Dr. Peter Merrill - Schmallenberg Syndrome and the Precautionary Principle: A Case Study in Contrasting Approaches for an Emerging Disease
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Dr. Peter Merrill - Schmallenberg Syndrome and the Precautionary Principle: A Case Study in Contrasting Approaches for an Emerging Disease

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Schmallenberg Syndrome and the Precautionary Principle: A Case Study in Contrasting Approaches for an Emerging Disease - Peter Merrill, DVM – USDA, APHIS, VS, Animal Permitting and Negotiation......

Schmallenberg Syndrome and the Precautionary Principle: A Case Study in Contrasting Approaches for an Emerging Disease - Peter Merrill, DVM – USDA, APHIS, VS, Animal Permitting and Negotiation Services, from the 2014 NIAA Annual Conference titled 'The Precautionary Principle: How Agriculture Will Thrive', March 31 - April 2, 2014, Omaha, NE, USA.

More presentations at http://www.trufflemedia.com/agmedia/conference/2014_niaa_how_animal_agriculture_will_thrive

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  • 1. Peter L. Merrill, DVM Director, Animal Imports National Import Export Services USDA APHIS Veterinary Services NIAA Conference Omaha, NE April 1, 2014
  • 2. Learning Objectives  Quick review of relevant Precautionary Principle issues, as well as APHIS’ missions  SBV: What, Who, Where, When, How  EU and US positions (past and current)  What’s at stake?
  • 3. Salient PP Issues  KNYK, NKWYN, KWYDK, NKWYDK  ‘Better safe than sorry’  ‘First, do no harm’  ‘The absence of evidence is not evidence of absence’  Proving the negative  If an action or policy has a suspected risk of causing harm to animal [public, environmental, etc.] health in the absence of scientific consensus that the action or policy is harmful, the burden of proof that it is NOT harmful falls on those taking an action  Problematic consensus regarding ‘suspected’, ‘risk’, ‘harm’, ‘science’  Zero-Risk Tolerance
  • 4. Salient Missions: USDA/APHIS/VS/NIES  Protecting American agriculture while facilitating (safe) trade  Gaining, expanding, or retaining (safe) market access for animals and animal products/byproducts  Prevent the introduction of dangerous and costly pests and diseases (vs. mitigating/eradicating post-entry)  Domestic animal health and export status linked
  • 5. What is Schmallenberg syndrome?  Disease caused by infection with Schmallenberg virus (SBV), named after region in North Rhine-Westphalia, Germany where virus was first isolated  Group V: enveloped, (-) sense, segmented, ssRNA  Family Bunyavirudae: Genus Orthobunyavirus: Simbu serogroup (e.g. Aino, Akabane, Shamonda viruses)  Closest relatives: Douglas/Sathuperi viruses  Causes a form of arthrogryposis-hydranencephaly syndrome (AHS)
  • 6. Who is affected?  Ruminants (cattle, sheep, goats, bison, water buffalo, camels, llamas, alpacas, mouflon, roe/red/fallow deer. moose)…others?  Horses  Wild boar  Dogs?  Not presumed zoonotic  Farmers, regulators
  • 7. Where did SBV come from, and where is it now?  Origin uncertain/unknown; first Simbu virus in Europe  19 EU Member States (Austria, Belgium, Czech Republic, Denmark, Estonia, Finland, France, Hungary, Germany, Ireland, Italy, Latvia, Luxembourg, Netherlands, Poland, Slovenia, Spain, Sweden and United Kingdom)  3 other European countries (Switzerland, Norway, Croatia)  Many thousands of farms/holdings affected in Europe  NOT in North America
  • 8. When did SBV appear?  Probably Summer 2011 (first cases reported November) in The Netherlands, Belgium and Germany  Continuous temporal distribution since 2011 has resulted in steady progression north and east Sept 2011--Apr 2012 Sept 2012--Oct 2012 Nov 2012--Apr 2013 May 2012--Aug 2012
  • 9. When did SBV appear? SBV (2011-13) BTV(2003-13)
  • 10. How is SBV transmitted?  Biting midges (Culicoides spp.); other insects?  Transdermal; secretions?  Viral incubation/replication  Infective virus shed in bovine/ovine/caprine semen  Trans-placental transmission to embryo/fetus
  • 11. How is SBV transmitted?  Wildlife reservoirs?  Vector over-wintering  Fomites  Other pathways?  Virulence factors; temporal evolution  Material found to be positive by virus isolation (up to October 2013):  Blood and semen from affected adults; and brain from infected fetus  Material found PCR-positive (up to October 2013):  Organs and blood of infected fetus, placenta, amniotic fluid, meconium  Following an acute infection, SBV RNA can be detected up to several weeks in different tissues like semen, lymphatic organs (esp. mesenteric lymph nodes), and spleen
  • 12. How is SBV detected?  Clinical signs (not pathognomonic); abortions; stillbirths; AHS  Viral culture: insect cells (KC); hamster cells (BHK), monkey kidney cells (VERO)  Serology: virus neutralization; serum neutralization, IFA, ELISA  Molecular: RT-PCR (blood, not semen), rRT-PCR, EM  Samples for pathogen detection in acute infection: serum or EDTA blood samples when clinical signs are observed (fever, drop in milk yield, diarrhea).  Samples for pathogen detection in fetuses, abortions, stillbirths and malformed ruminants: brain (cerebrum and brainstem), amniotic fluid and placenta.
  • 13. How is SBV neutralized*?  Temperature: Infectivity lost (or significantly reduced) at 50–60°C for at least 30 minutes.  Chemicals/Disinfectants: Susceptible to common disinfectants (1 % sodium hypochlorite, 2% glutaraldehyde, 70 % ethanol, formaldehyde)  Survival: Does not survive outside the host or vector for long periods *extrapolated from other Orthobunyaviruses
  • 14. How is disease* caused?  Incubation period 1-4 days; viremia lasts for 1 -5 days  AB response; avg. seroconversion by 14-28 dpi  Morbidity/mortality*: up to 100%/<1% respectively in adults  In adult animals that are NOT pregnant: infection leads to variably transient/relatively brief clinical symptoms including:  inappetance  fever  diarrhea  loss in milk production (up to 50% in dairy animals) * More studied in cattle than sheep/goats
  • 15. How is disease caused?  In pregnant females, infection also leads to variable levels of increased birth defects (species-dependent, but avg. ~4%?)  Critical gestational susceptibility: d. 40-150 (bovines); d. 20-80 (S/G)  Abortions; stillbirths  Arthrogryposis/ Hydranencephaly  Brachygnathia inferior  Ankylosis; torticollis; scoliosis  Hypoplasia of the central nervous system  Porencephaly  Subcutaneous edema (calves)
  • 16. How can SBV be prevented/treated?  No treatment once infected/clinical  Location in non-vector areas  Re-synchronization of breeding season  Vector-proofing breeding facilities  Test/remove/culling  Deliberate exposure (duration of immunity uncertain, or whether cross-protective against new serotypes)  Passive immunity via colostrum  Killed vaccine commercially available; 2 doses 4 wks apart (cattle); 1 dose S/G; cost variable but can be >$10/head; efficacy unknown  Passive immunity may interfere w/vaccine-stimulated ABs  Genetic resistance?
  • 17. European Approach (SBV)  Research (FLI, others)  EFSA reports  Impact Analysis  EC web portals  OIE Technical Fact Sheet
  • 18. Intra-European Trade (SBV)  The European Commission (EC) has not applied any specified trade restrictions due to SBV;  Not a reportable condition; some individual Member States require donor testing and certifications (Intra-Community movement eligibility similar to US interstate requirements)  The EC does not consider that live animals, meat, milk or animal by-products to pose a risk of transmission  The EC considers restrictive trade measures for SBV taken by trading partners against exports of ruminants and their products are not justified  Similar to position for Aino/Akabane/BT (retrospectively)  OIE Technical Fact Sheet/EFSA correlations
  • 19. EU Inventories and Statistics*  Bovines: ~115 million domestic head (2012)  Imports: none (from non-EU sources)  Exports: ~500,000/yr. (to non-EU countries)  S/G: (avg. annual 2007-11): ~90 million domestic sheep; ~13 million goats  ~1.9 million sheep exports/yr. to non-EU countries (zero imports)  Economic values: well over $100 billion  Overall impacts from SBV losses unknown, but substantial * Various sources
  • 20. APHIS approach for SBV as an emerging disease  SBV technically meets criteria for FAD  APHIS considered (and considers) SBV as a significant emerging disease not known to be present in the United States  Canadian import requirements generally similar  Mexico import requirements: none?  Questions remain about the transmission risks associated with SBV; more research and information is considered necessary in order to determine an appropriate level of trade restrictions to prevent the introduction or spread of the disease
  • 21. APHIS approach for SBV as an emerging disease  Pathways analysis  Culicoides vectors: C. obsoletus, C. dewulfi; others?  Case definition  Passive surveillance; AOS  APHIS fact sheets/outreach to industry  Laboratory collaborations  Scientific/trade information monitoring  Modified risk assessment through extensive literature review  Discussions with Canada and other trade partners/industry  Proactive import restrictions for ruminant germplasm
  • 22. APHIS approach for SBV as an emerging disease  NIES Import Alerts: first in Mar. 2012  Applicable to EU and countries following EU legislation (exc. Iceland)  Only allowed bovine S/E collected prior to June 1, 2011  Oct. 2012-- additional criteria:  Donors can be tested twice for SBV by a serum neutralization assay, with negative results (using a 1:8 cutoff titer). The first SBV test must be performed within 30 days prior to collection, and the second between 28 and 60 days after collection. Tests must be performed at a laboratory approved by the country’s competent authority for animal health. Any serologically positive resident donors were re-tested negative by real-time RT-PCR or virus isolation within 4 days after additional collection(s) for export to the United States  May 2013-- further revision of that last sentence above:  Until additional information is available, semen and embryos collected from bovines that are seropositive for SBV are not eligible for importation to the United States  2014: Comprehensive Systematic Review (KNYK, etc)  O/C semen still not eligible for importation
  • 23. Inventories and financial stats*: Ovines/Caprines  ~77,000 sheep farms in the U.S  ~138,000 goat farms in the U.S.  ~5.5 million domestic sheep; ~2.5 million goats  <10,000 live sheep/goats imported/yr. (Can/Aus/NZ)  Avg. U.S. annual economic importance: live S/G imports value of ~$300,000 ; germplasm much less  U.S. exports of live S/G: ~$5 million  Domestic market value: ~$500 million sheep; goats? *various sources
  • 24. Inventories and financial stats*: Bovines  ~750,000 beef cattle farms in the U.S.  ~50,000 dairy cattle farms in the U.S.  US (2014): 87.7 million domestic head (lowest since 1951)  Imports: ~2 million/yr.  Exports: ~100,000/yr.  Avg. U.S. annual economic importance: live bovine/germplasm import value of ~$4 billion  U.S. exports of live bovines/germplasm: ~$300 million  Domestic market value: ~$50 billion beef; ~$45 billion dairy * various sources
  • 25. Industry and other perspectives  Reported morbidity/mortality provided by EU farmers differ widely from EFSA estimates and conclusions  Many S/G farms experience between 20-50% birth defects  Actual economic consequences can be catastrophic depending on many exposure factors  US ruminant producers have generally been supportive of APHIS’s position/approaches  US germplasm industry also generally supportive to date  European Commission has been highly critical of APHIS and other countries’ risk-aversion positions to date  ‘Right’ vs. ‘wrong’ approaches?  Systematic Review results will help clarify the risk picture
  • 26. Questions?