Comparison of four methods for extracting DNA from dried blood on filter paper for PCR targeting the mitochondrial Plasmodium genome

BACKGROUND: Few studies comparing multiple methods for DNA extraction from dried blood spots (DBS) on filter paper for PCR targeting the Plasmodium genome have been done. METHODS: Frequently-used methods for DNA extraction from DBS using Chelex-100, InstaGene Matrix, QIAamp DNA Mini Kit and TE buffer were compared on a dilution series of a standardized Plasmodium falciparum positive sample. The two DNA extraction methods resulting in the lowest limits of detection were compared by testing both on 31 P. falciparum positive samples collected under field conditions and stored for 4 years. RESULTS: The Chelex-100, InstaGene Matrix and QIAamp DNA Mini Kit methods performed similarly, resulting in the detection of 0.5 to 2 parasites per microliter (p/µl). The same 13 clinical samples (13/31; 42%) were positive using both DNA extraction methods with the lowest limits of detection. CONCLUSIONS: Simple and low-cost methods can be sensitive and useful in extracting DNA from DBS. Poor results on stored clinical DBS indicate that further studies on the impact of storage duration and conditions, and choice of filter paper should be performed.