4. Leptospirosis

What is leptospirosis?

Zoonotic disease by **genus Leptospira**

What type of bacteria are Leptospira?

Spirochetes are gram-negative, motile, spiral bacteria characterized by the presence of endocellular flagella enclosed by an envelope

What is the aetiology of leptospirosis?

***Leptospira interrogans*** – serovars: icterohaemorrhagiae, canicola, Pomona, sejroe

* *23 serogroups with 200 servoars* 

*Leptospira biflexa.* – not medically important

How well can Leptospira survive in the environment?

Low resistance in outer conditions, these bacteria are susceptible to desiccation, but **survives well in water**. Often seen fishermen and swimmers it is a professional disease that shows **natural focality**.

What is the epizootiology of Leptospirosis?

Outbreaks of Leptospira is characterized by seasonality and natural foci

Humans become infected through contact with **water, food, or soil** that contains **urine** from infected animals. **Dogs are most affected**. Leptospirosis in cats is rare and appears to be mild.

What are the hosts of Leptospira?

**Dogs,** pigs, cattle, domestic animals, human. **Reservoir – rodents**

How is Leptospira transmitted?

**Direct contact, ingestion (mainly drinking water), veneral/ placental, bite wounds, intact skin, milk**

* mucous membranes (or skin with any wound) meet infected urine, urine-contaminated soil, water, food, or bedding.
* Leptospirosis also transmits via the semen of infected animals. 

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Rodent is an important reservoir (ictero., sejroe, grippotyphosa, Bratislava) but dog for canicola

What is the pathogenesis of leptospirosis?

Entrance 🡪 replication in blood (leptospiraemia) 🡪 replication in nephrons (bacteremia, **hemolysin,** hemoglobinuria, renal failure, liver failure, icterus)

* **High Ab titer**: do not show any signs of illness 
* **Moderate Ab titer**:  mild and transient illness and recover spontaneously 🡪Mild kidney damage 🡪 persistent infection
* **Low or no Ab titer**: severe illness and death due to kidney and liver damage🡪 icterus

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Immunity to one serotype does not confer immunity to another

How long is the incubation period for leptospirosis?

7-14 days

What are the clinical signs of leptospirosis?

**Per acute** – leptospiraemia (4-12 days pi), death, pyrexia, shivering, vomit, **dehydration,** tachypnoea, **PUPD**

**Acute and subacute** – fever, anorexia, vomit, increased thirst, hyperesthesia, conjunctivitis, rhinitis, cough, dyspnoea, erosions, ulcers in oral cavity, icterus, oliguria, haemorrhage

**Chronic – most common**, diarrheal, vomit, hepatitis, nephritis, uveitis. 

* **In cows – may be inapparent or manifested by abortions.** 
* **In horses – uveitis or abortions, mild fever, anorexia, hemolysis, vasculitis**

**Pigs 🡪 abortion 2-4 weeks before parturition**

What pathologies are caused in leptospirosis?

acute interstitial nephritis (AIN), tubular necrosis (ATN), interstitial nephritis (AIN)

What is the diagnosis for Leptospirosis??

Serology - sample: **blood, urine, CNS fluid, abortus (mandatory)**

* Ab are detectable on day 7-8 
* ELISA
* **Microscopic agglutination test (MAT) with paired samples 🡪 state authority**

bacteriological investigation sample: live animals – blood, urine placenta

* Dead – kidneys, liver, brain, eyes

Isolation (agar + native proteins, BSA, tween 80), identification with PCR, 

Haematology, biochemistry

Leptospira detection: dark field microscopy, **immunofluorescence**, PCR

Intermittent shedding: may be negative, paired sample (vaccine 1:400, infected 1:800)

What is the treatment for leptosporosis?

Ethiotropic – ATB (penicillin, streptomycin), specific antisera

Treat suspected as well as confirmed due to zoonotic risk

What is the prevention for leptospirosis?

Disinfection, rodent control. Reduction of reservoir population. Pasture and water

Immunoprophylaxis = **Vaccination: 6-12 month-lasting**. Not rare that a vaccinated patient get ill. Due to serotype was not included in the vaccination