Revealing diversity among extant blood flukes, and the patterns of relationships among them, has been hindered by the difficulty of determining if specimens described from different life cycle stages, hosts, geographic localities, and times represent the same or different species. Persistent collection of all available life cycle stages and provision of exact collection localities, host identification, reference DNA sequences for the parasite, and voucher specimens eventually will provide the framework needed to piece together individual life cycles and facilitate reconciliation with classical taxonomic descriptions, including those based on single life cycle stages. It also provides a means to document unique or rare species that might only ever be recovered from a single life cycle stage. With an emphasis on the value of new information from field collections of any available life cycle stages, here we provide data for several blood fluke cercariae from freshwater snails from Kenya, Uganda, and Australia. Similar data are provided for adult worms of Macrobilharzia macrobilharzia and miracidia of Bivitellobilharzia nairi. Some schistosome and sanguinicolid cercariae that we recovered have peculiar morphological features, and our phylogenetic analyses (18S and 28S rDNA and mtDNA CO1) suggest that 2 of the new schistosome specimens likely represent previously unknown lineages. Our results also provide new insights into 2 of the 4 remaining schistosome genera yet to be extensively characterized with respect to their position in molecular phylogenies, Macrobilharzia and Bivitellobilharzia. The accessibility of each life cycle stage is likely to vary dramatically from one parasite species to the next, and our examples validate the potential usefulness of information gleaned from even one such stage, whatever it might be.The Schistosomatidae is one of the best known of parasite families, yet even within this group much remains to be learned about global species diversity, biogeography, patterns of vertebrate and snail host usage, and evolutionary relationships. Our knowledge of schistosome origins and diversification also will be improved by better understanding the diversity inherent in closely-related digenean families, including the 2 other families of blood flukes (the Spirorchiidae of turtles and the Sanguinicolidae of fishes), and the Clinostomidae. Blood fluke systematics, particularly of schistosomes, has received considerable attention in the last several years (e.g., Carmichael, 1984;Rollinson et al., 1997;Snyder and Loker, 2000;Attwood et al., 2002;Lockyer et al., 2003;Morgan et al., 2003; Agatsuma et al., 2004). These studies have examined morphology, DNA sequence diversity, and patterns of host use. The molecular studies, in particular, have yielded intriguing new hypotheses that delineate the broad patterns of relationships within the family and have provided an invaluable framework to examine overall schistosome and blood fluke diversity.One of the long-standing impediments to assessing diversi...
Fasciolid flukes are among the largest and best known digenetic trematodes and have considerable historical and veterinary significance. Fasciola hepatica is commonly implicated in causing disease in humans. The origins, patterns of diversification, and biogeography of fasciolids are all poorly known. We have undertaken a molecular phylogenetic study using 28S, internal transcribed spacer 1 and 2 (ITS-1 and ITS-2) of nuclear ribosomal DNA, and mitochondrial nicotinamide dehydrogenase subunit 1 (nad1) that included seven of the nine recognized species in the family. The fasciolids examined comprise a monophyletic group with the most basal species recovered from African elephants. We hypothesize fasciolids migrated from Africa to Eurasia, with secondary colonization of Africa. Fasciolids have been conservative in maintaining relatively large adult body size, but anatomical features of their digestive and reproductive systems are available. These flukes have been opportunistic, with respect to switching to new snail (planorbid to lymnaeid) and mammalian hosts and from intestinal to hepatic habitats within mammals.
e Dengue virus (DENV) infection is considered a major public health problem in developing tropical countries where the virus is endemic and continues to cause major disease outbreaks every year. Here, we describe the development of a novel, inexpensive, and user-friendly diagnostic assay based on a reverse transcription-insulated isothermal PCR (RT-iiPCR) method for the detection of all four serotypes of DENV in clinical samples. The diagnostic performance of the newly established pan-DENV RT-iiPCR assay targeting a conserved 3= untranslated region of the viral genome was evaluated. The limit of detection with a 95% confidence was estimated to be 10 copies of in vitro-transcribed (IVT) RNA. Sensitivity analysis using RNA prepared from 10-fold serial dilutions of tissue culture fluid containing DENVs suggested that the RT-iiPCR assay was comparable to the multiplex real-time quantitative RT-PCR (qRT-PCR) assay for DENV-1, -3, and -4 detection but 10-fold less sensitive for DENV-2 detection. Subsequently, plasma collected from patients suspected of dengue virus infection (n ؍ 220) and individuals not suspected of dengue virus infection (n ؍ 45) were tested by the RT-iiPCR and compared to original test results using a DENV NS1 antigen rapid test and the qRT-PCR. The diagnostic agreement of the pan-DENV RT-iiPCR, NS1 antigen rapid test, and qRT-PCR tests was 93.9%, 84.5%, and 97.4%, respectively, compared to the composite reference results. This new RT-iiPCR assay along with the portable POCKIT nucleic acid analyzer could provide a highly reliable, sensitive, and specific point-of-need diagnostic assay for the diagnosis of DENV in clinics and hospitals in developing countries. Dengue virus (DENV) is a mosquito-borne human pathogen that belongs to the genus Flavivirus in the family Flaviviridae (1). DENV is an enveloped virus with a single-stranded, positivesense RNA genome approximately 10.7 kb in length (2). The genomic RNA includes 5= and 3= untranslated regions (UTRs) and a single open reading frame that encodes a single polyprotein that is cleaved into three structural proteins (capsid [C], premembrane/membrane [prM/M], and envelope [E]) and seven nonstructural proteins (NS1, NS2A, NS2B, NS3, NS4A, NS4B, and NS5) (3). DENV is comprised of four distinct serotypes (DENV-1, -2, -3, and -4), and all four serotypes are currently circulating in the Pacific Islands, Americas, Asia, and Africa. In addition to this, distinct genotypes have been identified within each serotype (4, 5), highlighting the extensive genetic variability of the DENV serotypes.DENV infection is considered a major public health problem in developing tropical countries where the virus is endemic, and it is continuously spreading to new geographical areas around the world (6, 7). Moreover, frequent international travel to regions where dengue is endemic or epidemic increases the risk of DENV infection for travelers (8,9), and travel contributes to the escalating numbers of imported dengue cases in temperate regions. More than 2.5 billion people ...
BackgroundDengue infection carries a potential risk of death despite stringent management of plasma leak and haemorrhage. It appears that the extent of liver dysfunction determines the outcome.MethodsWe present a postmortem study of five patients, died of dengue shock syndrome who had markedly elevated liver enzymes and irreparable circulatory failure.ResultsAll were females with a median age of 46 years (range 20–50 years). All had positive NS1 and IgM. Clinically, one patient developed severe degree of hepatic encephalopathy whilst three patients developed uncontrollable bleeding manifestations. Dengue virus was detected in three liver specimens by reverse transcription PCR. Histology of the liver revealed massive necrosis with haemorrhages in these patients with evidence of micro and macrovesicular steatosis with significant periportal inflammatory infiltrate. No significant ischaemic changes or necrosis was observed in the other organs.ConclusionsSevere haemorrhagic necrosis of the liver was the cause of death in these patients probably due to direct viral infection. Predilection for severe liver disease remains unknown. Therefore, it is prudent to think beyond plasma leak as the main pathology of dengue infection and attempts should be made to develop other treatment modalities to prevent and manage unforeseen fatal complications of dengue infection.
Schistosoma species have traditionally been arranged in groups based on egg morphology, geographical origins, and the genus or family of snail intermediate host. One of these groups is the`S. indicum group' comprising species from Asia that use pulmonate snails as intermediate hosts. DNA sequences were obtained from the four members of this group (S. indicum, S. spindale, S. nasale and S. incognitum) to provide information concerning their phylogenetic relationships with other Asian and African species and species groups. The sequences came from the second internal transcribed spacer (ITS2) of the ribosomal gene repeat, part of the 28S ribosomal RNA gene (28S), and part of the mitochondrial cytochrome c oxidase subunit 1 (CO1) gene. Tree analyses using both distance and parsimony methods showed the S. indicum group not to be monophyletic. Schistosoma indicum, S. spindale and S. nasale were clustered among African schistosomes, while S. incognitum was placed as sister to the African species (using ITS2 and 28S nucleotide sequences and CO1 amino acid sequences), or as sister to all other species of Schistosoma (CO1 nucleotide sequences). Based on the present molecular data, a scenario for the evolution of the S. indicum group is discussed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.