Distribution of Pfmdr 1 and Kelch 13 Genes Among the Children 5 Years and Below Attending a Secondary Health Facility, South-West, Nigeria.

Background: Malaria is a major public health concern in some part of the world especially in the tropical Africa where children are more vulnerable. The occurrence of resistant gene in Plasmodium falciparum to some antimalarial drugs could increase the malaria morbidity and mortality among the children. The study evaluates the distribution of P. falciparum resistant kelch protein gene on chromosome 13 (PfKelch 13) and multidrug resistant (Pfmdr1) mutant genes among children aged five years and below who attended Mother and Child Hospital, Akure, Nigeria. Methods: Thin and thick smears were prepared from the blood collected aseptically through venepuncture from five hundred (500) children (age 5years and below). Two hundred (200) malaria positive samples were randomly selected from the 500 samples for PCR analysis to detect Pfmdr1 and Kelch 13 mutant genes from the positive samples. Discussion: The results showed that of the 500 respondents who gave their consent to participate in the study, 288 (57.6%) were males while 212 (42.4%) were females. The distribution of Pfmdr1 are; mixed group (mutant/wild) 38.5% (77/200), mutant gene 35.5% (71/200), wild gene 20.5% (41/200) and the resistant genes were absent in 5.5% (11/200) of the infected children. The mixed group of Pfmdr1 gene was higher among infants (51.9%), male (44.3%), children with birth order 4 (60.0%) and children that have blood group B (51.3%), however, there is no significant difference in the distribution of Pfmdr1 between gender (χ2 = 0.634, df = 1, p>0.05). There was a point mutation in the codon position 557 where the amino acid Alanine was replaced by Serine in the PfK13. The research revealed high prevalence of Pfmdr1 mutant genes and point mutation in the PfK13 gene of P. falciparum among children which may be as a result of treatment of malaria with different antimalarial drugs which the parasite has developed resistance against. It is therefore important to administer other malaria drugs apart from the drugs the parasite has developed resistance against.

Molecular Detection of Mutations in the Propeller Domain of Kelch 13 and pfmdr1 Copy Number Variation in Plasmodium falciparum Isolates from Thailand Collected from 2002 to 2007

We determined the prevalence of Kelch 13 mutations and pfmdr1 copy number in samples collected from the Thailand–Myanmar border, the Thailand–Cambodia border, and southern Thailand from 2002 to 2007. C580Y was the most prevalent in Trat (Thailand–Cambodia border) and Ranong (Thailand–Myanmar border) at 42% (24/57) and 13% (6/48), respectively. Less predominant mutations were also identified including R539T (7%, 4/57) and Y493H (2%, 1/57) in Trat, P574L (6%, 3/48) and P553L (2%, 1/48) in Ranong, and N537I and D452E (7%, 1/15) in Sangkhlaburi (Thailand–Myanmar border). Samples from Mae sot (33%, 11/33) harbored the highest percentage of multiple pfmdr1 copies, followed by Trat (18%, 10/57), Chiang Dao in 2003 (13%, 4/30), Phang Nga (5%, 2/44), and Chiang Dao in 2002 (4%, 1/26). This retrospective study provides geographic diversity of K13 and pfmdr1 copies and the emergence of these molecular markers in Thailand, an important background information for future surveillance in the region.

A randomized, double-blind, phase 2b study to investigate the efficacy, safety, tolerability and pharmacokinetics of a single-dose regimen of ferroquine with artefenomel in adults and children with uncomplicated Plasmodium falciparum malaria

Background For uncomplicated Plasmodium falciparum malaria, highly efficacious single-dose treatments are expected to increase compliance and improve treatment outcomes, and thereby may slow the development of resistance. The efficacy and safety of a single-dose combination of artefenomel (800 mg) plus ferroquine (400/600/900/1200 mg doses) for the treatment of uncomplicated P. falciparum malaria were evaluated in Africa (focusing on children ≤ 5 years) and Asia. Methods The study was a randomized, double-blind, single-dose, multi-arm clinical trial in patients aged > 6 months to < 70 years, from six African countries and Vietnam. Patients were followed up for 63 days to assess treatment efficacy, safety and pharmacokinetics. The primary efficacy endpoint was the polymerase chain reaction (PCR)-adjusted adequate clinical and parasitological response (ACPR) at Day 28 in the Per-Protocol [PP] Set comprising only African patients ≤ 5 years. The exposure–response relationship for PCR-adjusted ACPR at Day 28 and prevalence of kelch-13 mutations were explored. Results A total of 373 patients were treated: 289 African patients ≤ 5 years (77.5%), 64 African patients > 5 years and 20 Asian patients. None of the treatment arms met the target efficacy criterion for PCR-adjusted ACPR at Day 28 (lower limit of 95% confidence interval [CI] > 90%). PCR-adjusted ACPR at Day 28 [95% CI] in the PP Set ranged from 78.4% [64.7; 88.7%] to 91.7% [81.6; 97.2%] for the 400 mg to 1200 mg ferroquine dose. Efficacy rates were low in Vietnamese patients, ranging from 20 to 40%. A clear relationship was found between drug exposure (artefenomel and ferroquine concentrations at Day 7) and efficacy (primary endpoint), with higher concentrations of both drugs resulting in higher efficacy. Six distinct kelch-13 mutations were detected in parasite isolates from 10/272 African patients (with 2 mutations known to be associated with artemisinin resistance) and 18/20 Asian patients (all C580Y mutation). Vomiting within 6 h of initial artefenomel administration was common (24.6%) and associated with lower drug exposures. Conclusion The efficacy of artefenomel/ferroquine combination was suboptimal in African children aged ≤ 5 years, the population of interest, and vomiting most likely had a negative impact on efficacy. Trial registration ClinicalTrials.gov, NCT02497612. Registered 14 Jul 2015, https://clinicaltrials.gov/ct2/show/NCT02497612?term=NCT02497612&draw=2&rank=1

Characterization of pfmdr1, pfcrt, pfK13, pfubp1, and pfap2mu in travelers returning from Africa with Plasmodium falciparum infections reported in China from 2014–2018

The artemisinin-based combination therapies (ACTs) used to treat Plasmodium falciparum in Africa are threatened by the emergence of parasites in Asia carrying variants of the Kelch 13 (K13) locus with delayed clearance in response to ACTs. Single nucleotide polymorphisms (SNPs) in other molecular markers, such as ap2mu and ubp1, were associated with artemisinin resistance in rodent malaria and clinical failure in African malaria patients. Here, we characterized the polymorphisms in pfmdr1, pfcrt, pfK13, pfubp1 and pfap2mu among African isolates reported in Shandong and Guangxi provinces in China. Among 144 patients with P. falciparum returning from Africa in 2014–2018, pfmdr1 N86Y (8.3%) and pfcrt K76T (2.1%) were the major mutant alleles. The most common genotype for pfcrt was I74E75T76 (8.3%), followed by E75T76 (2.1%). For K13 polymorphisms, a limited number of mutated alleles were observed, and A578S was the most frequently detected allele in 3 isolates (2.1%). A total of 27.1% (20/144) of the isolates were found to contain pfubp1 mutations, including 6 nonsynonymous and 2 synonymous mutations. The pfubp1 genotypes associated with ART resistance were D1525E (10.4%) and E1528D (8.3%). Furthermore, 11 SNPs were identified in pfap2mu, and S160N was the major polymorphism (4.2%). Additionally, 4 different types of insertions were found in pfap2mu, and the codon AAT, encoding aspartic acid, was more frequently observed at codons 226 (18.8%) and 326 (10.7%). Moreover, 4 different types of insertions were observed in pfubp1 at codon 1520, which was the most common (6.3%). These findings indicate a certain degree of variation in other potential molecular markers, such as pfubp1 and pfap2mu, and their roles either in the parasite’s mechanism of resistance or the mode of action should be evaluated or elucidated further.

Expansion of the Plasmodium falciparum Kelch 13 R622I mutation in Northwest Ethiopia

According to the WHO, almost two thirds of the Ethiopian population are at risk of contracting malaria, where infection with Plasmodium falciparum accounts for approximately 60% of cases today. The risk of artemisinin resistance spreading from SE Asia to Africa is a major concern. We conducted a 28-day in vivo efficacy trial of Artemether-Lumefantrine (Co-Artem) for treatment of uncomplicated malaria (n = 97) in the Gondar Region, North West Ethiopia in 2017–2018. Our results confirmed 100% adequate clinical and parasitological response (ACPR) with no parasites observed at day 3 by microscopy. Further analysis of day 0 samples showed the expansion of a kelch13 mutation R622I to 9.5% from 2.4% of isolates reported three years earlier. Closer examination of the R622I mutation in vitro is warranted.