Prevalence of canine leptospirosis has increased in recent years. As many as 8.2% of dogs are shedding leptospires, some asymptomatically.49 Weather changes, population growth, and habitat encroachment have all increased human and canine exposure to pathogens and their carriers. Transmission of leptospirosis can occur through direct contact or indirectly through environmental exposure. Leptospires enter the body through mucous membranes in the mouth, eyes, or nose, or through abraded or water-softened skin. Leptospires multiply in a host animal's bloodstream. Leptospires move from the bloodstream to the kidneys and other tissues to continue reproducing. Leptospires pass from the kidneys into the urine; then are shed back into the environment. Other dogs, wild animals, or people can become infected through direct or indirect contact. clinical signs Fever Lethargy Weight loss Anorexia Depression Acute renal failure Jaundice Abdominal discomfort Vomiting and diarrhea Blood in urine is uncommon, but may occur Respiratory distress Dogs at risk Dogs at risk for developing leptospirosis include those with Access to ponds, lakes, streams, or standing water Exposure to urine from other infected animals, including: Other dogs in shelters or other pet care facilities Wildlife (e.g. rodents, racoons, opossum, deer), either through direct contact with urine or through contaminated water Morbidity threats As leptospirosis progresses, it can result in Leptospiremia Leptospires can multiply in the bloodstream and spread to many tissues and organs Vascular damage/thrombocytopenia Can lead to kidney failure and interfere with liver function Contributes to coagulatory abnormalities and hemorrhages Severe kidney and liver damage Acute renal failure occurs in dogs with severe clinical signs Acute hepatic dysfunction or chronic hepatitis have been caused by specific serovars

1. LEPTOSPIROSIS
SEWAGE WORKERS DISEASE, WEIL’S DISEASE, FIELD FEVER,
RAT CATCHER’S YALLOW, STUTGUARD DISEASE
BY Dr RANJINI MANUEL

2. INTRODUCTION
 1st reported by Adolf Weil in Heidelberg in 1886
 Leptospirosis is a zoonotic disease of world wide
significance that affects many animal species
Caused by the infection with –leptospiral spirochetes of
the species- Leptospira interrogans sensu lato

3. ETIOLOGY
Leptospires are- thin, flexible, filamentous
bacteria
Possess fine spirals with hooked shaped ends
Motile- writhing and flexing movements- rotate in
their long axis
Composed of protoplasmic cylinder, wound
around the straight central axial filament
Outer envelop – lipopolysaccharide (LPS)

4. CLASSIFICATION
LEPTOSPIRA
L. Biflexa sensu latoL. Interrogans sensu lato
• Pathogenic strains • Saprophytic strains

5. EPIDEMIOLOGY
There are more than 250 serovars of L. interrogans- further classified –
antigenically related serovars, based on the LPS
Prevalent in parts of the world – higher rainfall and warm climate
In India – 4 canine serovars- Icterohaemorrhagiae, Canicola, Pomona &
Grippotyphsa – prevalent
2 additional serovars which infect humans – Autumnalis & Astralis – prevalent in
dog population of kerala

6. EPIDEMIOLOGY
Dogs of any age , sex, breed, kept outdoor are susceptible
Dogs in close contact with rodents/ rodent urine can develop leptospirosis
 Transmission of disease among maintenance host is efficient & incidence of
infection 
 Incidental host are NOT important reservoirs of infection & incidence of
transmission is 
 Do not replicate outside the host
Inactivated by heat, UV, disinfectants, freezing conditions
 Can survive in water , wet soil for weeks to months under optimal conditions
(alkaline PH, 0°- 25°C)

8. MAINTENANCE HOSTS OF SOME COMMON LEPTOSPIRAL SEROVARS
LEPTOSPIRAL SEROVARS MAINTENANCE HOST
Hardjo Cattle
Pomona pigs, skunks, Opossum
Bratislava Horses
Canicola Dogs
Icterohaemorrhagiae Rats
Grippotyphosa Raccons, Skunks, Opossum

9. SEROVAR PRIMARY RESERVOIR INCIDENTAL HOST
L. bataviae Dog, rat, mouse Dog , cat
L. bratislava Pig, horse, dog Dog
L. canicola Dog Dog, cat
L. grippotyphosa Vole, raccoon, skunk, opossum Dog , cat
L. hadjo Cow Dog
L. icterohaemorrhagiae Rat Dog, cat
L. pomona Cattle, Pig, skunk, opossum Dog , cat
L. autumnalis Mouse Dog

10. TRANSMISSION
TRANSMISSION
BETWEEN HOSTS
INDIRECTDIRECT
• Infected urine
• Venereal &
placental
• Bite wounds
• Ingestion of
infected tissues
• Exposure to
contaminated
water, soil &
food

13. PATHOGENESIS
Leptospires  intact mucous membranes of mouth, nose, eyes or abraded scratched,
water-softened skin
Transcriptional changes occur in the body  pathogenicity, organisms multiply after
entering blood vascular space
Further replicate in tissues including kidney, spleen, CNS, eyes, genital tract  capillary
damage

14. Tissue edema & vasculitis  acute endothelial injury and haemorrhagic manifestation
LPS stimulate neutrophil adherence and platelet activation  inflammatory and
coagulatory abnormalities
Renal colonization  Organisms replicate and persists in renal tubular epithelial cells,
reaches interstitium after 2 weeks of infection – onset of shedding
kidney swelling impaired renal blood perfusion decreased glomerular filtration
impairment of renal function

16. Host clears spirochetes from most of the organs, but may persist in kidney and shed in
urine for days –to- months
Liver being 2nd major organ affected – degree of icterus usually
corresponds with severity of hepatic necrosis
Hepatic dysfunction may occur without major cellular changes- due to
the subcellular damage produced by the leptospiral toxin.
 osmotic fragility has been detected in canine leptospirosis making
haemolysis less likely

17. Acute lung injury occurs due to effects of toxin in pulmonary tissues
Fluid exudation within the lungs may result from vasculitis
Pulmonary haemorrhage – rarely reported
When leptospira invades brain  benign meningitis
Uvetitis  documented in case of dogs and humans
Abortion/infertility  transplacental transmission in dogs – bataviae)
Serogroups – Canicola, Bratislava & Grippotyphosa – renal & hepatic involvement
icterohaemorrhagiae & Pomona – more hepatic

18. CLINICAL FINDINGS
Acute cases
 Fever (103°C to 104°C)
 Shivering
 Muscle tenderness
 Vomiting
 Dehydration
 Peripheral vascular collapse
 Intestinal intussusception
 Tachypnea
 Rapid irregular pulse
 poor capillary perfusion
 hematemesis
 Hematochezia
 Melena
 Epistaxis
 widespread petechiae
 Icterus

20. CLINICAL FINDINGS
Subacute
 Dehydration
 Polydipsia and polyuria
 Reluctance to move
 Paraspinal hyperesthesia
Congested mucous membrane
 Ecchymotic hemorrhages
 Conjuctivitis
 Uveitis
 Rhinitis
Tonsillitis
 Oliguria or anuria
 Coughing or dyspnea
 Icterus

21. DIAGNOSIS
CLINICAL LABORATORY FINDINGS
HEMATOLOGY : Leukocytosis & Thrombocytopenia
BIOCHEMISTRY : Na, Cl, K OR K, P,  blood sugar level
 ALT,  AST,  LDH,  ALP, bilirubin, serum amylase activities
serum lipase activity, azotemia
 URINALYSIS : Glucosuria, tubular or glomerular proteinuria, bilirubinuria, No. of cast,
Pyuria, haematuria.

22. ORGANISM IDENTIFICATION
 Organisms on body fluids are Identified by dark field microscopy
To the sensitivity of Direct microscopic examination special staining can be done
 silver staining and Wrthin-starry stains are commonly used histochemical stains
Immunofluorescence staining – urine, water , soil samples
Immunoperoxidase staining- blood and urine samples

23. They are visualized as – Thin, Bright ,Actively motile rods, Rapid spinning
with Jerky movements

24. CULTURE
 Organisms are cultured on EMJH medium (Ellinghausen, McCullough,
Johnson, Harris) incubation at 30°C for 7 days and observed under Dark field
microscopy
 Fletcher’s medium – growth occurs as a ringed area called dinger’s ring or
disk 1-3cm below the surface of the medium
Korthof media is also used in cultivating leptospires

25. SEROLOGICAL TESTS
Microscopic agglutination test (MAT)
ELISA- Pan Bio ELISA – detect IgM from single serum sample
PCR – rapid & direct, DNA is identified, used in early and convalescent stage
Indirect Haemagglutination
Latex agglutination
Lateral flow technique
Leptodipstick assay
 PCR in combination with ELISA  good sensitivity at initial phase

27. MAT
 Cornerstone for serodiagnosis for leptospira because of its sensitivity and
detection of group specific antibodies
Positive results are defined as 4 fold  in the titre between acute and
convalescent specimen
DISADVANTAGES
 Due to antigenic heterogencity it requires large no.of serovar as antigens
Not useful at early stages of infection where antibody is not present
Performance restricted to labs that are capable of maintain strain for the
preparation of live antigens

28. Test Advantages Disadvantages
Dark Field Microscopy (DFM) Visualize Leptospirosis Lack of sensitivity and specificity. 104
Leptospires/ml is necessary for one
organism/field to be visible under DFM.
IgM ELISA Most widely used False positive, IgM cannot be detected
in early stages of infection and can
persist in blood for years.
Microscopic Agglutination Test
(MAT)
Gold Standard Less sensitive in early phase of disease.
Labor intensive and complicated
procedure as there is a need to maintain
Leptospira strain for preparing live
antigen.
Polymerase Chain Reaction (PCR) Successful in detecting Leptospira
DNA in serum and urine samples of
patients
Expensive reagents, Requires large
quantity of DNA. Cannot identify the
infecting serovar.

29. TREATMENT
Ampicillin 22mg/kg , 8hr I/V or I/M -5-8days
Penicillin G 25,000-40,000IU/kg b.wt 12hr i/v
Doxycycline administered orally at 2.5 to 5.0 m g / kg eliminate the renal
carrier phase
Fluid therapy
Supportive therapy

30. CONTROL
Infected urine, contaminated water, and reservoir hosts - avoided
Infected dogs should be handled with wearing gloves
Contaminated surfaces should be cleaned with detergents and disinfected
Vaccination
Public health concerns