Enhanced detection of gametocytes by magnetic deposition microscopy predicts higher potential for Plasmodium falciparum transmission

Stephan Karl¹ , Makindi David² , Lee Moore³ , Brian T Grimberg⁴ , Pascal Michon² , Ivo Mueller² , Maciej Zborowski³ and Peter A Zimmerman⁴

¹Institute of Food Process and Bioprocess Engineering, University of Technology Dresden, 01062 Dresden, Germany

²Papua New Guinea Institute of Medical Research, P.O. Box 378, Madang, MP 511, Papua New Guinea

³Department of Biomedical Engineering/ND20, Lerner Research Institute, The Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH 44195, USA

⁴The Center for Global Health and Diseases, Case Western Reserve University, Wolstein Research Building, Room 4-125, 2103 Cornell Road, Cleveland, OH 44106-7286, USA

author email corresponding author email

Malaria Journal 2008, 7:66doi:10.1186/1475-2875-7-66


Published:	25 April 2008

Abstract

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).

Methods and findings

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.

Conclusion

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.