Detection and Impactof BVDV in Zoos and

Wildlife Parks

J.F. EvermannD.D. NelsonM.J. Dark*

College of Veterinary MedicineWashington State University

Pullman, WA 99164jfe@vetmed.wsu.edu

*University of Florida, Gainesville, FL1/26/09

Four Key Questions Applied to Infections of Livestock

1. Where is the virus when not causing disease (ecology)?

2. What are the contributing factors to the infection/disease process (epidemiology)?

3. What factors can we control to minimize or eliminate the infection/disease process?

4. Is the infection/disease zoonotic (public health risk)?

BVDV- Four Key Questions

1. Ecology: Transiently infected (TI) animals shed 4-12 wks, persistently infected (PI) animals shed for life (fecal, saliva, urine, semen, aerosol, etc)

2. Epidemiology: Close confinement; naïve immune status; pregnancy; have a BVD TI and/or BVD PI in pen

3. Control: Test for BVDV infection by PCR; VI; Ag ELISA. Vaccinate susceptible animals, especially pre-breeding. Want immune animals in the production cycle (herd immunity)

4. Zoonotic: No

How do these questions apply to BVDV in captive exotic/wild animals in zoos

and wildlife parks?

• Not new questions- disease associated with captive deer in 1950’s & 1960’s

– Infection documented using BVD-specific serologic assays 1970’s & 1980’s

– Lab capabilities have increased for virus detection (IHC on fixed tissues; PCR; VI)

Captive

Wildlife

Free-roaming wildlife

Sheep Goats

Cattle

?

What is the extent of BVDV infection?

“Serologic surveys in free-ranging and captive wildlife animal populations demonstrated prior infection with BVDV or related pestiviruses in more than 40 species in North America”

Van Campen,

Frolich & Hoffman,

2001

“While serologic surveys indicated exposure/infection of wild ruminants to BVDV is common, isolation of the virus from these species is only rarely reported”

Nelson, et al, 2008

BVDV isolation (hence susceptibility to infection and virus replication)

• Mule deer• White-tailed deer• Japanese serow• Canadian bison• Water buffalo• Roe deer• Mouse deer• Dorcus gazelle

• Elk• Red deer• Bongo• Eland• Wildebeest• Nilgai• Axis deer• Barasingha deer

Tale of Two Cases

• 1 year old male Dorcas gazelle• Originally from the National Zoo 4/87• Died 12/87 after several days of lethargy,

anorexia, and diarrhia• Necropsy revealed hemorrhagic gut, and

animal was thin (10Kg)• Dr. Briggs suspected parasitic enteritis and

possible debilitating condition, check for BVDV• BVDV isolated in cell culture, NCP/FA+• No typing conducted• No further epidemiology conducted

Case #1

Tale of Two Cases (continued)

• Involved two male mountain goats – 7 months old & 6 months old

• Originally obtained from a holding facility in Montana 9/04

• 1st animal died 1/05; 2nd animal died 5/05• Both goats not gaining weight/failure to thrive• Dr. Call submitted a full set of fixed and fresh

tissues for analysis• BVDV isolated from both goats, NCP/PCR+• Typing & epidemiology conducted

Case #2

Courtesy of Dr. J. Ridpath

Case #2 (continued)

Isolation of a pestivirus from goat 1 prompted a serosurvey of the ruminants in the collection. Both EDTA and serum were collected.

Questions to Answer

• How well does BVDV sustain itself in a given population?

• Is it acute/TI driven?• Is it persistent/PI driven?• Is there a hierarchy of infection/disease

susceptibility amongst domestic livestock and wildlife in captivity, and wildlife free roaming?

• Should we be shifting from reactive medicine, i.e. detection & diagnosis of disease to preventative medicine, and control (biosecurity)?

Evidence for BVD PI or susceptibility to BVD congenital

infections in wildlife

Eland*

Mouse deer (zoo)

White-tailed deer**

White-tailed deer**

Mule deer***

Mt. goats (captive)

Vilcek et al, 2000

Grondahl et al, 2003

Passler et al, 2003

Duncan et al, 2008

Duncan et al, 2008

Nelson et al, 2008

* Common cattle ranching area

** experimental infection

*** natural infection

Management of exotic animal collections I. i.e. zoos, wildlife parks, translocation

centers, etc

• Awareness of interspecies susceptibility and transmissibility of BVDV

• Quarantine, testing for carriers (PI’s)• Vaccinations for these animals• Integration w/ existing management plans

(species survival plans)• Diagnostic/detection capabilities increased

Management of exotic animal collections II.

• Understanding the risks associated with common winter feeding grounds (elk, deer, cattle, etc)

• Mixing more than one species in translocation pens

• Commingling animal collections to achieve ‘natural conditions’

Broader Implications

Biosecurity Plans

• Screening for TB; Johne’s; MCF; coronavirus; BVDV infections (TI and PI); etc

• Proper quarantine of pregnant animals - most vulnerable stage for congenital infection & establishing PI

• Proactive clinicians/diagnosticians• Vaccination?

Sporadic episodes of BVD have occurred in some zoos (& wildlife parks) with serious illness and death, suggests that BVD vaccination of captive wild ruminants can be justified. We recommend that only killed BVD vaccines be used in captive exotic ruminants.

Doyle & Heuschele, 1983

Acknowledgements

The authors wish to express their thanks to Drs. Neil Call and Mike Briggs for case referrals. Appreciation to the faculty and staff at Washington Animal Disease Diagnostic Lab for insights and case support. Thanks to Dr. Julia Ridpath for her support of the molecular epidemiology of BVDV and Ms. Trista Harvey and BCU crew for help with the PowerPoint.