CDFW Expanding Chronic Wasting Disease Surveillance in 2018

The Wildlife Investigations Laboratory is working with biologists and wardens throughout California to ramp up Chronic Wasting Disease (CWD) surveillance of deer. CWD is a fatal neurologic disease of deer and elk that has been detected in 25 states, 2 Canadian provinces, South Korea, Norway, and Finland. The disease has never been detected in California, but the best defense is a robust surveillance program, and an informed public. In 2017 effort was focused on collecting samples from hunter-harvested animals in the X-zones along California’s border. In total 100 animals were tested for CWD, and all came back negative. This year CDFW plans to expand surveillance throughout the state. Keep an eye on our CWD page for more information about CWD sampling locations during the 2018 hunt season. If you are planning to hunt out of state this year, be sure to follow the law, NO SKULL or BACKBONE. We also recommend to hunters who take a deer or elk in a CWD positive state to get your animal tested and processed in that state, and not to consume the meat until you have a negative test result.

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Click here to view the brochure on CWD.

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A Tale of Two Foxes

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Gray fox kits.  Photo credit:  Brian Murphy, Mt. Diablo Audubon Society

In February of 2018, a gray fox was brought to the Sonoma County Wildlife Rescue.  The fox appeared injured when it was found in a backyard in Glen Ellen. It was lying on its side, with back legs appearing immobile.  The rehab facility provided supportive care but the fox died during the night.  When the body was examined, no signs of trauma were found so the fox was sent to the Wildlife Investigations Lab to determine the cause of death.  During necropsy it was found that the fox was carrying two fetuses.  Tissues sent for analysis came back positive for bromethalin.  Bromethalin is a rodenticide sold under a variety of trade names over the counter to control rats and mice.  Labels specify that it must be placed in a bait station, but the wax blocks may be purchased separately.   Bromethalin is a neurotoxicant, which explains the lack of mobility found in the fox.

In April of 2018, another gray fox was found dead in Ben Lomand in Santa Cruz County.  When rescuers saw signs that she was lactating, they searched for her litter and were able to locate one of her kits.  This kit was brought to Wildlife Center of Silicon Valley and successfully reared with other kits.  The mother was sent to the Wildlife Investigations Lab to determine her cause of death.   This fox had died from anticoagulant rodenticide intoxication.  Four different anticoagulant rodenticides were found in her liver, three of which were second generation anticoagulants.  These materials were made restricted use in California in 2014, meaning that they can only be used by professionals for control of mice and rats in and around buildings.  They work by preventing the blood from clotting.  At necropsy, this fox had blood in her spinal cavity and chest cavity.  It is likely that she was exposed to the rodenticides when eating rodents.

Unfortunately, these cases are not rare.  They serve to remind us that we can unintentionally harm wildlife with our pest control practices.  For more information on rodent control that is safer for wildlife, please visit:

CDFW Rodenticide Page

Raptors are the Solution

 

A Busy First Year…

Andrew Di Salvo, DVM, the inaugural Free-Ranging Wildlife Health Veterinary Resident with the CDFW Wildlife Investigations Laboratory and the UC Davis Karen C. Drayer Wildlife Health Center, shares a photo from each month of his first year…

Deer viral hemorrhagic disease outbreak in San Gabriel Mountains, Los Angeles County

An outbreak of bluetongue (BTV) and epizootic hemorrhagic disease viruses (EHDV) occurred in free-ranging deer in the foothills of the San Gabriel Mountains in Los Angeles County this year. The outbreak started mid to late August and continued through October. Reports from concerned citizens in the Pasadena and Altadena areas adjacent to deer habitat, including the Jet Propulsion Laboratory grounds, suggested that multiple deer were affected (> 20), deer were often found dead near streams or other water sources, there were few or no sick deer observed, and no other species were affected. The history was consistent with an outbreak of one of a group of hemorrhagic disease viruses that can affect deer. In collaboration with CDFW South Coast Region biologists and the Pasadena Humane Society, three deer associated with this mortality event were necropsied and samples were submitted to the California Animal Food and Health Safety (CAHFS) laboratory in San Bernardino. Testing at CAHFS confirmed that EHDV was the cause of death for two of the deer tested and BTV the cause of death for the third.

The Department’s Wildlife Investigations Lab (WIL) is interested in outbreaks of viral hemorrhagic diseases in California’s free-ranging deer populations. These viruses include deer adenovirus and two closely related Orbiviruses, BTV and EHDV. None of these viruses are known to affect people. Deer adenovirus was first described following a 1993 outbreak in California involving multiple counties with mortality estimates of over a thousand deer. Since first being described in California deer, deer adenovirus has subsequently been detected in association with deer mortalities in most of the Western states and may be the most important hemorrhagic disease virus affecting California’s deer. Bluetongue virus has long been recognized as a disease of both domestic ungulates like cattle, sheep, and goats, and of free-ranging ungulates like deer. Epizootic hemorrhagic disease virus is one of the most significant infectious diseases of white-tailed deer with outbreaks occurring regularly in white-tailed deer from the Northern Great Plains down to Florida, and has been associated with disease in cattle. Historically, mule deer and black-tailed deer, the deer native to California, were considered less susceptible to the Orbiviruses than white-tailed deer; however, we do see localized outbreaks of BTV and EHDV in native deer throughout California.

The Wildlife Investigations Lab would like to thank the efforts of the local citizens that reported this outbreak and the Department staff, the Pasadena Humane Society, and the California Animal Health and Food Safety labs for their efforts in determining the causes of this outbreak.

Authored by: Dr. Brandon Munk

 

Bighorn Herds Studied for Health and Management

An understanding of the demography, distribution, behavior, and genetic diversity of animal populations enables the California Department of Fish & Wildlife to properly manage species statewide. Capturing bighorn sheep provides an opportunity to place GPS and VHF collars, as well as collect biological samples (e.g. blood, nasal swabs, hair, feces). This accumulation of data will offer insight into bighorn sheep population dynamics, genetic diversity, and overall health.

From October through November of this year, CDFW participated in helicopter captures of multiple bighorn sheep populations. After ensnaring the sheep in a net, a capture crew member would exit the helicopter, secure the sheep by placing leg hobbles and an eye cover, and then either process the sheep in the field or place it in a carry bag for long-line transport to a base camp for processing. Processing at the base camp consisted of weighing the sheep, collecting morphometrics (body measurements), blood, hair, feces, and nasal swabs (for detection of Mycoplasma ovipneumoniae, a bacteria that can cause a fatal pneumonia), administering vitamin E and selenium injections, followed by GPS and/or VHF collar placement and ear tagging. Additionally, an ultrasound examination was performed to both determine body condition score by measuring the thickness of subcutaneous fat and particular muscle bodies, as well as check if any ewes were pregnant. Following processing, sheep were either released from the base camp or returned by helicopter to the capture site for release.

Up first on the schedule were the endangered Sierra Nevada bighorn sheep. Over the course of six days in the Sierra Nevada Mountains, a total of 34 sheep were captured, including seven rams, with 33 sheep receiving at least one VHF or GPS collar (33 VHF, 31 GPS). Operations then moved to the Sespe Wilderness Area within Los Padres National Forest to capture desert bighorn sheep that had originally been translocated to the area, part of their historic range, back in the mid-1980s. This was quite the unique opportunity in that these sheep were thought to be all but gone from the range in the early 2000s and were only recently seen on the landscape. Furthermore, the population hadn’t been handled in the more than 30 years since their initial reintroduction. A total of 22 sheep were captured over three days, including 10 rams, with 19 sheep receiving at least one VHF or GPS collar (15 VHF, 13 GPS). The Sespe captures were followed by four days in Anza Borrego State Park and Palm Desert, CA for field processing of desert bighorn sheep from the Peninsular Ranges. These efforts yielded 42 total captures, all ewes, with each sheep receiving at least one VHF or GPS collar (18 VHF, 26 GPS). The capture team then moved to the Mojave Desert and Death Valley National Park for seven days of desert bighorn sheep processing, yielding 71 total captures, including 18 rams, with all but two sheep receiving both a VHF and GPS collar (69 VHF, 69 GPS). Capture operations wrapped up in the White Mountains just outside of Bishop, CA, where 33 desert bighorn sheep were captured over four days, including 12 rams, with all but two sheep receiving both a VHF and GPS collar (31 VHF, 31 GPS).

In less than one month, CDFW captured 202 bighorn sheep, placed 166 VHF and 170 GPS collars, and collected abundant biological samples that will be closely studied for the next few years. The information acquired through analysis of the biological samples, as well as the continual spatial data that the collars will generate, will provide CDFW with valuable material by which they can make educated and well-informed decisions regarding the management of the state’s bighorn sheep populations.

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Renewed Efforts in Chronic Wasting Disease (CWD) Surveillance

Chronic Wasting Disease (CWD) is a fatal neurologic disease of cervids (e.g. deer, elk, moose, reindeer). It is caused by a misfolded form of a normal protein, known as a prion. The misfolded proteins aggregate in nervous tissues causing progressive damage to the brain of infected animals. CWD belongs to a group of human and animal diseases called transmissible spongiform encephalopathies (TSE). Examples of TSEs in animals include bovine spongiform encephalopathy (BSE) in cattle, also known as “mad cow disease,” and scrapie in sheep and goats, which has been known to veterinary medicine for over 200 years. Creutzfeldt-Jakob disease (CJD), a sporadic prion disease arising in 1:1,000,000 people, and variant Creutzfeldt-Jakob disease (vCJD), which has been linked to the consumption of infected cattle during the “mad cow disease” outbreak in Great Britain and Europe in the 1990s, are examples of TSEs in humans.

Since 1999, California has tested 4500 deer and elk for CWD. To date, no CWD has been found. However, the potential for CWD to spread to California’s deer and elk populations still exists and surveillance for the disease remains important.

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In late September 2017, Dr. Brandon Munk (CDFW) provided information on CWD and necropsy training to CDFW biologists, USDA staff and CDFW natural resource volunteers in sampling the lymph nodes of deer.  These tissue samples will be submitted to a laboratory and tested for CWD.

CDFW is asking hunters in Hunt Zone X2-X7b to voluntarily participate in this sampling and disease surveillance by bringing harvested deer to one of the CWD Sampling/Hunter Check Stations. These stations will be open  during opening weekend (October 7-8, 2017).

Sampling is voluntary, easy and free. Department staff or volunteers will record the tag number and take two small lymph nodes from the neck of the deer. There will be no damage to skull or antlers, only an incision across the neck to identify and sample the lymph nodes. Hunt tags can also be validated at the same time. The entire process will only take minutes.

Necropsy Training: Studying disease in bighorn sheep

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Dr. Janet Moore (California Animal Health and Food Safety Laboratory – San Bernardino) instructs CDFW field staff in bighorn necropsy techniques.

On Thursday, September 14, 2017, the California Animal Health & Food Safety Laboratory (CAHFS) and the California Department of Fish & Wildlife (CDFW), Wildlife Investigations Laboratory (WIL) hosted a bighorn sheep necropsy course at the CAHFS Diagnostic Laboratory in San Bernardino, California. Assisting with the course were Dr. Peregrine Wolff and wildlife technician Chris Morris from the Nevada Department of Wildlife (NDOW). In attendance were CDFW regional biologists, scientific aides, and veterinarians. The course served as an opportunity for attendees to learn how to recognize, describe, and collect samples from bighorn sheep during field necropsies. It also provided a reminder of how important it is to keep domestic sheep populations separated from free-ranging bighorn populations in order to maintain healthy herds.

After introductory remarks from Dr. Ben Gonzales (CDFW WIL), Dr. Francsisco Uzal (CAHFS) led a discussion on how to describe macroscopic lesions (i.e. distribution, size, shape, demarcation, color, consistency, contour) along with a review of the pathology of a few select domestic and bighorn sheep diseases. Dr. Francisco Carvallo (CAHFS) then expanded upon the main respiratory pathogens of bighorn sheep, which includes lungworms (Protostrongillus spp.), bacteria (e.g. leukotoxin-positive Pasteurellaceae, Mycoplasma ovipneumoniae), and viruses (e.g. respiratory syncytial virus, parainfluenza-3 virus). Following an important review of appropriate PPE (personal protective equipment) to utilize during bighorn sheep necropsies led by Meridith Rhea (CAHFS), Dr. Peregrine Wolff (NDOW) led a discussion on field necropsy techniques and nasal tumors of bighorn sheep to wrap up the morning session.

The afternoon was spent observing a bighorn sheep necropsy demonstration performed by Janet Moore (CAHFS) and Akinyi Nyaoke (CAHFS). Attendees were then given the opportunity to perform their own bighorn sheep necropsies under the guidance of the aforementioned instructors, along with assistance from Karina Fresneda (CAHFS), Patricia Gaffney (CAHFS), Dr. Francsisco Uzal (CAHFS), Dr. Francisco Carvallo (CAHFS), Dr. Peregrine Wolff (NDOW), Chris Morris (NDOW), Dr. Brandon Munk (CDFW WIL), Dr. Ben Gonzales (CDFW WIL) and Dr. Andrew Di Salvo (CDFW WIL).

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Dr. Peregrine Wolff (Nevada Division of Wildlife) demonstrating locating sinus tumors in bighorn.