brand logo

Am Fam Physician. 2000;61(6):1640-1643

to the editor: I enjoyed the recent article “Case Studies in International Travelers,”1 in which Dr. Kitchen discussed several clinical vignettes of illnesses, including malaria, in travelers returning to the United States. Microscopy of serial blood smears to detect the presence of the malaria parasites (plasmodium species) continues to be the “gold standard” for clinical diagnosis because it allows estimation of parasitemia, distinction between parasite growth stages and identification of the four different plasmodium species of malaria. However, the article did not address the recent advances in rapid “dipstick” assays to detect malaria. Several commercially available immunochromatographic antigen detection assays are available (see the accompanying table). These assays have been used in various clinical settings in North America and endemic regions.

Assay (company; contact address)Plasmodium species identifiedParasite antigen detectedSensitivity (%)Specificity (%)
Flow Inc., Portland, OR
Web site:
P. falciparumParasite lactate dehydrogenase88-91 (P.f)92-99 (P.f)
P. vivax94 (P.v)100 (P.v)
ICT Malaria P.f/P.v6
AMRAD ICT, Sydney, NSW, Australia
Web site:
P. falciparumHRP-295 (P.f)89 (P.f)
P. vivax75 (P.v)95 (P.v)
PATH Falciparum Malaria IC Strip2
Quorum Diagnostics, Vancouver, Canada
P. falciparumHRP-29699
Parasight-F 3
Becton Dickinson Tropical Diagnostics, Sparks, MD
Web site:
P. falciparumHRP-29495
ICT Malaria P.f3
AMRAD ICT, Sydney, NSW, Australia
Web site:
P. falciparumHRP-29097

The older “dipstick” tests (Parasight-F, ICT Malaria P.f and PATH Falciparum Malaria IC Strip) detect only Plasmodium falciparum infection. All three assays detect histidine-rich protein 2, an antigen expressed only by P. falciparum trophozoites.2,3 However, the two newer tests (the OptiMAL assay, and the ICT Malaria P.f/P.v assay) have the advantage of detecting infection with P. falciparum or Plasmodium vivax. The OptiMAL assay detects parasite lactate dehydrogenase (pLDH) and can distinguish between P. falciparum and P. vivax because of antigenic differences between their pLDH isoenzymes.4,5 Because only live parasites produce pLDH, this test can be of clinical relevance because it distinguishes between living (current infection) and dead parasites (recently treated infection). The ICT Malaria P.f/P.v test detects histidine-rich protein 2 found only in P. falciparum and panmalarial antigens found in P. vivax, again, allowing the two species to be differentiated.6

Although some of these assays are relatively expensive and are awaiting final labeling approval from the U.S. Food and Drug Administration, they can provide excellent diagnostic aids for family physicians caring for immigrants or travelers who have recently returned from malarious areas, as well as for physicians providing health care to persons in developing countries—especially if a trained microscopist is not readily available.

in reply : Dr. Thompson's points are well taken. At the time I wrote my article,1 I was unaware of the newer multispecies “dipstick” malaria-detection tests he describes.

Email letter submissions to Letters should be fewer than 400 words and limited to six references, one table or figure, and three authors. Letters submitted for publication in AFP must not be submitted to any other publication. Letters may be edited to meet style and space requirements.

This series is coordinated by Kenny Lin, MD, MPH, deputy editor.

Continue Reading

More in AFP

More in Pubmed

Copyright © 2000 by the American Academy of Family Physicians.

This content is owned by the AAFP. A person viewing it online may make one printout of the material and may use that printout only for his or her personal, non-commercial reference. This material may not otherwise be downloaded, copied, printed, stored, transmitted or reproduced in any medium, whether now known or later invented, except as authorized in writing by the AAFP.  See permissions for copyright questions and/or permission requests.