Clinical and pathologic findings in an outbreak in rabbits of natural infection by rabbit hemorrhagic disease virus 2 in the northwestern United States

Abstract

Rabbit hemorrhagic disease virus 2 (RHDV2) causes an often-fatal disease of rabbits that has resulted in outbreaks in rabbitries in Europe, Africa, Australia, and Asia. RHD has historically been characterized as a foreign animal disease in the United States. In July 2019, RHDV2 was detected in rabbits on Orcas Island along the northwestern coast of Washington (WA) State following reports of deaths in multiple feral and domestic rabbits. We document and highlight here the unique clinical presentation and gross and histologic lesions observed in this recent WA outbreak. Affected rabbits died without premonitory signs or displayed hyporexia and/or lethargy for ≤1 d prior to death. The most consistent pathologic finding was random, multifocal hepatocellular necrosis, often with concurrent multifocal-to-diffuse splenic necrosis. The lack of significant clinical signs in conjunction with the random distribution of hepatic necrosis in the WA outbreak contrasts with previous reports of RHDV2 disease progression.

Early circulation of rabbit haemorrhagic disease virus type 2 in domestic and wild lagomorphs in southern California, USA (2020–2021)

“…Interestingly, this strain is more similar to the California strains (98.6%–98.7% nucleotide identity), than to Canada 2016 (92.7%) and New York 2020 (97.3%), which suggests that the southwestern USA outbreak may have originated from a strain that was introduced into British Columbia in 2018. In fact, between 2018 and 2019, there were RHDV2 detections in Washington State and Ohio (USDA‐APHIS, 2020; Williams et al., 2021) and, although WGS data are not available in GenBank for confirmation yet, a recent notice by the USDA stated that these sequences are highly homologous to those detected in British Columbia in 2018 (USDA‐APHIS, 2020), which would support this hypothesis. Interestingly, a strain collected in British Columbia in 2019 (Canada 2019) differed from the strains obtained the previous year in the same area and was more closely related to the New York 2020 strains.…”

“…There were further detections in Vancouver (British Columbia), Canada, in 2019, but the viral sequences differed from those obtained the previous year in the same region (Ambagala, Schwantje, et al, 2021;USDA-APHIS, 2018, 2020. At the same time, RHDV2 was detected in feral and domestic European rabbits in Washington State and Ohio, USA, in 2018 and 2019 (USDA-APHIS, 2020; Williams et al, 2021). Sequences from the Quebec 2016 episode differed from those detected in British Columbia in 2018 and 2019 (USDA-APHIS, 2020), and so far, no strain similar to the first known event in Quebec has been detected in North America.…”

A novel vaccine candidate against rabbit hemorrhagic disease virus 2 (RHDV2) confers protection in domestic rabbits

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R abbit hemorrhagic disease virus (RHDV [Lagovirus GI.1]), a calicivirus of the Lagovirus genus, is a highly pathogenic RNA virus that infects domestic (Oryctolagus cuniculus) and wild European (Oryctolagus cuniculus) rabbits. 1,2 The virus was first observed naturally in China in 1984 and was later deliberately introduced in Australia and New Zealand as a method for rabbit population control. 1 RHDV outbreaks in Europe and North America have occurred periodically for the past several decades, and in 2010 the emergence of a distinct genotype, now referred to as RHDV2 (Lagovirus G1.2), was documented in France.

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Utilizing blood filter paper and ear punch samples for the detection of rabbit hemorrhagic disease virus 2 by RT-rtPCR

“…31 In Wyoming, the list of potentially susceptible wildlife includes hares of the genus Lepus (snowshoe hare, L. americanus ; black-tailed jackrabbit, L. californicus ; white-tailed jackrabbit, L. townsendii ), North American cottontails of the genus Sylvilagus (eastern cottontail, S. floridanus ; mountain cottontail, S. nuttallii ; desert cottontail, S. audubonii ), pygmy rabbits ( Brachylagus idahoensis ), and the American pika ( Ochotona princeps ). 27 Although the current risk to these populations is not well defined, Wyoming has a strong interest in closely monitoring the outbreak given the important economic and ecologic status of these species, particularly species of concern, such as the pygmy rabbit.…”

“…31 In Wyoming, the list of potentially susceptible wildlife includes hares of the genus Lepus (snowshoe hare, L. americanus; black-tailed jackrabbit, L. californicus; white-tailed jackrabbit, L. townsendii), North American cottontails of the genus Sylvilagus (eastern cottontail, S. floridanus; mountain cottontail, S. nuttallii; desert cottontail, S. audubonii), pygmy rabbits (Brachylagus idahoensis), and the American pika (Ochotona princeps). 27 Although the current risk to these populations is not well defined, Wyoming has a strong interest in closely monitoring the outbreak given the important economic and ecologic status of these species, particularly species of concern, such as the pygmy rabbit.Wildlife disease monitoring and surveillance is essential for understanding the epizootiology of an infectious disease within wildlife populations. 20 Some of the limitations of wildlife disease monitoring and surveillance strategies are related to case acquisition, lack of properly validated diagnostic tests, and environmental characteristics within the natural 1116157V DIXXX10.…”