Interpretive Handbook

Test 9240 :
Malaria/Babesia Smear


Malaria is a major tropical disease infecting approximately 500 million people and causing 1.5 to 2.7 million deaths annually. Ninety percent of the deaths occur in sub-Saharan Africa and most of these occur in children <5 years old; it is the leading cause of mortality in this age group. This disease is also widespread in Central and South America, Hispaniola, the Indian subcontinent, the Middle East, Oceania, and Southeast Asia. In the United States, individuals at risk include travelers to, and visitors from endemic areas.


Malaria parasites undergo a life cycle which includes sexual mating of gametocytes in mosquitoes and asexual replication in the erythrocytes of humans who have been infected by the bites of mosquitoes. Infected erythrocytes rupture producing anemia and initiating the release of cytokines including tumor necrosis factor.


Malaria "pigment" and sluggish cerebral blood flow cause cerebral edema. Pulmonary and renal failures are dire consequences of malaria due to Plasmodium falciparum which can be a life-threatening infection. It is crucial to suspect malaria in any febrile patient who has been in an endemic area and to distinguish Plasmodium falciparum from other species since Plasmodium falciparum can cause life-threatening infections and is resistant to many commonly used antimalarial agents such as chloroquine.


The rapid and accurate detection and species identification of Plasmodium


Detection of Babesia, trypanosomes, and some species of microfilariae

Interpretation Provides information to assist in interpretation of the test results

A positive smear indicates infection with the identified species of Plasmodium or with Babesia.


Species identification can indicate the appropriate antimalarial therapy.


For most sensitive detection of Plasmodium, thick smears must be examined.


Any exam which does not include a thick smear cannot be considered adequate.


On rare occasions, LightCycler PCR may be used to confirm difficult smears.



If positive, organism identified


Hoffman SL: Diagnosis, treatment, and prevention of malaria. Med Clin North Am 1992;76:1327-1355