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Interpretive Handbook

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Test 9697 :
Leptospira Antibody, Serum

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Leptospirosis is a zoonotic disease of worldwide prevalence. Although wild mammals are the primary natural reservoir of pathogenic strains, domestic animals represent a major source of human infection. Most often, transmission is indirect-by human contact with soil, food, or water contaminated by urine from an infected animal.

 

The clinical manifestations of leptospirosis are variable, ranging from a mild infection with fever, chills, headache, conjunctivitis, myalgia, and gastrointestinal symptoms to icteric disease with severe kidney and liver involvement.

 

Leptospira organisms may be found in the blood at the onset of disease and may persist for approximately 1 week. The organisms also may be found in the urine after week one of the disease. They may persist in the urine for 2 to 3 months; however, shedding may be intermittent and the numbers of organisms present may be low. Urine must be cultured immediately because the organisms cannot survive in acidic urine for more than a few hours.

 

Leptospirosis is accompanied by a brisk antibody response.

Useful For Suggests clinical disorders or settings where the test may be helpful

As an aid in the diagnosis of leptospirosis

Interpretation Provides information to assist in interpretation of the test results

Both IgM and IgG classes of antibody are produced in response to any of 16 leptospira serovars that produce infection. IgM antibody is first detectable within 1 to 2 weeks after onset of illness and peaks at 2 to 4 weeks.

 

Titers of 1:50 are considered borderline and follow-up specimens should be drawn for isolation of live leptospires (ie, culture) and repeat serology.

 

Titers > or =1:100 represent recent or active infection.

 

The overall sensitivity of the assay is 100% and the specificity is 97% when compared to CDC reagents.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Serologic results must be correlated with the clinical picture.

 

Sera drawn too close to onset of symptoms may precede the initial IgM antibody response.

 

Acute titers may be delayed or substantially decreased by early and intensive antibiotic treatment.

 

The assay detects antibody to the genus Leptospira but will not determine which serovar is associated with the infection.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

Negative

Clinical References Provides recommendations for further in-depth reading of a clinical nature

1. Sulzer CR, Glosser JW, Rogers F, et al: Evaluation of an indirect hemagglutination test for the diagnosis of human leptospirosis. J Clin Microbiol 1975;2:218-221

2. Sulzer CR, Jones WL: Leptospirosis. Methods in laboratory diagnosis (revised edition). United States Deptartment of Health Education and Welfare, Centers for Disease Control, Publication No. 79:8275;1978

3. Tappero JW, Ashford DA, Perkins BA: Leptospirosis. In Principles and Practice of Infectious Diseases. 5th edition. Edited by GL Mandell, JE Bennet, R Dolin. New York, Churchill Livingstone, 1999

4. Weyant RS, Bragg SL, Kaufmann AF: Leptospira and leptonema. In Manual of Clinical Microbiology. 7th edition.  Edited by PR Murray, EF Baron, MA Pfaller, et al. Washington, DC, ASM Press, 1999;739-745


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