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Beaumont Laboratory

Legionella Antibody Hemagglutination Assay

MDCH# 0402, EPIC: LAB6498, SOFT: XLGHA

Instructions

Acute and convalescent samples must be labeled as such; parallel testing is preferred and convalescent samplemust be received within 30 days from receipt of the acute samples. Please mark sample plainly as "acute" or "convalescent."

Specimen Collection Criteria

Collect (preferred specimens): Two Gold-top SST tube.
Also acceptable: Two plain Red-top tube.

Physician Office/Drawsite Specimen Preparation

Let specimen clot 30-60 minutes then centrifuge to separate serum from cells. Transfer serum to a plastic transport tube and refrigerate (2-8°C or 36-46°F).

Preparation for Courier Transport

Transport: 3.0 mL serum, refrigerated (2-8°C or 36-46°F). (Min: 2.0 mL)

Rejection Criteria

  • Hemolyzed specimens.
  • Severely lipemic specimens.
  • Specimens with gross bacterial contamination.
  • Specimens not collected and processed as indicated.

Storage

Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): 7 days
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): 30 days

Specimen Storage in Department Prior to Disposal:

Specimen retention time is determined by the policy of the reference laboratory. Contact the Sendout Laboratory with any questions.

Laboratory

Sent to Michigan Department Human Health Services (MDHHS), Lansing, MI.

Performed

Every other Tuesday and Thursday.
Results avalible in 7-21 days.

Reference Range

By report.

Test Methodology

Hemmagglutination Assay.

Interpretation

  • An indirect hemmagglutination assay for the detection of anti-Legionella antibodies in human serum. Legionellosis is most commonly recognized as a causative agent of community acquired pneumonia and is often associated with immunosuppression. It may also present as a self-limiting illness with fever, myalgia, malaise and headache with no pneumonia. This form is called "Pontiac Fever".
  • A single titer of greater than 1:128 is presumptive evidence of legionellosis and a four-fold rise in titer between an acute and convalescent serum is considered diagnostic.
  • Up to 9 weeks may be required to develop a significant rise in titer in those who seroconvert. About 25% of patients seroconvert in the first week of illness, 50% seroconvert in the second week, 75% seroconvert in the third week, and 90% seroconvert in the fourth week, and the remaining 10% of patients seroconvert during the sixth to ninth week. Thus, testing of paired sera drawn during the first 2 weeks of illness has only about a 40% chance of yielding a positive result for patients with Legionnaires' disease. (1)
  • A fourfold rise in titer greater than 1:128 from the acute to the convalescent phase provides evidence of a recent infection with Legionella. A standard or single titer greater than 1:256 suggests past exposure or infection, but is inconclusive for diagnosis. Single titers of less than 1:256 are not considered evidence of infection. Diagnosis of acute infection can only be made with a fourfold or greater rise in titer between acute and convalescent specimens.

Clinical Utility

Legionella pneumophila is the causative agent for the infection Legionellosis.

Clinical Disease

  • Legionellosis has two forms. Legionnaires' disease and the milder infection Pontiac fever. The predominant clinical finding in patients with Legionnaires' disease is pneumonia. Patients usually have fever, malaise, anorexia, chills, and a cough. Chest x-rays often show pneumonia.
  • Pontiac fever is an acute, self-limiting, flulike illness without pneumonia. Symptoms include malaise, myalgias, fever, chills, headache, and a nonproductive cough. The chest x-ray is clear.

Disease Reporting

This is a reportable infection and positive results will be reported to the Oakland County Health Department. For more information on reportable diseases, contact the BH Epidemiology Department at (248) 551-4040.

Epidemiology

10,000 to 15,000 persons get Legionnaires' disease in the U.S. each year. The disease occurs more frequently in males and rarely affects children. Outbreaks of Legionnaire's disease usually occur in the summer and early fall, but cases can occur year-round.

Incubation Period

The incubation period for Legionnaires's disease is 2 to 10 days. The incubation period for Pontiac fever is 24-48 hours.

Transmission

The primary mode of transmission is airborne. L.pneumophila has been isolated from water-cooling towers or evaporative condensers in air-conditioning systems, contaminated plumbing fixtures and from soil.

Reference

  1. Edelstein P. Detection of antibodies to Legionella spp. In Rose, et al. Manual of Clinical Laboratory Immunology, Fifth Edition, 1997;503.
  2. Edelstein P. Detection of antibodies to Legionella. In Rose, et al. Manual of Clinical Laboratory Immunology, Fourth Edition, 1992;459-466.

CPT Code

N/A.

Test Codes

MDCH# 0402, EPIC: LAB6498, SOFT: XLGHA

Last Updated

12/12/2016

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This directory currently reflects information only for specimens collected and/or processed at the Farmington Hills, Grosse Pointe, Royal Oak, and Troy campuses.