Laboratory Confirmation

At a glance

CDC and the Council for State and Territorial Epidemiologist (CSTE) recommend a PCR test for all malaria cases to confirm plasmodium species. This is important to ensure proper treatment when a positive case is identified. CDC can assist with species confirmation through its DPDx site.

Laboratory confirmation

Malaria rapid diagnostic test (RDT) results, whether positive or negative, should be confirmed with a blood smear. Although it is possible to determine the Plasmodium species on a thin blood smear, this is often difficult to determine by microscopy alone and typically requires expertise. The Council for State and Territorial Epidemiologist (CSTE) recommends a PCR test be performed for all malaria cases to confirm the Plasmodium species. Determination of Plasmodium species is important to ensure additional treatment for P. vivax and P. ovale species and thus prevent relapsing illnesses.

The State Public Health laboratory (PHL) (if they have the capacity) should review, as soon as possible, blood smear microscopy and conduct confirmatory PCR for any malaria cases.

  • Determine if PHLs can routinely retain whole blood specimens (preferably pre-treatment) from patients with confirmed malaria. This is helpful for investigations where cases in proximity could be assessed for genetic relatedness (via CDC genomic testing).
  • CDC can assist with species confirmation via DPDx. Send an email for CDC testing approval and submission instructions:

Babesiosis is another intraerythrocytic parasitic infection that can have similar signs and symptoms as malaria. Babesia microti (and other species) are transmitted in some parts of the U.S. by ticks and can be difficult to differentiate from P. falciparum by blood smear. PCR should be ordered for both Babesia and Plasmodium to distinguish between these illnesses if there is any question, especially for individuals who have not traveled recently in a place where ongoing malaria transmission occurs.

  • CDC and some PHLs conduct routine molecular surveillance testing.
  • Consider routinely sending whole blood specimens for molecular surveillance testing to CDC: malarialab@cdc.gov

See Appendix B for additional information about malaria molecular testing.

Please copy the malaria hotline malaria@cdc.gov in emails regarding lab testing for cases under investigation.

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Content Source:
National Center for Emerging and Zoonotic Infectious Diseases (NCEZID)