Borrelia burgdorferi 2018 Flashcards
Where was Borellia burgdorferi cultured the most from in ponies that had been exposed and neropsied 9 months later?
Organism was cultured from the skin near the tick bite, as well as from connective tissue, muscle and around nerves and blood vessels near synovial membranes.
Some ponies also showed mild, nonsuppurative synovitis, perineuritis or meningitis.
What are the two types of ticks, and their region, that help maintain Borrelia burgdorferi.
Ixodes scapularis is the tick found in eastern North America
Ixodes pacificus is the thick found on the North American west cost.
What are reservoirs for Borrelia burgdorferi?
White footed mice in the east and gray squirrels in the west are common reservoir hosts for the spirochete. Deer and other large wild mammals help maintain the adult tick.
Why does it take several hours after tick attachment to successfully transfer Borrelia burgdorferi to the mammalian host?
B. burgdorferi needs to down-regulate outer membrane lipoprotein OspA. This helps the organism stay alive in the tick gut, and to be transferred to the host.
After transmission to the host, what is up-regulated and important for immune evasion and persistence of infection?
Variable major protein-like sequence expressed (VLsE) protein has invariant and variable regions, of which the variable regions contribute to immune evasion.
List the tests available for diagnosing B. burgdorferi. Which of these can distinguish between infection stages or between natural infection and vaccination?
Indirect fluorescent Ab test (IFAT)
ELISA whole cell
Western blot (WB)
Bead-based multiple antigen ELISA (Multiplex)
WB and Multiplex are able to assist in determining between acute and chronic infection, as well as vaccination status.
IFAT and ELISA do not distinguish between infection stages or between natural infection and vaccination. False positive results can cross react with Abs against common bacterial Ags such as flagellar proteins, thus requiring confirmation by WB.
What are some reasons for prolonged positive serology to B. burgdorferi, in horses that have been treated with antimicrobials?
- Persistence of infection
2. Continued IgG production against Borrelia antigens after elimination of the organisms
What does a positive test for B. burgdorferi mean?
Positive indicates presence of Abs against organism and may represent different infection stages depending on the test used. If positive in absence of previous vaccination, indicates exposure from either a current or previous infection.
When are OspA antibodies elevated, when found in horses suspected to have B. burgdorferi?
OspA Abs are commonly assoc. with prior vaccination, but a small number of unvacc. horses have persistently high OspA Ab levels.
What are the best documented, naturally occurring syndromes attributed to B. burgdorferi infections?
Neuroborreliosis, uveitis and cutaneous pseudolymphoma
List some clinical signs of neuroborreliosis.
Atrophy of spinous muscle, dysphagia, laryngeal dysfunction resulting in respiratory disease, facial paresis, spinal cord ataxia and paresis, behavioral changes, hyperesthesia, fasiculations, neck and back stiffness with pain
Describe pseudolymphoma in horses caused by B. burgdorferi.
Dermal, papular to nodular lesions that occurred at the site of the tick bite. IHC reveals mixed lymphoid hyperplasia.
How does B. burgdorferi cause stiffness and lameness in horses?
There is little research or overt clinical data to document generalized lameness and stiffness as an equine Lyme disease syndrome. The organism is commonly found in synovial membranes after equine experimental infection. Lameness could be attributed to neuroborreliosis or to lymphocytic-histiocytic and plasmacytic inflammation of the deep dermis, muscle and the panniculus.
What are some differential diagnoses for neuroborreliosis?
EPM, viral encephalitis, radiculoneuritis
What is the most common histopathologic lesion of Lyme disease?
Lymphohistiocytic and plasmacytic infiltrate
