Spirichetes

• Pirochetales includes four genera of veterinary importance: Treponema, Brachyspira, Leptospira, and Brevinema.
• Treponema includes species such as Treponema paraluis-cuniculi and Treponema brennaborense.
• Borrelia includes species such as Borrelia burgdorferi and Borrelia anserina.
• Brachyspira, formerly known as Treponema and then Serpulina, are anaerobes that include species such as Brachyspira hyodysenteriae.
• Leptospira includes serovars of Leptospira interrogans.
• Other genera of Pirochetales include Cristispira, Leptonema, Spirochaeta, and Brevinema.
• Pirochetales are characterized by being slender, spiral, round, actively motile, "gram-negative", and have an outer sheath (OS) that acts as a unit membrane covering the protoplasmic cylinder (PC).
• In a previous study, a group of strongly haemolytic isolates from pigs and mallards was provisionally described as a new species within genus Brachyspira, "Bsuanatina", and enteropathogenic properties were demonstrated in a porcine challenge model.
• The genus Brachyspira currently encompasses seven valid species that colonize the intestines of mammals and birds.
• Symptoms of Spirochete Disease may include diarrhea and wasting.
• Spirochete Disease is characterized by an overgrowth of spirochetes.
• Infections may occur in wild animals, humans, non-human primates, and particularly dogs, pigs, and birds, with infections in birds in the U.S increasing.
• Spirochetes attach to the intestinal wall and cause erosion of the epithelial layer, hyperplasia, and depletion of goblet cells.
• These species occur in the GI tracts of various animals and may cause disease (chronic mucoid diarrhea and wasting) or be asymptomatic.
• The axial filament (AF) of Pirochetales is inserted through a proximal hook and runs along the PC and under the OS, providing motility along a helical path through rotation around the long axis and flexation.
• Pirochetales may be aerobic, microaerophilic, or anaerobic and are identified by morphology and antigenic properties.
• Pirochetales are gram-negative, but too narrow to stain well by Gram stain.
• Pirochetales can be observed by darkfield, phase contrast, immunofluorescence or stains that make them thicker (silver impregnation).
• A 6-year-old, spayed female soft-coated wheaten terrier was presented to the Companion Animal Hospital of the Atlantic Veterinary College for investigation of undefined right front leg lameness, generalized peripheral lymphadenomegaly, decreased appetite, and weakness reported to be of 2 to 3 wk duration.
• The dog had lived in the province of Prince Edward Island except for a history of travel to Ontario, Canada, 1 y prior to presentation.
• Routine vaccinations were up-to-date.
• Physical examination showed that the dog had a dull, thin hair coat, pain upon palpation of the right elbow joint, and mild, palpable generalized lymphadenomegaly.
• Prevent exposure to ticks is the best way to prevent Lyme disease in cattle.
• Borrelia theileri is responsible for a mild febrile anemia of horses, cattle, and sheep in South Africa and Australia (bovine borreliosis).
• CNS infection in cattle may occur with cervical pain, seizures, and rarely, myocarditis.
• It may take 2-5 months after a tick bite for symptoms of Lyme disease to appear in cattle.
• Dogs may undergo asymptomatic spirochetemia, acting as carriers.
• Renal disease and arthritis may occur in cattle.
• Animals may also be a source of ticks.
• IDEXX SNAP 3DX® tests for Heartworm, Ehrlichia canis, and B. burgdorferri.
• Clarithromycin and erythromycin are also effective in treating Lyme disease in cattle.
• Treatment for Lyme disease in cattle includes tetracycline/doxycycline or amoxicillin for at least 10-14 days, with ceftriaxone (Rocephin) antibiotic added in chronic cases.
• Isolation and identification of B. burgdorferi can be done using modified Kelly medium.
• Episodes of lameness in cattle occur at intervals of 1 month to 1 year.
• Commercial Subunit vaccines are more useful for Lyme disease, directed to OspA, and the vaccine in humans was withdrawn in 2002 due to concerns raised by anti-vaccine groups regarding vaccine safety, vaccine cost, a difficult vaccination schedule and the potential need for boosters, class action lawsuits, uncertainty regarding risk of disease, and low public demand.
• IFA, ELISA, and Western blot are used for serology in cattle.
• Serology is more reliable than staining or isolation for diagnosing Lyme disease in cattle.
• Infections in cattle can be diagnosed through history, clinical signs, and testing of tissues and fluids.
• Blood, CSF, joint fluid, and urine are tested for Lyme disease using PCR if available.
• Serum biochemistry showed a mild increase in total protein concentration [72 g/L; reference interval (RI): 56 to 71 g/L], hypoalbuminemia at 18 g/L (RI: 30 to 36 g/L), and a hyperglobulinemia at 54 g/L (RI: 25 to 38 g/L).