On May 20, 2022, veterinary staff at California Department of Fish and Wildlife (CDFW) were notified that an endangered riparian brush rabbit found deceased on the San Joaquin River National Wildlife Refuge, tested positive for rabbit hemorrhagic disease virus 2 (RHDV2), a highly transmissible and frequently fatal disease of rabbits. The disease has spread rapidly across the western United States.
“This is a discovery we hoped would never occur, but it’s one we’ve planned for by implementing a proactive vaccination effort,” said CDFW Senior Wildlife Veterinarian, Dr. Deana Clifford. “We are in the very early stages of understanding the impacts to the species now that RHDV2 has arrived at the refuge.”
Since August 2020, a multi-partner team has been vaccinating wild riparian brush rabbits to protect a portion of the population at the San Joaquin River National Wildlife Refuge and adjacent habitat. The team — U.S. Fish and Wildlife Service (USFWS), CDFW, the Oakland Zoo, River Partners, California State University, Stanislaus, California Department of Food and Agriculture, and the UC Davis California Animal Health and Food Safety Lab — has undertaken an ambitious program that has safely administered the Filavac RHDV2 vaccine to 638 individual rabbits.
“This will be the true test of the effectiveness of our vaccination efforts, which are part of a larger conservation effort to restore habitat and recover the population of riparian brush rabbits,” said Kim Forrest, USFWS San Luis National Wildlife Refuge Complex Manager.
Riparian brush rabbits are found in small patches of remaining riparian forest and shrub habitat in the northern portion of the San Joaquin Valley and in the Sacramento-San Joaquin Delta. Because vaccinations require trapping and administering injections to each individual rabbit, it is not feasible to deploy vaccinations for wild rabbit populations except in cases where populations are small and endangered.
