Plasmodium falciparum gametocyte dynamics after pyronaridine-artesunate or artemether-lumefantrine treatment.

BACKGROUND: Artemisinin-based combinations differ in their impact on gametocyte prevalence and density. This study assessed female and male gametocyte dynamics after treating children with uncomplicated Plasmodium falciparum malaria with either pyronaridine-artesunate (PA) or artemether-lumefantrine (AL). METHODS: Kenyan children with uncomplicated Plasmodium falciparum malaria were included and randomly assigned to PA or AL treatment. Filter paper blood samples were collected as a source of RNA for quantitative reverse-transcription PCR (qRT-PCR) and nucleic acid sequence based amplification (QT-NASBA) to detect female gametocytes (targeting Pfs25 mRNA). Male gametocytes were detected by qRT-PCR (targeting PfMGET mRNA). Duration of gametocyte carriage, the female and male gametocyte response and the agreement between qRT-PCR and QT-NASBA were determined. RESULTS: The mean duration of female gametocyte carriage was significantly longer for PA (4.9 days) than for AL (3.8 days) as estimated by QT-NASBA (P = 0.036), but this difference was less clear when determined by Pfs25 qRT-PCR (4.5 days for PA and 3.7 for AL, P = 0.166). qRT-PCR based female gametocyte prevalence decreased from 100% (75/75) at baseline to 6.06% (4/66) at day 14 in the AL group and from 97.7% (83/85) to 13.9% (11/79) in the PA group. Male gametocyte prevalence decreased from 41.3% (31/75) at baseline to 19.7% (13/66) at day 14 in the AL group and from 35.3% (30/85) to 22.8% (18/79) in the PA group. There was good agreement between Pfs25 qRT-PCR and QT-NASBA female gametocyte prevalence (0.85, 95% CI 0.82-0.87). CONCLUSIONS: This study indicates that female gametocyte clearance may be slightly faster after AL compared to PA. Male gametocytes showed similar post-treatment clearance between study arms. Future studies should further address potential differences between the post-treatment transmission potential after PA compared to AL. Trial registration This study is registered at clinicaltrials.gov under NCT02411994. Registration date: 8 April 2015. https://clinicaltrials.gov/ct2/show/NCT02411994?term=pyronaridine-artesunate&cond=Malaria&cntry=KE&rank=1.

Pyronaridine-artesunate and artemether-lumefantrine for the treatment of uncomplicated Plasmodium falciparum malaria in Kenyan children: a randomized controlled non-inferiority trial.

BACKGROUND: Pyronaridine-artesunate is a novel artemisinin-based combination therapy. The efficacy and safety of pyronaridine-artesunate were compared with artemether-lumefantrine for the treatment of uncomplicated Plasmodium falciparum malaria in children. METHODS: This phase III open-label randomized controlled non-inferiority trial was conducted in Western Kenya. Children aged 6 months to ≤ 12 years with a bodyweight > 5 kg and microscopically confirmed P. falciparum malaria were randomly assigned in a 1:1 ratio to orally receive pyronaridine-artesunate or artemether-lumefantrine, dosed according to bodyweight, for 3 days. RESULTS: Of 197 participants, 101 received pyronaridine-artesunate and 96 received artemether-lumefantrine. The day-28 adequate clinical and parasitological response in the per-protocol population, PCR-corrected for reinfections, was 98.9% (93/94, 95% CI 94.2-99.8) for pyronaridine-artesunate and 96.4% (81/84, 95% CI 90.0-98.8) for artemether-lumefantrine. Pyronaridine-artesunate was found to be non-inferior to artemether-lumefantrine: the treatment difference was 2.5% (95% CI - 2.8 to 9.0). Adverse events occurred in 41.6% (42/101) and 34.4% (33/96) of patients in the pyronaridine-artesunate group and the artemether-lumefantrine group, respectively. No participants were found to have alanine or aspartate aminotransferase levels > 3 times the upper limit of normal. CONCLUSIONS: Pyronaridine-artesunate was well tolerated, efficacious and non-inferior to artemether-lumefantrine for the treatment of uncomplicated P. falciparum malaria in Kenyan children. Results are in line with previous reports and inclusion of pyronaridine-artesunate in paediatric malaria treatment programmes should be considered. This study is registered at clinicaltrials.gov under NCT02411994. Registration date: 8 April 2015. https://clinicaltrials.gov/ct2/show/NCT02411994?term=pyronaridine-artesunate&cond=Malaria&cntry=KE&rank=1.

Molecular Detection of Residual Parasitemia after Pyronaridine-Artesunate or Artemether-Lumefantrine Treatment of Uncomplicated Plasmodium falciparum Malaria in Kenyan Children.

Artemisinin resistance is rapidly rising in Southeast Asia and may spread to African countries, where efficacy estimates are currently still excellent. Extensive monitoring of parasite clearance dynamics after treatment is needed to determine whether responsiveness to artemisinin-based combination therapies (ACT) is changing in Africa. In this study, Kenyan children with uncomplicated falciparum malaria were randomly assigned to pyronaridine-artesunate (PA) or artemether-lumefantrine (AL) treatment. Parasite clearance was evaluated over 7 days following the start of treatment by quantitative polymerase chain reaction (qPCR) and direct-on-blood PCR nucleic acid lateral flow immunoassay (db-PCR-NALFIA), a simplified molecular malaria diagnostic. Residual parasitemia at day 7 was detected by qPCR in 37.1% (26/70) of AL-treated children and in 46.1% (35/76) of PA-treated participants (P = 0.275). Direct-on-blood PCR nucleic acid lateral flow immunoassay detected residual parasites at day 7 in 33.3% (23/69) and 30.3% (23/76) of AL and PA-treated participants, respectively (P = 0.692). qPCR-determined parasitemia at day 7 was associated with increased prevalence and density of gametocytes at baseline (P = 0.014 and P = 0.003, for prevalence and density, respectively) and during follow-up (P = 0.007 and P = 0.011, respectively, at day 7). A positive db-PCR-NALFIA outcome at day 7 was associated with treatment failure (odds ratio [OR]: 3.410, 95% confidence interval [CI]: 1.513-7.689, P = 0.003), but this association was not found for qPCR (OR: 0.701, 95% CI: 0.312-1.578, P = 0.391). Both qPCR and db-PCR-NALFIA detected substantial residual submicroscopic parasitemia after microscopically successful PA and AL treatment and can be useful tools to monitor parasite clearance. To predict treatment outcome, db-PCR-NALFIA may be more suitable than qPCR.

Plasmodium Detection and Differentiation by Direct-on-Blood PCR Nucleic Acid Lateral Flow Immunoassay: Development, Validation, and Evaluation.

Decreasing malaria transmission warrants the search for highly sensitive point-of-care diagnostics, especially in resource-limited settings. The direct-on-blood PCR nucleic acid lateral flow immunoassay (db-PCR-NALFIA) is a simplified PCR-based technique with a lateral flow readout that does not require sample preparation. Two duplex db-PCR-NALFIAs were developed: a pan-Plasmodium/Plasmodium falciparum (pan/P. falciparum) and a pan-Plasmodium/Plasmodium vivax (pan/P. vivax) assay. Confirmed positive samples (n = 61) and negative controls (n = 40) were used for laboratory validations. A prospective field evaluation of the pan/P. falciparum assay was performed in Kenya (n = 300). In the laboratory validation, sensitivity and specificity of the pan/P. falciparum assay were 100% (95% CI, 94.1%-100%) and 100% (95% CI, 91.2%-100%), respectively. Sensitivity and specificity of the pan/P. vivax assay were 100% (95% CI, 94.1%-100%) and 97.5% (95% CI, 86.8%-99.9%), respectively. In Kenya, sensitivity of the pan/P. falciparum db-PCR-NALFIA was 97.2% (95% CI, 93.0%-99.2%) and specificity was 74.2% (95% CI, 67.0%-81.0%) compared with reference standard microscopy. When using real-time quantitative PCR as a reference standard, sensitivity was 84.5% (95% CI, 78.7%-89.3%) and specificity was 85.4% (95% CI, 77.1%-91.6%). Db-PCR-NALFIA is a sensitive, specific, and easy method for the detection and species differentiation of Plasmodium. This test is especially of interest for malaria control or elimination programs in low-transmission settings that require accurate detection of low parasite densities.

Comparative field evaluation of the Mbita trap, the Centers for Disease Control light trap, and the human landing catch for sampling of malaria vectors in western Kenya.

The mosquito sampling efficiency of a new bed net trap (the Mbita trap) was compared with that of the Centers for Disease Control miniature light trap (hung adjacent to an occupied bed net) and the human landing catch in western Kenya. Overall, the Mbita trap caught 48.7 +/- 4.8% (mean +/- SEM) the number of Anopheles gambiae Giles sensu lato caught in the human landing catch and 27.4 +/- 8.2% of the number caught by the light trap. The corresponding figures for Anopheles funestus Giles were 74.6 +/- 1.3% and 39.2 +/- 1.9%, respectively. Despite the clear differences in the numbers of mosquitoes caught by each method, both the Mbita trap and light trap catches were directly proportional to human landing catches regardless of mosquito density. No significant differences in parity or sporozoite incidence were observed between mosquitoes caught by the three methods for either An. gambiae s.l. or An. funestus. Identification of the sibling species of the An. gambiae complex by a polymerase chain reaction indicated that the ratio of An. gambiae Giles sensu stricto to An. arabiensis Patton did not vary according to the sampling method used. It is concluded that the Mbita trap is a promising tool for sampling malaria vector populations since its catch can be readily converted into equivalent human biting catch, it can be applied more intensively, it requires neither expensive equipment nor skilled personnel, and it samples mosquitoes in an exposure-free manner. Such intensive sampling capability will allow cost-effective surveillance of malaria transmission at much finer spatial and temporal resolution than has been previously possible.