A practical review of leptospirosis (Proceedings) - Veterinary Healthcare
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A practical review of leptospirosis (Proceedings)


CVC IN SAN DIEGO PROCEEDINGS


Leptospirosis

•Most common zoonosis worldwide.

•Bacterial disease caused by pathogenic Leptospira species affecting domestic animals, wildlife, and humans.

Leptospira

•smallest spirochete bacteria

(0.1 Ám x 6-30 Ám)

•tightly coiled

•pointed ends which are bent into distinctive hooks

•gram negative

•Does not stain well!

•motile

•spirochetes - typical double membrane structure

•Cytoplasmic membrane and peptidoglycan cell wall are closely associated and overlain by an outer membrane

•Leptospiral lipopolysaccharide

•composition similar to other gram-negative bacteria, but lower endotoxic activity

•Surface protein/outer membrane proteins (OMPs)

•Lipopolysaccharides (LPS) and lipoproteins

•LPS – highly immunogenic, responsible for

serovar specifity

Cornell and Gluck are looking at these surface proteins to help improve serologic testing

ENVIRONMENT

•Leptospira in rivers, lakes, and sewage.

•Heat (>93 F) and Cold (< 50 F)

•Detrimental to the organism

•Alkaline Soil

•> 8 or < 6 pH not suitable for survival

•Soil contaminated with urine

•~ 2 weeks (RATS or VOLES)

•~ 7 weeks (New Zealand Winter)

PATHOGENESIS

•Increased prevalence during rainy periods in spring and fall.

•TEMPERATURES:

• September 23 – November 3 Average temp was >65 compared to ↓ 65 baseline year(Dr. Hall Thesis 2005)

•Host-adapted - most common reservoirs are raccoon, skunk, deer, cattle, swine, and rats.

•Equine - adapted host – Bratislava

• Never isolated from the horse but high titers (Persistent)

•Exposure occurs when horses consume contaminated groundwater that contains urine shed from a host-adapted species.

•Leptospira are able to penetrate mucous membranes and abraded skin.

•Rapidly gain access to vascular space.

•Bacteremia persists for about 8 days.

•FEVERS 103-106 F 7-9 days after exposure (US Livestock Sanitary Assoc- Morter et al, 1964, JAVMA 1969)

•Invasion of many internal organs occurs.

•No Tropism

•The infection induces a strong host antibody response – 1st detectable in serum 4-8 days after exposure. (US Livestock Sanitary Assoc- Morter et al, 1964, JAVMA 1969)

•Maintain for up to 7 years (Swart Aus Vet J 1982)

•Organisms are eliminated rapidly from the blood and most organs by host mechanisms – TH2-response.

•Interferon Gamma

•Localization of organisms may occur in :

•Genital tract

• Renal tubules


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Source: CVC IN SAN DIEGO PROCEEDINGS,
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