BackgroundThe efficacy and safety of artemether–lumefantrine (AL) and dihydroartemisinin–piperaquine (DP) against asexual parasites population has been documented. However, the effect of these anti-malarials on sexual parasites is still less clear. 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.MethodsChildren aged between 0.5 and 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 qRT-PCR and gametocyte prevalence, density and mean duration of gametocyte carriage were determined.ResultsAt baseline, all the 334 children had positive asexual parasites by microscopy, 12% (40/334) had detectable gametocyte by microscopy, and 83.7% (253/302) children had gametocytes by RT-qPCR. Gametocyte prevalence 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 average 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).ConclusionThe study identifies no significant difference between AL and DP in gametocyte clearance. Gametocytes persisted up to 42 days post treatment in minority of individuals in both treatment arms. A gametocytocidal drug, in combination with artemisinin-based combination therapy, will be useful in blocking malaria transmission more efficiently.

BackgroundThe use of saliva in diagnosis of infectious diseases is an attractive alternative to procedures that involve blood drawing. It promises to reduce risks associated with accidental needle pricks and improve patient compliance particularly in malaria survey and drug efficacy studies. Quantification of parasitaemia is useful in establishing severity of disease and in assessing individual patient response to treatment. In current practice, microscopy is the recommended technique, despite its limitations. This study measured the levels of Plasmodium falciparum lactate dehydrogenase (PfLDH) in saliva of malaria patients and investigated the relationship with blood parasitaemia.MethodsMatched pre-treatment blood and saliva samples were collected from patients at Msambweni District Hospital, Kenya. Parasitaemia was determined and only those confirmed to be Plasmodium falciparum mono-infected were recruited. PfLDH was quantified in saliva using a commercial ELISA kit. A total of 175 samples were collected. Relationship between blood parasitaemia and concentration of PfLDH in saliva was determined using Pearson correlation statistics. F test was used to determine whether there is a significant difference between levels of PfLDH in saliva of patients with moderate to high parasitaemia and those with low parasitaemia.ResultsOne-hundred and seventy-five patient samples were positive for malaria by microscopy. Of these, 62 (35%) tested positive for PfLDH in saliva, 113 (65%) were false negatives. For those that tested positive, (53) 85% were from patients with moderate to high parasitaemia while 9 (15%) were from patients with low parasitaemia. A correlation co-efficient of 0.18 indicated a weak positive relationship between the concentration of PfLDH in saliva and blood parasitaemia. There was a marginal difference between levels of PfLDH in saliva of patients with moderate to high parasitaemia and those with low parasitaemia [F (1, 59) = 1.83, p = 0.1807].ConclusionThe results indicate that there is a weak correlation between levels of PfLDH in saliva and blood parasitaemia. This is weak association could be as a result of low sensitivity of the assay used as well as presence of inhibitors and proteases in saliva. Further studies should be focused towards reducing the number of false negatives and developing a customised assay that is specific for detection of PfLDH in saliva.

Introduction: Emerging infectious diseases are infections that have recently appeared within a population or those whose incidence or geographic range is rapidly increasing or threatens to increase in the near future. The current study sought to re-evaluate malaria prevalence, susceptibility to ACTs, transmission patterns and the presence of malaria vectors in the Kikuyu area of the Kenyan Central highlands, a non-traditional/ low risk malaria transmission zone where there have been anecdotal reports of malaria cases The potential role of climate factors was also evaluated. The aim of the study was to generate data to inform malaria treatment policy and practice in the study area and country. Methodology: Sampling of adult mosquitoes was carried indoors by manual aspiration and using CDC light traps while mosquito larvae were sampled outdoors using larval dippers and reared to adults in the laboratory. Mosquitoes were identified by morphology and subsequently using PCR and the presence of malaria parasites in field sampled adult mosquitoes investigated using ELISA. The malaria clinical study was an open label nonrandomized clinical trial where the efficacy of one artemisinin-based antimalarial combination drug, Artemether Lumefantrine (AL) was evaluated. Two health facilities Lusigeti and Gikambura were identified for the study. Microscopy was used to identify positive cases at the health facility and nested PCR amplification targeting subunit 18s rRNA gene used to confirm positivity in the lab. P. falciparum isolates were genotyped using nested-PCR of MSP-1 (block 2) and MSP-2 (block 3) family alleles to determine the multiplicity of the infections (MOI) and characterize any subsequent infection. Antimalarial resistance gene markers Pfk13 and Pfmdr1 were analyzed Climate data for the study area was obtained from Climate Engine (http://climateengine.org) and analyzed to understand long term trends. Results: A rich repertoire of mosquito vector species was identified from the area, with the Anopheles funestus group being the predominant vector species and comprising 76.35% of all collections. Only two adult mosquitoes which were non-blood fed and negative for malaria parasites were collected. Of the 838 patients screened, 471, with a slide positivity rate of 2.1% (10) were from Lusigeti and 421, with a slide positivity rate of 7.4% (31) were from Gikambura. Parasitological analysis of microscopy outcome of the 41 cases revealed 100% (95% CI 1.96) as Adequate Clinical and Parasitological Response (ACPR). There was probable delayed parasite clearance (parasites present on Day 3) in 3(7.3%) of the cases, and no severe adverse reaction was observed. Analysis of the Pfk13 gene in the positive P. falciparum cases from the study sites revealed no SNP associated with artemisinin resistance. The pfmdr1 86Y mutation was found in 0% (0/41) of the isolates while the N86 wild allele was detected in 100%(37/37). Analysis of long term climate data showed an increase of about 1.3ºC in both the mean minimum and maximum temperatures consistent with forecasts from other sources. Conclusion: The positivity rate observed in the study site was very low but the fact that 87% of participants who tested positive did not report recent history of travel from the area and the finding of highly competent known vectors of malaria suggest a changing malaria transmission scenario requiring further investigations. That circulating parasite strains showed full sensitivity to the available treatment option indicating the absence of antimalarial drug resistance which is a positive finding.