Plasmodium Species - Malaria

  • Diagnosis
  • Background
  • Lab Tests
  • References
  • Related Topics

Indications for Testing

  • Clinical history and symptoms with residency in or travel to endemic area

Laboratory Testing

  • Diagnosis information (CDC)
  • Giemsa-stained blood smear (300 oil-immersion fields examined)
    • Demonstration of intraerythrocytic parasites is diagnostic
    • Specimen should be collected when patient's temperature is rising
    • Single specimen insufficient to rule out malaria
    • Detection threshold – 4-100 parasites/µL
    • Less sensitive in low-level parasitemia, partial immunity, partially treated patients, and in patients with malaria caused by Plasmodium species other than P. falciparum
  • Malaria antibody testing
    • Not useful in acute disease, but IgG response is rapid
    • Provides evidence of past exposure
    • Does not provide definitive identification of Plasmodium spp
  • Rapid antigen testing (eg, ParaHIT, MakroMed, HRP-II ELISA, BinaxNOW Malaria)
    • Most useful in rapid diagnosis or exclusion of P. falciparum
    • CDC recommends follow-up confirmation of rapid testing for U.S. patients
  • PCR
    • Many available platforms
      • Qualitative platforms cannot be used to monitor treatment
  • Other nucleic acid testing
    • High sensitivity and specificity
    • Accuracy of quantification of parasitemia depends on platform
    • Not readily available

Differential Diagnosis

Malaria is caused by the protozoan parasite Plasmodium and is transmitted by infected mosquitos.


  • Incidence
    • Worldwide distribution in tropical areas – endemic in >95 countries (CDC, 2016)
      • 3.2 billion people (half of world’s population) are at risk each year
      • ~214 million new cases reported every year
      • 438,000 deaths from malaria annually worldwide
      • ~1,500 cases in U.S. annually
  • Transmission
    • Vector – Anopheles mosquito


  • Most malarial infections in humans are caused by the following species of Plasmodium parasites
    • P. vivax – mostly in Asia, Latin America, and some regions of Africa; most prevalent species because of human population densities, especially in Asia
    • P. falciparum – found in all tropical and subtropical regions, predominates in Africa; causes most severe form of malaria, including death
    • P. ovale – mostly in western Pacific islands and Africa (especially West Africa)
    • P. malariae – in all tropical and subtropical regions; only plasmodium with quartan cycle
    • P. knowlesi – Southeast Asia

Risk Factors

  • Children <5 years
  • Pregnancy – women are most vulnerable during first pregnancy
    • Fetus is also at risk
  • Refugees from endemic countries
  • Nonimmune travelers to endemic areas


  • Characteristic malarial symptoms result from parasite-infected red blood cells that may accumulate and sequester in various organs, including heart, brain, lungs, and kidneys

Clinical Presentation

  • May be nonspecific flu-like presentation – malaise, fever, myalgias
    • Typically occurs 7-30 days after mosquito bite
  • Progresses to splenomegaly, anemia, jaundice
  • Severe infection, usually from P. falciparum species, may cause the following
  • Dormant infections can occur with P. vivax and P. ovale
    • Recurrence most common with P. vivax
  • Complications in infected pregnant women
    • Infection in mother can be more severe
    • Spontaneous abortion
    • Preterm labor
    • Low birth weight
    • Congenital infection – fever, hepatosplenomegaly, jaundice, anemia
Tests generally appear in the order most useful for common clinical situations. Click on number for test-specific information in the ARUP Laboratory Test Directory.

Parasites Smear (Giemsa Stain), Blood 0049025
Method: Stain


Blood collection during fever usually yields highest parasite numbers



Sequential blood samples may be required for diagnosis due to cyclical nature of disease

Malaria, Rapid Screen and Giemsa Stain 2001547
Method: Qualitative Immunochromatography/Stain


Rapid screen does not detect parasitemia less than 0.5%

Rapid screen should not be used for therapeutic monitoring


All rapid antigen test results are confirmed by blood smear examination

Malaria Antibody, IgG 0051356
Method: Semi-Quantitative Enzyme-Linked Immunosorbent Assay


False-positive results may be seen in up to 18% of patients positive for antinuclear antibodies or rheumatoid factor

Serological results from this assay alone should not determine diagnosis

Malaria Detection and Speciation, Qualitative by Real-Time PCR 2004963
Method: Qualitative Real-Time Polymerase Chain Reaction


Do not use to monitor treatment

Detection of asymptomatic parasitemia in individuals from malaria-endemic areas is possible; therefore, use only in conjunction with patient travel history and symptoms consistent with malaria

Latent-phase hypnozoites of P.ovale and P. vivax may not be detected

General References

Baird J. Malaria zoonoses. Travel Med Infect Dis. 2009; 7(5): 269-77. PubMed

Campuzano-Zuluaga G, Hänscheid T, Grobusch MP. Automated haematology analysis to diagnose malaria. Malar J. 2010; 9: 346. PubMed

Collins WE, Jeffery GM. Plasmodium malariae: parasite and disease. Clin Microbiol Rev. 2007; 20(4): 579-92. PubMed

Garcia LS. Malaria. Clin Lab Med. 2010; 30(1): 93-129. PubMed

Greer JP, et al. Wintrobe’s Clinical Hematology, 13th ed. Philadelphia: Lippincott Williams and Wilkins, 2013.

Malaria. Centers for Disease Control and Prevention. [Accessed: May 2016]

Malaria. World Health Organization. Geneva, Switzerland [Accessed: Nov 2015]

Murray CK, Gasser RA, Magill AJ, Miller S. Update on rapid diagnostic testing for malaria. Clin Microbiol Rev. 2008; 21(1): 97-110. PubMed

Rogerson SJ. Malaria in pregnancy and the newborn. Adv Exp Med Biol. 2010; 659: 139-52. PubMed

Rosenblatt JE. Laboratory diagnosis of infections due to blood and tissue parasites. Clin Infect Dis. 2009; 49(7): 1103-8. PubMed

Vasoo S, Pritt BS. Molecular diagnostics and parasitic disease. Clin Lab Med. 2013; 33(3): 461-503. PubMed

White NJ, Pukrittayakamee S, Hien TT, Faiz A, Mokuolu OA, Dondorp AM. Malaria. Lancet. 2014; 383(9918): 723-35. PubMed

Wilson ML. Laboratory diagnosis of malaria: conventional and rapid diagnostic methods. Arch Pathol Lab Med. 2013; 137(6): 805-11. PubMed

References from the ARUP Institute for Clinical and Experimental Pathology®

Petti CA, Polage CR, Quinn TC, Ronald AR, Sande MA. Laboratory medicine in Africa: a barrier to effective health care. Clin Infect Dis. 2006; 42(3): 377-82. PubMed

She RC, Rawlins ML, Mohl R, Perkins SL, Hill HR, Litwin CM. Comparison of immunofluorescence antibody testing and two enzyme immunoassays in the serologic diagnosis of malaria. J Travel Med. 2007; 14(2): 105-11. PubMed

Medical Reviewers

Last Update: August 2016