Chloroquine Clinical Failures in P. falciparum Malaria Are Associated with Mutant Pfmdr-1, Not Pfcrt in Madagascar

Molecular studies have demonstrated that mutations in the Plasmodium falciparum chloroquine resistance transporter gene (Pfcrt) play a major role in chloroquine resistance, while mutations in P. falciparum multidrug resistance gene (Pfmdr-1) act as modulator. In Madagascar, the high rate of chloroquine treatment failure (44%) appears disconnected from the overall level of in vitro CQ susceptibility (prevalence of CQ-resistant parasites <5%) or Pfcrt mutant isolates (<1%), strongly contrasting with sub-Saharan African countries. Previous studies showed a high frequency of Pfmdr-1 mutant parasites (>60% of isolates), but did not explore their association with P. falciparum chloroquine resistance. To document the association of Pfmdr-1 alleles with chloroquine resistance in Madagascar, 249 P. falciparum samples collected from patients enrolled in a chloroquine in vivo efficacy study were genotyped in Pfcrt/Pfmdr-1 genes as well as the estimation of the Pfmdr-1 copy number. Except 2 isolates, all samples displayed a wild-type Pfcrt allele without Pfmdr-1 amplification. Chloroquine treatment failures were significantly associated with Pfmdr-1 86Y mutant codon (OR = 4.6). The cumulative incidence of recurrence of patients carrying the Pfmdr-1 86Y mutation at day 0 (21 days) was shorter than patients carrying Pfmdr-1 86N wild type codon (28 days). In an independent set of 90 selected isolates, in vitro susceptibility to chloroquine was not associated with Pfmdr-1 polymorphisms. Analysis of two microsatellites flanking Pfmdr-1 allele showed that mutations occurred on multiple genetic backgrounds. In Madagascar, Pfmdr-1 polymorphism is associated with late chloroquine clinical failures and unrelated with in vitro susceptibility or Pfcrt genotype. These results highlight the limits of the current in vitro tests routinely used to monitor CQ drug resistance in this unique context. Gaining insight about the mechanisms that regulate polymorphism in Pfmdr1 remains important, particularly regarding the evolution and spread of Pfmdr-1 alleles in P. falciparum populations under changing drug pressure which may have important consequences in terms of antimalarial use management

Falciparum malaria molecular drug resistance in the Democratic Republic of Congo: a systematic review

peer reviewedBackground: Malaria cases were estimated to 207 million in 2013. One of the problems of malaria control is the emergence and spread of Plasmodium falciparum strains that become resistant to almost all drugs available. Monitoring drug resistance is essential for early detection and subsequent prevention of the spread of drug resistance by timely changes of treatment policy. This review was performed to gather all data available on P. falciparum molecular resistance in DR Congo, as baseline for future assessments. Methods: The search for this review was undertaken using the electronic databases PubMed and Google Scholar using the terms “malaria”, “Congo”, “resistance”, “molecular”, “antimalarial”, “efficacy”. Articles were classified based on year of collecting, year of publication, sample size and characteristics, molecular markers analysed and polymorphisms detected. Results: Thirteen articles were included and five genes have been analysed in these studies: pfcrt, pfdhps, pfdhfr, pfmdr1 and K13-propeller. The majority of studies included were not representative of the whole country. Conclusion: This systematic review demonstrates the lack of molecular resistance studies in DRC. Only 13 studies were identified in almost 15 years. The MOH must implement a national surveillance system for monitoring malaria drug resistance and this surveillance should be conducted frequently and country-representative

Automatic design of communication-based behaviors for robot swarms

We introduce Gianduja, an automatic design method that generates communication-based behaviors for robot swarms. Gianduja extends Chocolate, a previously published design method. It does so by providing the robots with the capability to communicate using one message. The semantics of the message is not a priori fixed. It is the automatic design process that implicitly defines it, on a per-mission basis, by prescribing the conditions under which the message is sent by a robot and how the receiving peers react to it. We empirically study Gianduja on three missions and we compare it with the aforementioned Chocolate and with EvoCom, a rather standard evolutionary robotics method that generates communication-based behaviors. We evaluate the behaviors produced by the three automatic design methods on a swarm of 20 e-puck robots. The results show that Gianduja uses communication meaningfully and effectively in all the three missions considered. The aggregate results indicate that, on the three missions considered, Gianduja performs significantly better than the two other methods under analysis.SCOPUS: cp.kinfo:eu-repo/semantics/publishe