Genome sequencing of Plasmodium malariae identifies continental segregation and mutations associated with reduced pyrimethamine susceptibility.

Plasmodium malariae parasites are widely observed across the tropics and sub-tropics. This slow-growing species, known to maintain chronic asymptomatic infections, has been associated with reduced antimalarial susceptibility. We analyse 251 P.

Inhibitors of malaria parasite cyclic nucleotide phosphodiesterases block asexual blood-stage development and mosquito transmission.

Cyclic nucleotide-dependent phosphodiesterases (PDEs) play essential roles in regulating the malaria parasite life cycle, suggesting that they may be promising antimalarial drug targets. PDE inhibitors are used safely to treat a range of noninfectious human disorders. Here, we report three subseries of fast-acting and potent PDEβ inhibitors that block asexual blood-stage parasite development and that are also active against human clinical isolates.

Treatment Failure in a UK Malaria Patient Harboring Genetically Variant Plasmodium falciparum From Uganda With Reduced In Vitro Susceptibility to Artemisinin and Lumefantrine.

Background: Recent cases of clinical failure in malaria patients in the United Kingdom (UK) treated with artemether-lumefantrine have implications for malaria chemotherapy worldwide.

Methods: Parasites were isolated from an index case of confirmed Plasmodium falciparum treatment failure after standard treatment, and from comparable travel-acquired UK malaria cases. Drug susceptibility in vitro and genotypes at 6 resistance-associated loci were determined for all parasite isolates and compared with clinical outcomes for each parasite donor.

Creating and Validating Ligase Primers to Detect Single Nucleotide Polymorphisms Associated with Atovaquone Resistance in Plasmodium falciparum.

Atovaquone-proguanil is one of the most commonly prescribed malaria prophylactic drugs. However, sporadic mutations conferring resistance to atovaquone have been detected in recent years associated with single nucleotide polymorphisms (SNPs) in the Plasmodium falciparum cytochrome b ( pfcytb) gene. Monitoring polymorphisms linked with resistance is essential in assessing the prevalence of drug resistance and may help in designing strategies for malaria control.

Diagnostic accuracy and limit of detection of ten malaria parasite lactate dehydrogenase-based rapid tests for and .

Background: causes zoonotic malaria across Southeast Asia. First-line diagnostic microscopy cannot reliably differentiate from other human malaria species. Rapid diagnostic tests (RDTs) designed for and are used routinely in co-endemic areas despite potential cross-reactivity for species-specific antibody targets.

Cation ATPase (ATP4) Orthologue Replacement in the Malaria Parasite Plasmodium knowlesi Reveals Species-Specific Responses to ATP4-Targeting Drugs.

Several unrelated classes of antimalarial compounds developed against Plasmodium falciparum target a parasite-specific P-type ATP-dependent Na pump, PfATP4. We have previously shown that other malaria parasite species infecting humans are less susceptible to these compounds. Here, we generated a series of transgenic Plasmodium knowlesi orthologue replacement (OR) lines in which the endogenous locus was replaced by a recodonized atp4 () coding region or the orthologous coding region from P.

Semi-Synthetic Analogues of Cryptolepine as a Potential Source of Sustainable Drugs for the Treatment of Malaria, Human African Trypanosomiasis, and Cancer.

The prospect of eradicating malaria continues to be challenging in the face of increasing parasite resistance to antimalarial drugs so that novel antimalarials active against asexual, sexual, and liver-stage malaria parasites are urgently needed. In addition, new antimalarials need to be affordable and available to those most in need and, bearing in mind climate change, should ideally be sustainable. The West African climbing shrub is used traditionally for the treatment of malaria; its principal alkaloid, cryptolepine (), has been shown to have antimalarial properties, and the synthetic analogue 2,7-dibromocryptolepine () is of interest as a lead toward new antimalarial agents.

Carcass Yields and Physical-Chemical Meat Quality Characteristics of Namibian Red Hartebeest () as Influenced by Sex and Muscle.

This study determined the carcass yields of red hartebeest from Namibia and compared the physical-chemical meat quality characteristics of six different muscles () for both males and females. Red hartebeest males were heavier (133.92 kg) than females (114.

Clinical management of Plasmodium knowlesi malaria.

The zoonotic parasite Plasmodium knowlesi has emerged as an important cause of human malaria in parts of Southeast Asia. The parasite is indistinguishable by microscopy from the more benign P. malariae, but can result in high parasitaemias with multiorgan failure, and deaths have been reported.

Ex vivo susceptibility to new antimalarial agents differs among human-infecting Plasmodium species.

Several promising antimalarial drugs are currently being tested in human trials, such as artefenomel, cipargamin, ferroquine and ganaplacide. Many of these compounds were identified using high throughput screens against a single species of human malaria, Plasmodium falciparum, under the assumption that effectiveness against all malaria species will be similar, as has been observed for other antimalarial drugs. However, using our in vitro adapted line, we demonstrated recently that P.

Failure of rapid diagnostic tests in Plasmodium falciparum malaria cases among travelers to the UK and Ireland: Identification and characterisation of the parasites.

Objectives: Our objective was to systematically investigate false-negative histidine-rich protein 2 rapid diagnostic tests (HRP2-RDT) in imported Plasmodium falciparum malaria cases from travelers to the UK and the Republic of Ireland (RoI).

Methods: Five imported malaria cases in travellers returning to the UK and RoI from East Africa were reported to the PHE Malaria Reference Laboratory as negative according to histidine-rich protein (HRP2)-RDT. The cases were systematically investigated using microscopic, RDT, molecular, genomic, and in in vitro approaches.

The antimalarial efficacy and mechanism of resistance of the novel chemotype DDD01034957.

New antimalarial therapeutics are needed to ensure that malaria cases continue to be driven down, as both emerging parasite resistance to frontline chemotherapies and mosquito resistance to current insecticides threaten control programmes. Plasmodium, the apicomplexan parasite responsible for malaria, causes disease pathology through repeated cycles of invasion and replication within host erythrocytes (the asexual cycle). Antimalarial drugs primarily target this cycle, seeking to reduce parasite burden within the host as fast as possible and to supress recrudescence for as long as possible.

Carcass yields and physiochemical meat quality characteristics of Namibian gemsbok (Oryx gazella) as influenced by muscle, gender and age.

The carcass yields and physiochemical meat quality characteristics of six different muscles (biceps femoris, infraspinatus, longissimus thoracis et lumborum, semimembranosus, semitendinosus, supraspinatus) for different sex and age groups of gemsbok antelope were determined. No live weight nor dressing percentage differences were observed for the different sex groups. While muscles, age and sex had an influence on the physiochemical parameters investigated, these differences were minor.

A novel multiplex qPCR assay for detection of Plasmodium falciparum with histidine-rich protein 2 and 3 (pfhrp2 and pfhrp3) deletions in polyclonal infections.

Background: Many health facilities in malaria endemic countries are dependent on Rapid diagnostic tests (RDTs) for diagnosis and some National Health Service (NHS) hospitals without expert microscopists rely on them for diagnosis out of hours. The emergence of P. falciparum lacking the gene encoding histidine-rich protein 2 and 3 (HRP2 and HRP3) and escaping RDT detection threatens progress in malaria control and elimination.

The Artemisinin Susceptibility-Associated AP-2 Adaptin μ Subunit is Clathrin Independent and Essential for Schizont Maturation.

The efficacy of current antimalarial drugs is threatened by reduced susceptibility of to artemisinin, associated with mutations in Another gene with variants known to modulate the response to artemisinin encodes the μ subunit of the AP-2 adaptin trafficking complex. To elucidate the cellular role of AP-2μ in , we performed a conditional gene knockout, which severely disrupted schizont organization and maturation, leading to mislocalization of key merozoite proteins. AP-2μ is thus essential for blood-stage replication.

Novel Endochin-Like Quinolones Exhibit Potent Activity against Plasmodium knowlesi but Do Not Synergize with Proguanil.

Quinolones, such as the antimalarial atovaquone, are inhibitors of the malarial mitochondrial cytochrome complex, a target critical to the survival of both liver- and blood-stage parasites, making these drugs useful as both prophylaxis and treatment. Recently, several derivatives of endochin have been optimized to produce novel quinolones that are active and in animal models. While these quinolones exhibit potent activity against and , their activity against the zoonotic agent is unknown.

Modification of and Markedly Reduces Ring-Stage Susceptibility of Plasmodium falciparum to Artemisinin .

Management of uncomplicated malaria worldwide is threatened by the emergence in Asia of carrying variants of the locus and exhibiting reduced susceptibility to artemisinin. Mutations in two other genes, and , are associated with artemisinin resistance in rodent malaria and with clinical failure of combination therapy in African malaria patients. Transgenic clones, each carrying orthologues of mutations in and associated with artemisinin resistance in , were derived by Cas9 gene editing.

Plasmodium knowlesi exhibits distinct in vitro drug susceptibility profiles from those of Plasmodium falciparum.

New antimalarial agents are identified and developed after extensive testing on Plasmodium falciparum parasites that can be grown in vitro. These susceptibility studies are important to inform lead optimisation and support further drug development. Until recently, little was known about the susceptibility of non-falciparum species as these had not been adapted to in vitro culture.

Transient temperature fluctuations severely decrease P. falciparum susceptibility to artemisinin in vitro.

Clinical studies suggest that outcomes for hospitalised malaria patients can be improved by managed hypothermia during treatment. We examined the impact of short pulses of low temperature on ring-stage susceptibility of Plasmodium falciparum to artemisinin in vitro. The usually artemisinin-sensitive clone 3D7 exhibited substantially reduced ring-stage susceptibility to a 4-h pulse of 700 nM dihydro-artemisinin administered during a 5-h pulse of low temperature down to 17 °C.

Clinical Validation of a Commercial LAMP Test for Ruling out Malaria in Returning Travelers: A Prospective Diagnostic Trial.

The mainstay of malaria diagnosis relies on rapid diagnostic tests (RDTs) and microscopy, both of which lack analytical sensitivity. This leads to repeat testing to rule out malaria. A prospective diagnostic trial of the Meridian Malaria assay (loop-mediated isothermal amplification [LAMP]) was conducted comparing it with reference microscopy and RDTs (BinaxNOW Malaria) in returning travelers between June 2017 and January 2018.

Comparison of the susceptibility of Plasmodium knowlesi and Plasmodium falciparum to antimalarial agents.

Background: The simian malaria parasite Plasmodium knowlesi is now a well-recognized pathogen of humans in South-East Asia. Clinical infections appear adequately treated with existing drug regimens, but the evidence base for this practice remains weak. The availability of P.

-Independent Treatment Failure in Four Imported Cases of Plasmodium falciparum Malaria Treated with Artemether-Lumefantrine in the United Kingdom.

We present case histories of four patients treated with artemether-lumefantrine for falciparum malaria in UK hospitals in 2015 to 2016. Each subsequently presented with recurrent symptoms and parasitemia within 6 weeks of treatment with no intervening travel to countries where malaria is endemic. Parasite isolates, all of African origin, harbored variants at some candidate resistance loci.

Paper-Origami-Based Multiplexed Malaria Diagnostics from Whole Blood.

We demonstrate, for the first time, the multiplexed determination of microbial species from whole blood using the paper-folding technique of origami to enable the sequential steps of DNA extraction, loop-mediated isothermal amplification (LAMP), and array-based fluorescence detection. A low-cost handheld flashlight reveals the presence of the final DNA amplicon to the naked eye, providing a "sample-to-answer" diagnosis from a finger-prick volume of human blood, within 45 min, with minimal user intervention. To demonstrate the method, we showed the identification of three species of Plasmodium, analyzing 80 patient samples benchmarked against the gold-standard polymerase chain reaction (PCR) assay in an operator-blinded study.