Leptospirosis

•Most common zoonosis worldwide.

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

•smallest spirochete bacteria

(0.1 µm x 6-30 µm)

•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 – 1^st 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