Malaria – Five Species Detected
Featured Topic Archive
Updated: June 2013
Published: June 2011
Malaria is a life-threatening disease caused by parasites in the genus Plasmodium. It is transmitted by female Anopheles mosquitoes, which are found worldwide. The 4 main species causing human malaria are Plasmodium falciparum (the deadliest species), Plasmodium ovale, Plasmodium vivax, and Plasmodium malariae. A fifth species, Plasmodium knowlesi (pronounced nolls-eye) is now recognized as an important cause of human disease in Southeast Asia. This species is responsible for up to 75% of malaria infections in some areas, and has been transmitted to travelers from the United States, Sweden, Spain, France, Australia, and New Zealand.
Mayo Clinic’s Malaria Polymerase Chain Reaction (PCR) test now detects and differentiates the fifth human malaria species, Plasmodium knowlesi. This species is often misidentified by blood smear morphology due to its resemblance to Plasmodium malariae, a less virulent species.
- Confirmation of a suspected diagnosis based on blood film examinations or rapid antigen detection methods
- Plasmodium speciation—important since different species receive different treatment and have different prognoses
- Plasmodium knowlesi identification—an emerging public health concern in travelers to Southeast Asia
- Differentiation of Plasmodium species from Babesia species—parasites appear similar by blood smear morphology but cause very different diseases and are treated differently
- Detection of low-level parasitemia—PCR has greater sensitivity than blood films
NOTE: All specimens with a positive malaria PCR result receive a blood smear for determination of percent parasitemia.