Disease Threats Endemic in Wildlife Populations that Pose Threats to U.S. Livestock and Our Export Markets

Transcription

1 Disease Threats Endemic in Wildlife Populations that Pose Threats to U.S. Livestock and Our Export Markets Ray Waters, DVM, PhD Tuberculosis Research Project National Animal Disease Center Ames, Iowa

2 Emerging Diseases of Wildlife Encroachment Introduction Spill-over and spillback Wildlife Feeding Habitat destruction Translocation of wildlife Domestic Animals Humans Daszak, P. et al., Science 2000;287:

3 Impact on Federal Eradication Programs Bovine Tuberculosis (TB) in White-Tailed Deer (MI, MN, IN) Brucellosis in Elk, Bison, (Yellowstone, B. abortus) & Feral Swine (B. suis) Pseudorabies (PRV) in Feral Swine Others Johne sdisease in White-tailed Deer Bovine Viral Diarrhea Virus (BVDV) in White-tailed Deer PRRSV, SIV, PCV-2, Leptospira (~50% prevalence & may harbor serovars not covered by current bacterins used for cattle), CWD? in feral swine Potential Host for Foreign Animal Diseases

4 So, where did these diseases come from? Circa 1500 A.D.: Horses are introduced to America And cattle & pigs w/ hitchhikers: (e.g., Mycobacterium bovis, Brucella spp, PRV, Johne s, and BVDV)

5 Game Management: Increased carrying capacity Encroachment, Introduction, Feeding, Spill-Over and Spill-Back Expanding Range Interaction w/ our Livestock

6 Feeding, Encroachment, Spill Back Contamination of Feed lib.colostate.edu Feeding / Baiting Practices

7 Expanding Range!!!

8 Expanding Range and Natural Interactions w/ Transitional Production Swine

9 Natural Interactions w/ Cattle in Pastures

10 PRV in Feral Swine 1991: USAHA, Feral Swine Subcommittee: Feral swine recognized as a significant threat to PRV and Brucellosis eradication. Low virulence strains w/ delayed seroconversion can result in spread w/o detection when transmitted to domestic pigs Out of 2,849 sera samples ( ), 18% seropositive for PRV in 25 of 35 states (Pederson et al, 2013) While all states achieved PRV-free status in 2004; feral swine remain as a reservoir of PRV and a threat to transitional operations

11 Brucellosis in Feral Swine B. suis: risk for transitional swine operations; thereby hindering eradication efforts B. suis in pigs: poor accuracy of serologic tests, bacteremia of longer duration than B. abortus, and B. suis is frequently shed in urine B. suis can infect cattle and shed at high levels in milk (demonstrated risk w/ unpasteurized dairy products) B. suis infection in humans (e.g., hunters, trappers): often severe disease and may relapse

12 Bovine TB Primarily due to Mycobacterium bovis Wildlife reservoir hosts US eradication program initiated in 1917 Current issues (US): tuberculous cattle from Mexico, occasional inter-herd spread, WTD in MI, & captive cervids 2000 present: 144 TB-affected herds: MI (51 beef, 15 dairy, 4 cervid, 1 dairy), MN (12 beef), TX (7 dairy, 3 beef, 1 mixed), CA (11 dairy), CO (5 beef, 2 dairy), IN (3 beef, 3 cervid), NM (4 dairy, 1 mixed), SD (4 beef) AZ, KS, KY, MS, NE, NY, ND, OH, OK, & OR (all < 3) Pulsar.Two-worlds.com

13 Example of Human Impact on Wildlife Populations from U. of Missouri Extension publication

14 The Tale of Michigan Deer densities > 30/sq. mile - SCWDS /sq. mile MI DNR 1990

15 Gogebic 136/4877 Ontonagon 5/202 Hou`ghton 54/2410 Baraga Iron 1/64 30/2655 Keweenaw 0/959`` Marquette 10/268 Dickinson 16/ /1435 Menominee Alger 25/2494 Delta 69/3413 1/118 Chippewa Schoolcraft Mackinac 1/89 2/109 Mason Lake Bovine TB Reactor Rates in Michigan s Cattle Herd Roscommon ManisteeWexford Missaukee Ogemaw 7/469 Bay OceanaNewaygo Mecosta IsabellaMidland Muskegon Leelanau BenzieTraverse Grand KalkaskaCrawfordOscoda Alcona 29/528 Ottawa Luce Kent Emmet 32/2497 Cheboygan Presque Isle Charlevoix 3/67 38/2513 Montmorency Antrim Otsego Alpena Osceola Clare Gladwin Arenac 10/287 5/68 4/ /210112/ /3686 7/1201 2/103 2/49 67/ /2012 1/246 MontcalmGratiot 43/645 Ionia 294/ / /1931 3/64 2/76 16/ / / / /552 Saginaw Iosco Tuscola Huron Sanilac Genesee Lapeer ClintonShiawassee St. Clair 30/852 2/209 2/130 7/ / /138 16/104 32/ / /2049 1/17 31/97 3/95 24/ / / / / / /857 0% Reactors 0%-2% Reactors 2%-5% Reactors 5%-10% Reactors 10% or more Reactors Berrien Allegan Barry Eaton InghamLivingston OaklandMacomb 233/4845 Van Buren Calhoun Jackson Washtenaw Wayne Kalamazoo 75/ /2931 Cass St. JosephBranch Hillsdale Lenawee Monroe 211/ / / / / / / / / / / / / / / / / /1550

16 Spill-Over to Deer

17 Spill-Over to Deer

18 43 Spill-Back to Cattle!

19 Why does TB persist in deer in Michigan?

20 Supplemental Feeding and Baiting High deer numbers Decreased winter death loss Crowding & Stress Contaminated feed Increased risk of disease transmission Indirect transmission through contaminated feed (deer to deer and deer to cattle) Supplemental feeding drastically increased by hunt clubs in the core area 1980s & 90s

21 Mitigation Actions beginning in 1996 Prevalence decreased from 5% to 2% in the TB Core Area w/ increased hunter harvest as well as decreased baiting & supplemental feeding; yet transmission to cattle persists Since 2000: TB Prevalence in WTD persists at ~ % Could these efforts be more aggressive? Other Strategies (e.g., vaccines for deer)? Political Will Rights of Hunters vs Rights of Cattleman

22 Culture of WTD hunting in Michigan In 2015, 654,579 licensed hunters harvested ~334,612 deer statewide These hunters purchased 1.27 million harvest tags Opening day ( Nov 15) is a holiday for most schools in Northern Michigan Hunting is deeply ingrained in the culture in the TB core region w/ many hunt clubs

23 WTD hunting in Michigan: Economic value and political clout Big game hunters (mostly WTD) expenditures in MI: ~$1.4 billion yearly Hunting-related taxes generate another $24.2 million yearly for wildlife conservation By comparison, total market value of cattle and calves sold: ~$604 million yearly for MI TB Core Area: accounts for only 2% of cattle and dairy product sales in MI Persistent and intense public intolerance of drastic reductions in the deer population has proven more influential than protests by cattlemen and their advocates, O Brien et al., 2006 U.S. Dept. Interior, 2011; U.S. Dept. Agriculture, 2012

24 Disease Management in Wildlife: Surveillance, Population Control, Exclusion, Vaccination

25 Exclusion: Use of Guard Dogs

26 Exclusion: Fences around Feed Storage Areas

27 1. Gonacon: Licensed for WTD and feral horses 2. Zonastat-P, Zonastat-D, Zonastat-H 3. One Hit Permanent Sterility (cytotoxins to oocytes as chemosterilants): 1 st target is feral pigs 4. Genetic Biocontrol w/ Natural or Synthetic Gene Drives: 1 st target is invasive rodents on islands NWRC: Led by Doug Eckery in collaboration w/ CSU

28 Vaccine Efficacy Studies (bovine TB) in White-tailed Deer

29 Camille Guerin Albert Calmette BCG for Bovine TB: White-tailed Deer BCG Danish and Pasteur provide similar levels of protection Oral administration provides similar to superior efficacy as does subcutaneous BCG is detectable within lymph nodes (not tissues normally consumed by hunters) 9 to 12 months after vaccination and may transmit between deer

30 Vaccines, free-ranging deer Without a vaccine it will be very difficult, maybe impossible, to eradicate TB in deer in Michigan S. Schmitt, Michigan DNR Trap, test and cull or vaccinate strategy

31 Baits for BCG Delivery Vaccine Uptake (NADC captive deer, MI free-ranging deer) Bait / Vaccine Viability Bait Dispersal Strategies Efficacy / safety of 100X dose

32 Vaccine delivery units (VDUs: alfalfa/molasses-based, cornbased, apple-based) for BCG in White-tailed Deer in MI

33 Vaccine Delivery Unit Dispersal Techniques Drones

34 Rhodamine B-laced baits to assess coverage (70%) Game cameras to monitor bait uptake

35 Many images and supportive data provided by: Kurt Vercauteran & Chris Ellis, APHIS, WS Dan O Brien, MI DNR Bill Hench, USDA, APHIS, VS, TB program staff David Dressel, MSU NADC: Mitch Palmer/Tyler Thacker (TB), Steve Olsen (Brucella), Kelly Lager (PRV), Jarlath Nally (Lepto), Jim Fosse (Visual Services)

36 Kavango-Zambezi Transfrontier Conservation Area in southern Africa Courtesy of Michele Miller, Stellenbosch Univ.

37 Minnesota vs. Michigan Minnesota Michigan Size of btb core area 425 km km 2 Topography/land cover Flat; mixed forest (25%), lowland marsh (35%), open agricultural (40%) Core area land ownership Number cattle producers in core area 60% public 40% private Flat to rolling; mixed forest (50%), lowland swamp (15%), open agricultural (30%) 10% public 90% private Free-ranging deer density 2-3 per km per km 2 Annual expenditures by big game hunters US rank, total agricultural products sold US rank, value of cattle and calves sold US$259 million US$1.4 billion 5 th of th of th of th of 50

38 Photo by George W. Beran 1813: Dr. Hildreth, a physician in Marietta Ohio notes a case of mad itch in one of his client s cows 1 st account in the US of what was later to be known as PRV 1902: Hungarian Veterinarian Aladar Aujeszky 1 st recognizes Pseudorabies as a fatal disease in a bull, cat and dog. About this time, it was determined that pigs are the reservoir host Assumption PRV arrived in the new world from European domestic pigs

39 Mycobacterium tuberculosis complex DNA isolated from an extinct long horned bison metacarpal bone (dated at ~17,870 yrs) in Wyoming Not M. bovis M. bovis likely diverged from M. tuberculosis ~5000 yrs ago Assumption: the vast majority, if not all, of M. bovis strains arrived in the New World with the settlers