, Canada, show signs of exposure to a dangerous bird flu virus, suggesting they could spread it to other animals and humans.

## Contribution

This study provides the first serological evidence of HPAI H5N1 in wild pigs in Canada, highlighting their potential role in virus transmission.

## Key findings

- Seropositive wild pigs showed exposure to HPAI H5N1 during the 2022–2024 epizootic.
- No IAV genetic material was detected, but serological evidence suggests interspecies transmission.
- Wild pigs may serve as a new host for HPAI H5N1 in Canada, raising concerns about spillover risks.

## Abstract

Influenza A virus (IAV) can infect a wide range of hosts, including wild and domestic pigs. Swine play an important role in influenza evolution and epidemiology due to their ability to get infected with both avian and human influenza viruses, potentially leading to reassorted virus variants. Interactions at the wild-domestic swine interface have been documented on multiple occasions, raising concern about pathogen transmission and the emergence of novel influenza strains. This study investigates the occurrence and subtypes of IAV infecting invasive wild pigs in Alberta, Canada. A total of 267 wild pigs were captured between 2021–2024. Exposure to IAV was initially detected by cELISA, with further confirmation of exposure to the H5Nx virus by hemagglutination inhibition (HI) and virus neutralization (VN) assays. Although no IAV genetic material was detected by qPCR, the seropositive samples by cELISA (4.17%; 5/120) coincided with the 2022–2024 highly pathogenic avian influenza virus (HPAI) H5N1 epizootic in Alberta, which involved outbreaks in wild species and domestic birds. These findings, combined with the epidemiological context, suggest interspecies transmission of HPAI H5N1 clade 2.3.4.4b to wild pigs. These results highlight the potential role of wild pigs as a new host in Canada and emphasize the need for continued surveillance of IAV in wild pig populations to assess the risk of spillover events at the wildlife, livestock, and human interfaces.