Leptospirosis

Leptospirosis is caused by direct contact with the urine or tissues of infected wild and domestic animals or indirectly through urine-contaminated water or urine-contaminated soil or plants. Hemorrhage, meningitis, jaundice, myocarditis, and hepatorenal failure occur in severe cases.

CASES/YEAR
750 (US); 1,000,000 (Global)
CATEGORY
Zoonoses
AGENT TYPE
Spirochetes
OTHER NAMES
Weil disease; Canicola fever; Hemorrhagic jaundice; Mud fever; Swineherd disease; Leptospira interrogans infection; Weil's syndrome;
ACUITY
Acute-Severe
INCUBATION
Usually 5 days to 2 weeks; range of 2-30 days; [CCDM]
INITIAL SYMPTOMS
The most common clinical presentations are: 1. Flu-like syndrome; 2. Weil's syndrome; 3. Meningitis; and 4. Pulmonary hemorrhage; [CCDM, p. 348]
PRECAUTIONS
Standard; "Not transmitted from person to person." [CDC 2007 Guideline for Isolation Precautions]
COMMENTS
FINDINGS
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. 1714-5; ID, p. 1466-8; PPID, p. 2898-904] 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. 1714] "Serologic assays have been developed. Their use generally is limited by the large number of pathogenic and intermediate serotypes that result in human disease worldwide." [CDC Travel, p. 623]

WEIL'S SYNDROME:
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. 1714-5; ID, p. 1466-8; PPID, p. 2898-904]

LABORATORY:
CSF analysis shows lymphocytic pleocytosis (usually <500/uL), protein <100 mg/dL, and normal glucose. [Merck Manual, p. 1715; ID, p. 1466-8; PPID, p. 2898-904] 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, 24th Ed, p. 1938]

EPIDEMIOLOGY:
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. 2899] 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. 263] "Infection by Leptospira does not occur via inhalation." [Harrison ID, 2nd, Ed, p. 711] Occasional transmission by ingestion of contaminated food/water or by inhalation of aerosols; [CCDM, p. 351]
DIAGNOSTIC
Rapid IgM EIA: highest sensitivity 14-21 days after onset of symptoms; Microscopic agglutination testing (MAT) for 4-fold rise in titers is gold standard (reference labs only); [MMWR, 2/10/06] Culture is insensitive. PCR can detect organism. [CDC Travel]
SCOPE
Global, except polar regions; [CCDM] Outbreaks in Hawaii, Florida, and Puerto Rico; Reported in tourists returning from areas with outbreaks after heavy rainfall and flooding; [CDC Travel, p. 263-4]
SIGNS & SYMPTOMS
  • >arthralgia
  • >fatigue, weakness
  • >fever
  • >fever, biphasic or relapsing
  • >myalgia
  • E epistaxis
  • E pharyngitis
  • G abdominal pain
  • G blood in stool
  • G diarrhea
  • G hepatomegaly
  • G jaundice
  • G liver function test, abnormal
  • G nausea, vomiting
  • H anemia
  • H hemolysis
  • H leukocytosis
  • H lymphadenopathy
  • H splenomegaly
  • H thrombocytopenia
  • N confusion, delirium
  • N headache
  • N stiff neck
  • O conjunctivitis, acute
  • R chest pain
  • R cough
  • R dyspnea
  • R hemoptysis
  • S papules or plaques
  • S petechiae and ecchymoses
  • S rash (exanthem)
  • S urticaria
  • U hematuria
  • U pyuria
  • X lung infiltrates
  • X pleural effusions
  • *acute renal failure
  • *ARDS
  • *bleeding tendency
  • *cranial neuropathy
  • *encephalitis
  • *erythema nodosum
  • *glomerulonephritis
  • *hepatitis
  • *meningitis
  • *myelitis
  • *myocarditis
  • *pancreatitis
  • *paralysis
  • *pericarditis
  • *peripheral neuropathy
  • *pneumonia
  • *pneumonitis
  • *pulmonary edema
  • *rhabdomyolysis
  • *shock
  • *stupor, coma
  • *uveitis
ANTIMICROBIC

Yes

VACCINE

No

ENTRY
Ingestion, Skin or Mucous Membranes (Includes Conjunctiva), Animal Bite, Swimming
SOURCE
Animal Excreta, Animal Tissue, Soil or Dust (Ingesting or Inhaling), Waterborne (Ingesting, Inhaling, or Swimming)
RESERVOIR
Cattle, Goats and Sheep, Deer, Elk and Antelope, Dogs, Horses, Monkeys, Rodents, Swine, Wild Animals
RISK FACTORS
  • Handle animal carcasses or placentas
  • Handle domestic animals
  • Handle infected rodents (not bite)
  • Ingest infectious agents in food/water
  • Raise dust of excreta from rodents
  • Swim in contaminated water (skin)
  • Travel to endemic area
  • Victim--air release of infectious agents
  • Walk barefooted in contaminated soil
DRUG LINK
Merck Manual: Leptospirosis
REFERENCES FOR CASES/YEAR
1. (US) About 50 to 100 cases/yr passively reported to CDC, mostly from Hawaii; [Harrison ID, 2nd Ed, p. 711] Use correction factor of 10 for reported diseases; 10 X 75 = 750;
2. (Global) "Approximately 1 million severe cases per year"; [Harrison ID, p. 672] Incidence rates estimated 41,000 per 100,000 from surveillance of US Army units training in Panama from 1977-1982; 11,000 per 100,000 for New Zealand dairy farmers and 2000 per 100,000 for Hawaiian taro farmers; [ID, p. 1466] Estimate of over 350,000 cases per year worldwide; A major public health problem in poor, tropical countries among farmers, herders and in urban slums; [Cecil, p. 1998] Cases reported in England & Wales: 62 (2008), 52 (2009), 39 (2010), 44 (2011), 72 (2012); [Public Health England website]