African Horse Sickness

1. African Horse Sickness Perdesiekte, Pestis Equorum, La Peste Equina, Peste Equina Africana

2. Overview • Etiology • Species Affected • Epidemiology • Economic Importance • Clinical Signs • Diagnosis and Treatment • Prevention and Control • Actions to Take Center for Food Security and Public Health, Iowa State University, 2011

3. Etiology Center for Food Security and Public Health, Iowa State University, 2011

4. African Horse Sickness Virus • Non-enveloped RNA • Family Reoviridae • Genus Orbivirus • Nine serotypes (1-9) • All viscerotropic • Serotype 9 • Endemic areas • Outbreaks outside of Africa • Serotypes 1-8 • Limited geographical areas Center for Food Security and Public Health, Iowa State University, 2011

5. African Horse Sickness Virus • Inactivated by • Heat (temps greater than 140oF) • pH less than 6, or 12 or greater • Acidic disinfectants • Rapidly destroyed in carcasses that have undergone rigor mortis Center for Food Security and Public Health, Iowa State University, 2011

6. Epidemiology Center for Food Security and Public Health, Iowa State University, 2011

7. Species Affected • Equidae • Horses, donkeys, mules • Zebras • Other • Camels • Dogs Center for Food Security and Public Health, Iowa State University, 2011

8. Geographic Distribution • Endemic in sub-Saharan Africa • Outbreaks • Southern and northern Africa • Near and Middle East • Spain and Portugal Center for Food Security and Public Health, Iowa State University, 2011

9. OIE Disease Distribution Map Center for Food Security and Public Health, Iowa State University, 2011

10. Incidence/Prevalence • Seasonal • Late summer - early autumn • Cyclic • Drought followed by heavy rains • Influences insect breeding • Epizootics halted by • Frost • Lack of long-term vertebrate reservoir • Reduced numbers of vectors • Control measures • Vaccination, vector abatement Center for Food Security and Public Health, Iowa State University, 2011

11. Morbidity/Mortality • Varies with species, previous immunity, form of disease • Mortality based on species • Horse particularly susceptible Center for Food Security and Public Health, Iowa State University, 2011

12. Morbidity/Mortality • Mortality based on form of disease Center for Food Security and Public Health, Iowa State University, 2011

13. Transmission Center for Food Security and Public Health, Iowa State University, 2011

14. Transmission • Not contagious • Vector-borne: Culicoides spp. • Culicoides imicola – principal vector • C. bolitinos • C. variipennis • Other potential arthropods • Viremia in Equidae • Horses: 12 to 40 days • Zebras, African donkeys: up to 6 weeks Center for Food Security and Public Health, Iowa State University, 2011

15. Culicoides spp. • Biting midges, “punkies”, “no-see-ums” • Extremely small ~1/8” • Species identified by wing pattern • Habitat • Margins of water sources • Life cycle: 2-6 weeks • Eggs hatch in 2-10 days • Females are bloodsucking • Greatest biting activity dusk to dawn Center for Food Security and Public Health, Iowa State University, 2011

16. Economic importance Center for Food Security and Public Health, Iowa State University, 2011

17. History • 1600: First recorded • Horses to southern Africa • 1921: Sir Arnold Theiler • Described 7 major epizootics in South Africa from 1780-1918 • 1959-61: Middle East • 1st outbreak outside Africa • 1987-91: Spain, Portugal • Imported zebra reservoirs • New Culicoides species Center for Food Security and Public Health, Iowa State University, 2011

18. Economic Impact • 1989: Portugal • 137 outbreaks • 104 farms • 206 equines destroyed • 170,000 equinesvaccinated • Cost $1.9 million SPAIN Center for Food Security and Public Health, Iowa State University, 2011

19. U.S. Economic Impact • U.S. Horse Industry (2007) • Inventory: 4 million horses • Sales: $2.0 billion • Employment: 4.6 million Americans • Risk factors • Disease not in U.S. – naïve population • Arthropod vector is in U.S. • Outbreak would result in movement and trade restrictions Center for Food Security and Public Health, Iowa State University, 2011

20. African Horse Sickness in Animals Center for Food Security and Public Health, Iowa State University, 2011

21. Incubation Period • Experimental: 2-21 days • Natural infection: 3-14 days Center for Food Security and Public Health, Iowa State University, 2011

22. Clinical Signs • Four forms of the disease • Peracute (pulmonary) • Subacute edematous (cardiac) • Acute (mixed) • Horsesickness fever • Symptomatic infections most common in horse and mules • Zebras typically asymptomatic Center for Food Security and Public Health, Iowa State University, 2011

23. Peracute - Pulmonary Form • Acute fever • Sudden, severerespiratory distress • Dyspnea, tachypnea • Profuse sweating • Spasmodic coughing • Frothy serofibrinous nasal exudate • Rapid death (few hours) Foam from the nares due to pulmonary edema Center for Food Security and Public Health, Iowa State University, 2011

24. Subacute Edematous - Cardiac Form • Edema • Supraorbital fossae, eyelids • Cheeks, lips, tongue, intermandibular space • Neck, thorax, chest • Not in lower legs • If animal recovers, swellings subsideover 3-8 days Center for Food Security and Public Health, Iowa State University, 2011

25. Subacute - Cardiac Form • Terminal stages • Severe depression, colic, petechiae of conjunctivae and ventral tongue • Death from cardiac failure • Mortality 50% or higher • Death within 4-8 days Center for Food Security and Public Health, Iowa State University, 2011

26. Acute - Mixed Form • Pulmonary and cardiac forms • Cardiac signs usually subclinical • Followed by severe respiratory distress • Mild respiratory signs • Followed by edema and death • Diagnosed by necropsy • Mortality 70-80% Center for Food Security and Public Health, Iowa State University, 2011

27. Horsesickness Fever • Mild clinical signs • Characteristic fever (3 to 8 days) • Morning remission (undetectable) • Afternoon exacerbation • Other signs • Mild anorexia or depression • Congested mucous membranes • Increased heart rate • Rarely fatal Center for Food Security and Public Health, Iowa State University, 2011

28. Post Mortem Lesions • Pulmonary form • Severe, diffusepulmonary edema • Hydrothorax • Fluid in abdominal and thoracic cavity • Enlarged endematous lymph nodes • Hyperemia and petechial hemorrhages in intestines Center for Food Security and Public Health, Iowa State University, 2011

29. Post Mortem Lesions • Cardiac form • Yellow gelatinous infiltrate • Head, neck, shoulders • Brisket, ventral abdomen, rump • Hydropericardium • Submucosal edema of cecum, large colon, rectum • Mixed form • Mixture of above findings Center for Food Security and Public Health, Iowa State University, 2011

30. AHS in Other Species • Dogs • Ingestion of infected horse meat • Not usually by insect bites • No role in spread or maintenance • Dogs usually have the pulmonary form • Camels, zebras • Inapparent infection Center for Food Security and Public Health, Iowa State University, 2011

31. Diagnosis and Treatment Center for Food Security and Public Health, Iowa State University, 2011

32. Differential Diagnosis • Equine viral arteritis • Equine infectious anemia • Hendra virus infection • Purpura hemorrhagica • Equine piroplasmosis • Equine encephalosis virus • Anthrax • Toxins Center for Food Security and Public Health, Iowa State University, 2011

33. Diagnosis • Clinical signs • Supraorbital swelling is characteristic • History • Prevalence or exposure to competent vectors • Travel from enzootic area • Laboratory tests - definitive diagnosis • Serotype needed for control measures Center for Food Security and Public Health, Iowa State University, 2011

34. Laboratory Diagnosis • Laboratory tests • Virus isolation • ELISA, RT-PCR • Serology (tentative) • Necropsy: spleen, lung, lymph node • More than one test should be used • AHSV does not cross-react with other known orbiviruses Center for Food Security and Public Health, Iowa State University, 2011

35. Sampling • Before collecting or sending any samples, the proper authorities should be contacted. • Samples should only be sent under secure conditions and to authorized laboratories to prevent the spread of the disease. Center for Food Security and Public Health, Iowa State University, 2011

36. Samples To Collect • For virus isolation • Blood samples • Necropsy samples • Spleen, lung, lymph nodes • Paired serum samples are recommended • Store and transport samples at 39oF Center for Food Security and Public Health, Iowa State University, 2011

37. African Horse Sickness in Humans Center for Food Security and Public Health, Iowa State University, 2011

38. AHS in Humans • No natural infection in humans • Neurotropic vaccine strains • Transnasal infection can lead to encephalitis or retinitis • Handle modified live AHS vaccine strains with caution Center for Food Security and Public Health, Iowa State University, 2011

39. Prevention and Control Center for Food Security and Public Health, Iowa State University, 2011

40. Recommended Actions • IMMEDIATELY notify authorities • OIE reportable disease • In the U.S. notify • Federal Area Veterinarian in Charge (AVIC) www.aphis.usda.gov/animal_health/area_offices/ • State Veterinarian www.usaha.org/Portals/6/StateAnimalHealthOfficials.pdf • Quarantine premises Center for Food Security and Public Health, Iowa State University, 2011

41. Disinfection • Disinfectants • Sodium hypochlorite (bleach) • 2% acetic or citric acid • Killed • pH less than 6 • pH 12 or greater • Rapidly destroyed in carcasses that have undergone rigor mortis Center for Food Security and Public Health, Iowa State University, 2011

42. Control • Quarantine • Equidae from endemic areas • Asia, Africa, Mediterranean • Minimum 60 days at point of entry • Vector control and protection • Insect repellants • Stable in insect-proof housingfrom dusk to dawn Center for Food Security and Public Health, Iowa State University, 2011

43. Control • Monitor temperature of all equids • If febrile • Euthanize or isolate in an insect-free stable until cause is determined • Vaccination • In endemic areas • Surrounding protection zone • Not available in the U.S. Center for Food Security and Public Health, Iowa State University, 2011

44. Vaccination • Attenuated live vaccine available • Horses, mules, donkeys • Not in U.S. • Reassortment possible • Teratogenic • No killed or subunit vaccine available • Recovering animals • Lifelong immunity post-infection to the infecting serotype Center for Food Security and Public Health, Iowa State University, 2011

45. Additional Resources • World Organization for Animal Health (OIE) • www.oie.int • Center for Food Security and Public Health • www.cfsph.iastate.edu • USAHA Foreign Animal Diseases (“The Gray Book”) • www.aphis.usda.gov/emergency_response/downloads/nahems/fad.pdf • Center for Infectious Disease Research and Policy • www.cidrap.umn.edu/cidrap/content/biosecurity/ag-biosec/anim-disease/ahs.htm • African Horse Sickness Trust • www.africanhorsesickness.co.za Center for Food Security and Public Health, Iowa State University, 2011

46. Acknowledgments Development of this presentation was made possible through grants provided to the Center for Food Security and Public Health at Iowa State University, College of Veterinary Medicine from the Centers for Disease Control and Prevention, the U.S. Department of Agriculture, the Iowa Homeland Security and Emergency Management Division, and the Multi-State Partnership for Security in Agriculture. Authors: Glenda Dvorak, DVM, MPH, DACVPM; Anna Rovid Spickler, DVM, PhD Reviewers: James A. Roth, DVM, PhD; Bindy Comito, BA; Katie Spaulding, BS; Meghan Blankenship, BS; Kerry Leedom Larson, DVM, MPH, PhD, DACVPM Center for Food Security and Public Health, Iowa State University, 2011