Parasite Examination, Whole Blood

CPT: 87207
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Test Details

Synonyms

  • Loa loa Smear
  • Plasmodium Smear
  • Wuchereria Smear
  • Blood Smear for Parasites
  • Microfilarial Smear
  • Parasitology Examination for Malaria

Use

Establish the diagnosis of Plasmodium or other parasitic infection; diagnose malarial parasitic infestation of blood; evaluate febrile disease of unknown origin

Limitations

One negative result does not rule out the possibility of parasitic infestation. If protozoal, filarial, or trypanosomal infection is strongly suspected, test should be performed at least three times with samples obtained at different times in the fever cycle.

Methodology

Wright stain; microscopic examination of thick and thin peripheral blood smears stained with Romanovsky dye (in particular Giemsa). Thick films are more difficult to interpret but greatly increase sensitivity (by concentrating cells and organisms). Thick smears require considerable experience with malaria, as they increase the number of cells examined in a given time period by a factor of about 12.1

Reference Interval

No organisms identified

Additional Information

Proper therapy depends on identification of the specific variety of malaria parasite. Release of trophozoites and RBC debris results in a febrile response. Periodicity of fever correlates with type of malaria (see table). Organisms are most likely to be detected just before onset of fever, which is predictable in many cases. Sampling immediately upon onset of fever is the most desirable time to obtain blood. Alternatively, in cases negative by these means but with a strong clinical history, multiple sampling at different times in the fever cycle may prove successful.

Changes in Infected RBCs Useful to Identify Malaria Species

Plasmodium Species

Infected RBC Enlarged

Presence of Schüffner Dots

Presence of Maurer Dots

Multiple Parasites per RBC

Parasite With Double Chromatin Dots

Parasite With Sausage- Shaped Gametocytes

P vivax

+

+

Rare

Rare

P falciparum

+

+

+

+

P ovale

±

+

P malariae

+

Specimen Requirements

Specimen

Smears made from fresh whole capillary (fingerstick) blood and/or capillary blood in EDTA (Microtainer™), or 3 to 5 mL fresh whole venous blood in EDTA

Volume

Films (two thin and two thick) or 3 to 5 mL fresh whole venous blood in EDTA

Container

Glass slide, lavender-top (EDTA) tube

Patient Preparation

Prepare sterile venipuncture site

Collection

Air dry

Storage Instructions

Maintain EDTA whole blood specimen at room temperature for no longer than 24 to 48 hours.

Causes for Rejection

Specimen clotted; improper labeling

Clinical Information

Footnotes

1. Dacie JV, Lewis SM. Practical Haematology. 7th ed. New York, NY: Churchill Livingstone;1991:80-81.
6163210

References

Friedman MJ, Trager W. The biochemistry of resistance to malaria. Sci Am. 1981 Mar, 244(3):154-155,158-164. 6163210
Henry JB, Nelson DA, Tomar RH, et al. Clinical Diagnosis and Management by Laboratory Methods. 18th ed. Philadelphia, Pa: WB Saunders Co;1991:1168-1172.
Makler MT, Gibbins B. Laboratory diagnosis of malaria. Clin Lab Med. 1991 Dec; 11(4):941-956. 1802530

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
008185 Parasite Exam, Blood 24429-3 008185 Parasite Exam, Blood 24429-3
Reflex Table for Parasite Exam, Blood
Order Code Order Name Result Code Result Name UofM Result LOINC
Reflex 1 008186 Limitations 008186 Limitations N/A

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