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For further information, see CMDT Part 34-10: Leptospirosis

Key Features

Essentials of Diagnosis

  • Clinical illness can vary from asymptomatic to fatal liver and kidney disease

  • Anicteric leptospirosis is the more common and milder form of the disease

  • Icteric leptospirosis (Weil syndrome) is more severe form of the disease

General Considerations

  • Leptospirosis is an acute and sometimes severe infection caused by 22 species within the genus Leptospira

  • Leptospirosis

    • Occurs worldwide

    • Transmitted to humans by the ingestion of food and drink contaminated by the urine of the infected animal

  • The organism may also enter through minor skin lesions and probably via the conjunctiva

  • Cases have occurred in international travelers after swimming or rafting in contaminated water

  • Occupational cases occur among sewer workers, rice planters, abattoir workers, and farmers

  • Sporadic urban cases have been seen in homeless persons exposed to rat urine

  • The incubation period is 2–20 days

Clinical Findings

Symptoms and Signs

  • Anicteric leptospirosis is often biphasic

  • Initial or "septicemic" phase characterized by

    • Abrupt fever to 39–40°C

    • Chills

    • Abdominal pain

    • Severe headache

    • Myalgias

    • Marked conjunctival suffusion

  • The second or "immune" phase begins after a 1- to 3-day period of improvement and is characterized by

    • Appearance of specific antibodies

    • Recurrence of symptoms with the onset of meningitis

    • Uveitis—unilateral or bilateral

    • Rash and adenopathy

  • However, in severe disease the phases may appear indistinct

  • Icteric leptospirosis (Weil syndrome) is often continuous and is characterized by

    • Impaired kidney and liver function

    • Abnormal mental status

    • Hemorrhagic pneumonia

    • Hypotension

Differential Diagnosis

  • Bacterial meningitis

  • Influenza

  • Viral hepatitis

  • Yellow fever

  • Dengue

  • Rickettsial disease

  • Hemorrhagic fever, eg, hantavirus

  • Relapsing fever


Laboratory Tests

  • Early in the disease, the organism may be identified by

    • Darkfield examination of the patient's blood (a test requiring expertise since false-positives are frequent in inexperienced hands)

    • Culture on a semisolid medium (eg, Fletcher EMJH); cultures may take 1–6 weeks to become positive but may remain negative if antibiotics were started prior

  • Leptospires are excreted in the urine, and urine cultures may be positive from 10 days to 6 weeks

  • Leukocyte count may be normal or as high as 50,000/mcL (50 × 109/L)

  • Urine bile, protein, casts, and red cells

  • Oliguria is common; uremia may occur in severe cases

  • Elevated bilirubin and aminotransferases in 75%

  • Elevated creatinine (> 1.5 mg/dL [> 132.6 mcmol/L]) in 50%

  • Serum creatine kinase is usually elevated

  • Diagnosis is usually made by serologic tests

  • Agglutination tests show a fourfold or greater rise in titer

  • Indirect hemagglutination, enzyme immunosorbent assay (EIA), and ELISA tests are also available. The IgM EIA is particularly useful (positive as early as 2 days into illness, extremely sensitive and specific [93%])

  • Polymerase chain reaction methods

    • Appear to be sensitive, specific, positive early ...

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