Leptospira Species - Leptospirosis

Human leptospirosis is an acute febrile illness that presents with many manifestations and is found worldwide. A severe form, which includes jaundice, kidney failure, and bleeding, is called Weil disease. Laboratory studies can confirm the diagnosis and determine the extent of organ involvement. Testing may include culture and/or serology.

Tabs Content

Clinical Overview

Diagnosis

Indications for Testing

Fever >3 days with severe myalgia in patients with
- Contact with infected animals or
- Contact with water or soil contaminated with urine of infected animal

Laboratory Testing

Darkfield microscopic exam of peripheral blood smear during first few days may demonstrate leptospires
- Low sensitivity and specificity
- May also use urine or cerebrospinal fluid (CSF) specimens
- 1x10⁴ leptospires/mL necessary to observe 1 cell/field
Antibody testing
- IgM testing in acute phase
  - Low sensitivity in first week of illness
  - Methods include microscopic agglutination (MAT), enzyme-linked immunosorbent assay (ELISA), indirect hemagglutination antibody (IHA) – MAT has highest specificity
  - Titer >1:200 and compatible symptoms are suggestive of human infection
- IgG testing in convalescent phase
  - ≥2 weeks after initial testing
  - 4-fold increase in titer confirms human infection
Molecular testing – polymerase chain reaction (PCR)
- Sensitive and rapid but not widely available
- First 7 days of illness only
Culture – gold standard, but not often used in diagnosis
- Organism is fastidious and slow growing, occasionally requiring weeks to grow
- May be isolated from blood, CSF, and peritoneal dialysate within first 10 days of illness
- Urine preferable after 10 days

Differential Diagnosis

Background

Epidemiology

Incidence – ~100-200 cases annually in U.S. (approximately half in Hawaii)
Transmission
- Zoonotic disease caused by the spirochete Leptospira interrogans
  - Wild mammals (eg, rodents) – primary natural reservoir
  - Domestic animals (dogs, cattle, swine, horses) – major source of human infection
- ~50% of infections occur from July to October
- Transmission to humans – most often indirect by human contact with soil, food, or water contaminated by urine from infected animals
  - Common sources include contaminated well water, spring water, and food preparation surfaces
  - Transmission also occurs by swimming, rafting, or kayaking in water sources where livestock have been pastured
  - Certain occupational groups (agriculture, sewer, construction, veterinarians, and livestock/farm workers) are at higher risk for leptospirosis

Organism

Spirochete
- Member of the family Spirochaetaceae – also includes Treponema and Borrelia

Risk Factors

Occupational exposure – farmers, ranchers, trappers, lab workers
Recreational exposure – canoeing, kayaking, rafting, swimming, wading
Household exposure – livestock, pets, rodents
Other – flooding, walking barefoot through surface water

Clinical Presentation

Variable clinical course
- Subclinical – only detectable by serologic means (~90% of infections)
- Self-limiting influenza-like illness
  - Fever, chills, rigor, myalgia, abdominal pain, vomiting, and diarrhea
  - Coincides with leptospiremia following a 2-day to 4-week (CDC, 2017) incubation period
- Severe, life-threatening multiorgan failure – often follows influenza-like stage and transient reduction in severity of symptoms (immune phase)
Leptospiral meningitis – accounts for 5-13% of sporadic lymphocytic meningitis cases
Renal involvement common
- Urine analysis demonstrates mild proteinuria, leukocytes, casts, and variable hematuria
- Jaundice with nephritis – Weil disease
  - May also have pulmonary dysfunction, hemorrhagic disease
  - Mortality 5-40% in severe case

ARUP Lab Tests

Tests generally appear in the order most useful for common clinical situations. Click on number for test-specific information in the ARUP Laboratory Test Directory

Leptospira Antibody, IgM by Dot Blot 0055233
Method: Qualitative Immunoblot

Recommended Use

Aid in the detection of acute leptospirosis

Follow-up

Antibodies may not be present during early disease; confirmation 2-3 weeks later is recommended

Leptospira Culture 0060158
Method: Culture

Recommended Use

May provide definitive diagnosis, but sensitivity is low and culture may take several weeks to yield result

Limitations

Time-sensitive test

Medical Experts

Couturier, Marc Roger, PhD, D(ABMM), Medical Director, Microbial Immunology, Parasitology and Fecal Testing, and Infectious Disease Antigen Testing at ARUP Laboratories; Associate Professor of Clinical Pathology, University of Utah

Fisher, Mark A., PhD, D(ABMM), Medical Director, Bacteriology, and Special Microbiology, Antimicrobial Susceptibility Testing, at ARUP Laboratories; Associate Professor of Clinical Pathology, University of Utah

References

Guidelines

U.S. Department of Health and Human Services, Centers for Disease Control and Prevention. Adventure Racing and Leptospirosis. Atlanta, GA [Last updated: Apr 2015; Accessed: Nov 2017]

General References

Goeijenbier M, Wagenaar J, Goris M, Martina B, Henttonen H, Vaheri A, Reusken C, Hartskeerl R, Osterhaus A, Van Gorp E. Rodent-borne hemorrhagic fevers: under-recognized, widely spread and preventable - epidemiology, diagnostics and treatment. Crit Rev Microbiol. 2013; 39(1): 26-42. PubMed

Lau C, Smythe L, Weinstein P. Leptospirosis: an emerging disease in travellers. Travel Med Infect Dis. 2010; 8(1): 33-9. PubMed

Leggat PA. Assessment of febrile illness in the returned traveller. Aust Fam Physician. 2007; 36(5): 328-32. PubMed

Palaniappan RU, Ramanujam S, Chang Y. Leptospirosis: pathogenesis, immunity, and diagnosis. Curr Opin Infect Dis. 2007; 20(3): 284-92. PubMed

Rajapakse S, Rodrigo C, Handunnetti SM, Fernando SD. Current immunological and molecular tools for leptospirosis: diagnostics, vaccine design, and biomarkers for predicting severity. Ann Clin Microbiol Antimicrob. 2015 Jan 16;14:2. PubMed

Toyokawa T, Ohnishi M, Koizumi N. Diagnosis of acute leptospirosis. Expert Rev Anti Infect Ther. 2011; 9(1): 111-21. PubMed

Content Review:

November 2017

Last Update: July 2018