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A Brief Review of Ticks and Tick-Borne Diseases ...with a little radiology

A Brief Review of Ticks and Tick-Borne Diseases ...with a little radiology. Billy MacDonald. Ticks. Class Arachnida closely related to mites. Ticks. Class Arachnida closely related to mites obligate blood-feeding ectoparasites vectors. Ticks of Veterinary Importance. Ixodidae.

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A Brief Review of Ticks and Tick-Borne Diseases ...with a little radiology

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  1. A Brief Review of Ticksand Tick-Borne Diseases...with a little radiology Billy MacDonald

  2. Ticks • Class Arachnida • closely related to mites

  3. Ticks • Class Arachnida • closely related to mites • obligate blood-feeding ectoparasites • vectors

  4. Ticks of Veterinary Importance Ixodidae Argasidae unsclerotized “soft ticks” • sclerotized dorsal shield • “hard ticks”

  5. Ticks of Veterinary Importance Ixodidae Argasidae unsclerotized “soft ticks” little sexual dimorphism • sclerotized dorsal shield • “hard ticks” • sexually dimorphic • females larger • male scutum covers dorsum

  6. Ticks of Veterinary Importance Ixodidae Argasidae live in close proximity to host mate off host require mins - hrs to feed and feed repeatedly live in dwelling/sleeping places of hosts • primarily off host • “sit-and-wait” • mate on host • require days to complete engorgement • live outdoors

  7. Tick Pathogenesis • anemia • heavy infestations

  8. Tick Pathogenesis • anemia • dermatosis • inflammation, swelling, itching, ulceration from tick’s saliva and mouthparts

  9. Tick Pathogenesis • anemia • dermatosis • paralysis • neurotoxin present in saliva of some species Dermacentor sp.

  10. Tick Pathogenesis • anemia • dermatosis • paralysis • vector-borne diseases • viral, bacterial, and protozoal

  11. Tick-borne Viral Diseases • Colorado tick fever rodents Dermacentor human

  12. Tick-borne Viral Diseases • Colorado tick fever rodents Dermacentor human • tick-borne encephalitis humans, cattle, horses, dogs

  13. Tick-borne Viral Diseases • Colorado tick fever rodents Dermacentor human • tick-borne encephalitis humans, cattle, horses, dogs • African swine fever wild suids Ornithodorus pig

  14. Tick-borne Rickettsial Diseases • Rickettsia rickettsii RMSF rabbits, rodents Dermacentor dogs, humans

  15. Tick-borne Rickettsial Diseases • Rickettsia rickettsii • Anaplasma sp. bovine anaplasmosis: cattle Dermacentor canine anaplasmosis: rodents, ruminants, dogs Ixodes

  16. Tick-borne Rickettsial Diseases • Rickettsia rickettsii • Anaplasma sp. • Ehrlichia sp. canine ehrlichiosis dogs, white-tail deer Rhipicephalus

  17. Tick-borne Rickettsial Diseases • Rickettsia rickettsii • Anaplasma sp. • Ehrlichia sp. obligate intracellular parasites

  18. Tick-borne Rickettsial Diseases • Rickettsia rickettsii • Anaplasma sp. • Ehrlichia sp. • Coxiella burnetti...no longer grouped with Rickettsia • Q fever obligate intracellular parasites

  19. Tick-borne Bacterial Diseases • Borrelia sp. Lyme disease bovine borreliosis avian spirochetosis

  20. Tick-borne Bacterial Diseases • Borrelia sp. • Mycoplasma haemocanis canine hemoplasmosis dogs Rhipicephalus

  21. Tick-borne Bacterial Diseases • Borrelia sp. • Mycoplasma haemocanis • Francisella tularensis tularemia rabbits various ticks humans, dogs

  22. Tick-borne Protozoal Diseases • Hepatozoon canis Rhipicephalus dog

  23. Tick-borne Protozoal Diseases • Hepatozoon canis • Babesia sp. bovine, canine, feline babesiosis, equine piroplasmosis Rhipicephalus

  24. Tick-borne Protozoal Diseases • Hepatozoon canis • Babesia sp. • Cytauxzoon felis wild felids Dermacentor cats

  25. Lyme Disease...a closer look Ixodes pacificus Ixodes scapularis

  26. Lyme Disease...a closer look etiologic agent: Borrelia burgdorferi white-footed deer mouse Ixodes sp. humans, dogs, cattle, horses

  27. clinical signs...in dogs • fever, anorexia, malaise • lymphadenomegaly • shifting leg lameness • sudden onset • painful articular swelling • *nonerosive polyarthritis • pathologic changes in the joints are progressive • rarely: renal disease (glomerulonephritis), neurological disease

  28. diagnosis • clinical lab findings • inflammatory changes in synovial fluid • serology • ELISA detects antibodies to B. burgdorferi • Isolation • culture is most definitive...but also most difficult due to limited number of organisms present • PCR

  29. treatment • antibiotic therapy • for arthritis: doxycycline, amoxicillin, azithromycin • for neurological manifestations: cefotaxime, chloramphenicol • vaccines

  30. Hepatozoonosis...a closer look • etiologic agent: • Hepatozoon canis...an intracellular parasite in various tissues • transmitted via ingestion of infected tick (Rhipicephalus sanguineous)

  31. dog ingests tick

  32. dog ingests tick sporozoites in GI tract circulation striated muscle

  33. dog ingests tick sporozoites in GI tract circulation striated muscle “onion skin” cyst in skeletal muscle

  34. dog ingests tick sporozoites in GI tract circulation striated muscle “onion skin” cyst in skeletal muscle asexual reprod. (merogony) merozoites released into surrounding tissues severe inflamm. reaction neutrophilic granuloma formation ~ 4 weeks...parasite infected neutrophils (gamonts) present in peripheral blood

  35. Hepatozoonosis...a closer look • etiologic agent: • Hepatozoon canis...an intracellular parasite in various tissues • transmitted via ingestion of infected tick (Rhipicephalus sanguineous) • clinical signs: • fever, anorexia, weight loss, diarrhea...wax and wane • diagnosis: • CBC, Biochem.: non-specific inflammation • UA: +/- proteinuria • muscle biopsy for definitive diagnosis • treatment: • symptomatic: NSAIDs

  36. Hepatozoonosis via radiology? Periosteal proliferation on the femur, tibia, pelvis and lumbar vertebrae of a dog infected with H. canis

  37. Hepatozoonosis via radiology? Periosteal proliferation on the femur, tibia, pelvis and lumbar vertebrae of a dog infected with H. canis ...lesions resemble HO

  38. Hepatozoonosis via radiology? Periosteal proliferation on the femur of a dog infected with H. canis

  39. Hepatozoonosis via Bone Scan Skeletal lesions in a dog infected with H. canis (americanum)

  40. References • Craig, T.M. 1998. Hepatozoonosis, pp 458-465, In: Infectious Diseases of the Dog and Cat, 2nd Edition; Craig E. Greene (Ed), W.B. Saunders, Pennsylvania. • Greiner, E.C. 2006. Diagnosis of arthropod parasites, pp 185-263, In: Veterinary Clinical Parasitology, 7th Edition; Anne M. Zajak and Gary A. Conboy (Eds), Blackwell Publishing, Iowa. • Holman, P.J., and K.F. Snowden. 2009. Canine hepatozoonosis and babesiosis, and feline cytauxzoonosis. Vet Clin Small Anim 39: 1035-53. • Little, S.E. 2009. Vector-borne diseases, pp 240-253, In: Georgis’ Parasitology for Veterinarians, 9th Edition; Dwight D. Bowman (Ed), Saunders Publishing, Missouri. • Panciera, R.J., Mathew, J.S., Ewing, S.A., Cummings, C.A., Drost, W.T., and A.A. Kocan. 2000. Skeletal lesions of canine hepatozoonosis caused by Hepatozoon americanum. Vet Pathol 37: 225-230. • Shaw, D. and S. Ihle. 2006. Joint diseases, pp 439-450, In: Small Animal Internal Medicine; Shaw, D. and S. Ihle (Eds), Blackwell Publishing, Iowa.

  41. Questions??

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