Bacteriology Lecture 30 & 31

50% of all horses in endemic areas are seropositive; clinical signs are observed in <10% of exposed horses

Extensive sloughing of skin and tissues in progressed states; severe edema of the head of rams after infection

Titer reaches highest levels by 3m and last 2y; antigen preparations, techniques, + interpretations not standardized

d-w post bite; Facial or Bell's palsy; severe headaches + neck stiffness; pain + swelling in joints; shooting pains

Lyme disease is the most prevalent vector-borne disease in the Northern Hemisphere

Lesions are soft swellings that pit on pressure + extend rapidly b/c formation of large quantities of exudate in SQ/CT

Horses and pigs are susceptible to malignant edema but not to blackleg; important differential is anthrax

Longer and wider than other spirochaetes; gram negative (poor); spirochetes transmitted and maintained by ticks

Common in beef breeds that have excellent health and are gaining weight; 6-24m, but as young as 6w or as old as 10-12y

Sudden onset; dead w/out premonitory signs; acute, severe lameness, hind legs; marked depression; fever that resolves

RECOMBITEK Lyme (Merial) vxn

Acute, generally fatal toxemia affecting all species and ages of animals and is usually caused by Clostridium septicum

Diagnosis of Blackleg:

Poor performance; Changes in behavior and skin sensitivity, both w/ rapid onset; neurological signs in chronic cases

I. persulcatus -> rodents (Eurasia) -> lyme disease

Can be used for direct identification and differentiation of clostridia associated with malignant edema

Also found is C. chauvoei, C. perfringens type A, C. novyi type A, + C. sordellii

Can be used for direct identification and differentiation of clostridia associated with malignant edema

Malignant edema is also known as Gas gangrene

Edamatous and crepitant swellings in hip, shoulder, chest, back, neck; swelling is focal, hot, and painful

B. burgdorferi sensu stricto; B. garinii; B. afzelii

Treatment and Control of Lyme Disease:

Obligate pathogens in a variety of vertebrate hosts

Found naturally in intestinal tract; spores remain viable in soil for years; outbreaks w/ excavations + flooding

Prevention by tick control in dogs:

Helps identify sera that produce false-positive results in whole-spirochaete assays; vxn dogs react w/ 31, 34, 28, 93kDa

Clinical lab findings of Lyme disease:

A __ vaccine containing C. chauvoei, C. septicum, + C. novyi antigens is safe and reliable for cattle and sheep

Confirmed rapidly via __ of C. septicum from tissue smear; presence in animal dead for >24h is not significant

70-90% of all dogs in endemic areas are seropositive; clinical signs are observed in <10% of exposed dogs; illness vary

Ornithodoros spp.; cattle, deer; associated with epizootic bovine abortions

LYMEVAX (Zoetis); DURAMUNE Lyme (bi-vetmedica); NOBIVAC Lyme (Merek) vxns

Acute, febrile, highly fatal disease of cattle/sheep via C. chauvoei; emphysematous swelling + necrotizing myositis

Obligate parasites; infection have a blood-borne phase accompanied or followed by general and localized manifestations

Argas spp.; Birds; fever, weight loss, and anemia in domestic poultry

Sheep: result of wound infection; shearing cuts, docking; case fatality rate 100%; New Zealand -> more in sheep

Control of Blackleg:

Many tick species; cattle, sheep, horses; mild febrile disease with anemia

Antibody measurements using whole spirochetes; IgG-ELISA positive titer by 4-6 weeks after exposure

Sudden onset: anorexia, vomiting, lethargy, weight loss; uremia, hyperphosphatemia, + severe protein-losing nephropathy

Arthritis w/ severe joint pain + swelling; 5% -> chronic neurological complaints m-yrs later; numb, pain, memory loss

Serologic testing of Lyme disease:

Found in soil + intestinal contents; via contamination of wounds containing devitalized tissue, soil, or spores

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

Lodging of immune complexes in kidneys; labrador, golden retrievers, Bernese mountain dogs

Wounds caused by accident, castration, docking, insanitary vxn, + parturition; toxins cause systemic signs -> death

Ixodes spp.; rodents, birds, lizards; arthritic, neurological + cardiac disease in dogs/humans; horse, cattle, sheep

Tick control in environment by targeting mice population

C. chauvoei spores are oval, central to subterminal and bulge the motehr cell; citron "lemon-shaped" forms

Swelling enlarges; crepitation on palpation; cold + insensitive skin; decreased blood supply; prostration + tremors

Invariable region of borrelial protein VIsE; can diff. between vxn + naturally infected dogs; does not react w/ others

Assoc. w/ lacerations of the vulva @ parturition -> marked edema of vulva, severe toxemia, + death in 24-28h

Black leg is also known as Black Quarter

Death w/in 12-48h; cattle: lesions restricted to myocardium + diaphragm; abnormal breathing + pericardial friction rub

Ixodes scapularis, I. pacificus, I. ricinus, and I. persulcatus

Fever (103-105F); shifting leg lameness; articular swelling; polyarthritis; lymphadenomegaly; anorexia; general malaise

Local exotoxins -> excessive inflammation -> severe edema, necrosis, gangrene; horse/cow have dormant spores in muscles

SNAP 4Dx Plus Test; Lyme Quant C6 Test; levels decline sharply after treatment

Cattle: endogenous infection; lesions w/out any history of wound, bruising/excessive exercise may precipitate disease

Ixodes scapularis -> rodents (east, midwest USA); I. pacificus -> rodents (western USA); both -> lyme disease

Chronic weight loss, sporadic lameness, shifting leg lameness, low-grade fever, muscle tenderness, swollen joints

Cross-reactivity with Leptospira-positive sera, and sera from other disease moieties

Clinical illness is seen 2-5m after exposure; clinical syndromes - polyarthritis and glomerulopathy

I. ricinus -> rodents, birds (Europe) -> lyme disease

0.2-0.5um wide and 3-20um long; gram negative (stain poorly); visualized w/ silver, Giemsa, Wright's, or darkfield

Ingested, pass through wall of GIT -> bloodstream -> muscle + other tissues (spleen, liver, GIT) -> dormant

Anorexia, fever; local lesions w/in 6-48h; muscle is dark brown/black; accumulations of gas in SQ tissue + muscle fascia

Treatment and Control of Malignant Edema:

3-30d post bite; Red, expanding rash: erythema migrans (EM); fatigue, fever, headache, muscle + joint aches, swollen LN