Malaria parasite density estimated with white blood cells count reference value agrees with density estimated with absolute in children less than 5 years in central ghana

Efficacy and safety of artemether-lumefantrine and dihydroartemisinin-piperaquine for the treatment of uncomplicated Plasmodium falciparum malaria and prevalence of molecular markers associated with artemisinin and partner drug resistance in Uganda

Background

In Uganda, artemether-lumefantrine (AL) is first-line therapy and dihydroartemisinin-piperaquine (DP) second-line therapy for the treatment of uncomplicated malaria. This study evaluated the efficacy and safety of AL and DP in the management of uncomplicated falciparum malaria and measured the prevalence of molecular markers of resistance in three sentinel sites in Uganda from 2018 to 2019.

Methods

This was a randomized, open-label, phase IV clinical trial. Children aged 6 months to 10 years with uncomplicated falciparum malaria were randomly assigned to treatment with AL or DP and followed for 28 and 42 days, respectively. Genotyping was used to distinguish recrudescence from new infection, and a Bayesian algorithm was used to assign each treatment failure a posterior probability of recrudescence. For monitoring resistance, Pfk13 and Pfmdr1 genes were Sanger sequenced and plasmepsin-2 copy number was assessed by qPCR.

Results

There were no early treatment failures. The uncorrected 28-day cumulative efficacy of AL ranged from 41.2 to 71.2% and the PCR-corrected cumulative 28-day efficacy of AL ranged from 87.2 to 94.4%. The uncorrected 28-day cumulative efficacy of DP ranged from 95.8 to 97.9% and the PCR-corrected cumulative 28-day efficacy of DP ranged from 98.9 to 100%. The uncorrected 42-day efficacy of DP ranged from 73.5 to 87.4% and the PCR-corrected 42-day efficacy of DP ranged from 92.1 to 97.5%. There were no reported serious adverse events associated with any of the regimens. No resistance-associated mutations in the Pfk13 gene were found in the successfully sequenced samples. In the AL arm, the NFD haplotype (N86Y, Y184F, D1246Y) was the predominant Pfmdr1 haplotype, present in 78 of 127 (61%) and 76 of 110 (69%) of the day 0 and day of failure samples, respectively. All the day 0 samples in the DP arm had one copy of the plasmepsin-2 gene.

Conclusions

DP remains highly effective and safe for the treatment of uncomplicated malaria in Uganda. Recurrent infections with AL were common. In Busia and Arua, the 95% confidence interval for PCR-corrected AL efficacy fell below 90%. Further efficacy monitoring for AL, including pharmacokinetic studies, is recommended.

Trial registration The trail was also registered with the ISRCTN registry with study Trial No. PACTR201811640750761

Supplementary Information

The online version contains supplementary material available at 10.1186/s12936-021-04021-5.

A seven-year surveillance of epidemiology of malaria reveals travel and gender are the key drivers of dispersion of drug resistant genotypes in Kenya

Malaria drug resistance is a global public health concern. Though parasite mutations have been associated with resistance, other factors could influence the resistance. A robust surveillance system is required to monitor and help contain the resistance. This study established the role of travel and gender in dispersion of chloroquine resistant genotypes in malaria epidemic zones in Kenya. A total of 1,776 individuals presenting with uncomplicated malaria at hospitals selected from four malaria transmission zones in Kenya between 2008 and 2014 were enrolled in a prospective surveillance study assessing the epidemiology of malaria drug resistance patterns. Demographic and clinical information per individual was obtained using a structured questionnaire. Further, 2 mL of blood was collected for malaria diagnosis, parasitemia quantification and molecular analysis. DNA extracted from dried blood spots collected from each of the individuals was genotyped for polymorphisms in Plasmodium falciparum chloroquine transporter gene (Pfcrt 76), Plasmodium falciparum multidrug resistant gene 1 (Pfmdr1 86 and Pfmdr1 184) regions that are putative drug resistance genes using both conventional polymerase chain reaction (PCR) and real-time PCR. The molecular and demographic data was analyzed using Stata version 13 (College Station, TX: StataCorp LP) while mapping of cases at the selected geographic zones was done in QGIS version 2.18. Chloroquine resistant (CQR) genotypes across gender revealed an association with chloroquine resistance by both univariate model (p = 0.027) and by multivariate model (p = 0.025), female as reference group in both models. Prior treatment with antimalarial drugs within the last 6 weeks before enrollment was associated with carriage of CQR genotype by multivariate model (p = 0.034). Further, a significant relationship was observed between travel and CQR carriage both by univariate model (p = 0.001) and multivariate model (p = 0.002). These findings suggest that gender and travel are significantly associated with chloroquine resistance. From a gender perspective, males are more likely to harbor resistant strains than females hence involved in strain dispersion. On the other hand, travel underscores the role of transport network in introducing spread of resistant genotypes, bringing in to focus the need to monitor gene flow and establish strategies to minimize the introduction of resistance strains by controlling malaria among frequent transporters.

Single-nucleotide polymorphism characterization of gametocyte development 1 gene in Plasmodium falciparum isolates from Baringo, Uasin Gishu, and Nandi Counties, Kenya

INTRODUCTION

Plasmodium falciparum relies on gametocytogenesis to transmit from humans to mosquitoes. Gametocyte development 1 (Pfgdv1) is an upstream activator and epigenetic controller of gametocytogenesis. The emergence of drug resistance is a major public health concern and this requires the development of new strategies that target the transmission of malaria. As a putative drug target, Pfgdv1 has not been characterized to identify its polymorphisms and alleles under selection and how such polymorphisms influence protein structure.

METHODS

This study characterized single-nucleotide polymorphisms (SNPs) in primary sequences (n = 30) of Pfgdv1 gene generated from thirty blood samples collected from patients infected with P. falciparum and secondary sequences (n = 216) retrieved from PlasmoDB. ChromasPro, MUSCLE, Tajima's D statistic, SLAC, and STRUM were used in editing raw sequences, performing multiple sequence alignment (MSA), identifying signatures of selection, detecting codon sites under selection pressure, and determining the effect of SNPs, respectively.

RESULTS

MSA of primary and secondary sequences established the existence of five SNPs, consisting of four non-synonymous substitutions (nsSNPs) (p.P217H, p.R398Q, p.H417N, and p.D497E), and a synonymous substitution (p.S514S). The analysis of amino acid changes reveals that p.P217H, p.R398Q, and p.H417N comprise non-conservative changes. Tajima's D statistic showed that these SNPs were under balancing selection, while SLAC analysis identified p.P217H to be under the strongest positive selection. . Further analysis based on thermodynamics indicated that p.P217H has a destabilizing effect, while p.R398Q and p.D497E have stabilizing effects on the protein structure.

CONCLUSIONS

The existence of four nsSNPs implies that Pfgdv1 has a minimal diversity in the encoded protein. Selection analysis demonstrates that these nsSNPs are under balancing selection in both local and global populations. However, p.P217H exhibits positive directional selection consistent with previous reports where it showed differentiatial selection of P. falciparum in low and high transmission regions. Therefore, in-silico prediction and experimental determination of protein structure are necessary to evaluate Pfgdv1 as a target candidate for drug design and development.

Antiplasmodial activity of methanol leaf extract of Citrus aurantifolia (Christm) Swingle

Introduction: Citrus aurantifolia (Christm) is a plant used for the treatment of various ailments including malaria. This study aimed to evaluate the in vivo antiplasmodial efficacy of methanol leaf extract of C. aurantifolia in Swiss albino mice. Methods: The median lethal dose (LD50) was determined by intraperitoneal administration of different doses of the extract (100–4000 mg/kg) to 6 groups of 3 mice each and the animals were observed for 24 hours for physical signs of toxicity. To evaluate the antiplasmodial activity of the extract, three models were used: suppressive, curative and repository. Doses of the extract used were 320, 640 and 960 mg/kg/d in mice, with Chloroquine (5 mg/kg/d) as standard drug. Pyrimethamine (1.2 mg/kg/d) was used as the standard drug for the repository test and distilled water (10 mL/kg/d) as control in all models. Results: In all models, the low dose (320 mg/kg) of the extract produced the highest chemosuppressive effects in all models (P < 0.001). Mice treated with extract lived longer than those in the control group (P < 0.001). Phytochemical screening revealed the presence of alkaloids, flavonoids, saponins, tannins and cardiac glycosides and the LD50 of 3280 mg/kg ± 0.01 shows that the extract has low toxicity. Conclusion: The result of this study shows that C. aurantifolia has antiplasmodial properties which support its use in ethnomedicine in the treatment of malaria.

Malaria Parasite Density Estimation using Actual and Assumed White Blood Cells Count in Children in Eastern Sudan

BACKGROUND

Estimating malaria parasite count is needed for estimating the severity of the disease and during the follow-up.

OBJECTIVE

This study was conducted to determine the malaria parasite density among children using actual white blood cell (WBC) and the assumed WBC counts (8.0 × 10(9)/l).

METHODS

A cross-sectional study was conducted at New Halfa Hospital, Sudan. WBC count and count of asexual malaria parasite were performed on blood films.

RESULTS

One hundred and three children were enrolled. The mean (SD) WBCs was 6.2 (2.9) cells × 10(9)/l. The geometric mean (SD) of the parasite count using the assumed WBCs (8.0 × 10(9)/l cells/μl) was significantly higher than that estimated using the actual WBC count [7345.76 (31,038.56) vs. 5965 (28,061.57) rings/μl,p = 0.042].

CONCLUSION

Malaria parasitemia based on assumed (8.0 × 10(9)/) WBCs is higher than parasitemia based on actual WBCs.

Provider compliance to artemisinin-based combination therapy at primary health care facilities in the middle belt of Ghana

BACKGROUND

In 2004, Ghana implemented the artemisinin-based combination therapy (ACT) policy. Health worker (HW) adherence to the national malaria guidelines on case-management with ACT for children below 5 years of age and older patients presenting at health facilities (HF) for primary illness consultations was evaluated 5 years post-ACT policy change.

METHODS

Cross-sectional surveys were conducted from 2010 to 2011 at HFs that provide curative care as part of outpatient activities in two districts located in the middle belt of Ghana to coincide with the periods of low and high malaria transmission seasons. A review of patient medical records, HW interviews, HF inventories and finger-pricked blood obtained for independent malaria microscopy were used to assess HW practices on malaria case-management.

RESULTS

Data from 130 HW interviews, 769 patient medical records at 20 HFs over 75 survey days were individually linked and evaluated. The majority of consultations were performed at health centres/clinics (68.3 %) by medical assistants (28.6 %) and nurse aids (23.5 %). About 68.4 % of HWs had received ACT-specific training and 51.9 %, supervisory visits in the preceding 6 months. Despite the availability of malaria diagnostic test at most HFs (94 %), only 39.8 % (241) out of 605 (78.7 %) patients who reported fever were investigated for malaria. Treatment with ACT in line with the guidelines was 66.7 %; higher in <5 children compared to patients ≥5 years old. Judged against reference microscopy, only 44.8 % (107/239) of ACT prescriptions that conformed to the guidelines were "truly malaria". Multivariate logistic regression analysis showed that HW were significantly more likely to comply with the guidelines if treatment were by low cadre of health staff, were for children below 5 years of age, and malaria test was performed.

CONCLUSION

Although the majority of patients presenting with malaria received treatment according to the national malaria guidelines, there were widespread inappropriate treatment with ACT. Compliance with the guidelines on ACT use was low, 5 years post-ACT policy change. The Ghana NMCP needs to strengthen HW capacity on malaria case-management through regular training supported by effective laboratory quality control measures.