Enhanced detection of gametocytes by magnetic deposition microscopy predicts higher potential for Plasmodium falciparum transmission.
BACKGROUND
Aggregated haemozoin crystals within malaria-infected erythrocytes confer susceptibility of parasitized cells to a magnetic field. Here the utility of this method for diagnosis of human malaria is evaluated in a malaria-endemic region of Papua New Guinea (PNG).


RESULTS
Individuals with Plasmodium falciparum malaria symptoms (n = 55) provided samples for conventional blood smear (CBS) and magnetic deposition microscopy (MDM) diagnosis. Standard Giemsa staining and light microscopy was performed to evaluate all preparations. Plasmodium falciparum parasitaemia observed on MDM slides was consistently higher than parasitaemia observed by (CBS) for ring (CBS = 2.6 vs. MDM = 3.4%; t-test P-value = 0.13), trophozoite (CBS = 0.5 vs. MDM = 1.6%; t-test P-value = 0.01), schizont (CBS = 0.003 vs. MDM = 0.1%; t-test P-value = 0.08) and gametocyte (CBS = 0.001 vs. MDM = 0.4%; t-test P-value = 0.0002) parasitaemias. Gametocyte prevalence determined by CBS compared to MDM increased from 7.3% to 45%, respectively.


CONCLUSIONS
MDM increased detection sensitivity of P. falciparum-infected, haemozoin-containing erythrocytes from infected humans while maintaining detection of ring-stage parasites. Gametocyte prevalence five-fold higher than observed by CBS suggests higher malaria transmission potential in PNG endemic sites compared to previous estimates.
Karl
Stephan
S
Institute of Food Process and Bioprocess Engineering, University of Technology Dresden, 01062 Dresden, Germany. stephanunkarl@googlemail.com
David
Makindi
M
Moore
Lee
L
Grimberg
Brian T
BT
Michon
Pascal
P
Mueller
Ivo
I
Zborowski
Maciej
M
Zimmerman
Peter A
PA
D000818:Animals; D016054:DNA, Protozoan / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics; D004912:Erythrocytes / Q000166:cytology / Q000469:parasitology*; D006420:Hemeproteins / Q000378:metabolism; D006801:Humans; D008280:Magnetics; D016778:Malaria, Falciparum / Q000175:diagnosis* / Q000453:epidemiology / Q000469:parasitology*; D008853:Microscopy / Q000379:methods*; D010219:Papua New Guinea / Q000453:epidemiology; D010963:Plasmodium falciparum / Q000166:cytology / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification*; D052939:Schizonts / Q000166:cytology; D053058:Trophozoites / Q000166:cytology
D016054:DNA, Protozoan; D004275:DNA, Ribosomal; D006420:Hemeproteins; C020753:hemozoin