Parasite最新文献

Filarial nematodes of the Dipetalonema lineage are widespread parasites and include some species that are transmitted by ticks. In this study, we conducted a large molecular survey of ticks in French Guiana, South America, to understand the overall diversity of tick-borne filarioids in this remote region largely covered by dense tropical forests. Out of 682 ticks belonging to 22 species and 6 genera, 21 ticks (3.1%) of the species Amblyomma cajennense, A. oblongoguttatum, A. romitii, Ixodes luciae and Rhipicephalus sanguineus sensu lato were positive for infection by filarioids. Molecular typing and phylogenetic analysis identified all these filarioids as members of the Dipetalonema lineage. While the filarioid of R. sanguineus sensu lato is a previously described species, the canine worm Cercopithifilaria bainae Almeida & Vicente, 1984, all other filarioids detected in this study are related but distinct to already known species in the genera Cercopithifilaria, Cruorifilaria and Dipetalonema. Their vertebrate host range may include a wide variety of mammals present in French Guiana, but dogs, capybaras, and opossums are the best candidate hosts for some of these filarioids. Although the detection of members of the Dipetalonema lineage in ticks of significant medical or veterinary interest is of concern, the risk of contracting a tick-borne filarial infection is still largely unknown. The pathogenicity of these filarioids, their epidemiology, developmental cycles, and mechanisms of transmission by South American tick species now require further study.

Fish are often speckled with "black spots" caused by metacercarial trematode infection, inducing a host response. Cryptocotyle spp. (Opisthorchiidae) are among the parasites responsible for this phenomenon. So far, the impact on human health is still unknown. In addition, few publications dealing with black spot recovery, identification, distribution and diversity among commercially important fish are available. Moreover, "black spots" have been observed by fishermen on marine fish, revealing an appreciable but unquantified presence in consumed fish. An epidemiological survey of 1,586 fish from seven commercial species (herring, sprat, whiting, pout, dab, flounder, and plaice) was conducted in the Eastern English Channel and the North Sea in January 2019 and 2020. Encysted metacercariae were found in 325 out of 1,586 fish, with a total prevalence of 20.5%. Intensity of infection varied from 1 to 1,104 parasites. The recorded encysted metacercariae were identified either by microscopic examination or with molecular tools. Partial sequences of the mtDNA cox1 gene and of the rDNA ITS region were obtained. Two species of Cryptocotyle, Cryptocotyle lingua (Creplin, 1825) and Cryptocotyle concava (Creplin, 1825) were found. Metacercariae belonging to other trematode families were also identified. Molecular phylogenetic analysis and haplotype network construction were performed to confirm the identification and to study the potential presence of different populations of Cryptocotyle spp. This survey enabled us to describe the distribution of two species of Cryptocotyle in the English Channel and North Sea ecosystems. The observed differences in infestation levels between fish species and geographical areas will contribute to better understanding of the ecology of these parasites.

Malaria is a major public health problem in Madagascar, particularly in coastal areas. We conducted a randomized, controlled, parallel-group study of artemisinin-based combination therapy (ACT) in Mananjary and Farafangana, two localities on the rainy south-east coast of Madagascar, from March to September 2018. The efficacy and safety of artesunate + amodiaquine (ASAQ) and artemether + lumefantrine (AL) were assessed according to the WHO protocol with a 28-day follow-up. Children aged 6 months to 14 years with uncomplicated Plasmodium falciparum malaria were randomized to receive ASAQ or AL for three days (1:1). 347/352 (98.5%) randomized patients reached the study endpoint on day 28. Crude adequate clinical and parasitological response (ACPR) rates were 100% (95% CI: 98.8-100%) in the ASAQ group and 96% (95% CI: 93.1-98.9%) in the AL group (per protocol population). However, the PCR-corrected ACPR rate was 97.7% (95% CI: 95.4-100%) in the AL group. Two cases of recrudescence and three of re-infection were observed. Mild and moderate adverse events, including gastrointestinal and/or nervous disorders, were reported in 11.9% (42/352) of patients. We found that ASAQ and AL were safe and efficacious for treating uncomplicated P. falciparum malaria. They may be used for treatment at health facilities and at the community level, and for mass drug administration campaigns.

Mermithid nematodes (Nematoda, Mermithidae) parasitising mosquitoes could be useful as biological agents for the control of host populations. Nine female mosquitoes belonging to the species Aedes cantans, Ae. communis, and Ae. rusticus were found parasitised by mermithids in Northern France. Sequencing of partial 18S rDNA showed 100% sequence homology for all processed specimens. The mermithid sequences were closely related to specimens previously recorded from Anopheles gambiae in Senegal. However, 18S sequences do not allow for identification of nematodes at the genus or species level. Our specimens could also be related to Strelkovimermis spiculatus, or belong to other genera not yet sequenced such as Empidomermis, the only mermithid genus recorded from mosquitoes in France.

A literature review for a recent ultrastructural study of a trichinelloid eggshell revealed consistently occurring errors in the literature on nematode eggshell anatomy. Examples included nematodes of medical, veterinary, and agricultural importance in several orders. Previous researchers had warned of some of these errors decades ago, but a comprehensive solution was not offered until 2012 when a clarifying new anatomical and developmental interpretation of nematode eggshells was proposed by members of the Caenorhabditis elegans Research Community. However, their findings were explained using arcane acronyms and technical jargon intended for an audience of experimental molecular geneticists, and so their papers have rarely been cited outside the C. elegans community. Herein we (1) provide a critical review of nematode eggshell literature in which we correct errors and relabel imagery in important historical reports; (2) describe common reporting errors and their causes using language familiar to researchers having a basic understanding of microscopy and nematode eggs; (3) recommend a new hexalaminar anatomical and terminological framework for nematode eggshells based on the 2012 C. elegans framework; and (4) recommend new unambiguous terms appropriate for the embryonated/larvated eggs regularly encountered by practicing nematodologists to replace ambiguous or ontogenetically restricted terms in the 2012 C. elegans framework. We also (5) propose a resolution to conflicting claims made by the C. elegans team versus classical literature regarding Layer #3, (6) extend the C. elegans hexalaminar framework to include the polar plugs of trichinelloids, and (7) report new findings regarding trichinelloid eggshell structure.

Molecular identification of rare human infectious pathogens appears to be one of the most relevant current methods for rapid diagnosis and management of patients. PCR techniques, in particular real-time quantitative PCR, are best suited for the detection of DNA from the pathogens, even at low concentrations. Echinococcosis infections are due to helminths of the Echinococcus genus, with closely related species involved in parasitic lesions affecting animals and, accidentally, humans. We developed a multiplex qPCR (MLX qPCR) assay allowing for the detection of four Echinococcus species involved in Europe in alveolar echinococcosis (AE) and cystic echinococcosis (CE) (Echinococcus multilocularis, E. granulosus sensu stricto, E. ortleppi, and E. canadensis), based on short mitochondrial targets. A collection of 81 fresh and formalin-fixed paraffin-embedded tissues (FFPE) of AE and CE lesions was assembled. The qPCR assays were performed in triplex for Echinococcus spp. detection, associated with a qPCR inhibitor control. A duplex qPCR was also designed to enable diagnosis of two other dead-end helminthiases (cysticercosis (Taenia solium), and toxocariasis (Toxocara cati and T. canis)). The sensitivity of the qPCR was assessed and ranged from 1 to 5 × 10^-4 ng/μL (seven PCR assays positive), corresponding to 37-42 cycles for quantifiable DNA. The specificity was 100% for all the targets. This multiplex qPCR, adapted to low amounts of DNA can be implemented in the laboratory for the rapid molecular diagnosis of Echinococcosis species.

The family Anaplasmataceae includes tick-borne bacteria of major public and veterinary health interest, as best illustrated by members of the genera Anaplasma and Ehrlichia. Recent epidemiological surveys have also reported on the presence of a novel putative genus in the Anaplasmataceae, Candidatus Allocryptoplasma, previously described as Candidatus Cryptoplasma in the western black-legged tick, Ixodes pacificus. However, the genetic diversity of Ca. Allocryptoplasma and its phylogenetic relationship with other Anaplasmataceae remain unclear. In this study, we developed a multi-locus sequence typing approach, examining the DNA sequence variation at five genes of Ca. Allocryptoplasma found in ticks. Combining this multi-locus sequence typing and genetic data available on public databases, we found that substantial genetic diversity of Ca. Allocryptoplasma is present in Ixodes, Amblyomma and Haemaphysalis spp. ticks on most continents. Further analyses confirmed that the Ca. Allocryptoplasma of ticks, the Ca. Allocryptoplasma of lizards and some Anaplasma-like bacteria of wild mice cluster into a monophyletic genus, divergent from all other genera of the family Anaplasmataceae. Candidatus Allocryptoplasma appears as a sister genus of Anaplasma and, with the genera Ehrlichia and Neoehrlichia, they form a monophyletic subgroup of Anaplasmataceae associated with tick-borne diseases. The detection of genetically distinct Ca. Allocryptoplasma in ticks of significant medical or veterinary interest supports the hypothesis that it is an emergent genus of tick-borne pathogens of general concern.