Top 10 Tick-borne Dz pt. 1

*

Cytauxzoonosis, carried by bobcats, has spread to more than 14 states since it was first discovered in Missouri in 1976.


*

Cattle infected with anaplasmosis average $300 million per year to treat in the U.S.

Zuku's Top 10 Tick-borne Diseases To Know For NAVLE® Success: Part 1

  1. Lyme borreliosis

    The white-footed mouse is the preferred host for larval Ixodes ticks and is the major reservoir of B. burgdorferi

    A vial of juvenile deer ticks (Ixodes scapularis ) next to a penny—Ixodes spp. are the vectors for Lyme borreliosis

    Photomicrograph of B. burgdorferi bacterium

    • Classic case:
      • Canine:
        • Usually asymptomatic
        • Lyme arthritis:
          • Lethargy, anorexia
          • Fever
          • Lymphadenopathy
          • Joint pain +/- swelling
        • Lyme nephropathy:
          • Labrador retrievers, golden retrievers, and Shetland sheepdogs may be predisposed
          • Peripheral edema or ascites
          • Dyspnea
          • Retinal detachment or hemorrhage secondary to hypertension
          • Paraparesis with cool pelvic limbs and loss of femoral pulses due to saddle thrombus
      • Equine: 3 documented syndromes
        • Uveitis
        • Neuroborreliosis:
          • Ataxia
          • Cranial nerve deficits
          • Poor tongue tone
          • Muzzle tremors
        • Pseudolymphoma
        • Unproven, but often diagnosed: Classic Lyme borreliosis
          • Muscle atrophy
          • Spooking
          • Anorexia, weight loss
    • Dx:
      • Etiology:
        • Borrelia burgdorferia sensu stricto (spirochete)
        • Tick vectors: Ixodes spp.
        • Reservoir: White-footed mouse
        • Pathogenesis is thought to be immune-mediated
      • Canine:
        • SNAP-4Dx Plus test for C6 peptide that indicates natural exposure
        • Lyme nephropathy:
          • Hypoalbuminemia
          • Hypercholesterolemia
          • Proteinuria with microalbuminuria
          • Elevated protein/creatinine ratio
          • +/- Glucosuria
          • +/- Hyperphosphatemia
          • +/- Azotemia
          • +/- Anemia
          • +/- Thrombocytopenia
      • Equine:
        • CSF-serum ratio using Lyme multiplex (detects 3 different antibodies) is sometimes suggestive but only post-mortem is definitive
        • Serology:
          • Lyme multiplex is best option
          • C6 ELISA antibody test is also used; lots of false positives and negatives
          • Serology alone (positive or negative) is not diagnostic as it only indicates exposure
    • Rx:
      • Canine:
        • Do not treat dogs with positive titers if asymptomatic
        • Doxycycline or amoxicillin for 28 d
        • Immunosuppression may be necessary
        • Lyme nephropathy:
          • ACE inhibitor (e.g., enalapril or benazepril)
          • Low-dose aspirin
          • Omega-3 fatty acids
        • Click here for information on tick prevention
      • Equine: Doxycycline or minocycline
    • Pearls:
      • Prognosis:
        • Canine:
          • Lyme arthritis: Good
          • Lyme nephropathy: Guarded to poor
        • Equine:
          • Uveitis: Poor
          • Neuroborreliosis: Poor
          • Pseudolymphoma: Good
      • In dogs, co-infection with anaplasmosis, Rocky Mountain spotted fever, ehrlichiosis, and leptospirosis is common
      • Vaccination is controversial because of possible immune-mediated sequelae
      • Many horses around the U.S. have been exposed and most do not show clinical signs
      • Click here to see CDC's FAQ for Lyme disease in humans

  2. Anaplasmosis

    A. phagocytophilum morulae in neutrophils (arrows)

    Inclusion bodies due to A. centrale in a blood smear from a cow—A. centrale causes similar, but milder signs as A. marginale (inclusion bodies due to A. marginale are seen at the periphery of the erythrocytes)

    • Classic case:
      • Canine:
        • Seen often in Labrador and golden retrievers
        • Lethargy, anorexia
        • Lameness, reluctance to walk, joint swelling of carpi and stifles
        • Fever
        • Splenomegaly
        • Mild lymphadenopathy
        • +/- Epistaxis, petechiae, other hemorrhages
      • Equine: (a.k.a. "equine granulocytic ehrlichiosis")
        • More severe in older horses
        • Fever
        • Depression
        • Reluctance to move
        • Peripheral edema
        • Petechiae or ecchymoses
        • Ataxia
        • Icterus
      • Bovine:
        • More severe in older cattle
        • Loss of condition and milk production
        • Weakness
        • Pale or icteric mucous membranes
        • Abortion
    • Dx:
      • Canine:
        • Etiology:
          • Anaplasma phagocytophilum (also affects cats, humans, and other animals)
          • Main vectors are deer ticks (Ixodes spp.)
        • Thrombocytopenia
        • Reactive lymphocytes
        • Arthrocentesis and buffy coat smears may reveal neutrophils with cytoplasmic morulae
        • Paired IFA titers with 4X increase
        • SNAP 4Dx Plus (in-clinic ELISA test) may detect antibodies to A. phagocytophilum
        • PCR may be negative in chronic carriers
      • Equine:
        • Etiology:
          • A. phagocytophilum
          • Main vectors are Ixodes spp.
        • Cytoplasmic morulae in neutrophils on blood smear
        • PCR of whole blood or buffy coat
        • Paired IFA titers with 4X increase
      • Bovine:
        • Etiology:
          • A. marginale
          • Main tick vectors in U.S. are Dermacentor spp.; horse flies are another major vector
        • Anemia
        • Giemsa-stained blood smears reveal dark blue inclusions on periphery of erythrocyte (click here to see photomicrograph of A. marginale)
        • Msp5 ELISA, CF, card agglutination may identify carriers
    • Rx:
      • Canine:
        • Doxycycline (or minocycline) for 4 wks
        • NSAIDs if necessary (most respond to antibiotics within 2 d)
      • Equine:
        • Oxytetracylcine for 8 d
        • +/- NSAIDs and/or short-term corticosteroids
      • Bovine:
        • Single injection of long-acting oxytetracycline (give a second injection after 1 wk to eliminate carrier state)
        • Blood transfusion may be necessary
      • Prevention: Tick control
    • Pearls:
      • Good prognosis in dogs and horses with prompt treatment
      • Dogs may be co-infected with other tick-borne organisms
      • Recovered horses develop long-term immunity
      • 30% of cattle infected in a naive herd will usually succumb to the disease

  3. Cytauxzoonosis (bobcat fever)

    Bobcats are the primary host for C. felis

    Life cycle of C. felis. Published in Tarigo, et al. (2013)—A Novel Candidate Vaccine for Cytauxzoonosis Inferred from Comparative Apicomplexan Genomics. PloS one. 8. e71233. 10.1371/journal.pone.0071233

    • Classic case:
      • Outdoor cats, predominantly in south central and southeast U.S.
      • In the past has been highly fatal, but increased survival in recent years
      • Biphasic waves of infection March-June, then August and September
      • Acute anorexia, lethargy
      • Fever
      • Hepatosplenomegaly
      • Dyspnea
      • Pale mucous membranes
      • Icterus
      • Seizures, yowling, coma
      • Death in a few days if untreated
    • Dx:
      • Etiology:
        • Cytauxzoon felis
        • Host: Bobcat (Lynx rufus )
        • Tick vectors: Amblyoma americanum or D. variabilis
      • CBC:
        • Leukopenia with toxic neutrophils
        • Thrombocytopenia
        • Normocytic, normochromic anemia
      • Serum chemistries:
        • Hyperbilirubinemia
        • Hypoalbuminemia
        • Hyperglycemia
      • Bilirubinuria
      • Coombs' test positive
      • Cytology of blood smear or aspirate of bone marrow, lymph node, liver, or spleen:
      • PCR confirms infection
    • Rx:
      • IV fluids, blood transfusion (or packed RBCs or polymerized hemoglobin)
      • Oxygen
      • Avoid stress (feeding tube may help for medicating as well as nutrition)
      • Antiprotozoal therapy: Atovaquone and azithromycin combination is ideal
      • Doxycycline if co-infections with other tick-borne diseases
      • Antiinflammatories (e.g., meloxicam) if not azotemic
      • Heparin for DIC
      • Prevention:
        • Keep cats indoors in areas with bobcats
        • Tick prevention may help, but not always successful
      • Click here for more guidelines for treatment and prevention
    • Pearls:
      • Prognosis:
        • A 65% survival rate was seen with aggressive treatment in experimentally infected cats
        • Prognosis is extremely poor if hypothermic, icteric, severely anemic, or nonambulatory
        • Survivors may develop immunity

  4. Babesiosis

    Several pairs of B. canis vogeli trophozoites in erythrocytes (arrow) in a Giemsa-stained blood smear from a dog with babesiosis

    Pair of B. bovis trophozoites in an erythrocyte (arrow) in a Giemsa-stained blood smear from a cow

    • Classic case:
      • Canine:
        • Mild to severe illness
        • Fever
        • Weakness, lethargy
        • Anorexia
        • Pale or icteric mucous membranes
        • Splenomegaly
        • +/- Lymphadenopathy
      • Bovine:
        • Fever
        • Anorexia
        • Weakness
        • Reluctance to move
        • Pale mucous membranes (+/- icterus)
        • Tachycardia
        • Abortions
        • +/- Neurologic signs: Bruxism, ataxia, behavioral changes (Babesia bovis only)
      • Equine:
        • Fever
        • Depression
        • Weakness, exercise intolerance
        • Anorexia
        • Pale or icteric mucous membranes
        • Petechiae
        • Colic
        • Sudden death
        • Asymptomatic carrier state
    • Dx:
      • Canine:
        • Etiologies: Protozoan
          • B. canis vogeli :
            • Large babesia
            • Greater risk in greyhounds
          • B. gibsoni :
            • Small babesia
            • Greater risk in American pit bull terriers and Tosa Inus
          • Transmission of either type:
            • Blood (dog fights, blood transfusions, contaminated needles or surgical instruments)
            • Ticks (Rhipicephalus or Dermacentor spp.)
            • Vertical transmission
        • PCR
        • CBC:
          • Thrombocytopenia
          • Visible organisms on Giemsa-stained blood smear
          • +/- Regenerative anemia
        • Serum chemistries: Hyperglobulinemia, +/- bilirubinemia
        • Coombs' test positive
        • Radiography: Splenomegaly
        • Serology (IFA greater than 1:64)
      • Bovine:
        • Etiologies:
          • B. bigemina and B. bovis (more severe)
          • Most common tick vectors are Rhipicephalus spp.
        • CBC:
          • Anemia
          • Visible organisms on Giemsa-stained blood smear
          • Hemoglobinemia more often seen with B. bigemina
        • Serology (IFA or ELISA)
        • Necropsy:
          • Marked splenomegaly (dark and friable)
          • Darkened kidneys
      • Equine:
        • Etiologies:
          • B. caballi or Theileria equi
          • Spread by various tick vectors, other blood contamination
        • See intracellular parasites in erythrocytes on blood smears
        • Serology
        • PCR
    • Rx:
      • Canine:
        • Anemia: Blood transfusion or hemoglobin polymer
        • B.canis vogeli : Imidocarb (pretreat with atropine)
        • B. gibsoni : Atovaquone and azithromycin combination
        • IV fluids
      • Bovine:
        • Diminazene
        • Imidocarb
        • Blood transfusion for anemia
        • Antiinflammatories
        • IV fluids
      • Equine:
        • Imidocarb: Difficult to clear carrier state
        • Blood transfusion
        • Intranasal oxygen
    • Pearls:
      • Canine:
        • Prognosis: Good with early treatment
        • Has not been documented as zoonotic
        • Dogs may be co-infected with other tick-borne organisms from the same tick
      • Equine:
        • REPORTABLE
        • Considered a foreign animal disease with rare outbreaks in U.S.
      • B. divergens is most common cause of human babesiosis and is very serious in splenectomized individuals

  5. Ehrlichiosis

    German shepherds are predisposed to a more severe form of ehrlichiosis

    Giemsa-stained blood smear showing an E. canis morula in a macrophage; this dog also happened to be co-infected with babesiosis

    • Classic case:
      • Mostly dogs, rarely cats or humans
      • German shepherds are predisposed to a more severe form of disease
      • Lethargy
      • Anorexia, severe weight loss
      • Hemorrhages (epistaxis, petechiae, ocular hemorrhage)
      • Fever
      • Lymphadenopathy
      • Splenomegaly
      • Arthritic lameness
      • Neurologic signs (cerebellar signs, paresis, depression)
      • PU/PD secondary to glomerulonephritis
    • Dx:
      • Etiology:
        • Ehrlichia canis
        • Tick vector: Rhipicephalus sanguineus
        • Incubation is 1-3 wks
        • Can also be transmitted via blood transfusion
      • CBC:
        • Thrombocytopenia very common (90% of cases)
        • Anemia
      • Serum chemistries:
        • Hyperglobulinemia (sometimes monoclonal)
        • Elevated liver enzymes
        • Azotemia
        • Hypoalbuminemia
      • Buffy coat smear may show morulae in mononuclear cells (seen in less than 5% of infected dogs)
      • Serology: IFA with 4X increase 2-4 wks apart
      • In-house SNAP test may be positive in clinically normal cases
      • PCR (may be negative in chronic cases)
    • Rx:
      • Treat SNAP positive animals if clinical signs and lab results indicative of ehrlichiosis (treat ALL German shepherds regardless of clinical appearance)
      • Doxycycline or minocycline for 4 wks is best
      • Imidocarb and enrofloxacin are NOT effective treatments
      • Prevention: Tick removal and tick control
    • Pearls:
      • Prognosis:
        • Good for most cases and improvement usually occurs within a day or two
        • Guarded in hemorrhagic dogs
        • Grave with pancytopenia
      • Co-infection with Anaplasma spp. or Babesia spp. may occur

Images courtesy of CDC/NCID (A. phagocytophium ), Charles Homler (white-footed mouse), Summer M. Tribble (bobcat kittens at top), Keith Kissel (bobcat), NIAID (juvenile ticks next to penny), Artem Asanov (German shepherd), Richard Bartz (engorged castor bean tick), CDC (B. burgdoerferi and I. scapularis life stages), and Alan R Walker (A. centrale , B. canis vogeli , B. bovis , and E. canis ).