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The discovery and development of transmission-blocking therapies challenge malaria elimination and necessitate standard and reproducible bioassays to measure the blocking properties of antimalarial drugs and candidate compounds. Most of the current bioassays evaluating the transmission-blocking activity of compounds rely on laboratory-adapted Plasmodium strains.

The discovery and development of transmission-blocking therapies challenge malaria elimination and necessitate standard and reproducible bioassays to measure the blocking properties of antimalarial drugs and candidate compounds. Most of the current bioassays evaluating the transmission-blocking activity of compounds rely on laboratory-adapted

Background In some settings, sensitive field diagnostic tools may be needed to achieve elimination of falciparum malaria. To this end, rapid diagnostic tests (RDTs) based on the detection of the Plasmodium falciparum protein HRP-2 are being developed with increasingly lower limits of detection. However, it is currently unclear how parasite stages that are unaffected by standard drug treatments may contribute to HRP-2 detectability and potentially confound RDT results even after clearance of blood stage infection. In this study, we assessed the detectability of HRP-2 in periods of post-treatment residual gametocytaemia. Methods A cohort of 100 Plasmodium falciparum infected, gametocyte positive individuals were treated with or without the gametocytocidal drug primaquine (PQ), alongside standard artemisinin-based combination therapy (ACT), in the context of a randomised clinical trial in Ouelessebougou, Mali. We used a quantitative ELISA to measure levels of HRP-2, and compared time to test negativity using a standard and ultra-sensitive RDT (uRDT) between residual gametocyte positive and negative groups. Findings Time to test negativity was longest by uRDT, followed by ELISA and then standard RDT. No significant difference in time to negativity was found between the treatment groups with and without residual gametocytes: uRDT (HR 0.79 [95% CI 0.52–1.21], p = 0.28), RDT (HR 0.77 [95% CI 0.51–1.15], p = 0.20) or ELISA (HR 0.88 [95% CI 0.59–1.32], p = 0.53). Similarly, no difference was observed when adjusting for baseline asexual parasite density. Quantified levels of HRP-2 over time were similar between groups, with differences attributable to asexual parasite densities. Furthermore, no difference in levels of HRP-2 was found between individuals who were or were not infectious to mosquitoes (OR 1.19 [95% CI 0.98–1.46], p = 0.077). Interpretation Surviving sexual stage parasites after standard ACT treatment do not contribute to the persistence of HRP-2 antigenaemia, and appear to have little impact on RDT results.

Contains fulltext : 251206.pdf (Publisher’s version ) (Open Access) BACKGROUND: Tafenoquine was recently approved as a prophylaxis and radical cure for Plasmodium vivax infection, but its Plasmodium falciparum transmission-blocking efficacy is unclear. We aimed to establish the efficacy and safety of three single low doses of tafenoquine in combination with dihydroartemisinin-piperaquine for reducing gametocyte density and transmission to mosquitoes. METHODS: In this four-arm, single-blind, phase 2, randomised controlled trial, participants were recruited at the Clinical Research Unit of the Malaria Research and Training Centre of the University of Bamako in Mali. Eligible participants were aged 12-50 years, with asymptomatic P falciparum microscopy-detected gametocyte carriage, had a bodyweight of 80 kg or less, and had no clinical signs of malaria defined by fever. Participants were randomly assigned (1:1:1:1) to standard treatment with dihydroartemisinin-piperaquine, or dihydroartemisinin-piperaquine plus a single dose of tafenoquine (in solution) at a final dosage of 0·42 mg/kg, 0·83 mg/kg, or 1·66 mg/kg. Randomisation was done with a computer-generated randomisation list and concealed with sealed, opaque envelopes. Dihydroartemisinin-piperaquine was administered as oral tablets over 3 days (day 0, 1, and 2), as per manufacturer instructions. A single dose of tafenoquine was administered as oral solution on day 0 in parallel with the first dose of dihydroartemisinin-piperaquine. Tafenoquine dosing was based on bodyweight to standardise efficacy and risk variance. The primary endpoint, assessed in the per-protocol population, was median percentage change in mosquito infection rate 7 days after treatment compared with baseline. Safety endpoints included frequency and incidence of adverse events. The final follow-up visit was on Dec 23, 2021; the trial is registered with ClinicalTrials.gov, NCT04609098. FINDINGS: From Oct 29 to Nov 25, 2020, 1091 individuals were screened for eligibility, 80 of whom were enrolled and randomly assigned (20 per treatment group). Before treatment, 53 (66%) individuals were infectious to mosquitoes, infecting median 12·50% of mosquitoes (IQR 3·64-35·00). Within-group reduction in mosquito infection rate on day 7 was 79·95% (IQR 57·15-100; p=0·0005 for difference from baseline) following dihydroartemisinin-piperaquine only, 100% (98·36-100; p=0·0005) following dihydroartemisinin-piperaquine plus tafenoquine 0·42 mg/kg, 100% (100-100; p=0·0001) following dihydroartemisinin-piperaquine plus tafenoquine 0·83 mg/kg, and 100% (100-100; p=0·0001) following dihydroartemisinin-piperaquine plus tafenoquine 1·66 mg/kg. 55 (69%) of 80 participants had a total of 94 adverse events over the course of the trial; 86 (92%) adverse events were categorised as mild, seven (7%) as moderate, and one (1%) as severe. The most common treatment-related adverse event was mild or moderate headache, which occurred in 15 (19%) participants (dihydroartemisinin-piperaquine n=2; dihydroartemisinin-piperaquine plus tafenoquine 0·42 mg/kg n=6; dihydroartemisinin-piperaquine plus tafenoquine 0·83 mg/kg n=3; and dihydroartemisinin-piperaquine plus tafenoquine 1·66 mg/kg n=4). No serious adverse events occurred. No significant differences in the incidence of all adverse events (p=0·73) or treatment-related adverse events (p=0·62) were observed between treatment groups. INTERPRETATION: Tafenoquine was well tolerated at all doses and accelerated P falciparum gametocyte clearance. All tafenoquine doses showed improved transmission reduction at day 7 compared with dihydroartemisinin-piperaquine alone. These data support the case for further research on tafenoquine as a transmission-blocking supplement to standard antimalarials. FUNDING: Bill & Melinda Gates Foundation. TRANSLATIONS: For the French, Portuguese, Spanish and Swahili translations of the abstract see Supplementary Materials section.

Background: Tafenoquine (TQ) was recently approved as prophylaxis and radical cure for P. vivax infection, but its P. falciparum transmission-blocking efficacy is unclear. We determined efficacy and safety of single doses of TQ in combination with dihydroartemisinin-piperaquine (DP) for reducing gametocyte density and transmission to mosquitoes. Methods: In this single-blind, phase 2 randomised clinical trial, participants (12-50 years of age) with asymptomatic P. falciparum microscopy-detected gametocyte carriage (n=80) were randomized to standard treatment with DP, or with DP plus a single dose of TQ (in solution) at a final concentration of 0·42mg/kg, 0·83mg/kg, or 1·66mg/kg. The primary endpoint was percent reduction in mosquito infection rate 7 days after treatment compared to baseline. Safety endpoints included frequency and incidence of adverse events (AE). The final follow-up visit was on the 23 rd December 2021; the trial is registered on ClinicalTrials.gov (NCT04609098). Findings: Participants were enrolled from 29th October to 25th November 2020. Before treatment, 66% (53/80) of individuals were infectious to mosquitoes, infecting on average 12·5% of mosquitoes (Interquartile range [IQR] 3·64-35). Within-arm percent reduction in mosquito infection rate on day 7 was 79·95% (IQR 57·15-100) following DP (p=0·0005 for difference from baseline), 100% (IQR 98·36-100) following DP-TQ 0·42mg/kg (p=0·0005), 100% (IQR 100-100) following DP -TQ 0·83mg/kg (p

Summary: Pyronaridine-artesunate (PA) is a recommended anti-malarial in areas of Plasmodium resistance to first-line artemisinin combination therapies. This study shows that PA may be combined with a single low dose of primaquine for highly effective P. falciparum transmission reduction. Background: Pyronaridine-artesunate (PA) is the most recently licenced artemisinin combination therapies (ACT). The World Health Organization recommends that a single lose dose of primaquine may be added to ACTs to reduce P. falciparum transmission in areas aiming for elimination or threatened by artemisinin resistance. The transmission reducing efficacy of PA and PA combined with primaquine have never been tested. Methods: In a four-arm, single-blind, randomised clinical trial, we determined the effectiveness of PA and dihydroartemisinin-piperaquine (DP) with and without 0.25mg/kg primaquine for reducing gametocyte density and transmission to mosquitoes in asymptomatic Malian P. falciparum gametocyte carriers (n=100). Findings: Before treatment, 66% (66/100) of individuals were infectious to mosquitoes, with an average mosquito infection rate of 15.8% (IQR 5.41-31.94). The percentage of individuals who infected mosquitoes (p 0.129). Interpretation: These data strongly support the use of SLD PQ as an effective supplement to PA for blocking P. falciparum transmission, and are of immediate relevance to African regions in which the containment of ACT resistance and sustainability of ACT efficacy are growing concerns. Trial Registration: The trial was registered on clinicaltrials.gov under identifier NCT04049916. Funding Statement: This work was supported by the Bill and Melinda Gates Foundation (#INV-002098). JB received support from the UK MRC and the UK DFID (#MR/K012126/1) under the MRC/DFID Concordat agreement and as part of the EDCTP2 programme supported by the European Union. TB is further supported by a fellowship from the The Netherlands Organisation for Scientific Research (Vidi fellowship NWO project number 016.158.306). WS is supported by a Sir Henry Wellcome fellowship (218676/Z/19/Z). Declaration of Interests: We have no competing interests. Ethics Approval Statement: Ethical approval was granted by the Ethics Committee of the Faculty of Medicine, Pharmacy, and Dentistry of the University of Science, Techniques, and Technologies of Bamako (Bamako, Mali), and the Research Ethics Committee of the London School of Hygiene and Tropical Medicine (London, UK).Participants provided informed consent (≥18 years), assent with parental consent (12-17 years) or parental consent (

Plasmodium falciparum remains one of the leading causes of child mortality, and nearly half of the world’s population is at risk of contracting malaria. While pathogenesis results from replication of asexual forms in human red blood cells, it is the sexually differentiated forms, gametocytes, which are responsible for the spread of the disease. For transmission to succeed, both mature male and female gametocytes must be taken up by a female Anopheles mosquito during its blood meal for subsequent differentiation into gametes and mating inside the mosquito gut. Observed circulating numbers of gametocytes in the human host are often surprisingly low. A pre-fertilization behavior, such as skin sequestration, has been hypothesized to explain the efficiency of human-to-mosquito transmission but has not been sufficiently tested due to a lack of appropriate tools. In this study, we describe the optimization of a qPCR tool that enables the relative quantification of gametocytes within very small input samples. Such a tool allows for the quantification of gametocytes in different compartments of the host and the vector that could potentially unravel mechanisms that enable highly efficient malaria transmission. We demonstrate the use of our gametocyte quantification method in mosquito blood meals from both direct skin feeding on Plasmodium gametocyte carriers and standard membrane feeding assay. Relative gametocyte abundance was not different between mosquitoes fed through a membrane or directly on the skin suggesting that there is no systematic enrichment of gametocytes picked up in the skin.

Plasmodium falciparum remains one of the leading causes of child mortality, and nearly half of the world’s population is at risk of contracting malaria. While pathogenesis results from replication of asexual forms in human red blood cells, it is the sexually differentiated forms, gametocytes, which are responsible for the spread of the disease. For transmission to succeed, both mature male and female gametocytes must be taken up by a female Anopheles mosquito during its blood meal for subsequent differentiation into gametes and mating inside the mosquito gut. Observed circulating numbers of gametocytes in the human host are often surprisingly low. A pre-fertilization behavior, such as skin sequestration, has been hypothesized to explain the efficiency of human-to-mosquito transmission but has not been sufficiently tested due to a lack of appropriate tools. In this study, we describe the optimization of a qPCR tool that enables the relative quantification of gametocytes within very small input samples. Such a tool allows for the quantification of gametocytes in different compartments of the host and the vector that could potentially unravel mechanisms that enable highly efficient malaria transmission. We demonstrate the use of our gametocyte quantification method in mosquito blood meals from both direct skin feeding on Plasmodium gametocyte carriers and standard membrane feeding assay. Relative gametocyte abundance was not different between mosquitoes fed through a membrane or directly on the skin suggesting that there is no systematic enrichment of gametocytes picked up in the skin.

Functional independence in glioblastoma (GBM) patients is a key factor in measuring the quality of life. Progression free survival (PFS) and overall survival (OS) have been largely described. However, the evolution over time of the performance status during the patients’ life remains understudied. We thus studied the time to loss of functional independence as assessed by a Karnosky Performance Status (KPS) below 70 % in GBM patients. We analysed all GBM patients treated in our institution between 2008 and 2013 and meeting the following criteria: age >18 years, supratentorial location, post-surgical KPS ≥ 70 %, initially treated with concomitant radiotherapy (RT) and Temozolomide. Within the 84 patients studied, the median PFS was 9 months and the median OS was 18.7 months. The median survival time with functional independence (KPS ≥ 70 %) was 14.5 months. On average, the patients spent 73 % of their lifespan with a KPS ≥ 70 %. Surgical resection and low steroid dosage were statistically associated with increased survival time with KPS ≥ 70 % (p = 0.015 and p = 0.03, respectively). Sixty-two (62) patients received one or several lines of chemotherapy at recurrence. Under treatment with Bevacizumab (42 Bev-based regimens), radiological responses were seen in 35 % and improvement in KPS occurred in 24 % whereas no response and rare improvement of KPS (3 %) were seen with other type of chemotherapy (97 non Bev-based regimens). In GBM patients, median survival with KPS ≥ 70 % largely exceeds PFS. Surgical resection and low steroids dosage at RT-onset appeared as good prognosis factors for survival with functional independence.

Malaria transmission-blocking vaccines (TBV) have been evaluated in field trials in Mali since 2013. However, the assays currently used to measure serum antibody TB activity (TBA) after vaccination are highly variable, in part due to the lack of optimization and standardization for field assays in which mosquitoes feed on gametocytemic blood. Herein, we report a study conducted in Bancoumana village, Mali, where we identify and optimize the parameters that contribute to successful mosquito feeding outcomes in both direct skin feeds (DSFs) and direct membrane feeding assays (DMFA). These parameters include: 1) mosquito age, 2) duration of mosquito starvation prior to feeding, 3) membrane selection for DMFA, 4) anatomical location of DSF feeding (arm, calf, and ankle), and 5) time of day for DSF (dawn or dusk). We found that younger mosquitoes were significantly associated with higher feeding, survival, and infection rates. Longer starvation times were positively, but not significantly, associated with higher infection rates, but were negatively associated with feeding and survival. Membrane type and body location did not affect infection outcome significantly. Although dusk was found to be associated with higher infection rates, this may be confounded by the time from positive blood smear. Based on these findings, we make specific recommendations for optimal feeding parameters in the different assay types to maximize the chance of detecting parasite transmission in a standardized manner.

International audience; Malaria transmission-blocking vaccines (TBV) have been evaluated in field trials in Mali since 2013. However, the assays currently used to measure serum antibody TB activity (TBA) after vaccination are highly variable, in part due to the lack of optimization and standardization for field assays in which mosquitoes feed on gametocytemic blood. Herein, we report a study conducted in Bancoumana village, Mali, where we identify and optimize the parameters that contribute to successful mosquito feeding outcomes in both direct skin feeds (DSFs) and direct membrane feeding assays (DMFA). These parameters include: 1) mosquito age, 2) duration of mosquito starvation prior to feeding, 3) membrane selection for DMFA, 4) anatomical location of DSF feeding (arm, calf, and ankle), and 5) time of day for DSF (dawn or dusk). We found that younger mosquitoes were significantly associated with higher feeding, survival, and infection rates. Longer starvation times were positively, but not significantly, associated with higher infection rates, but were negatively associated with feeding and survival. Membrane type and body location did not affect infection outcome significantly. Although dusk was found to be associated with higher infection rates, this may be confounded by the time from positive blood smear. Based on these findings, we make specific recommendations for optimal feeding parameters in the different assay types to maximize the chance of detecting parasite transmission in a standardized manner.

TLR-9 agonists are immunostimulating agents that have antitumor effects in animal models. A phase I trial was conducted to define the safety profile of subcutaneous injections, combined with intrathecally administration of CpG-28, a TRL 9 agonist, in patients with neoplastic meningitis (NM). Cohorts of 3–6 patients with NM were treated for 5 weeks with escalating doses of CpG-28. The primary endpoint was tolerance. Secondary endpoints were progression free survival (PFS) and overall survival (OS). Twenty-nine patients were treated with CpG-28. The primary cancers were malignant glioma, lung carcinoma, breast cancer, melanoma or melanocytoma, ependymoma, and colorectal cancer. The median age was 56 years and median Karnovsky Performance status (KPS) was 70%. The treatment was well tolerated. Adverse effects that were possibly or probably related to the studied drug were grade 2 lymphopenia, anemia and neutropenia, local erythema at injection sites, fever and seizure. There were five serious adverse events: two confusions, two infections of ventricular devices and one grade 4 thrombopenia and neutropenia. The median PFS was 7 weeks and median OS was 15 weeks. Interestingly, the median survival was slightly (but not significantly) higher in the eight patients who were concomitantly treated with bevacizumab (19 weeks vs 15 weeks; P = 0.11). CpG-28 was well tolerated at doses up to 0.3 mg/kg subcutaneously and 18 mg intrathecally. Additional trials are warranted.

OBJECT: To investigate peritumoral edema and its prognostic factors in brain metastases of lung and breast cancers, and more specifically to evaluate the effect of treatment with angiotensine-II (Ang2) inhibitors. This treatment was shown in a recent study to display a significant effect in primary brain tumor edema. MATERIALS AND METHODS: We retrospectively reviewed the medical files of all patients with newly diagnosed brain metastases consulting in our institution in the years 2012 and 2013. We measured the maximal diameter of lesions DL (contrast enhancement) and peritumoral edema DE (diameter of edema minus contrast enhancement) on the first diagnostic imaging of brain metastasis. Patients under steroids or files with insufficient informations were excluded from analysis. RESULTS: A total of 157 medical files were reviewed from which 54 patients with 170 metastases were selected for analysis. There were 87 metastases of lung adenocarcinomas, 35 of small cell carcinomas, 18 of epidermoiid lung cancer, 7 of undifferentiated and 23 of breast cancer. Median DL was 9.35mm (1-74.3), median DE was 5,98mm (0-69,5). There was no significant difference in DL or DE between the histology groups. Younger age (

Successful malaria management in Mali includes the use of pyrethroids and insecticide-treated nets (ITNs) for mosquito control; however, management is threatened by the spread of insecticide resistance detected via the knockdown resistance (kdr) allele. In a preliminary study, we compared the knockdown times of Anopheles gambiae from Mali using a novel ITN bioassay and the World Health Organization (WHO) bottle bioassay. Additionally, the frequency and relationship between kdr genotypes, molecular forms, and pyrethroid resistance were analyzed. The S molecular form was predominant and accounted for 76% of the assayed population. Both kdr resistant alleles, West Africa resistant (kdr-w) and East Africa resistant (kdr-e), were observed. There was no significant difference in knockdown time based on kdr genotype or molecular form of individual mosquitoes, but mosquitoes in the ITN bioassay homozygous for the kdr-w allele were knocked down significantly faster than those in the WHO bottle bioassay. The ITN bioassay provides an additional indicator of insecticide efficacy because ITNs, frequently used within homes, are the most common form of vector control and malaria prevention, and the ITN bioassays can evaluate seasonal field effects.

Sulfadoxine-pyrimethamine (SP) treatment increases the rate of gametocyte carriage and selects SP resistance-conferring mutations in Plasmodium falciparum dihydrofolate reductase (DHFR) and dihydropteroate synthase (DHPS), raising concerns of increased malaria transmission and spread of drug resistance. In a setting in Mali where SP was highly efficacious, we measured the prevalence of DHFR and DHPS mutations in P. falciparum infections with microscopy-detected gametocytes following SP treatment, and used direct feeding to assess infectivity to Anopheles gambiae sensu lato. Children and young adults presenting with uncomplicated malaria were treated with SP or chloroquine and followed for 28 days. Gametocyte carriage peaked at 67% 1 week after treatment with a single dose of SP. Those post-SP gametocytes carried significantly more DHFR and DHPS mutations than pre-treatment asexual parasites from the same population. Only 0.5% of 1728 mosquitoes fed on SP-treated gametocyte carriers developed oocysts, while 11% of 198 mosquitoes fed on chloroquine-treated gametocyte carriers were positive for oocysts. This study shows that in an area of high SP efficacy, although SP treatment sharply increased gametocyte carriage, the infectiousness of these gametocytes to the vector may be very low. Accurate and robust methods for measuring infectivity are needed to guide malaria control interventions that affect transmission.

Anopheles gambiae sensu stricto, the main vector of malaria in Africa, is characterized by its vast geographical range and complex population structure. Assortative mating amongst the reproductively isolated cryptic forms that co-occur in many areas poses unique challenges for programs aiming to decrease malaria incidence via the release of sterile or genetically-modified mosquitoes. Importantly, whether laboratory-rearing affects the ability of An. gambiae individuals of a given cryptic taxa to successfully mate with individuals of their own form in field conditions is still unknown and yet crucial for mosquito-releases. Here, the independent effects of genetic and environmental factors associated with laboratory rearing on male and female survival, mating success and assortative mating were evaluated in the Mopti form of An. gambiae over 2010 and 2011. In semi-field enclosures experiments and despite strong variation between years, the overall survival and mating success of male and female progeny from a laboratory strain was not found to be significantly lower than those of the progeny of field females from the same population. Adult progeny from field-caught females reared at the larval stage in the laboratory and from laboratory females reared outdoors exhibited a significant decrease in survival but not in mating success. Importantly, laboratory individuals reared as larvae indoors were unable to mate assortatively as adults, whilst field progeny reared either outdoors or in the laboratory, as well as laboratory progeny reared outdoors all mated significantly assortatively. These results highlight the importance of genetic and environment interactions for the development of An. gambiae's full mating behavioral repertoire and the challenges this creates for mosquito rearing and release-based control strategies.