Two deer fawns

Disease Outbreak Strikes California Deer Herds

The California Department of Fish and Wildlife (CDFW) has confirmed outbreaks of adenovirus hemorrhagic disease in deer in several northern California counties, and is asking California residents to help curb the spread by not feeding wild animals, and reporting potential cases to the department.

“Providing attractants for deer – food, salt licks or even water – is against the law for good reason,” said Dr. Brandon Munk, senior wildlife veterinarian with CDFW’s Wildlife Investigations Laboratory. “Because these artificial attractants can congregate animals and promote the spread of disease, it’s particularly imperative to leave wildlife alone during an outbreak. There is no cure or vaccine for this disease, so our best management strategies right now are to track it carefully, and to take preventative measures to limit the spread.”

Beginning in May, CDFW began receiving increased reports of mortality in deer, both free-ranging and at fawn rehabilitation facilities. With the assistance of wildlife rehabilitation facilities and the California Animal Health and Food Safety Laboratory, CDFW confirmed cervid adenovirus 1 (CdAdV-1) as the cause of hemorrhagic disease outbreaks in Napa, Santa Clara, Sonoma, Tehama and Yolo counties.

The disease is typically fatal to deer and can be spread by animals in close contact with each other. The virus is not known to affect people, pets or domestic livestock.

CdAdV-1 was the cause of a 1993-1994 outbreak of hemorrhagic disease in black tailed deer and mule deer that spanned at least 18 California counties. Since then, CdAdV-1 has been identified as the cause of sporadic, often widespread, outbreaks of hemorrhagic disease in California and other western states. Deer fawns are at greatest risk, with high rates of mortality following infection. Yearlings and adult deer are more resistant but mortalities in these age groups occur as well. Outbreaks can be widespread and have significant impact on affected deer populations.

Affected deer are often found dead without any obvious symptoms. They may be found near water. Sick animals may have excessive salivation (drooling or foaming at the mouth), diarrhea, regurgitation or seizures.

In addition to removing food and other attractants, Californians can help wildlife veterinarians track and study the disease by reporting sightings of sick or dead deer. Anyone who observes a deer exhibiting symptoms, or encountering a deer that has died from unknown causes, can submit the information to CDFW through the department’s online mortality reporting system.

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Media Contacts:
Dr. Brandon Munk, CDFW Wildlife Investigations Laboratory, (916) 261-2124

Kirsten Macintyre, CDFW Communications, (916) 804-1714

Bacterial Outbreak Forces Euthanization of Fish at Three Southern California Hatcheries

Three California Department of Fish and Wildlife (CDFW) fish hatchery facilities in the eastern Sierra and Southern California have been battling a bacterial outbreak that has affected 3.2 million fish. This week, after consultation with fish pathology experts and exhausting all avenues of treatment, CDFW announced that the fish, which are all trout, at the affected facilities must be euthanized in order to stop the spread of the outbreak.

The affected facilities – Mojave River Hatchery, Black Rock Hatchery and Fish Springs Hatchery – usually provide fish for stocking waterways in CDFW’s South Coast Region and Inland Deserts Region. The euthanization of all the fish at these facilities will have a profound effect on CDFW’s ability to stock fish for anglers in those regions in the near future.

“Euthanizing our hatchery stocks was not a decision we came to lightly, but it had to be done,” said Jay Rowan environmental program manager for CDFW hatcheries. “This bacterium is resistant to all the treatment options we have available for fish. The fish losses were getting worse despite our treatments. The best option we have available that will get us back to planting fish from these hatcheries in the shortest timeline is to clear the raceways, thoroughly disinfect the facilities, and start over.”

CDFW has had the three facilities under quarantine for more than a month, while pathologists and hatchery staff treated the affected fish and researched potential options. The outbreak of Lactococcus garvieae, which is similar to streptococcus, has been reported in cattle and poultry farms as well as fresh and salt water fish and shellfish hatcheries around the world, but had never before been detected in fish in California. Research of treatment options employed at trout farms in Europe and other parts of the world show there is almost no chance for successfully eliminating the bacteria from a facility without depopulation and disinfection.

Fish that are infected with Lactococcus garvieae can show symptoms including bulging eyes, lethargic or erratic swimming and increased mortality, or be asymptomatic and show no signs of infection depending on a several factors including water temperature and stress. Fish-to-human transmission of this bacteria is rare and unlikely but there are several documented instances associated with immunocompromised people consuming infected raw fish and unpasteurized milk products.

Hot Creek Hatchery in the eastern Sierra has tested negative for the bacteria and is still planting eight waters in Inyo and Mono counties. CDFW is in the process of developing a modified stocking plan to reallocate fish from central and northern California hatcheries to a small number of high angler use, easily accessible waters in geographically distinct parts of the eastern Sierra and Southern California.

For real-time updates, California anglers can refer to CDFW’s Fish Planting Schedule. This schedule is updated directly by CDFW hatchery staff. Although it contains current information, all fish plants are subject to change depending on road, water, weather and operational conditions.

For additional information, please see CDFW’s frequently asked questions about the L. garvieae outbreak. Also, members of the public can email questions to hatcherybacteriainfo@wildlife.ca.gov.

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Media Contacts:
Jay Rowan, CDFW Hatchery Program, (916) 212-3164
Harry Morse, CDFW Communications, (208) 220-1169

Mojave River Hatchery raceway

Bacterial Outbreak at CDFW Hatcheries Temporarily Halts Fish Stocking in Southern California

Several California Department of Fish and Wildlife (CDFW) fish hatchery facilities in the eastern Sierra and Southern California are battling a bacterial outbreak that has the potential to cause significant losses to both hatchery and wild fish populations. The outbreak of Lactococcus garvieae, which is similar to streptococcus, has sickened fish at the Mojave River Hatchery and has been detected at both the Black Rock and Fish Springs hatcheries. A fourth CDFW hatchery, Hot Creek Hatchery, was originally quarantined out of caution but after testing that quarantine has been lifted.

The L. garvieae bacteria has never before been detected in fish in California, and CDFW must take a cautious and careful approach to ensure the protection of the state’s aquatic resources – fish, hatchery facilities and public waterways. Infected fish can show symptoms including bulging eyes, lethargic or erratic swimming and increased mortality, or be asymptomatic and show no signs of infection depending on a several factors including water temperature and stress. Fish-to-human transmission of this bacteria is rare and unlikely.

Fish stocking has temporarily been halted from the facilities under quarantine while hatchery staff treats the affected fish populations and takes measures to prevent the spread of the bacteria. Planting will resume when fish have recovered from the infections and fisheries pathologists have determined that they no longer present a threat to the environment.

“This is a challenge for our hatcheries because the bacteria is previously unknown in California, and we don’t have tried-and-true strategies on hand to combat it,” said Jay Rowan, environmental program manager for CDFW’s Hatchery Production and Fish Health Laboratory. “A successful approach will have three components: Treating the affected fish at the hatcheries, finding the origin of the outbreak, and planning ahead to contain and prevent the spread of the bacteria. Unfortunately, we may be in for a long battle here, which means there will not be a lot of fish plants in the near future in the eastern Sierra and Southern California. I wish we could give anglers a target date for when we think we can start planting again, but it’s all up to how fast and how well the fish respond to the treatments.”

Current treatment measures at the hatcheries include keeping water temperatures low, reducing stress due to crowding and other factors, introducing antibiotic medication and special diet in order to assist the fish in fighting off the infection. CDFW is currently investigating the source of the outbreak. For additional information, please see CDFW’s frequently asked questions about the L. garvieae outbreak.

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Media Contacts:
Jay Rowan, CDFW Hatchery Program, (916) 212-3164
Harry Morse, CDFW Communications, (208) 220-1169

riparian brush rabbit

Deadly Disease Detected in California Wild Rabbits for the First Time

The California Department of Fish and Wildlife (CDFW), in conjunction with the California Animal Health and Food Safety Lab, San Bernardino has diagnosed Rabbit Hemorrhagic Disease (RHD) in a black-tailed jackrabbit carcass submitted from private property near Palm Springs in early May. Samples submitted to the National Veterinary Services Laboratory in Plum Island, New York, confirmed the presence of the RHD virus type 2 (RHDV2) in California for the first time. This disease is highly contagious and often lethal to both wild and domestic rabbits. The carcass that was tested was one of about 10 dead jackrabbits observed on the Palm Springs property.

RHDV2 is not related to coronavirus; it is a calicivirus that does not affect humans or domestic animals other than rabbits. At this time, no other California rabbit populations are known to be infected, but the disease has spread quickly in other states, prompting CDFW biologists to prepare for more reports in the coming months. A “quick facts” reference guide can be found on CDFW’s website.

Since March 2020, RHDV2 has caused mortalities of both wild and domestic rabbits in New Mexico, Colorado, Arizona, Texas and Mexico. Deaths of both wild rabbits and jackrabbits have occurred. Infected rabbits and jackrabbits may exhibit no symptoms leading up to their sudden death, or may suffer from fever, swelling, internal bleeding and liver necrosis. The range of susceptible species in North America is currently unknown, but all rabbit, jackrabbit, hare and pika species are likely susceptible.

CDFW Senior Wildlife Veterinarian Deana Clifford noted the introduction of RHDV2 to California could significantly impact wild rabbit populations, particularly those already at risk, such as the endangered riparian brush rabbit (Sylvilagus bachmani riparius) and those with limited distribution in the state, such as the pygmy rabbit (Brachylagus idahoensis).

“Unfortunately, we may also see impacts to species that depend on rabbits for food, as rabbits are a common prey species for many predators,” noted Dr. Clifford.

CDFW will carefully monitor the progression of RHDV2 in California, including investigating and testing rabbits found dead, monitoring populations of endangered rabbits and working with partners, including the U.S. Fish and Wildlife Service, the California Department of Food and Agriculture (CDFA) and the U.S. Department of Agriculture.

Public reports are an extremely helpful tool as wildlife veterinarians monitor the situation. CDFW is asking anyone who lives, works or recreates in wild rabbit habitat to report any sightings of sick or dead rabbits to CDFW’s Wildlife Investigations Laboratory. To report sightings of sick or dead wild rabbits, hares or pikas contact the CDFW Wildlife Investigations Lab at (916) 358-2790 or file an online mortality report through CDFW’s website.

Outdoor recreationists should take precaution when hiking, camping or backpacking and not handle or disturb carcasses to minimize the potential spread of RHDV2. Additionally, hunters should take precautions to prevent spreading the virus, such as wearing gloves when field dressing rabbits, washing hands and burying remains onsite so that scavengers cannot spread the virus. The virus is hardy and can remain viable on meat, fur, clothing and equipment for a very long time, making it easily transmissible to other areas.

In California, hunting season for brush rabbits and cottontails opens July 1 and runs through the last Sunday in January. The season is open statewide, except for a closed area in the Central Valley near the riparian brush rabbit range. Hunting season for jackrabbits is year-round and statewide.

A vaccine for RHDV2 is not currently available in the U.S., thus domestic rabbit owners should practice good biosecurity measures to protect their animals from this disease, such as washing hands before and after working with rabbits, not sharing equipment with other owners and keeping their rabbits isolated from wild or feral rabbits.

Domestic rabbit owners who have a sick rabbit should contact their veterinarian. If domestic rabbits are found dead, please contact the local CDFA Animal Health Branch or call (916) 900-5002.

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Media Contacts:
Dr. Deana Clifford, CDFW Wildlife Investigations Laboratory, (916) 358-2378
Kirsten Macintyre, CDFW Communications, (916) 804-1714

Riparian brush rabbit photo courtesy of Moose Peterson. All rights reserved.

raccoon eating from a dog bowl

Distemper Cases Rise Among California’s Foxes, Raccoons, Skunks

Residents Reminded to Vaccinate Pets, Remove Wildlife Attractants

The California Department of Fish and Wildlife (CDFW) is reporting an unusually high number of canine distemper virus (CDV) cases in wildlife populations throughout the state. CDV can infect a wide range of domestic and wild carnivores, including some non-canids. Gray foxes, raccoons and skunks are the most commonly affected species.

Unvaccinated domestic dogs can potentially contract the disease through contact with food or water bowls that are “shared” with infected wild carnivores. Pet owners should be particularly vigilant in their efforts to keep their domestic animals from coming into contact with wildlife. CDV is not transmissible to humans.

“Keeping dogs up to date on vaccinations not only protects pets, it protects wildlife,” said CDFW Senior Wildlife Veterinarian Deana Clifford. “Wild animals can spread distemper to domestic dogs, but unvaccinated domestic dogs can also spread the disease to wild animals.”

Dr. Clifford noted that distemper is the most common disease CDFW finds as the cause of death in California’s carnivores. Large outbreaks of distemper may temporarily reduce some local carnivore populations, thus wildlife biologists and veterinarians monitor reports of sick animals and confirm disease cases when possible to track potential impacts.

Transmission of CDV typically occurs similar to the common cold, via inhalation of infected respiratory droplets or direct contact with saliva, nasal discharge and tears. Occasionally other body fluids (feces and urine) contain the virus. Environmental transmission of canine distemper is rare because the virus does not survive long in the environment. For this reason, CDV presents more of a problem for dense wild carnivore populations as close contact between animals is necessary to spread the disease. While distemper may occur at any time of year, CDV is more common in adult animals during the winter and is thought to be more common in juvenile animals in the spring and summer.

Distemper can cause respiratory, neurologic and gastrointestinal illness. Clinical signs may vary depending on the strain of the virus, the environment, the host species and the age of the infected animal. Signs include (but are not limited to) depression, fever, labored breathing, diarrhea, anorexia, incoordination, moving in small circles, yellow to clear discharge from the nose and eyes, and crusting on the nose, eyes, mouth or footpads. There is no treatment for sick animals except supportive care. Infected animals may or may not survive the illness. Animals with the virus may not show clinical signs but can still spread the virus for up to 90 days.

In addition to removing food and other attractants, CDFW urges the public to keep a safe distance from sick or injured wild animals, as animals that are ill or feel threatened may act aggressively. Please report the sick animal’s behavior and location to the closest CDFW office and/or to a local animal control agency, as soon as possible.

Any wildlife encounter that is an emergency should be reported to 9-1-1. For non-urgent questions concerning wildlife, please contact your local CDFW Regional Office or your local animal control service. Additional information about living with wildlife can be found on CDFW’s website.  If you are bitten or scratched by a wild animal, please wash the wound vigorously with soap and water and consult a physician and/or contact your County Public Health Department. Neurologic signs of CDV may not be distinguishable from rabies virus infection, which is a public health risk.

Do not handle carcasses of wild animals with bare hands. CDFW’s has protocol for safe handling and disposal of carcasses on its website.

For questions regarding distemper in wildlife or concerns about sick animals, contact CDFW’s Wildlife Investigations Laboratory at (916) 358-2790.

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Media Contact: 
Kirsten Macintyre, CDFW Communications, (916) 322-8988