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FINDINGS: Cases range from mild, inapparent infections and flu-like illnesses to severe cases with hemorrhage, hemoptysis, meningitis, hemolytic anemia, jaundice, myocarditis, and hepatorenal failure. [CCDM, p.306-9] The disease is biphasic with the septicemic phase lasting 4-9 days, then a defervescence of fever and the immune phase when aseptic meningitis ensues in about 80% of cases. CSF analysis shows lymphocytic pleocytosis (usually <500/microliter), elevated protein (50-100 mg/mL) and normal glucose. Conjunctival suffusion (no purulent discharge) is often seen on day 3-4. Some patients have calf and lumbar muscle pain. Infrequent findings are iridocyclitis, optic neuritis, and neuropathy. Weil's syndrome is a severe form of leptospirosis with jaundice, proteinuria, hematuria, azotemia, bleeding tendency, anemia, and thrombocytopenia. [Merck Manual, p. 1477; ID, p. 1466-8; PPID, p. 2791-2] 90% of patients have the mild anicteric disease, and 10% have the severe icteric disease (Weil's syndrome). Transient maculopapular and urticarial skin rashes may be seen. In the second phase of the illness, patients may have headache and stiff neck. Petechiae and purpura appear along with conjunctival, GI, and pulmonary hemorrhages. The WBC count is usually normal with a left shift (increased immature forms). Hepatomegaly is present, especially in icteric cases. Hyperamylasemia is common in severe disease, but pancreatitis is rare. Other findings sometime seen are pericarditis, lung infiltrates, pulmonary edema, and ARDS. The pattern of very high bilirubin and moderate elevation of transaminases is opposite the pattern seen in viral hepatitis (+++ transaminases and + bilirubin). [Guerrant, p. 511-15] 15-20% of patients have splenomegaly. In severe icteric disease, patients have mildly elevated transaminases but marked elevated CPKs (MM fraction). [Lexi-ID, p. 196] EPIDEMIOLOGY: Humans are exposed directly by contact with the urine or tissues of infected wild and domestic animals or indirectly through urine-contaminated water in lakes, streams, sewers, and swimming pools. An animal vaccine is available. Leptospirosis is rarely transmitted person-to-person. Natural hosts include: rats, swine, cattle, dogs, raccoons, badgers, feral rodents, deer, squirrels, foxes, skunks, opossums, and insectivores. [CCDM] In nature, these spirochetes survive as a chronic renal infection of animals. [PPID, p. 2790] It is the most common zoonosis worldwide. Two cases were reported after flooding at the University of Hawaii. The spirochete can enter through broken skin or mucous membranes. [MMWR 2/10/06] |
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