Internal Medicine


Zoonotic disease of worldwide distribution, caused by spirochetes Leptospira.

Zoonotic disease of worldwide distribution, caused by spirochetes Leptospira.


  • Principal source: Rats
    • Humans acquire infection after getting exposure to water or soil contaminated with rat urine
  • Other reservoirs:
    • Dogs, cats, livestock and wild animals 


This scanning electron micrograph (SEM) depicts a number of Leptospira sp. bacteria atop a 0.1. µm polycarbonate filter. Leptospires are long, thin motile spirochetes that may be free-living or associated with animal hosts and survive well in fresh water, soil, and mud in tropical areas. Organisms are antigenically complex, with over 200 known pathogenic serologic variants. Molecular taxonomic studies at CDC and elsewhere have identified 13 named and 4 unnamed species of pathogenic leptospires. Leptospirosis causes a wide range of symptoms, and some infected persons may have no symptoms at all. Symptoms of leptospirosis include high fever, severe headache, chills, muscle aches, and vomiting, and may include jaundice (yellow skin and eyes), red eyes, abdominal pain, diarrhea, or a rash. | CDC/ Rob Weyant –, Public Domain,

Risk factors:

  • Occupational:
    • Agricultural workers
    • Veterinarians
    • Meat handlers
    • Rodent control workers
    • Laboratory personnel
  • Seasonal:
    • Monsoons
    • During flooding


Abrasions and cuts
(skin or mucous membranes)

Enter body

Hematogenous spread

Small blood vessels

  • Damage endothelial lining
  • Leakage and extravasation of blood cells
  • Haemorrhage
  • Ischemic damage to various organs:
    • Liver, kidneys, meninges and muscles

Clinical features

  • Biphasic presentation:
    1. Initial/septicemic phase (2-7 days)
    2. Immune/leptospiruric phase

A. Initial/septicemic phase (2-7 days)

Abrupt onset
  • Anicteric febrile illness (70% cases)
    • High-grade fever with rigors and chills
    • Lethargy
    • Severe myalgia
    • Headache
    • Nausea & vomiting
  • Conjunctival suffusion
    • Photophobia and orbital pain
  • Generalized lymphadenopathy
  • Hepatosplenomegaly
  • Transient maculopapular rash (<10% cases)
  • Rare:
    • Hypotension with bradycardia and circulatory collapse 
    • Acute respiratory distress syndrome with respiratory failure

Most are asymptomatic within one week

(Brief) Asymptomatic phase

B. Immune/leptospiruric phase

Leptospira localize to tissues to cause specific signs and symptoms

  • Circulating autoantibodies to Leptospira are present
  • Organisms can no more be isolated from blood or CSF
    • But persist in tissues like kidneys and aqueous humour
  • Aseptic meningitis (20% cases) or uveitis with recurrence of fever
  • Rare:
    • Encephalitis, cranial nerve palsies, paralysis and papilledema

Central nervous system abnormalities usually normalize within 1 week; mortality is rare.

Icteric Leptospirosis (Weil syndrome)

After the initial phase of fever patients develop severe hepatic and renal dysfunction

  • Jaundice and hepatomegaly
  • Splenomegaly (20% cases)
  • Renal failure
    • Second week of illness
  • Urinalysis:
    • Abnormal urinary findings:
      • Hematuria
      • Proteinuria
      • Casts
      • Azotemia, often associated with oliguria or anuria
    • Rare:
      • Hemorrhagic manifestations
        • Epistaxis, hemoptysis and gastrointestinal and adrenal hemorrhage.
      • Transient thrombocytopenia

Mortality is 5-15%

Case study


Non-specific diagnoses:

  • Complete blood count (CBC):
    • Anemia
    • Leukocytosis with polymorph predominance
    • Thrombocytopenia
  • ↑ CRP
  • ↑ Liver enzymes (SGOT > SGPT)
  • ↑ CPK
  • Weil disease:
    • ↑ Serum creatinine
    • Deranged coagulation parameters
    • Direct hyperbilirubinemia with raised transaminases

Specific diagnoses:

  • Serologic diagnosis:
    • Reference centres:
      • Microscopic agglutination test (MAT) (GOLD STANDARD)
    • Commercial kits:
      • Rapid tests
      • IgM ELISA
  • Demonstration of organism in tissues or urine:
    • Darkfield microscopy
    • Immunofluorescence
    • Cultures

Differential diagnosis:

Other febrile illnesses commonly seen in the monsoon season
  • Malaria
  • Dengue
  • Enteric fever
  • Acute viral hepatitis
  • Hantavirus infections


Severe cases:

  • Parenteral treatment:
    • Penicillin G (6-8 million U /m2 /24 hr q 4 hr IV) for 7 days (DRUG OF CHOICE)
    • Alternatives:
      • Ceftriaxone
      • IV tetracycline

Mild cases:

  • Oral treatment:
    • Amoxicillin and doxycycline (children > 8 yr)

Leave a Reply

%d bloggers like this: