OAHN Wildlife Network Project: Rabbit Hemorrhagic Disease Virus PCR Method Development

Project Lead: Dr. Claire Jardine

Collaborators:  Dr. Alex Reid

Rabbit hemorrhagic disease virus 2 (RHDV2) has been detected twice in Ontario so far in 2022. Both cases so far have occurred in fairly close geographical proximity to Michigan, which has Michigan rabbit calicivirus but is not currently known to be positive for RHDV2, although there are cases in nearby New York State.  RHDV2 is a calicivirus that is extremely contagious, has a low infectious threshold, is extremely persistent in the environment and is considered less pathogenic than RHDV1, although may still cause mortality rates of over 70%. While this virus is typically devastating to European rabbits in production and noncommercial settings, there is a southwestern USA strain of RHDV2 that seems more virulent and has a wider host range, potentially infecting all North American leporids. This strain is established in a naturalized zone where disease pressure is maintained and presents a continual risk to rabbits. In Ontario, this may include the ubiquitous Eastern cottontail, which have been confirmed to be infected with clinical disease in experimental and natural infection by the United States Department of Agriculture’s Animal and Plant Health Inspection Service (USDA APHIS). Currently, the only laboratory offering diagnostic testing for this devastating disease is the National Centre for Foreign Animal Disease (NCFAD) in Winnipeg. The BC provincial lab normally offers the test but has been unable to do so since flooding in November 2021. The ability to test within Ontario not only allows for more rapid detection of clinical cases of RHDV2, but also would allow for screening of wild and feral leporids, obtain more information about the extent of RHDV2 within Ontario, greatly assist clinicians making decisions with live rabbits, wildlife rehabilitators to make decisions about releasing cottontails, and identify any potentially widely affected areas of wild leporids. The ability to test in Ontario has allowed further opportunities for companion and wild rabbit surveillance.