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Schmallenberg Syndrome: Contrasting Approaches to an Emerging Disease. Peter L. Merrill, DVM Director, Animal Imports National Import Export Services USDA APHIS Veterinary Services. NIAA Conference Omaha, NE April 1 , 2014. Learning Objectives.
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Schmallenberg Syndrome: Contrasting Approaches to an Emerging Disease Peter L. Merrill, DVM Director, Animal Imports National Import Export Services USDA APHIS Veterinary Services NIAA Conference Omaha, NE April 1, 2014
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?
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
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
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: Simbuserogroup(e.g. Aino, Akabane, Shamonda viruses) • Closest relatives: Douglas/Sathuperi viruses • Causes a form of arthrogryposis-hydranencephalysyndrome (AHS)
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
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
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 May 2012--Aug 2012 Sept 2012--Oct 2012 Nov 2012--Apr 2013
When did SBV appear? BTV(2003-13) SBV (2011-13)
How is SBV transmitted? • Biting midges (Culicoides spp.); other insects? • Transdermal; secretions? • Viral incubation/replication • Infective virus shed in bovine/ovine/caprinesemen • Trans-placental transmission to embryo/fetus
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
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. K
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
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
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)
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?
European Approach (SBV) • Research (FLI, others) • EFSA reports • Impact Analysis • EC web portals • OIE Technical Fact Sheet
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
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
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
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
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
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
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
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