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New study details pathology of rabbit hemorrhagic disease virus 2

Native North American rabbits and hares (lagomorphs) show similar lesions from rabbit hemorrhagic disease virus 2 (RHDV2) as those reported in European rabbits (Oryctolagus cuniculus) and other hare (Lepus) species, according to a new study published in the Journal of Wildlife Diseases.

A pathologist performs a necropsy on a rabbit
NWHC pathologist performs a necropsy on a cottontail rabbit (Sylvilagus spp.). (Credit: Stephanie Steinfeldt, USGS National Wildlife Health Center. Public domain.)

This study contributes timely information on the nature of rabbit hemorrhagic disease as the virus continues to spread in North America.

Rabbit hemorrhagic disease, a notifiable foreign animal disease in the United States, was reported for the first time in wild, native, North American rabbits and hares in April 2020 in the southwestern United States. Affected species include wild black-tailed jackrabbits (Lepus californicus), antelope jackrabbits (L. alleni), desert cottontails (Sylvilagus audubonii), mountain cottontails (S. nuttallii), Eastern cottontails (S. floridanus), and feral (released domestic) European rabbits.

Desert cottontails and black-tailed jackrabbits were necropsied at the U.S. Geological Survey National Wildlife Health Center (NWHC) in April and May 2020 and tested positive for RHDV2 by real-time PCR, with confirmatory testing completed at the U.S. Department of Agriculture’s Foreign Animal Disease Diagnostic Laboratory. Gross and microscopic lesions were similar to those reported in European lagomorphs with RHDV2 infection and included epistaxis, massive hepatocellular dissociation and necrosis/apoptosis, pulmonary congestion, edema, hemorrhage, and acute renal tubular injury. As in previous reports, massive hepatocellular dissociation and necrosis/apoptosis was the most diagnostically distinct finding in RHDV2-positive rabbits and hares.

According to David Blehert, Chief of NWHC’s Laboratory Sciences Branch, “This work provides critical and timely information to wildlife resource managers and other conservation partners on the susceptibility of North American Sylvilagus and Lepus species to fatal RHDV2 infection. Work is ongoing to better understand virus host range, pathogenicity, and potential population impacts of RHDV2 on North American species of rabbits.”

For up to date, continental-scale information on the RHDV2 event in wild and feral lagomorphs, please visit the Wildlife Health Information Sharing Partnership-event reporting system (WHISPers).


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