Livestock Orbiviruses: The Tip of the Iceberg in a Warming Climate?

Transcription

1 Livestock Orbiviruses: The Tip of the Iceberg in a Warming Climate? Nicole Nemeth, Asst. Professor Dept. of Pathobiology, University of Guelph Canadian Wildlife Health CooperaGve 11 December 2015 LRIC Climate VariaGon Workshop

2 Livestock Orbiviruses Genus Orbivirus, Family Reoviridae EpizooGc hemorrhagic disease viruses (EHDV) Bluetongue viruses (BTV) Arthropod- transmiued viruses Culicoides bigng midges (blood feeders) Infect domesgc & wild ruminant hosts Strict seasonality of transmission MAMMALIAN HOST INSECT VECTOR INFECTIOUS AGENT

3 Orbivirus Transmission ClimaGc condigons Temperature, moisture, winds Oviposition in a variety of habitats Culicoides often remain near productive breeding sites but may disperse to seek host Virus disseminates to salivary glands Extrinsic incubation period Viremic hosts Survivorship Activity Find host Naïve hosts Courtesy of Mark Ruder

4 Global Climate Changes Increasing average temperatures of earth s surface, air, water bodies Altered season lengths Rising ocean levels Extreme weather Floods, drought, hurricanes, tornados Predicted increased drought in Canada, especially south and interior climate.shtml

5 Courtesy of Mark Ruder EHD/BT are complex diseases with many uncertainties in the epidemiological triad Host Pathogen Disease Environment L Cohnstaedt

6 Vector- borne Diseases and Warmer Climates Altered spagal and temporal distribugon Longer pathogen transmission seasons Vector expansion (north, elevagon) Increased diversity of competent vectors Increased vector- host- pathogen interacgons Exposure of naïve host populagons Faster larval development Shorter pathogen incubagon periods within vectors Increased temperature and rainfall anomalies could destabilize agricultural producgon, alter health prioriges and produce condigons that result in explosive changes in vector populagons. Patz & Reisen TRENDS in Immunology 22:171-2.

7 Global EHDV/BTV DistribuGon 50 N 58 N 40 N 35 S 30 S Courtesy of Mark Ruder EHDV outbreaks in cattle since 2003: Reunion Island, Morocco, Algeria, Israel, Jordan, Morocco, Tunisia, Turkey, US BTV outbreaks in cattle and sheep: US, Europe (Sweden, Denmark, Norway )

8 Global DistribuGon of BTV Serotypes and Culicoides spp. BTV-11 C. variipennis occidentalis C. sonorensis

9 Climate Change and INSECT VECTOR Vector- borne Diseases MAMMALIAN HOST INFECTIOUS AGENT The emergence of exogc viruses in the North may be driven by changes in climate, land use, trade, animal husbandry Culicoides- borne virus systems are complex MulGple vectors and hosts within a single region These systems are subject to change New Culicoides species and new wild reservoir hosts have been implicated in transmission in some regions Purse et al Ann. Rev. Entomol. 60:

10 Orbiviruses BTV (26 serotypes) BTV- 2, 10, 11, 13, 17 are historically endemic in the U.S.; immediately noffiable Since 1999, BTV- 1, 3, 5, 6, 9, 12, 14, 19, 22, 24 detected in the SE US (non- endemic); reportable EHDV (7 serotypes) North America: EHDV- 1, 2, 6 EHDV- 2 is the most common isolate in the U.S. Not reportable in Canada/U.S.

11 Orbiviruses in Canada Most of Canada is BTV- free Past 30 yr: BTV in Okanagan Valley, BC Sporadic outbreaks along the U.S. Canada border (Montana Alberta) EHDV incursion into southern Alberta & south- central BC 1962 à 2013; deer mortality Culicoides sonorensis and others are in Ontario (Hunter & Jewiss- Weiss, unpub. data) Local BTV- 13 transmission in SW Ontario Wilson, Darpel & Mellor Lysyk & Dergousoff J. Med. Entomol. 51:

12 Changes in the Epidemiology of EHD and BT in the past Years Emergence of nine BTV serotypes in Europe Losses in sheep, caule industries DetecGon of ten historically non- endemic BTV serotypes and an exogc EHDV sero- type in the U.S. Saegerman et al Emerg Infect Dis 14:

13 Molecular Epidemiology of BTV in Europe ( ): Routes of IntroducGon of Serotypes and Virus Strains Culicoides imicola C. obsletus C. sco0cus C. pulicaris -Unusually high virulence of specific BTV-8 strain (sheep, goats, cattle) -Wide geographical spread in a completely naïve animal population -Economic damage to livestock industry -Illegal use of vaccine strains contributed to further serotype outbreaks (-6, -11) km spread in 2014 Saegerman et al Emerg Infect Dis 14:

14 Courtesy of Mark Ruder Monthly DistribuGon of BTV- 8 outbreaks in Northern and Central Europe (August 17, February 1, 2007) Culicoides duwulfi Saegerman et al Bluetongue Epidemiology in the European Union. EID 14: Outbreak spread widely, over 1500 km from the inigal outbreak in southern Greece; 2015 outbreak BTV- 4 in goats (recent reports)

15 DistribuGon of Hemorrhagic Disease in the US: Northern Expansion and Increased Frequency Stallknecht et al J Wildl Dis 51: Ruder et al Vector-borne Zoon Dis 15: Historically, HD outbreaks in wild ruminants occurred at 2-3-year intervals in endemic areas and 8-10-year intervals in epidemic areas. However, in the past decade, patterns are changing outbreaks in the northern areas are more frequent.

16 US Drought Monitor August 28, 2007 Significant caule morbidity during 2007 and 2012 outbreaks in the U.S. Reported HD Mortality in Wild Ruminants: 2007 (BTV-17) US Drought Monitor August 28, 2012 Reported HD Mortality in Wild Ruminants: 2012 (EHDV-2) Courtesy of Mark Ruder

17 Courtesy of Mark Ruder EHD: Northern Expansion and Increased Frequency Michigan has transigoned from the 20- year plan to the annual plan What are the drivers? 2011 Will this trend continue? What Culicoides species is/are involved? Similar trends in NJ, PA, NY, ND

18 Culicoides CollecGons in Michigan MICHIGAN LIGHT TRAP LOCATIONS Culicoides species n % of Known C. sonorensis distribution total C. stellifer % C. haematopotus % C. stellifer represented 63% of Culicoides collected C. sonorensis was not collected in any trap C. crepuscularis 50 6% C. venustus 15 2% C. biguratus, C. chiopterus, C. mulrennani, C. obsoletus, C. paraensis, C. sanguisuga, C. spinousus, C. variipennis 57 <1 % ea Courtesy of Mark Ruder

19 EHDV in CaUle What we know: Widely distributed CaUle commonly infected Can cause significant producgon loss Events of the past decade indicate that the distribugon is dynamic Shiss in vector abundance, distribugon and/or competence? What has changed? Increased reports in caule Expanding geographical distribugon Apparent increase in frequency and intensity of outbreaks Reports in new species Lack an understanding of transmission and vector biology

20 BTV in Ruminants Hemorrhagic disease - mainly in sheep and deer; sporadically in caule Fever, conjuncgvigs, rhinigs, nasal exudate, ulceragon; coronigs, edema (face, lungs), muscle necrosis Case fatality can be high in sheep (30-70%) Wilson et al PLoS Biology 6: University of Pretoria, Faculty of Veterinary Science D. Hughes & R. Dudley, NE Dept. of Agriculture

21 EHDV in Ruminants CaUle Low mortality Fever, weakness, sgff gait, low milk yield, nasal discharge, conjuncgval hyperemia & edema, oral hemorrhage & ulceragon - salivagon, coronigs - lameness B. Sharir, Hachaklait Vet Services, Israel D. Hughes and R. Dudley, NE Dept. of Agriculture

22 M. Ruder, SCWDS Shane Hesting, KDWPT

23 Epizootic hemorrhagic disease Field signs Shane Hesting, KDWPT

24 Ruder et al J Wildl Dis 48:676-85; T Gidlewski, T Spraker

25 Hemorrhagic Disease of Deer PaUerns of InfecGon and Disease Acute Chronic Subclinical In general: outbreak frequency but disease severity with latitude

26 Our ability to detect outbreaks varies with the populagon of animals

27 Ontario Orbivirus Incursion Tip of the Iceberg? Northern lagtudes may be more suscepgble to the effects of climate change on vector- borne diseases Models project C. sonorensis will move above 53 N 1 For comparison, Toronto is at 43 N Hemorrhagic disease incidence posigvely correlated with average temperatures and inversely with June precipitagon 2 Temporal associagon between hemorrhagic disease reports and drought 3 1 Zuliani et al PLoS One DOI: Sleeman et al EcoHealth 6: Stallknecht et al J Wildl Dis 51:

28 Key Knowledge Gaps Vector biology: distribugon and diversity of Culicoides midges Which species are present where and when? Which species may be important in transmission? The extent of Orbivirus transmission in Ontario Current baseline for future comparison Smoldering flame? CaUle and deer serology Highly visible die- offs of sheep (BTV) or deer (EHDV) Land use and climate pauerns Baseline establishment and long- term studies

29 Why is this Knowledge Crucial? Lessons from BTV in Europe Climate change is deemed responsible for the emergence of BTV in Europe Dogma of BTV between 35 S- 40 N was challenged with its emergence in Europe, where C. imicola was absent Other Culicoides spp. responsible for virus transmission Late applicagon of vaccinagon to livestock led to widespread disease & economic losses Numerous serotypes emerged, some more virulent than previously observed

30 PrevenGve Strategies RestricGon zones, stamping- out Early in outbreak in naïve populagons ReducGon of vector populagon or feeding rates InsecGcide applied to environment, animals ImmunisaGon of sheep and other suscepgble ruminants, including goats and caule, has proven the most effecgve tool against BTV spread Recommended by the World OrganisaGon for Animal Health as an effecgve eradicagon method Kyriakis et al Veterinary Microbiology 181:66-74.

31 Take- home Points INSECT VECTOR The complexity of the system limits our ability to predict MAMMALIAN HOST INFECTIOUS AGENT outcomes of viral introducgons or climate change Changes that will affect the acgvity of Orbiviruses ARE taking place NOW in Europe and N. America Ideally, groundwork will be laid ahead of substangal Orbivirus acgvity in Ontario To develop vector control or vaccine strategies, we must first understand the epidemiology and vector biology Ruder et al Vector Borne Zoon Dis 15:

32 Take- home Points Veterinarians and farmers should be well Farmers-back-humane-badger-slaughter-in-war-over-cattle-TB.html informed and on- guard to immediately report possible outbreaks of the disease and nagonal authoriges should have ready- to- implement congngency plans. Vigorous virological surveillance in domesgc and wild ruminant populagons in high- risk regions is of paramount importance and may offer an early warning against the emergence of the virus. Kyriakis et al Veterinary Microbiology 181:66-74.

33 Future Research at UoG (?) Proposal (in review) to establish baseline and help understand vector biology and serosurveillance in caule in southwestern ON Farm locagons for vector trapping or collecgon of caule blood White- tailed deer serosurveillance and educagon Funding sources Beefmagazine.com

34 Ques;ons or comments? Nicole Nemeth Pathobiology Department University of Guelph Thanks to: Mark Ruder Southeastern Coopera;ve Wildlife Disease Study University of Georgia