First case of rabbit haemorrhagic disease in Canada: contaminated flying insect, vs. long‐term infection hypothesis

Abstract

Following the announcement of the first case of rabbit haemorrhagic disease (RHD) in a pet rabbit, housed indoors in Canada for more than 1 year, I submitted an evidence-based explanation to ProMed explaining how RHD might have caused the death of 'one' of the three pet rabbits. I suggested with supporting evidence, that it may have been persistently infected with rabbit haemorrhagic disease virus (RHDV) which may have reactivated to cause the fatal disease. However, in this issue, Peacock etal. have proposed an alternative 'hypothesis' for the appearance of RHD in the pet rabbit. They hypothesise that a non-identified insect or fomite might have become contaminated by a Chinese strain of RHDV somewhere in the US. This insect/fomite then flew or was windborne, from the US to Canada where it entered the house containing three pet rabbits and infected one of them. RHD is non-endemic and is rarely reported in the US, where it has only been observed in domestic European rabbits, held in rabbitries. My proposal was based on the details provided by ProMed, the veterinary report from Canada, where RHDV has never previously been identified and the epidemiological, ecological and evolutionary history of RHDV which includes serological and phylogenetic evidence that ancestral RHDV lineages circulated before 1984. The flying insect hypothesis of Peacock etal. is based on circumstantial evidence and, I believe, has a lower probability of being correct than my evidence-based long-term infection proposal.