Sensitive and inexpensive molecular test for falciparum malaria: detecting Plasmodium falciparum DNA directly from heat-treated blood by loop-mediated isothermal amplification.
BACKGROUND
Malaria is one of the most important parasitic infections in humans. A sensitive diagnostic test for malaria that could be applied at the community level could be useful in programs to control the disease. The aim of the present work was to develop a simple, inexpensive molecular test for Plasmodium falciparum.


METHODS
Blood was collected from controls (n = 100) and from patients diagnosed with falciparum malaria infection (n = 102), who were recruited to the study. Heat-treated blood samples were tested by a loop-mediated isothermal amplification (LAMP) assay for P. falciparum. Results were interpreted by a turbidity meter in real time or visually at the end of the assay. To evaluate the assay, DNA from these samples was purified and tested by PCR. Results from the LAMP and PCR assays were compared.


RESULTS
The LAMP assay detected P. falciparum directly from heat-treated blood. The quantitative data from the assay correlated to the parasite counts obtained by blood-film microscopic analyses. When we used the PCR assay as the comparison method, the sensitivity and specificity of the LAMP assay were 95% and 99%, respectively.


CONCLUSIONS
Unlike PCR, the LAMP assay does not require purified DNA for efficient DNA amplification, thereby reducing the cost and turnaround time for P. falciparum diagnosis. The assay requires only basic instruments, and assay positivity can be verified by visual inspection.
Poon
Leo L M
LL
Department of Microbiology, The University of Hong Kong, Hong Kong SAR. llmpoon@hkucc.hku.hk
Wong
Bonnie W Y
BW
Ma
Edmund H T
EH
Chan
Kwok H
KH
Chow
Larry M C
LM
Abeyewickreme
Wimal
W
Tangpukdee
Noppadon
N
Yuen
Kwok Y
KY
Guan
Yi
Y
Looareesuwan
Sornchai
S
Peiris
J S Malik
JS
D000818:Animals; D001483:Base Sequence; D002138:Calibration; D016054:DNA, Protozoan / Q000097:blood* / Q000235:genetics; D006358:Hot Temperature; D006801:Humans; D016778:Malaria, Falciparum / Q000097:blood / Q000175:diagnosis*; D008969:Molecular Sequence Data; D010963:Plasmodium falciparum / Q000235:genetics / Q000302:isolation & purification*; D016133:Polymerase Chain Reaction / Q000191:economics / Q000379:methods / Q000592:standards; D012680:Sensitivity and Specificity; D013048:Specimen Handling / Q000379:methods*
D016054:DNA, Protozoan