Test Catalog

Test Id : LCMAL

Malaria, Molecular Detection, PCR, Varies

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

Detection of Plasmodium DNA and identification of the infecting species

 

An adjunct to conventional microscopy of Giemsa-stained films, particularly in cases of low percent parasitemia or suboptimal parasite morphology

 

Detection and confirmatory identification of Plasmodium species: P falciparum, P vivax, P ovale, P malariae, and P knowlesi

 

This test should not be used to screen asymptomatic patients.

Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

See Malaria Laboratory Testing Algorithm in Special Instructions.

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Method Name
A short description of the method used to perform the test

Real-Time Polymerase Chain Reaction (PCR)/DNA Probe Hybridization

NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.

Yes

Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test

Malaria PCR

Aliases
Lists additional common names for a test, as an aid in searching

Plasmodium falciparum

Plasmodium knowlesi

Plasmodium malariae

Plasmodium ovale

Plasmodium vivax

Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

See Malaria Laboratory Testing Algorithm in Special Instructions.

Specimen Type
Describes the specimen type validated for testing

Varies

Ordering Guidance

1. This test is not performed on a STAT basis and, therefore, should not be used as a primary screening test for malaria.

2. This test is used primarily for confirmation of a presumptive malaria diagnosis and determination of infecting Plasmodium species-particularly when the parasite morphology on traditional blood films is suboptimal.

3. Clients in the Rochester, MN area who are seeking a primary test for malaria and who can deliver the specimen within 4 hours of collection should order the MAL / Rapid Malaria/Babesia Smear, Varies.

4. Laboratories that are unable to deliver a specimen within 4 hours of collection should perform an initial screen for malaria and other blood parasites in their laboratory prior to sending a specimen to Mayo Clinic Laboratories.

5. This test does not include blood smear examination/calculation of parasitemia. If calculation of percent parasitemia is also desired for cases that are PCR positive for Plasmodium species, clients should order LMALP / Malaria PCR with Parasitemia Reflex, Varies.

Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing

Both blood and slides are required.

 

Specimen Type: Blood

Container/Tube: Lavender top (EDTA)

Specimen Volume: 4 mL

Collection Instructions:

1. Invert several times to mix blood.

2. Do not transfer blood to other containers. Send specimen in original tube.

 

Specimen Type: Blood films

Container/Tube: Clean, grease-free slides in plastic slide container

Specimen Volume: 2 thin blood films and 2 thick blood films

Collection Instructions:

1. Ideally, blood films should be made directly from uncoagulated blood acquired via fingerstick. However, EDTA anticoagulated blood is also acceptable.

2. Prepare thin blood films as follows:

a. Prepare a thin film with a "feathered edge" that is no more than a single cell thick.

b. Allow the film to thoroughly air dry and then fix by briefly immersing in either absolute or 95% methyl alcohol.

c. Allow to air dry after fixation.

3. Prepare thick blood films as follows:

a. Place a large drop of blood (approximately the size of a dime and preferably from a fingerstick) on a slide.

b. Using a corner of a second slide, spread the drop in a circular motion while applying firm pressure to literally scratch the blood onto the carrier slide. This technique allows the blood to dry quickly and adhere well to the slide. Use approximately 20 circular sweeps with the second slide. The drop of blood should be about the size of a quarter when finished.

c. Do not fix. Air dry thoroughly (approximately 45 minutes) before placing in transport container.

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Forms

If not ordering electronically, complete, print, and send a Microbiology Test Request (T244) with the specimen.

Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the Testing Laboratory

Blood: 1 mL

Slides: See Specimen Required.

Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected

Gross hemolysis Reject
Gross lipemia Reject

Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included

Specimen Type Temperature Time Special Container
Varies Refrigerated (preferred) 7 days
Ambient 7 days

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

Detection of Plasmodium DNA and identification of the infecting species

 

An adjunct to conventional microscopy of Giemsa-stained films, particularly in cases of low percent parasitemia or suboptimal parasite morphology

 

Detection and confirmatory identification of Plasmodium species: P falciparum, P vivax, P ovale, P malariae, and P knowlesi

 

This test should not be used to screen asymptomatic patients.

Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

See Malaria Laboratory Testing Algorithm in Special Instructions.

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

Malaria is a mosquito-transmitted disease caused by apicomplexan parasites in the genus Plasmodium. It is an important cause of morbidity and mortality worldwide, with the World Health Organization (WHO) estimating 219 million cases and 435,000 malaria-related deaths in 2017. Malaria disproportionately affects individuals living in Africa (90% of cases), with individuals living in southeast Asia and the eastern Mediterranean regions next most affected. Malaria is also encountered outside of endemic regions such as the United States, usually in returning travelers.

 

Malaria is caused primarily by 4 species of the protozoa Plasmodium: P falciparum, P vivax, P malariae, and P ovale. A fifth Plasmodium species, P knowlesi, is a simian parasite that may be an important source of human infection in some regions of Southeast Asia. Differentiating P falciparum and P knowlesi from other species is important since both can cause life-threatening infections. In addition, P falciparum is typically resistant to many commonly used antimalarial agents such as chloroquine.

 

Microscopy of Giemsa-stained thick and thin blood films is the standard laboratory method for diagnosis and differentiation of malaria parasites. Under optimal conditions, the sensitivity of the thick film microscopy is estimated to be 10 to 30 parasites per microliter of blood. However, microscopic diagnosis requires considerable expertise and may be insensitive or nonspecific when inadequate training and facilities are available. Furthermore, prolonged exposure to EDTA, transportation conditions, and prior use of antimalarial drugs may alter parasite morphology and negatively impact the ability to perform species identification by microscopy. Finally, Babesia parasites have a similar appearance to P falciparum ring forms (early trophozoites) on peripheral blood films, resulting in potential diagnostic confusion.

 

PCR is an alternative method of malaria diagnosis that allows for sensitive and specific detection of Plasmodium species DNA from peripheral blood. PCR may be more sensitive than conventional microscopy in very low parasitemias, and is more specific for species identification. It may be particularly useful when subjective microscopy does not permit certain identification of the species present. Malaria PCR can be used in conjunction with a traditional blood film or Babesia PCR when the clinical or morphologic differential includes both babesiosis and malaria. Examination of the thin film also allows for calculation of percent parasitemia, which can be used to predict prognosis and monitor response to treatment. This test does not include blood smear examination or calculation of parasitemia.

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

Interpretation
Provides information to assist in interpretation of the test results

A positive result indicates the presence of Plasmodium nucleic acid and melting curve analysis indicates the infecting species.

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

Malaria is potentially a life-threatening disease, and it is imperative to test for parasites as rapidly as possible. Therefore, this test is for confirmation only except for clients in the immediate Rochester, Minnesota area who can provide rapid delivery of specimens to Mayo Clinic Laboratories.

 

Assay may be negative in very low parasitemias.

 

Species of Plasmodium present in mixed infections may not be clearly delineated.

 

In some instances, the closely related species, P ovale and P vivax, cannot be differentiated from one another by this test. In this instance, results will be reported as "Plasmodium vivax/Plasmodium ovale." These 2 species have similar prognosis and treatment, and can often be distinguished based on patient travel history.

 

This is a qualitative test only. If calculation of percent parasitemia is desired, order LMALP / Malaria PCR with Parasitemia Reflex, Varies.

 

This assay does not distinguish between residual nucleic acid (which may persist after adequate treatment) and viable intact parasites. It also does not distinguish between gametocytes (nonpathogenic forms that may be present in resolving infections) and virulent trophozoites.

 

Although the reference range is considered "negative" for individuals living in nonendemic areas, this assay may detect low-grade asymptomatic parasitemia from individuals exposed to malaria-endemic areas. However, this assay is designed to detect only Plasmodium species of clinical significance and is to be used for patients with a clinical history and symptoms consistent with malaria. This test should not be used to screen asymptomatic patients.

 

This PCR assay does not detect other parasites that may be present in the blood and have similar disease presentations including Babesia and Trypanosoma species.

Supportive Data

The following supports the use of this assay for clinical testing.

 

Accuracy/Diagnostic Sensitivity and Specificity:

160 clinical whole blood specimens were evaluated for the presence of Plasmodium species DNA or the 18S rRNA gene using this real-time PCR assay. The assay detects and differentiates DNA of P falciparum, P vivax, P ovale, P malariae, and P knowlesi. The results were compared to results of microscopy, a nested PCR method and sequencing. The specimens comprised 48 negative and 108 positive specimens (32 P falciparum, 8 P malariae, 20 P ovale, 45 P vivax, 2 unable to speciate by morphology, and 1 mixed infection of P vivax/falciparum). The sensitivity and specificity of the real-time Plasmodium assay compared to microscopy, nested PCR and sequencing was 99% and 94% respectively, with all species determinations by the PCR assay matching the original result. No P knowlesi clinical specimens were available so spiking studies were performed. 30 EDTA-anticoagulated blood specimens received in the laboratory for unrelated testing were spiked with P knowlesi plasmid near the limit of detection (50-100 targets per microliter) and tested in a blinded fashion with negative blood specimens. 100% concordance was achieved in the spiking studies.

 

Analytical Sensitivity/Limit of Detection:

The lower limit of detection (LoD) of this assay is 10 to 50 DNA target copies per microliter in whole blood.

 

Analytical Specificity:

No PCR signal was obtained from extracts of 31 other bacterial, viral, rickettsial, and parasitic isolates that could be found in whole blood and cause similar symptoms, including Babesia, Borrelia, Anaplasma, and Ehrlichia species.

 

Precision:

Interassay precision was 100% and the intra-assay precision was 100%. 

 

Reportable Range:

This is a qualitative assay and the results are reported as either negative or positive for the targeted Plasmodium species.

Clinical Reference
Recommendations for in-depth reading of a clinical nature

1. Mathison BA, Pritt BS: Update on Malaria Diagnostics and Test Utilization. J Clin Microbiol. 2017 Jul;55(7):2009-2017

2. Swan H, Sloan L, Muyombwe A, et al: Evaluation of a real-time polymerase chain reaction assay for the diagnosis of malaria in patients from Thailand. Am J Trop Med Hyg 2005 Nov;73(5):850-854

3. World Health Organization Malaria Page: www.who.int/topics/malaria/en/

4. Cox-Singh J, Davis T, Lee K, et al: Plasmodium knowlesi malaria in humans is widely distributed and potentially life-threatening. Clin Infect Dis 2008 January 15;46(2):165-171

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Method Description
Describes how the test is performed and provides a method-specific reference

DNA from EDTA-anticoagulated whole blood is extracted and tested using real-time PCR on the LightCycler 2.0 instrument (Roche Applied Science) with primers and fluorescence resonance energy transfer (FRET) probes. A genus-specific primer set corresponding to 18S rRNA is used to amplify target sequence. One pair of FRET hybridization probes was designed for Plasmodium falciparum over a region containing base pair mismatches allowing for differentiation of other Plasmodium species by use of melting curve analysis, while a second probe set is specific for P knowlesi.(Babady NE, Sloan LM, Rosenblatt JE, Pritt BS: Detection of Plasmodium knowlesi by Real-Time Polymerase Chain Reaction. Am J Trop Med Hyg 2009 Sept;81(3):516-518)

PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information

No

Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.

Monday through Sunday

Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.

Same day/1 to 3 days

Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

7 days

Performing Laboratory Location
Indicates the location of the laboratory that performs the test

Rochester

Fees
Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.

  • Authorized users can sign in to Test Prices for detailed fee information.
  • Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
  • Prospective clients should contact their Regional Manager. For assistance, contact Customer Service.

Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.

This test was developed, and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.

CPT codes are provided by the performing laboratory.

87798

LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.

Test Id Test Order Name Order LOINC Value
LCMAL Malaria PCR 47260-5
Result Id Test Result Name Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
87860 Malaria PCR 47260-5

Test Setup Resources

Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | Pdf

Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports