Age-dependent distribution of Plasmodium falciparum gametocytes quantified by Pfs25 real-time QT-NASBA in a cross-sectional study in Burkina Faso.
Sexual stages of Plasmodium falciparum play a key role in the transmission of malaria. Studies on gametocytes are generally based on microscopic detection, but more sensitive detection methods for P. falciparum gametocytes frequently detect sub-patent gametocytes. We used Pfs25 mRNA quantitative-nucleic acid sequence-based amplification (QT-NASBA) to quantify gametocytes in 412 samples from a cross-sectional study in Burkina Faso, covering all age groups, to determine age-related patterns in gametocyte carriage and gametocyte density. The more sensitive QT-NASBA technique gave estimates of gametocyte prevalence 3.3-fold higher than microscopy (70.1% versus 21.4%, respectively). Prevalence of gametocytes significantly decreased with age. Our data suggest that asexual parasite densities are primarily responsible for the age-related decrease of gametocyte prevalence, possibly because of developing asexual stage immunity. Gametocyte densities decrease also with age, primarily because of decreasing asexual parasite densities; only a small but significant age effect on gametocyte density may be caused by developing sexual stage-specific immunity.
Ouédraogo
André Lin
AL
Department of Medical Microbiology, University Medical Centre Nijmegen, Nijmegen, The Netherlands. andre_lin_o@yahoo.fr
Schneider
Petra
P
de Kruijf
Marcel
M
Nébié
Issa
I
Verhave
Jan Peter
JP
Cuzin-Ouattara
Nadine
N
Sauerwein
Robert W
RW
D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000818:Animals; D002050:Burkina Faso / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D006801:Humans; D016778:Malaria, Falciparum / Q000453:epidemiology* / Q000469:parasitology*; D010963:Plasmodium falciparum / Q000254:growth & development* / Q000302:isolation & purification*; D015800:Protozoan Proteins / Q000302:isolation & purification*; D021161:Self-Sustained Sequence Replication
C071284:Pfs25 protein, Plasmodium falciparum; D015800:Protozoan Proteins