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.

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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.

Restoring the historic home of the Amargosa vole

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WIL staff and partners assessing the recent habitat restoration efforts. Photo credit: Austin Roy (CDFW)

WIL and our partners at USFWS, UC Davis, CDFW-Region 6, BLM, Amargosa Conservancy, and Shoshone Village are continuing to restore historic vole habitat in Shoshone, CA.  The Amargosa vole was first discovered in Shoshone in the late 1800s, but a myriad of habitat changes resulted in its local extinction from the northern part of its range.

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A recently installed interpretive sign explains the restoration project to visitors and local community members. Photo credit: Deana Clifford (CDFW)

Over the past year non-native vegetation was cleared, soil was contoured and irrigation installed in select areas to more evenly distribute water throughout the fledgling marsh.   The team’s goal was to have a light touch on the land and let the marsh do much of the work regenerating itself.

The beginnings of a marsh capable of becoming vole habitat are appearing!

This restoration project is made possible due to the dedication of local private landowners, volunteers and a community nonprofit.  The effort is funded by a Traditional Section 6 grant and a Partners for Fish and Wildlife grant through the USFWS, funds from CDFW WIL and private matching funds.  Once the marsh is fully restored, we hope to bring voles back to Shoshone and create a new population of voles which will aid in reducing the chance of this species becoming extinct.

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An example of what the marsh looked like during (a) and after (b) initial habitat restoration efforts. Photo credit: Tanya Henderson (Amargosa Conservancy) and Austin Roy (CDFW)

UPDATE: Restoring Habitat for the Endangered Amargosa Vole – Watching the Bulrush Grow (Pt. 2)

WIL and UC Davis just completed their one-year followup to last year’s emergency efforts to restore and rescue Marsh 1, one of the largest and most important habitat patches for the endangered Amargosa vole. That effort included reflooding the marsh, clearing out debris from dead plants, and relocating resident voles into nearby marshes during the restoration.

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Senescent plant stems, called standing litter, show evidence of last season’s growth. Photo credit: Stephanie Castle (CDFW)

In addition to checking in on the voles that were relocated during the restoration work (see our “Update Pt. 1” for more details), the team assessed the progress of Marsh 1 after the restoration. We monitored  water levels in the marsh by measuring the area of the marsh that was still flooded with standing water, as well as measuring how far below the surface the water table is in areas without standing water. Our measurements showed some great news! – water levels were just as high this year as they were last year right after the restoration.  This will help to foster a healthy crop of three-square bulrush (Schoenoplectus americanus), the plant vital to survival of the Amargosa voles.

 

Three-square bulrush is a perennial plant, its leaves die back (aka “senesce”) each winter, kind of like a deciduous tree or a lily. Because it was still so early in the growing season, we expected the bulrush hadn’t started sending up new shoots just yet. When we got out into the marsh, we actually saw a bunch of little green bulrush stems just starting to peek out of the soil. In fact, we saw twice as much bulrush this year as we have seen in previous years.

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Image of Marsh 1, 1-year post restoration. It is still early in the season and has just started popping up, but standing litter from last season’s growth shows us the extent of plant restoration. Photo credit: Stephanie Castle (CDFW).

It’s hard to tell from the pictures, but underneath all of the senesced plants from last year’s growth there were lots and lots of 4-5 inch tall stems. CDFW-WIL researchers are excited to see how much bulrush we will have in the marsh this year once the plants are in full swing (July-August). We will keep you updated this summer!

The success of this program has continued to highlight how productive partnerships between agencies, universities, non-profits, and communities can positively benefit the conservation of endangered species.

The translocations and restoration were funded by the BLM (partially through NCLS funds), and Drought Response Implementation Program (DRIP) funds from CDFW.

Prepared by: Stephanie Castle (CDFW/UC Davis)

UPDATE: Restoring habitat for the endangered Amargosa vole (Pt. 1)

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Habitat where voles are trapped.   Voles almost exclusively utilize bulrush habitat in the Mojave Desert. Photo credit: Austin Roy (CDFW)

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Staff from WIL processing an Amargosa vole. Animals are handled for less than 5 min before being released where they were captured. Photo credit: Stephanie Castle (CDFW)

WIL just completed its one-year followup to last year’s emergency efforts to rescue Marsh 1, one of the largest and most important habitat patches for the endangered Amargosa vole. That effort included raising water in the marsh, clearing out debris, and translocating voles into nearby marshes during the restoration. In February 2017, researchers from CDFW-WIL and UC Davis with the help of the Amargosa Conservancy trapped the release marshes and conducted sign surveys to determine if voles were still present. They collected fecal and tissue samples from voles for genetic testing to detect if translocated voles might have reproduced in their new homes. Additionally, the team successfully trapped five new voles and one recapture in Marsh 1, indicating that voles survived the habitat restoration activities and potentially may have immigrated from nearby marshes.  As Marsh 1 habitat quality improves and the size of the marsh expands, our hope is that the vole population in the marsh will also grow.

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An Amargosa vole captured during field work. Photo credit: Stephanie Castle (CDFW)

The successful progress of this project highlights how productive partnerships between agencies, universities, and communities can positively benefit the conservation of endangered species.

The translocations and restoration were funded by the BLM (NCLS funds also), and Drought Response Implementation Program funds (DRIP) from CDFW.

WRMD-S (Wildlife Rehabilitation Medical Database-Surveillance): A novel wildlife disease surveillance tool for improving our understanding of wildlife health threats in California

 

Wildlife health is a key part of why the Wildlife Investigations Lab was formed and a vital part of the California Wildlife Action Plan. Disease and human impacts, such as land use change, invasive species and climate change, are significant drivers of wildlife health.  The impact on wildlife from these threats is rapidly increasing the need for an enhanced understanding of the major hazards to the health and survival of wild species, especially those that are difficult to monitor. In addition, given the increasing realization that wildlife diseases have a significant impact on human and domestic animal health, more efficient approaches for detection and monitoring of wildlife disease are necessary.

Developers at the Wild Neighbors Data Base, in collaboration with investigators at the Karen C. Drayer Wildlife Health Center (WHC) at the University of California Davis and the Wildlife Investigations Laboratory (WIL) at California Department of Fish and Wildlife (CDFW), designed and developed a web application that works in parallel with the free online Wildlife Rehabilitation Medical Database (WRMD) pronounced “wormed”.

The primary objective is to augment the on-line medical database (WRMD), with mechanisms to integrate and aggregate data from wildlife rehabilitation centers and detect and signal investigators to potential wildlife health events, and facilitate information sharing among wildlife rehabilitation centers and between centers and the CDFW and the WHC.

This project is the first of its kind and uses the valuable information collected by wildlife rehabilitation centers to enhance wildlife disease surveillance for many different species of birds, mammals, reptiles and amphibians across the state. In California, every year, between 65,000- 80,000 wild animals are found sick, injured or orphaned by the public and are taken to wildlife rehabilitation centers. Because of this, the wildlife rehabilitation centers in California are on the front line against wildlife disease and mortality events.

The project incorporates both disease specific and non-disease specific data in order to detect events that may warrant further investigation and diagnosis by WIL. The data is aggregated by species and then sorted against programmed thresholds, generated from four years of wildlife rehabilitation center admission data obtained from CDFW wildlife rehabilitation annual reports.  Species with numbers of admissions exceeding the thresholds, signifying a potential wildlife health event, are displayed as alerts.

The detailed view for each species exceeding the threshold includes a chart showing one or more years of data allowing for visualizations of trends over time (Fig.1).  By using Google Maps API the application includes a feature in which the location found for each case is displayed on the map (Fig.2).

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Figure 1. Chart displaying number of individuals admitted weekly over one year (top) and over 15 year period (bottom). This feature can be used to visualize long-term trends of admissions of each species.

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Figure 2. Map displaying the spatial distribution of cases in an alert and underlying data for a selected case.

Alerts are assessed each week and also evaluated for clusters of syndromes and specific diseases. Depending on the circumstances of the alerts, investigators at CDFW and the Wildlife Health Center conduct health investigations in collaboration with rehabilitation centers.  Data is collected on the outcome of the investigations, including any post-mortem examination findings and results of the diagnostic tests.  Data is also collected on the numbers of admissions for threatened and endangered species and animals on the species of special concerns list for California. Since launching the program in July, the numbers of alerts per week ranged from 11-58 (median = 48).  Alerts included clusters of specific diseases (lead poisoning, trichomonas) and/or syndromes (neurologic disease, hemorrhagic disease) as well as animals affected by oil and suspect poisoning cases. On average, four alerts were followed up on by investigators each week to request samples and/or in collaboration with the rehabilitation centers.

Recently, the application has alerted investigators to an adverse health event in Western and Clark’s Grebes and Double-crested cormorants. Several grebes and cormorants are presenting to centers in central and southern California with emaciation. CDFW is working with centers and field biologists to conduct post-mortem examinations and laboratory analyses to investigate the cause(s). These alerts mirror findings by scientists documenting a downward trend in these populations along the Pacific Coast, which is hypothesized to be due in part to a change in the abundance and availability of their food base.

This pilot project began on July 1, 2016 and will continue through 2018. Around 30 wildlife rehabilitation centers around the state are participating in the pilot project.

Prepared by Nicole Carion and Terra Kelly, DVM, PhD, Dipl. ACZM