Understanding and Managing Rickettsial Diseases in Ruminants

1. Rickettsia Diseases in Ruminanats

2. What are rickettsial diseases? • Encompasses a group of diseases caused by the microorganisms rickettsiae. • Rickettsiae occupy a position between bacteria and viruses. • They can only survive inside cells. • Rickettsial diseases vary considerably in severity from self-limiting mild illnesses to severe life-threatening infections. • The organisms cause disease by damaging blood vessels in various tissues and organs.

3. Rickettsial Diseases • Rickettsias as a group have a worldwide distribution • Many new rickettsial diseases were discovered in recent years, and the list is growing • Rickettsias are associated with variety of different vectors and hosts • Most types of rickettsiosis are geographic area-specific

11. Common Geographical Location

12. Rickettsia & Rickettsia-like Pathogens Phylogenetic trees based on molecular taxonomic methods show three major groups of rickettsias: • Rickettsia, Ehrlichia, Anaplasma • Bartonella • Coxiella

13. Rickettsial Diseases In Ruminants • Q- fever • Heart Water • Tick born fever • Bovine ehrlichiosis • Ovine ehrlichiosis • Bovine patechial fever • KeratoConjuctivitis

14. Q Fever • Coxiellaburnetii • Rickettsial agent • Obligate intracellular parasite • Stable and resistant • Killed by pasteurization • Two antigenic phases • Phase 1: virulent • Phase 2: less pathogenic

15. Transmission • Aerosol • Parturient fluids • 109 bacteria per gram of placenta • Urine, feces, milk • Wind-borne • Direct contact • Fomites • Ingestion • Arthropods (ticks)

16. Transmission • Animal-to-animal(rare) • Transplacental (congenital) • Blood transfusions • Bone marrow transplants • Intradermal inoculation • Possibly sexually transmitted

17. Epidemiology • Worldwide • Except New Zealand • Reservoirs • Domestic animals • Sheep, cattle, goats • Dogs, cats • Birds • Reptiles • Wildlife

18. Epidemiology • Occupational and environmental hazards • Farmers, producers • Veterinarians and technicians • Meat processors, abattoir • Laboratory workers

19. Large Animal • Sudden onset • Fever, chills, cough • Weight loss • Initially thought it was influenza • Symptoms persisted for 2 weeks • Presented to emergency room • Again influenza was the diagnosis

20. Large Animal • Referral to infectious disease specialist • Tested positive for Q fever • Antibiotics for 5 days • Resolved in 2 weeks • Epidemiology • No recent calvings on his farm • Two beef cattle herds across the road • 2 out of 14 tested positive for Q fever

21. Case Points • Naturally occurring cases occur • Recognize the signs and seek medical attention • Isolated incident • What if it was more serious or a cluster of producers were ill?

22. Small Animal Case • Most common symptoms • Fever, sweats, chills, fatigue, myalgia, headache • Cat tested positive for C. burnetii • 1:152 to phase I antigen • 1:1024 to phase II antigen

23. Animal Disease • Sheep, cattle, goats • Usually asymptomatic • Reproductive failure • Abortions, stillbirths • Retained placenta • Infertility • Weak newborns • Low birth weights • Mastitis in dairy cattle • Carrier state

24. Animal Disease • Other animal species • Dogs, cats, horses, pigs, camels, buffalo, pigeons, other fowl • Asymptomatic • Reproductive failure • Laboratory Animals • Rats, rabbits, guinea pigs, hamsters • Varies from asymptomatic to fever, granulomas, or death

25. Diagnosis • Diagnosis • Identification of organism • Histology, IHC • Serologic tests: IFA, ELISA, CF • PCR • Isolation of organism • Hazardous - Biosafety level 3

26. Morbidity &Mortality • Prevalence unknown • Endemic areas • 18-55% of sheep with antibodies • 82% of dairy cattle • Morbidity in sheep: 5-50%

27. Post Mortem Lesions • Placentitis • Placenta • Leathery and thickened • Purulent exudate • Edges of cotyledons • Intercotyledonary areas • Aborted fetus • Non-specific

28. Heartwater

29. The Cause

30. Heartwater • Ehrlichiaruminantium • Rickettsia • Found in blood vessels of infected animals • Especially ruminant brain • Causes “leaking” • Cannot live very long outside host

31. Importance

32. History • 1830: South Africa – sheep • 1898: Spread through blood • 1900: Tropical bont tick vector • 1925: Caused by Rickettsial agent • 1980: Found in Western Hemisphere • 1992 and 1997: Florida-imported vector ticks

33. Economic Impact • Zimbabwe • US $5.6 million annual losses • Acaricide, milk loss, treatment cost • Serious threat to the United States • Caribbean Islands with infected ticks • Migratory cattle egrets • Susceptible cattle and deer population • 40% to 100% death in U.S. expected

34. Distribution

35. Geographic Distribution • Sub-Saharan Africa • The Caribbean Islands • Puerto Rico, Guadeloupe, Barbados, St. Vincent, Antigua, Marie, Galante • Not reported in Asia • U.S. has ticks that spread heartwater

36. Sickness/Death • Susceptible cattle, sheep, goats • Sickness: Approaches 100% • Death rate: • 80% in Merino sheep and Angora goats • 60% in cattle • 6% in Persian or Afrikander sheep

37. Transmission Spread of the rickettsia

38. Animal Transmission • Vector-borne • Amblyommaticks • Live 1-4 years • Each year on a different host • Develop to next stage • Egg- larvae – nymph - adult • 3 host tick • Once larvae, nymph infected,spread to next life stage Center for Food Security and Public Health Iowa State University 2006

39. Animal Transmission • Oral • Via colostrum- cow to calf • Vector spread - ticks • Wild ruminant reservoir • Blesbok • Wildebeest • Wild bird reservoir • Cattle egret • Helmeted guinea fowl

40. Animals with Heartwater

41. Affected Species • Severe disease • Cattle, sheep, goats, water buffalo • White-tailed deer (experimentally) • Mild disease • Indigenous African breeds of sheep and goats • Inapparent disease • Blesbok, wildebeest, eland, springbok

42. Clinical Signs • Time period from exposure to signs of disease: 14 to 28 days • Four forms of disease • Peracute- rare • Acute- most common • Subacute- rare • Mild or subclinical- calves

43. Clinical Signs: Acute • Most common form • Sudden fever (107oF) • Loss of appetite, depression, rapid breathing, respiratory distress • Nervous signs • Chewing movements, eyelid twitching, tongue protrusion, circling, high stepping gait, “moonstruck” • Death in 1 week

44. Clinical Signs: Subclinical • “Heartwater fever” • Asymptomatic • Fluctuating fever

45. Clinical Signs: Other Forms • Peracute- rare • Heavily pregnant cows • Sudden death • Fever, severe respiratory distress, convulsions, ± severe diarrhea • Subacute- rare • Prolonged fever, coughing, fluid in lungs, mild incoordination • Recovery or death in 1-2 weeks

46. EHRLICHIOSIS The Organism

47. The Organism(s) • Coccobacilli • Small, pleomorphic • Gram negative • Obligate intracellular • Three intracytoplasmic forms • Initial body • Elementary body • Morula

48. Zoonotic Species • Ehrlichia chaffeensis • Ehrlichia ewingii • Anaplasma phagocytophilum • Neorickettsia sennetsu • Ehrlichia canis (possibly)

49. Non-zoonotic Species • Ehrlichia bovis • Ehrlichia muris • Ehrlichia ondiri • Ehrlichia ovina • Ehrlichia ruminantium • Anaplasma platys • Neorickettsia risticii

50. Ehrlichial Diseases