The most common clinical presentations are: 1. Flu-like syndrome; 2. Weil's syndrome; 3. Meningitis; and 4. Pulmonary hemorrhage; [CCDM, p. 348]
Cases range from mild, inapparent infections and flu-like illnesses to severe cases with hemorrhage, hemoptysis, meningitis, jaundice, myocarditis, and hepatorenal failure. Cases are often misdiagnosed as dengue, malaria, meningitis, encephalitis, or influenza. [CCDM, p.348-53] The disease is biphasic with the septicemic phase lasting 4-9 days, then a defervescence of fever and the immune phase when aseptic meningitis develops in about 80% of cases. Conjunctival suffusion (no purulent discharge) is often seen on day 3-4. Some patients have severe muscle aches in the septicemic phase. Infrequent findings are iridocyclitis, optic neuritis, and neuropathy. [Merck Manual, p. 1267-8; ID, p. 1466-8; PPID, p. 2714-20] 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. Hepatomegaly is present, especially in icteric cases. Other findings sometime seen are pericarditis, lung infiltrates, pulmonary edema, and ARDS. [Guerrant, p. 303-7] Hepatomegaly and splenomegaly are uncommon. Weil's syndrome has a 5-10% mortality rate. [Merck Manual, p. 1267-8]
Weil's syndrome is a severe form of leptospirosis with jaundice, proteinuria, hematuria, azotemia, bleeding tendency, anemia, and thrombocytopenia. Renal biopsy shows interstitial nephritis, but immune-complex glomerulonephritis may occur. Severe pulmonary hemorrhage syndrome (SPHS) may occur. This syndrome includes ARDS and septic shock. Cardiovascular collapse with shock is another complication. Severe neurological complications (encephalitis, myelitis, and coma) are rare. [Merck Manual, p. 1267-8; ID, p. 1466-8; PPID, p. 2714-20]
CSF analysis shows lymphocytic pleocytosis (usually <500/uL), protein <100 mg/dL, and normal glucose. [Merck Manual, p. 1268; ID, p. 1466-8; PPID, p. 2714-20] The WBC count is usually normal with a left shift (increased immature forms). Hyperamylasemia is common in severe disease, but pancreatitis is rare. The pattern of very high bilirubin and moderate elevation of transaminases is opposite the pattern seen in viral hepatitis (+++ transaminases and + bilirubin). [Guerrant, p. 303-7] Unlike cases of viral hepatitis, patients with severe leptospirosis have elevated serum creatine phosphokinase. Unlike other infectious causes of acute renal failure, patients with severe leptospirosis have hypokalemia. [Cecil, p. 1938]
Humans are exposed directly by contact with the urine or tissues of infected wild and domestic animals or indirectly through urine-contaminated water (lakes, streams, sewers, and swimming pools) or urine-contaminated soil or plants. 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, and opossums. [CCDM] In nature, these spirochetes survive as a chronic renal infection of animals. [PPID, p. 2715] 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] "Infection rarely occurs through animal bites or human-to-human contact." [CDC Travel, p. 233] "Infection by Leptospira does not occur via inhalation." [Harrison ID, p. 711] Occasional transmission by ingestion of contaminated food/water or by inhalation of aerosols; [CCDM, p. 351]
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