A virus that kills rabbits has reached California, officials with the California Department of Fish and Wildlife announced.

Rabbit hemorrhagic disease virus 2, or RHDV2, was found in a deceased riparian brush rabbit at the San Joaquin River National Wildlife Refuge on May 20. The riparian brush rabbit is endangered and closely monitored by wildlife agencies.

“This is a discovery we hoped would never occur,” said CDFW Senior Wildlife veterinarian Dr. Deana Clifford. The vet said they had planned for the virus’ arrival with a proactive vaccination effort, but that “we are in the very early stages of understanding the impacts to the species now that RHDV2 has arrived at the refuge.”

A multi-partner team has been busily vaccinating the rabbits at the refuge and have vaxxed 638 of the little lagomorphs since August 2020, the CDFW said. They said that live rabbits have been found elsewhere in the state where the virus has been present since 2020, which has given biologists some hope that some rabbits are surviving infection. The ultimate goal is similar to that of any pandemic — rabbits reaching herd immunity. Or in this case, fluffle immunity, as a “fluffle” is what a group of wild rabbits is called.

The vaccination efforts are part of a larger conservation effort to restore habitat and recover the population of the riparian brush rabbits.

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. “Riparian” means located on the banks of a river.

RHDV2 was first observed in wild rabbits in the southwestern U.S. in March 2020, experts say. Since then it has spread rapidly to other states. In California, the virus has been found in Alameda, Kern, Los Angeles, Orange, Riverside, San Bernardino, San Benito and San Diego Counties. Cases in domestic rabbits have been found in Fresno, Sonoma, Ventura and San Luis Obispo Counties.

The public can assist by reporting any sick or dead wild rabbits to the CDFW, as veterinarians continue to monitor the situation. They can be reached at 916-358-2790. An online mortality report can also be filed at the CDFW website. The site also has a lot of information about the virus and strategies to prevent its spread.

Katy St. Clair got her start in journalism by working in the classifieds department at the East Bay Express during the height of alt weeklies, then sweet talked her way into becoming staff writer, submissions editor, and music editor. She has been a columnist in the East Bay Express, SF Weekly, and the San Francisco Examiner. Starting in 2015, she begrudgingly scaled the inverted pyramid at dailies such as the Vallejo Times-Herald, The Vacaville Reporter, and the Daily Republic. She has her own independent news site and blog that covers the delightfully dysfunctional town of Vallejo, California, where she also collaborates with the investigative team at Open Vallejo. A passionate advocate for people with developmental disabilities, she serves on both the Board of the Arc of Solano and the Arc of California. She lives in Vallejo.