Lecture 30

• Borerelia burgdorferi characteristics:


  -0.2-0.5 um wide and 3-20 um long

  -gram negative (stain poorly)
• Borerelia burgdorferi can be better visualized if stained with


  silver, Giemsa Wright's stains, or by dark field microscopy
• Borerelia burgdorferi are


  obligate pathogens in a variety of vertebrate hosts
• Borrelia are _____ and ______ than other spirochaetes

  longer; wider
• How are spirochetes transmitted and maintained?

  by ticks, obligate parasites in a variety of vertebrate hosts
• Lyme disease characteristics:


  -borrelia bungdorferi

  -tick borne

  -most prevalent vector borne disease in the northern hemisphere
• What is the arthropod vectors for B. burgdorferi?


  Ixodes scapularis and I. pacificus
• What is the arthropod vector for B. afzelii?

  I. ricinus
• What is the arthropod vector for B. garinii?

  I. persulcatus
• Lyme disease in humans, early localized stage (3-30 days post tick bite)


  -red, expanding rash: erythema migrans (EM)

  -Fatigue, chills, fever, headache, muscle and joint aches, and swollen lymph nodes
• Lyme disease in humans, early disseminated stage (days to weeks post tick-bite)

  -facial or Bell's palsy

  -severe headaches and neck stiffness

  -pains and swelling in the large joints (knees)

  -shooting pains that may interfere with sleep
• Lyme disease in humans, late disseminated stage (months to years post tick bite)


  -arthritis with severe joint pain and swelling

  -up to 5% of untreated patients may develop chronic neurological complaints months to years after infection
• Lyme disease in dogs


  -70-90% of all dogs in endemic areas are seropositive

  -clinical signs are observed in <10% of exposed dogs

  -clinical illness is seen 2-5 months after tick exposure

  -severity and propensity to develop signs of illness vary inversely with the animals immune status
• What are clinical syndromes of lyme disease in dogs

  polyarthritis and glomerulopathy
• Symptoms of lyme arthritis


  -fever

  -shifting leg lameness

  -articular swelling

  -polyarthritis

  -lymphadenomegaly

  -anorexia

  -general malaise
• Lyme nephritis


  -sudden onset of anorexia, vomiting, lethargy, and weight loss

  -uremia, hyperphosphatemia and severe protein losing nephropathy

  -lodging of immune complexes in kidneys
• What breed is commonly seen with lyme nephritis

  labrador, golden retrievers, bernese mountain dogs
• Lyme disease in horses

  50% of all horses in endemic areas are seropositive and clinical signs are observed in <10% of exposed horses
• Clinical signs of lyme disease in horses


  -chronic weight loss, sporadic lameness, shifting lef lameness, low-grade fever, muscle tenderness, chronically poor performance, swollen joints

  -changes in behavior and skin sensitivity, both with rapid onset

  -neurological signs- depression, dysphagia, head tilt and encephalitis were reported in chronic cases
• T or F: no specific hematologic or biochemical changes are pathogenomonic of borreliosis


  True
• If a dog in a lyme disease endemic area has leukopenia or thrombocytopenia, these hematologic changes are likely caused by infection or co-infection with a


  rickettsial pathogen
• Synovial fluids of lyme arthritic dogs have increased cell counts of _______ to __________ cells/ul with neutrophils predominating (up to 95%)

  5,000; 100,000
• Seropositivity =


  exposure
• Seropositivity does not necessarily mean?

  that the clinical illness is caused by the organism
• Serological assays:


  -whole cell ELISA and Immunoblot

  -C6 peptide based assays

  -Multiplex assay
• Whole Cell ELISA


  -Antibody measurements using whole spirochetes

  -IgG-ELISA positive titer by 4-6 weeks after exposure. Reach highest levels by 3 months and last for 2 years

  -Antigen preparations, techniques, and interpretations of different laboratories are not standardized

  -Cross-reactivity with Leptospira-positive sera and sera from other disease moieties
• Whole cell Immunoblotting


  -helps identify sera that produce false-positive results in whole spirochaete assays

  -After natural exposure, antibodies develop to proteins in the range of 58, 41, 39, and 23 kDa

  -In general, vaccinated dogs show reactivity to 31, 34, 28, and 93 kDa
• C6 peptide based assays


  -detect antibodies against C6 peptide, the invariable region the borrelial protein VIsE

  -can differentiate between vaccinated and naturally infected dogs

  -C6 does not react with sera from healthy dogs or infected with other infectious diseases
• Types of C6 peptide based commercial assays


  -SNAP 4Dx Plus Test

  -Lyme Quant C6 Test
• T or F: C6 antibody levels decline sharply after treatment

  True
• Treatment and control


  -Acute cases responds to beta lactams (such as amoxicillin) and tetracyclines (doxy)

  -Chronic cases require longer therapy

  -tick control

  -vaccines, bacterins and subunit vaccines

  -important tick borne diseases for humans
• Prevention by tick control (Dogs)


  -Collars (permethrin or amitraz)

  -Topical powders, shampoos (selamectin, fipronil, and permethrin)

  -Daily combing and tick removal

  -In the environment: tick control by targeting mice population
• Prevention by vaccines


  -Recombinant, subunit vaccine (OspA): RECOMBITEK Lyme (Merial)

  -Killed, whole-cell, bivalent bacterin (OspA, OspC): LYMEVAX (Zoetis), DURAMUNE Lyme (bi-vetmedica), and NOBIVAC Lyme (Merck)