Rapid and Specific Action of Methylene Blue against Plasmodium Transmission Stages

Methylene blue (MB) is the oldest synthetic anti-infective. Its high potency against asexual and sexual stages of malaria parasites is well documented. This study aimed to investigate possible additional activities of MB in interfering with parasite transmission and determine target stages in Anopheles vectors and humans. MB’s transmission-blocking activity was first evaluated by an ex vivo direct membrane feeding assay (DMFA) using Plasmodium falciparum field isolates. To investigate anti-mosquito stage activity, Plasmodium berghei-infected Anopheles stephensi mosquitoes were fed a second blood meal on mice that had been treated with methylene blue, 3, 6- and 15-days after the initial infectious blood meal. Anti-sporozoite and liver stage activities were evaluated in vitro and in vivo via sporozoite invasion and liver stage development assays, respectively. MB exhibited a robust inhibition of P. falciparum transmission in An. gambiae, even when added shortly before the DMFA but only a moderate effect against P. berghei oocyst development. Exposure of mature P. berghei and P. falciparum sporozoites to MB blocked hepatocyte invasion, yet P. berghei liver stage development was unaffected by MB. Our results indicate previously underappreciated rapid specific activities of methylene blue against Plasmodium transmission stages, preventing the establishment of both mosquito midgut and liver infections as the first essential steps in both hosts

Resistance and evolution of human lice, Pediculus Humanus

Dans ce travail, nous avons voulu apporter notre contribution dans le domaine de la recherche sur les poux humains, afin d’en savoir plus sur l’origine et la phylogéographie des clades, les pathogènes qui leurs sont associés et comprendre les mécanismes impliqués dans la résistance à l’ivermectine. Nous avons obtenu des résultats concrets dans chacune des thématiques abordées. En effet, nous avons (i) pour la première fois rapporté la présence de clade B au Moyen-Orient datant de plus de 2000 ans, supportant une origine asiatique pour ce clade, (ii) mis en évidence l'existence d'un nouveau clade mitochondrial (Clade F), (iii) mis en place une nouvelle technique de PCR en temps réel pour l’identification moléculaire rapide des clades de poux, (iv) mis en évidence chez des poux de tête la présence de l’ADN de plusieurs bactéries, dont plusieurs bactéries qui ne sont pas habituellement vectorisées par les poux telles que Coxiella burnetii, Rickettsia aeschlimannii et de potentielles nouvelles espèces de genre Anaplasma et Ehrlichia ont été détectées pour la première fois chez les poux. Enfin, nous rapportons des données nouvelles sur la résistance des poux à l’ivermectine : (v) en mettant en évidence la présence de trois mutations non-synonymes au niveau de GluCl des poux cliniquement résistants à l’ivermectine, (vi) et en démontrant, pour la première fois, chez une population de poux de laboratoire résistante à l’ivermectine qu’une répression significative de la complexine est à l’origine de la résistance. Cette découverte représente la première évidence liant la complexine à la résistance aux insecticides.In this thesis, we are interested in studying human lice and we aimed to learn more about the origin and phylogeography of clades, lice-borne associated pathogens and to investigate potential mechanisms underlying resistance to ivermectin in lice. We obtained concrete results that have led to scientific publications. Indeed, (i) we reported for the first time the existence of the clade B in the Middle East, dating approximately to 2,000 years old, supporting an Asian origin for this clade, (ii) we highlighted the existence of a sixth mitochondrial clade (Clade F), (iii) we developed a new qPCR for a quick molecular identification of all the known clades of lice, (iv) we identified the presence of the DNA of several bacterial pathogens in head lice, among which several bacteria are not usually associated with lice, such as Coxiella burnetii, Rickettsia aeschlimannii, Borrelia theileri and potential new species from the Anaplasma and Ehrlichia. We finally, investigated mechanisms underlying resistance to ivermectin in lice: (v) we have identified, for the first time, the occurrence of three non-synonymous mutations in GluCl gene in clinically confirmed ivermectin resistant head lice, (vi) and we have identified the involvement of neuronal protein, a complexin, in laboratory ivermectin-selected resistant lice. This finding represents the first evidence linking complexin to insecticide resistance

Where Are We With Human Lice? A Review of the Current State of Knowledge

International audiencePediculus humanus is an obligate bloodsucking ectoparasite of human that includes two ecotypes, head louse and body louse, which differ slightly in morphology and biology, but have distinct ecologies. Phylogenetically, they are classified on six mitochondrial clades (A, B, C, D, E, and F), head louse encompasses the full genetic diversity of clades, while body louse belongs to clades A and D. Recent studies suggested that not only body louse, but also head louse can transmit disease, which warrants greater attention as a serious public health problem. The recent sequencing of body louse genome confirmed that P. humanus has the smallest genome of any hemimetabolous insect reported to date, and also revealed numerous interesting characteristics in the nuclear and mitochondrial genomes. The transcriptome analyses showed that body and head lice were almost genetically identical. Indeed, the phenotypic flexibility associated with the emergence of body lice, is probably a result of regulatory changes, perhaps epigenetic in origin, triggered by environmental signals. Current lice control strategies have proven unsuccessful. For instance, ivermectin represents a relatively new and very promising pediculicide. However, ivermectin resistance in the field has begun to be reported. Therefore, novel opportunities for pest control strategies are needed. Our objective here is to review the current state of knowledge on the biology, epidemiology, phylogeny, disease-vector and control of this fascinating and very intimate human parasite

Putative native South Amerindian origin of head lice clade F: evidence from head lice nits infesting human shrunken heads

International audienceAbstract The head louse, Pediculus humanus capitis , is a strictly obligate human ectoparasite with a long history of association with humans. Here, 17 ancient head lice nits were recovered from six shrunken human heads (known as tsantsas ) of individuals from the Shuar/Jivaro tribe, a native Amazonian population from Ecuador, South America. Cytochrome b DNA analysis revealed the presence of three known mitochondrial clades. Clade A was the most frequent (52.94%), followed by F (35.29%), and B (11.76%). Eleven haplotypes were found in 17 samples, and nine of the haplotypes were novel, indicating an unusually high genetic diversity. In conclusion, we confirmed the presence of clades A, B and F in South Amerindian population. Moreover, the description of clade F, together with its previous reports in another Amerindian population from French Guiana, strongly support the hypothesis of a native South American origin for this clade, and probably derived from clade B which was carried to America by an ancestral Eurasian Beringian population. Further support to our conclusion and new insights might come from the analysis of a larger collection of modern and ancient native American lice

Mutations in GluCl associated with field ivermectin-resistant head lice from Senegal

International audienceThrough its unique mode of action, ivermectin represents a relatively new and very promising tool to fight against human lice, especially in cases of resistance to commonly used pediculicides. However, ivermectin resistance in the field has already begun to be reported. Therefore, understanding the mechanisms involved is a key step in delaying and tackling this phenomenon. In this study, field head lice with confirmed clinical resistance to ivermectin in rural human populations from Senegal were subjected to genetic analysis targeting the GluCl gene, the primary target of ivermectin known to be involved in resistance. Through DNA-polymorphism analysis, three relevant non-synonymous mutations in GluCl which were found only in ivermectin-resistant head lice (76 head lice tested), were identified. The A251V mutation found in the TM3 transmembrane domain was the most prevalent (allelic frequency of 0.33), followed by the S46P mutation (0.28) located at the N-terminal extracellular domain. The H272R was in the M3-M4 linker transmembrane region of GluCl and has shown the lowest frequency (0.18). Polymerase chain reaction restriction fragment length polymorphism (PCRRFLP) diagnostic assays were also developed for their accurate genotyping. Our study is the first to report the presence of GluCl point mutations in clinical ivermectin-resistant head lice occurring in rural human populations of Senegal. (C) 2018 Elsevier B.V. and International Society of Chemotherapy. All rights reserved

Multiple vector-borne pathogens of domestic animals in Egypt

International audienceVector Borne Diseases (VBDs) are considered emerging and re-emerging diseases that represent a global burden. The aim of this study was to explore and characterize vector-borne pathogens in different domestic animal hosts in Egypt. A total of 557 blood samples were collected from different animals using a convenience sampling strategy (203 dogs, 149 camels, 88 cattle, 26 buffaloes, 58 sheep and 33 goats). All samples were tested for multiple pathogens using quantitative PCR and standard PCR coupled with sequencing. We identified Theileria annulata and Babesia bigemina in cattle (15.9 and 1.1%, respectively), T . ovis in sheep and buffaloes (8.6 and 7.7%, respectively) and Ba . canis in dogs (0.5%) as well as Anaplasma marginale in cattle, sheep and camels (20.4, 3.4 and 0.7%, respectively) and Coxiella burnetii in sheep and goats (1.7 and 3%; respectively). New genotypes of An . centrale , An . ovis , An . platys -like and Borrelia theileri were found in cattle (1.1,3.4, 3.4 and 3.4%, respectively), An . platys -like in buffaloes (7.7%), An . marginale , An . ovis , An . platys -like and Bo . theileri in sheep (3.4, 1.7, 1.7 and 3.4%, respectively), An . platys , An . platys -like and Setaria digitata in camels (0.7, 5.4 and 0.7%, respectively) and Rickettsia africae -like, An . platys , Dirofilaria repens and Acanthocheilonema reconditum in dogs (1.5, 3.4, 1 and 0.5%, respectively). Co-infections were found in cattle, sheep and dogs (5.7, 1.7, 0.5%, respectively). For the first time, we have demonstrated the presence of several vector-borne zoonoses in the blood of domestic animals in Egypt. Dogs and ruminants seem to play a significant role in the epidemiological cycle of VBDs

Mitochondrial diversity and phylogeographic analysis of Pediculus humanus reveals a new Amazonian clade “F”

International audiencePediculus humanus is an obligate and highly intimate bloodsucking insect parasite of humans that has two ecotypes, head louse and body louse. This study analyzed genetic diversity at three mitochondrial genes (cy-tochrome b [cytb], cytochrome oxidase subunit 1 [cox1] and 12S ribosomal RNA [12S]) in 98 head lice collected from an isolated Native American population from the Wayampi community in Trois-Sauts, French Guiana. These results are integrated with all prior data of P. humanus (1402 cytb, 743 cox1 and 344 12S) from other parts of the world. The phylogenetic analysis revealed six highly divergent and well-supported monophyletic clades. Five clades corresponded to the previously recognized mitochondrial clades A, D, B, C and E, while the sixth (clade F) was novel, as it exhibited 5.4%, 3.7% and 3.6% divergence at cytb, cox1 and 12S, respectively, from its nearest neighbor clade B. Interestingly, the clade F has only been recovered in a few lice sequences from Mexico and Argentina, while it was the most common lineage in the Amazonian lice, which hints its association with the Native American region. Furthermore, Pediculus mjobergi, a New World monkeys' louse, which is thought to be transmitted to monkeys from the first humans that had reached the American continent thousands of years ago, also belonged to this clade, suggesting that this louse may not be a separate species but an evolutionary lineage of P. humanus. The discovery of new Amazonian clade F with the recovery of additional haplotypes within each of the five clades demonstrates that the levels of genetic diversity in P. humanus are higher than previously thought

High Ancient Genetic Diversity of Human Lice, Pediculus humanus, from Israel Reveals New Insights into the Origin of Clade B Lice

International audienceThe human head louse, Pediculus humanus capitis, is subdivided into several significantly divergent mitochondrial haplogroups, each with particular geographical distributions. Historically, they are among the oldest human parasites, representing an excellent marker for tracking older events in human evolutionary history. In this study, ancient DNA analysis using real-time polymerase chain reaction (qPCR), combined with conventional PCR, was applied to the remains of twenty-four ancient head lice and their eggs from the Roman period which were recovered from Israel. The lice and eggs were found in three combs, one of which was recovered from archaeological excavations in the Hatzeva area of the Judean desert, and two of which found in Moa, in the Arava region, close to the Dead Sea. Results show that the head lice remains dating approximately to 2,000 years old have a cytb haplogroup A, which is worldwide in distribution, and haplogroup B, which has thus far only been found in contemporary lice from America, Europe, Australia and, most recently, Africa. More specifically, this haplogroup B has a B36 haplotype, the most common among B haplogroups, and has been present in America for at least 4,000 years. The present findings confirm that clade B lice existed, at least in the Middle East, prior to contacts between Native Americans and Europeans. These results support a Middle Eastern origin for clade B followed by its introduction into the New World with the early peoples. Lastly, the presence of Acinetobacter baumannii DNA was demonstrated by qPCR and sequencing in four head lice remains belonging to clade A

High Genetic Diversity and Rickettsia felis in Pediculus humanus Lice Infesting Mbuti (pygmy people), -Democratic Republic of Congo

International audiencePediculus humanus is an obligate bloodsucking parasite of humans that has two ecotypes, the head louse and the body louse, which share an intimate history of coevolution with their human host. In the present work, we obtained and analysed head and body lice collected from Mbuti pygmies living in the Orientale province of the Democratic Republic of the Congo. Cytochrome b DNA analysis was performed in order to type the six known lice clades (A, D, B, F, C and E). The results revealed the presence of two mitochondrial clades. Clade D was the most frequent (61.7% of 47), followed by clade A (38.3% of 47). Sixteen haplotypes were found in 47 samples, of which thirteen were novel haplotypes, indicating an unusually high genetic diversity that closely mirrors the diversity of their hosts. Moreover, we report for the first time the presence of the DNA of R. felis in three (6.4% of 47) head and body lice belonging to both clades A and D. Additional studies are needed to clarify whether the Pediculus lice can indeed transmit this emerging zoonotic bacterium to their human hosts

Molecular Evidence of Bacteria in Clothes Lice Collected from Homeless People Living in Shelters in Marseille

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