GAMETOCYTE CLEARANCE IN CHILDREN, FROM WESTERN KENYA, WITH UNCOMPLICATED PLASMODIUM FALCIPARUM MALARIA AFTER ARTEMETHER–LUMEFANTRINE OR DIHYDROARTEMISININ–PIPERAQUINE TREATMENT

Background

The efficacy and safety of Artemether-lumefantrine(AL) and Dihydroartemisinin-piperaquine (DP) against asexual parasite population has been documented. However, the effect of these antimalarials on sexual parasites is still unclear. Gametocyte clearance following treatment is essential for malaria control and elimination efforts; therefore, the study sought to determine trends in gametocyte clearance after AL or DP treatment in children from a malaria-endemic site in Kenya.

Methods

Children aged between 0.5 to 12 years from Busia, western Kenya with uncomplicated Plasmodium falciparum malaria were assigned randomly to AL or DP treatment. A total of 334 children were enrolled, and dried blood spot samples were collected for up to 6 weeks after treatment during the peak malaria transmission season in 2016 and preserved. Plasmodium falciparum gametocytes were detected by Pfs25 qRT-PCR and gametocytes prevalence, density and duration of gametocyte carriage were determined.

Results

At baseline, all the 334 children had positive asexual parasite by microscopy, 12% (40/334) had detectable gametocyte by microscopy, and 83.7% (253/302) children had gametocytes by RT-qPCR. The prevalence of gametocytes by RT-qPCR decreased from 85.1% (126/148) at day 0 to 7.04% (5/71) at day 42 in AL group and from 82.4 % (127/154) at day 0 to 14.5% (11/74) at day 42 in DP group. The duration of gametocyte carriage as estimated by qRT-PCR was slightly shorter in the AL group (4.5 days) than in the DP group (5.1 days) but not significantly different (p=0.301). Sub-microscopic gametocytes persisted in some patients up to day 42 despite all the children being microscopy negative for asexual parasites by day 7.

Conclusion

The study showed that AL cleared P. falciparum gametocytes slightly faster than DP although the difference not significant. However, there is a need to interpret the findings in the context of transmission intensity since submicroscopic gametocyte densities persisted after treatment with both AL and DP. This finding highlights the limitation of interventions that aim to reduce malaria transmission by use of antimalarial drugs. Therefore, a gametocidal drug, in combination with ACTs, will be useful in blocking malaria transmission more efficiently.

Key Words

Gametocyte
Artemether Lumefantrine
Plasmodium Falciparum
Artemisinin Combination Therapy
Polymerase Chain Reaction
Microscopy