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For further information, see CMDT Part 34-10: Leptospirosis
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Essentials of Diagnosis
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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
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General Considerations
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Leptospirosis is an acute and sometimes severe infection caused by 22 species within the genus Leptospira
Leptospirosis
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
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Anicteric leptospirosis is often biphasic
Initial or "septicemic" phase characterized by
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
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Differential Diagnosis
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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