Post-elimination surveillance in formerly onchocerciasis endemic focus in Southern Mexico

BACKGROUND

All formerly endemic communities of the Southern Chiapas focus of onchocerciasis in Mexico were treated with ivermectin until parasite transmission was eliminated by 2015. Transmission of onchocerciasis did not resume during a period of three years (2012-2014) following the final distribution of ivermectin in 2011; it was thus concluded that transmission remained undetectable without intervention. WHO thus declared the elimination of transmission of onchocerciasis from Mexico in 2015.

METHODOLOGY/PRINCIPAL FINDINGS

From 2016 to the present, post-elimination surveillance (PES) based on examination for suspected onchocercomas was performed in the former Southern Chiapas focus. Each year, over 60% of the total population (range = 85,347-104,106 individuals) of the formerly endemic communities were examined for onchocercomas. Thirty-four individuals were found harboring suspected onchocercomas in the PES surveys conducted from 2016-2019. Of these, one female of 7 years of age who had immigrated from a formerly endemic focus, harbored an infertile (sterile) female in the suspected onchocercoma; all others were negative. Skin biopsy assessments were performed from March through May 2017 in three communities where the female resided. None of the 83 individuals of the three communities examined by skin biopsy were mf positive. Similarly, none of the biopsies from the individuals were found to contain parasite DNA when tested by polymerase chain reaction-enzyme-linked immunosorbent assay (PCR-ELISA).

CONCLUSIONS/SIGNIFICANCE

These provide support to the conclusion that onchocerciasis has been eliminated from Mexico.

A novel protocol to isolate, detect and differentiate taeniid eggs in leafy greens and berries using real-time PCR with melting curve analysis

BACKGROUND

Zoonotic taeniid cestodes are amongst the most important food-borne parasites affecting human health worldwide. Contamination of fresh produce with the eggs of Echinococcus granulosus (s.l.), Echinococcus multilocularis, and some Taenia species pose a potential food safety risk. However, very few studies have attempted to investigate the potential contamination of fresh produce with taeniid eggs and the available methods are not standardized for this purpose. Established protocols do exist for testing leafy greens and berries for contamination with protozoan parasites and are used in national surveillance programmes. This methodology could be suitable for the detection of taeniids. The objective of this project was to develop and standardize a sensitive and reliable method to detect contamination of leafy greens and berries with eggs of zoonotic taeniids and to differentiate between E. multilocularis, E. granulosus (s.l.) and Taenia spp.

METHODS

We compared the efficacy of different wash solutions to remove Taenia spp. eggs from spiked produce, assessed two DNA extraction kits for their performance on Taenia spp. eggs, and adapted a published conventional multiplex PCR into a real-time PCR with fluorescence melting curve analysis (MCA) that was optimized for use on produce washes. Analytical specificity of this protocol was assessed using non-spiked produce washes as well as a variety of other potentially contaminating parasites.

RESULTS

The protocol as established in this study had an analytical sensitivity of detecting five eggs per spiked sample for both romaine lettuce and strawberries. Unequivocal identification of E. multilocularis, E. granulosus (s.l.) and Taenia spp. was possible through MCA. Amplicon sequencing allowed identification of Taenia to the species level. The real-time PCR also amplified DNA from Dicrocoelium sp., but with a clearly discernable melting curve profile.

CONCLUSION

The new protocol for screening produce for taeniid contamination was highly sensitive. Melting curve analysis and the possibility of amplicon sequencing made this assay very specific. Once further validated, this method could be employed for surveillance of produce for contamination with taeniid parasites to assess potential risks for consumers.

Comparative analyses of complete ribosomal DNA sequences of Clonorchis sinensis and Metorchis orientalis: IGS sequences may provide a novel genetic marker for intraspecific variation

Both Clonorchis sinensis and Metorchis orientalis are the fish-borne zoonotic trematodes, and have a wide distribution of southeastern Asia, especially in China. Due to the similar morphology, life cycle, and parasitic positions are difficult to differentiate between both metacercariae. In the present study, the complete rDNA sequences of five C. sinensis and five M. orientalis were obtained and compared for the first time. And the IGS rDNA sequences were tested as a genetic marker. The results showed complete rDNA lengths of C. sinensis were range from 8049 bp to 8391 bp, including 1991 bp, 1116 bp, 3854 bp, and 1088-1430 bp belonging to 18S, ITS, 28S and IGS, respectively. And the complete rDNA lengths of M. orientalis were range from 7881 bp to 9355 bp, including 1991 bp, 1077 bp, 3856 bp, and 957-2431 bp belonging to 18S, ITS, 28S and IGS, respectively. Comparative analyses reveal length difference main in IGS, which has higher intraspecific and interspecific variations than other ribosomal regions. Forty four repeat (forward and inverted) sequences were found in the complete rDNAs of C. sinensis and M. orientalis. The phylogenetic analyses showed that the sequences of ITS1, ITS2, 18S and 28S could be used as different level genetic markers. In IGS phylogenetic tree, Opisthorchiidae, Paramphistomidae, Dicrocoeliidae, and Schistosomatidae formed monophyletic groups, and the same length sequences were clustered together in the same species. These findings of the present study provide the new molecular data for studying the complete rDNA of C. sinensis and M. orientalis, and indicate IGS sequences may used as a novel genetic marker for studying intraspecific variation in trematodes.

Progress in loop-mediated isothermal amplification assay for detection of Schistosoma mansoni DNA: towards a ready-to-use test

Schistosomiasis is one of the most prevalent Neglected Tropical Disease, affecting approximately 250 million people worldwide. Schistosoma mansoni is the most important species causing human intestinal schistosomiasis. Despite significant efforts in recent decades, the global disease burden of schistosomiasis remains extremely high. This could partly be attributed to the absence of accurate diagnostic tools, primarily in endemic areas. Loop-mediated isothermal amplification (LAMP) is increasingly used in molecular diagnostics as a field-friendly alternative to many other complex molecular methods and it has been proposed as an ideal candidate for revolutionizing point-of-care molecular diagnostics. In a previous work, a LAMP-based method to detect S. mansoni DNA (SmMIT-LAMP) was developed by our research group for early diagnosis of active schistosomiasis in an experimental infection murine model. The SmMIT-LAMP has been further successfully evaluated in both human stool and snail samples and, recently, in human urine samples. In this study, we developed an important improvement for SmMIT-LAMP molecular assay, transforming it into a cold maintenance dry format suitable for potentially manufacturing as kit for ready-to-use for schistosomiasis diagnosis. This procedure could be applied to create dry LAMP kits for a laboratory setting and for diagnostic applications for other neglected tropical diseases.

Genetic characterization of Angiostrongylus larvae and their intermediate host, Achatina fulica, in Thailand

Angiostrongyliasis is a parasitic disease caused by nematodes of the genus Angiostrongylus. Distribution of this worm corresponds to the dispersal of its main intermediate host, the giant African land snail Achatina fulica. Genetic characterization can help identify parasitic pathogens and control the spreading of disease. The present study describes infection of A. fulica by Angiostrongylus, and provides a genetic outlook based on sequencing of specific regions. We collected 343 land snails from 22 provinces across six regions of Thailand between May 2017 and July 2018. Artificial digestion and Baermann’s technique were employed to isolate Angiostrongylus larvae. The worm and its intermediate host were identified by sequencing with specific nucleotide regions. Phylogenetic tree was constructed to evaluate the relationship with other isolates. A. fulica from Chaiyaphum province was infected with A. cantonensis, whereas snails collected from Phrae and Chiang Rai provinces were infected with A. malaysiensis. The maximum likelihood tree based on 74 A. fulica COI sequences revealed monophyletic groups and identified two haplotypes: AF1 and AF2. Only AF1, which is distributed in all regions of Thailand, harbored the larvae of A. cantonensis and A. malaysiensis. Two mitochondrial genes (COI and cytb) and two nuclear regions (ITS2 and SSU rRNA) were sequenced in 41 Angiostrongylus specimens. The COI gene indicated that A. cantonensis was closely related to the AC10 haplotype; whereas the cytb gene revealed two new haplotypes: AC19 and AC20. SSU rRNA was useful for the identification of A. cantonensis; whereas ITS2 was a good genetic marker for differentiating between A. cantonensis and A. malaysiensis. This study provides genetic information about the parasite Angiostrongylus and its snail intermediate host. The data in this work may be useful for further study on the identification of Angiostrongylus spp., the genetic relationship between intermediate host and parasite, and control of parasites.

Validation of Bifurcohaptor spp. (Monogenoidea: Dactylogyridae) reported from India using molecular methods with inclusion of insilico study: A brief report on its host-specificity

A total of 17 species of the genus Bifurcohaptor Jain, 1958 have been reported from two fish families namely Bagridae Bleeker, 1858 (Mystus vittatus (Bloch, 1794), M. tengara (Hamilton, 1822), M. keletius (Valenciennes, 1840), Hemibagrus nemurus (Valenciennes, 1840), Rita rita (Hamilton, 1822) and Sperata seenghala (Sykes, 1839)) and Sisoridae Bleeker, 1858 (Bagarius bagarius (Hamilton, 1822)). Out of these, only two species viz. B. indicus and B. giganticus are found valid in India, parasitizing gills of Mystus spp. and Bagarius sp. Taxonomic studies suggest, present specimen of B. indicus and B. giganticus, both are morphologically close to species described by Jain (1958), except morphometric variations and posses 7 pairs of marginal hooks instead of 6 pairs. Present manuscript delves with the characterization of B. indicus and B. giganticus reported from India, using molecular techniques. Partial mt COI nucleotide sequence based insilico protein analysis and partial 28S and ITS-1 rDNA based phylogenetic analysis, estimated by Neighbour-joining (NJ) and Minimum Evolution (ME) methods revealed that the species of the genus Bifurcohaptor are genetically distinct and valid. The grouping of Bifurcohaptor spp. with other representatives of family Dactylogyridae supports morphology based placement into family Dactylogyridae. Present and previous host-parasite information suggests both Bifurcohaptor spp. are species specialist however, the genus Bifurcohaptor is generalist at generic level.

A New Species of Ascarophis (Nematoda: Cystidicolidae) Parasitizing Clinocottus analis (Pisces: Cottidae) from Baja California, Mexico

A new species of nematode, Ascarophis morronei n. sp. (Cystidicolidae), is described from the stomach wall of the woolly sculpin Clinocottus analis (Cottidae) collected in the rocky intertidal from northwestern Baja California, Mexico. Collected nematodes were studied using both light and scanning electron microscopy. Sequence fragments for 18S rDNA molecular markers were obtained from the new nematode species, in order to test its position within the family Cystidicolidae under a phylogenetic context. Main characters distinguishing this new species include the reduced labia and the morphology of the eggs, distances of nerve ring and excretory pore from the anterior end, and left spicule of males. The new species described here is the second for the genus Ascarophis reported as adult in the Southern California Bight, and the first one recorded for the fish genus Clinocottus.

Genetic Analysis of Small-Subunit Ribosomal RNA, Internal Transcribed Spacer 2, and ATP Synthase Subunit 8 of Trichuris trichiura Ancient DNA Retrieved from the 15th to 18th Century Joseon Dynasty Mummies' Coprolites from Korea

Although parasitic infection by Trichuris trichiura is a very common intestinal helminthic disease worldwide, there is still insufficient information on the genetic characteristics of ancient T. trichiura in different spatiotemporal perspectives. Utilizing coprolite specimens obtained from 15th-18th century mummies dating to the Joseon Dynasty, we analyzed small-subunit ribosomal RNA, internal transcribed spacer 2, and ATP synthase subunit 8 of T. trichiura ancient DNA (aDNA). In BLAST and phylogenetic analyses, the T. trichiura aDNA sequences of this study belong to a separate cluster that is evidently distinct from the other genus Trichuris spp. reported in GenBank. This report characterizes T. trichiura aDNA of pre-20th century East Asia, and in so doing, it also proves the potential of aDNA analysis for differential diagnosis of T. trichiura in cases where ancient parasite eggs are morphologically indeterminate for species identification.

Single Nucleotide Polymorphism Analysis Using KASP Assay Reveals Genetic Variability in Rotylenchulus reniformis

This study employed single nucleotide polymorphisms (SNPs) to determine the genetic variability present in 26 isolates of Rotylenchulus reniformis from Louisiana, Mississippi, Arkansas, South Carolina, Georgia, Hawaii, and Alabama. Genomic DNA from reniform nematode was extracted and increased quantitatively using the process of whole genome amplification. More than 162 putative SNPs were identified, 31 of which were tested using a KASP kompetitive allele-specific PCR genotyping assay. Of the SNPs tested, 13, 17, and 19 SNPs revealed genetic variability within reniform nematode isolates from Louisiana, Mississippi, and Arkansas, respectively. Seven SNPs elucidated genetic differences among isolates of reniform nematode from Louisiana, Mississippi, and Arkansas. Eight SNPs determined genetic variability among individual isolates from South Carolina, Georgia, Hawaii, and Alabama. This study is the first to report genetic variability in geographic isolates of reniform nematode employing a SNP assay. This study also demonstrated that SNP markers can be used to evaluate isolates of R. reniformis and could be useful to assess their genetic diversity, origin, and distribution. Such information would be extremely useful in resistance breeding programs.

The phylogenetic position of Anacanthorus (Monogenea, Dactylogyridae) parasitizing Brazilian serrasalmids (Characiformes)

Anacanthorus (Anacanthorinae) is one of the most speciose and common genera of neotropical monogeneans, yet there are still many gaps in our knowledge concerning their diversity and phylogeny. We performed phylogenetic analyses of molecular sequences in order to investigate the phylogenetic position within the Dactylogyridae of Anacanthorus spp. infesting serrasalmids from two Brazilian river basins. Sequences of partial 28S rDNA obtained for nine species of Anacanthorus and Mymarothecium viatorum parasitizing serrasalmids and the published sequences of other members of the Dactylogyridae were included in the phylogenetic reconstruction. Phylogenetic analyses supported the monophyly of anacanthorine monogeneans. The Anacanthorinae (represented in this study by Anacanthorus spp.) formed a monophyletic group included in a large clade together with a group of solely freshwater Ancyrocephalinae and species of the Ancylodiscoidinae. Mymarothecium viatorum (Ancyrocephalinae) was placed within the clade of freshwater Ancyrocephalinae. The phylogenetic analyses indicated that the relationships among species of Anacanthorus reflect those of their serrasalmid hosts: the first subgroup includes a species specific to hosts assigned to Piaractus, a member of the "pacus" lineage; the second subgroup includes a species parasitizing the "Myleus-like pacus" lineage; and the third subgroup includes species parasitizing the lineage of the "true piranhas". We suggest that Anacanthorus and their serrasalmid hosts can be considered a useful model to assess host-parasite biogeography and coevolution in the neotropics. However, future studies focusing on a wider spectrum of host species and their specific Anacanthorus spp. are needed in order to investigate coevolution in this highly diversified system.

The complete mitochondrial genome of Echinostoma miyagawai: Comparisons with closely related species and phylogenetic implications

Echinostoma miyagawai (Trematoda: Echinostomatidae) is a common parasite of poultry that also infects humans. Es. miyagawai belongs to the "37 collar-spined" or "revolutum" group, which is very difficult to identify and classify based only on morphological characters. Molecular techniques can resolve this problem. The present study, for the first time, determined, and presented the complete Es. miyagawai mitochondrial genome. A comparative analysis of closely related species, and a reconstruction of Echinostomatidae phylogeny among the trematodes, is also presented. The Es. miyagawai mitochondrial genome is 14,416 bp in size, and contains 12 protein-coding genes (cox1-3, nad1-6, nad4L, cytb, and atp6), 22 transfer RNA genes (tRNAs), two ribosomal RNA genes (rRNAs), and one non-coding region (NCR). All Es. miyagawai genes are transcribed in the same direction, and gene arrangement in Es. miyagawai is identical to six other Echinostomatidae and Echinochasmidae species. The complete Es. miyagawai mitochondrial genome A + T content is 65.3%, and full-length, pair-wise nucleotide sequence identity between the six species within the two families range from 64.2-84.6%. The Es. miyagawai sequences is most similar to Echinostoma caproni. Sequence difference are 15.0-33.5% at the nucleotide level, and 8.6-44.2% at the amino acid level, among the six species, for the 12 protein-coding genes. ATG and TAG are the most common initiation and termination codons, respectively. Twenty of the Es. miyagawai transfer RNA genes transcribe products of the conventional cloverleaf structure, while two of the transfer RNA genes, namely trnS1^(AGC) and trnS2^(UGA), have unpaired D-arms. Phylogenetic analyses using our mitochondrial data indicate that Es. miyagawai is closely related to other Echinostomatidae species, except for Echinostoma hortense, which forms a distinct paraphyletic branch, and Echinochasmus japonicus, which is outside the clade containing all other Echinostomatidae species. These phylogenetic results support the elevation of subfamily Echinostomatidae. Our dataset also provides a significant resource of molecular markers to study the taxonomy, population genetics, and systematics of the echinostomatids.

Genetic and morphological characterization of Mawsonascaris vulvolacinata n. sp. (Nematoda: Anisakidae) and associated histopathology in a wild caught cowtail stingray, Pastinachus ater

There are limited reports of infectious agents affecting Australian cowtail stingrays. In the present study, a new species of ascaridoid nematode belonging to the genus Mawsonascaris is described. The most distinct characteristic features were observed in females (the presence of a polar spine in the eggs and a flap-like projection in the vulval area). An identification key for Mawsonascaris spp. is provided. Additionally, internal transcribed spacers (ITS) sequences were obtained for the new species. Alignment of the ITS sequence of the specimens in the present study with those deposited in GenBank showed that there exists no other highly similar sequence. Phylogenetic analyses resulted in a distinct grouping of our specimens supporting morphological distinction from previously described Mawsonascaris spp. Histology was used to investigate the pathology caused by the infection. Necrosis, inflammation and fibrosis were evident at the border of the nodules formed by parasite. A large number of parasites were present in muscularis mucosae and submucosa but not in the muscularis of the stomach. The parasites were associated with an increased inflammatory response, which was also found in the muscularis mucosae and submucosa. Similar pathology has been described in elasmobranchs infected by cestodes, although with more severe lesions.

Distribution records of three species of Leucochloridium (Trematoda: Leucochloridiidae) in Japan, with comments on their microtaxonomy and ecology

Insectivorous birds serve as definitive hosts for trematodes of the genus Leucochloridium. The parasites exclusively use amber snails of the family Succineidae as intermediate hosts. A pulsating and colorful display of the larval broodsac in the snail's eyestalk seems to be a caterpillar mimic for attracting birds. A colored design of the broodsac is very useful for parasite identification. In Japan, characteristic broodsacs from amber snails have been recorded from 1980's, but their taxonomic discrimination from Asian, European, and North American species has not been achieved. In this study, old scientific records, sighting information on broodsacs from the general public, and direct molecular evidence by DNA barcoding clearly showed that at least three species of Leucochloridium are distributed in Japan. A vertical-striped broodsac found from Succinea sp. in Okinawa, the subtropical island of Japan, were treated as Leucochloridium sp., but being almost identical to that of Leucochloridium passeri in neighboring Taiwan. The European species of Leucochloridium perturbatum and Leucochloridium paradoxum were frequently detected from Succinea lauta in Hokkaido, the northernmost island of Japan. The former species was common in inland areas of Hokkaido, whereas the latter species was frequently seen in the coastal areas. A possible explanation for the parasite distribution pattern is that principal definitive hosts (migratory or resident birds) differ in each parasite. The conspecificity of Leucochloridium variae in North America and L. perturbatum in Europe and the Far East is also discussed.

Microfilariae infestation of goliath frogs (Conraua goliath) from Cameroon

The goliath frog (Conraua goliath) is endemic to Equatorial Guinea and Cameroon. It is an endangered species but little information is known about its parasites. To understand the impact of blood parasites on this species, we microscopically examined blood smears from 78 goliath frogs in February and November 2016 (dry and wet seasons) from six localities in Littoral Region of Cameroon, and we sequenced mitochondrial DNA from positive samples. Microfilariae were found in 33/78 (42.3%) goliath frogs at six locations. No other haemoparasite species was detected. Morphological characteristics of microfilariae were also described, and specimens from each frog species were similar. DNA sequencing data from the mitochondrial Cytochrome Oxidases sub unit I (COI) gene revealed a close relationship with Icosiella neglecta, a microfilaria documented in other European, Asian, and African frogs. However, sequences were sufficiently genetically distant (0.118) that they may define a new species of Icosiella. The infection burden of microfilariae varied by site, with season (65% in dry season to 23% in rainy season), and by sex, (male frogs had significantly higher parasite burdens than females (p < 0.0001)). However, this may have been confounded by size as the microfilaria intensity increased with frog weight (p < 0.0001), and males were larger than females. Microfilaria infection intensity varied from 1 to 120 per 50 μl of blood. Microfilaria induced a significant increase (p < 0.05) in the number of white blood cells (WBC) counted compared to uninfected frogs, but there was no statistically significant variation in red blood cell (RBC) count, plasma cholesterol level (p = 0.210) or plasma glucose level (p = 0.100).

PCR detection of Heterakis gallinarum in environmental samples

Heterakis gallinarum is a widely distributed cecal nematode that parasitizes gallinaceous birds including chickens and turkeys. H. gallinarum infection poses a problem for the poultry industry as the nematode egg serves as a vector for the protozoan parasite, Histomonas meleagridis, the causative agent of histomonosis. The only means of detecting H. gallinarum in the environment is microscopic identification of the eggs in soil or feces; however, H. gallinarum eggs are often mistaken for those of Ascaridia galli. Three primer sets were designed from sequences cloned from the H. gallinarum genome to develop a diagnostic PCR. Each of these primer sets amplified a single product from H. gallinarum, but were unable to amplify DNA from H. meleagridis, Ascaridia galli, or Cestode sp. H. gallinarum DNA was amplified from Lumbricus sp. (earthworms) and Alphitobius diaperinus (darkling beetles), confirming that the earthworm acts as a paratenic host for H. gallinarum and suggesting that the darkling beetle may be a carrier for this nematode.

Characterization of a non-sexual population of Strongyloides stercoralis with hybrid 18S rDNA haplotypes in Guangxi, Southern China

Strongyloidiasis is a much-neglected but sometimes fatal soil born helminthiasis. The causing agent, the small intestinal parasitic nematode Strongyloides stercoralis can reproduce sexually through the indirect/heterogonic life cycle, or asexually through the auto-infective or the direct/homogonic life cycles. Usually, among the progeny of the parasitic females both, parthenogenetic parasitic (females only) and sexual free-living (females and males) individuals, are present simultaneously. We isolated S. stercoralis from people living in a village with a high incidence of parasitic helminths, in particular liver flukes (Clonorchis sinensis) and hookworms, in the southern Chinese province Guangxi. We determined nuclear and mitochondrial DNA sequences of individual S. stercoralis isolated from this village and from close by hospitals and we compared these S. stercoralis among themselves and with selected published S. stercoralis from other geographic locations. For comparison, we also analyzed the hookworms present in the same location. We found that, compared to earlier studies of S. stercoralis populations in South East Asia, all S. stercoralis sampled in our study area were very closely related, suggesting a recent common source of infection for all patients. In contrast, the hookworms from the same location, while all belonging to the species Necator americanus, showed rather extensive genetic diversity even within host individuals. Different from earlier studies conducted in other geographic locations, almost all S. stercoralis in this study appeared heterozygous for different sequence variants of the 18S rDNA hypervariable regions (HVR) I and IV. In contrast to earlier investigations, except for three males, all S. stercoralis we isolated in this study were infective larvae, suggesting that the sampled population reproduces predominantly, if not exclusively through the clonal life cycles. Consistently, whole genome sequencing of individual worms revealed higher heterozygosity than reported earlier for likely sexual populations of S. stercoralis. Elevated heterozygosity is frequently associated with asexual clonal reproduction.

A taxonomic review and revisions of Microstomidae (Platyhelminthes: Macrostomorpha)

Microstomidae (Platyhelminthes: Macrostomorpha) diversity has been almost entirely ignored within recent years, likely due to inconsistent and often old taxonomic literature and a general rarity of sexually mature collected specimens. Herein, we reconstruct the phylogenetic relationships of the group using both previously published and new 18S and CO1 gene sequences. We present some taxonomic revisions of Microstomidae and further describe 8 new species of Microstomum based on both molecular and morphological evidence. Finally, we briefly review the morphological taxonomy of each species and provide a key to aid in future research and identification that is not dependent on reproductive morphology. Our goal is to clarify the taxonomy and facilitate future research into an otherwise very understudied group of tiny (but important) flatworms.

Outbreak of Trichinella T9 Infections Associated with Consumption of Bear Meat, Japan

An outbreak of trichinellosis occurred in Japan in December 2016. All case-patients had eaten undercooked bear meat, from which Trichinella larvae were subsequently isolated. DNA sequencing analysis of the mitochondrial genes cytochrome c-oxidase subunit 1 and internal transcribed spacer 2 confirmed that Trichinella T9 had caused the outbreak.

A New Species of Pentaloculum (Cestoda: "Tetraphyllidea") from the Taiwan Saddled Carpetshark, Cirrhoscyllium formosanum (Orectolobiformes: Parascylliidae)

Collection of cestodes from the Taiwan saddled carpetshark, Cirrhoscyllium formosanum, for the first time led to the discovery of Pentaloculum hoi n. sp. This species provided important insights into the identity of the heretofore monotypic Pentaloculum-known previously only from the blind electric ray, Typhlonarke aysoni, in New Zealand. The new species differs from Pentaloculum macrocephalum in testis number, vitelline follicle and cirrus sac configuration, and in that it is hyperapolytic rather than euapolytic. Maximum-likelihood analysis of sequence data generated for the D1-D3 region of the 28S rDNA gene not only confirmed this generic placement but also confirmed the close affinities between both species of Pentaloculum and specimens previously referred to in the literature as new genus 7 n. sp. 1. Examination of limited material of the latter, including that of a second specimen from which partial 28S rDNA sequence data were generated here, led to the realization that new genus 7 n. sp. 1 represents an undescribed species of Pentaloculum, referred to here as Pentaloculum n. sp. 2. All 3 species share bothridia divided into 1 anterior and 2 consecutive pairs of loculi. Given that Pentaloculum n. sp. 2 parasitizes a member of the second and only other genus of parascylliid sharks (i.e., Parascyllium), we predict that the 4 other species of Parascyllium and the 2 other species of Cirrhoscyllium are likely to host other species of Pentaloculum. The factors that might account for the eclectic host associations of Pentaloculum, which include a torpediniform ray and 2 species of orectilobiform sharks, are currently unclear. The compilation of diet data for these elasmobranchs and determination of the final intermediate hosts for these cestodes would be interesting avenues of further investigation given that cestodes are trophically transmitted between their intermediate and definitive hosts. The phylogenetic affinities of Pentaloculum among elasmobranch cestodes remain unresolved.

Detection of Schistosoma mansoni-derived DNA in human urine samples by loop-mediated isothermal amplification (LAMP)

BACKGROUND

Schistosoma mansoni is the main species causing hepatic and intestinal schistosomiasis in Sub-Saharan Africa, and it is the only species in South America. Adult stages of the parasite reside in the mesenteric venous plexus of infected hosts, and eggs are shed in feces. Collecting patient stool samples for S. mansoni diagnostic purposes is difficult in large-scale field trials. Urine samples would be an alternative approach for molecular S. mansoni detection since they have several advantages over stool samples, including better handling, management and storage. Additionally, loop-mediated isothermal amplification (LAMP) technology is a powerful molecular diagnostic tool for infectious diseases, particularly under field conditions in developing countries. The present study aimed to assess the effectiveness of our previously developed LAMP assay (SmMIT-LAMP) for S. mansoni-specific detection in clinical urine samples.

METHODOLOGY/PRINCIPAL FINDINGS

The sensitivity of SmMIT-LAMP in urine was established in simulated fresh human urine samples artificially spiked with genomic DNA from S. mansoni. LAMP for 120 min instead of 60 min improved the sensitivity, reaching values of 0.01 fg/μL. A set of well-defined frozen stored human urine samples collected from Sub-Saharan immigrant patients was selected from a biobank to evaluate the diagnostic validity of SmMIT-LAMP. The set included urine samples from patients with microscopy-confirmed infections with S. mansoni, S. haematobium and other nonschistosome parasites, as well as urine samples from patients with microscopy-negative eosinophilia without a confirmed diagnosis. The SmMIT-LAMP was incubated for 60 and 120 min. A longer incubation time was shown to increase the LAMP-positive results in patient urine samples. We also tested urine samples from mice experimentally infected with S. mansoni, and LAMP-positive results were obtained from the third week after infection. A real-time LAMP assay was also performed with three individual urine samples.

CONCLUSIONS/SIGNIFICANCE

The SmMIT-LAMP could effectively detect S. mansoni DNA in mouse urine samples and produced promising results for human clinical samples. The detection of S. mansoni DNA in mouse urine samples from the third week after infection indicates that early diagnosis of active S. mansoni infection is possible using urine as a source of DNA. Further studies are still needed, but our method could be used as a promising molecular tool applicable to urine samples to diagnose human intestinal schistosomiasis caused by S. mansoni.

New insight into genetic variation and haplotype diversity of Fasciola hepatica from Algeria

The liver fluke Fasciola hepatica is the main cause of fasciolosis in North Africa leading to significant economic losses and public health problems. In this study, the ribosomal internal transcribed spacer (ITS), cytochrome c oxidase I (COI), the mitochondrial region spanning the COI-trnT-rrnL, and the NADH dehydrogenase subunit I (NADI) markers were used to characterize Fasciola flukes from Algeria. Fasciola appeared widespread from the east to the west of Algeria. Among 1701 sampled cattle from 8 Algerian provinces, 5% were infected. Using morphological and morphometric analysis, one morphotype of Fasciola was observed. Nuclear ITS marker indicated that all collected flukes belong to F. hepatica. Multiple alignments of ITS dataset revealed two haplotypes, one described here for the first time. Analysis of molecular variance (AMOVA) of mitochondrial markers revealed weak population structure in Algeria. Mismatch distributions, neutrality tests, and median-joining network analysis all were compatible with a recent expansion of Algerian F. hepatica population. Fasciolosis appeared common in Algerian cattle, it seems that the absence of control strategy coupled to the favorable Mediterranean climate may lead to a reconstruction and dispersion of its populations. This study provides important results concerning the genetic characterization and variability of F. hepatica in Algeria as well as the significant role of cattle importation in shaping its dispersal route worldwide.

Developing a One-Step Multiplex PCR Assay for Rapid Detection of Four Stubby-Root Nematode Species, Paratrichodorus allius, P. minor, P. porosus, and Trichodorus obtusus

Four trichodorid species, Paratrichodorus allius, P. minor, P. porosus, and Trichodorus obtusus, were found in multiple states in the United States. Traditional diagnosis based on morphology and morphometrics is laborious and requires an experienced taxonomist. Additionally, end-point diagnosis using PCR was only available for P. allius. To increase diagnostic efficiency and reduce costs, a one-step multiplex PCR assay was developed to simultaneously identify these four species using one PCR reaction. Available sequences of 18S ribosomal DNA and internal transcribed spacer 1 (ITS1) region of these species were aligned and five primers were designed. The conserved forward primer located in the 18S region, in combination with the species-specific antisense primer in the ITS1 region, amplified a single distinctive PCR fragment for each species (421/425 bp for P. allius, 190 bp for P. minor, 513 bp for P. porosus, and 353 bp for T. obtusus). In silico analysis with 10 other trichodorid species and experimental analysis using samples with these four species, 20 other plant-parasitic and three non-plant-parasitic nematodes demonstrated high specificity with the primers designed. The multiplex PCR amplified desirable fragments using a set of artificially mixed templates containing one, two, three, or four targeted species. The reliability of multiplex PCR results was demonstrated by using nematode populations isolated from infested fields from diverse geographic regions in eight states. The multiplex PCR-based tool developed in this study for the first time provides a simple, rapid, and cost-friendly assay for accurate diagnosis of the four major trichodorid nematodes in the United States.

Molecular characterization and phylogenetic analysis of Taenia multiceps from China

Taenia multiceps, one of the most widely distributed zoonotic tapeworm parasites, is able to parasitize the small intestine of canids. The metacestode of T.multiceps is fatal to ruminants and causes important economic losses in livestock. However, molecular characteristics of T.multiceps and coenurus in China are still unclear. In this study, 36 goat isolates of the coenurus stage and 18 dog isolates of the adult stage of T.multiceps were obtained from three geographical areas in China and the isolated parasite above were analyzed by amplifying the partial of cytochrome coxidase subunit 1(pcox1), 12S ribosomal RNA (12S rRNA) from mitochondrial DNA (mtDNA) regions and an internal transcribed spacer (ITS) of ribosomal DNA (rDNA). These DNA sequences obtained from T.multiceps and coenurus were employed to evaluate the nucleotide diversity and confirm the relationship between T.multiceps and coenurus. Sequences variation were 0-1.4%, 0-1.5%, 0-4.2% for pcox1, 12S rRNA and ITS, respectively, among T.multiceps and coenurus isolates obtained in this study. In Sichuan province, sequence variations for Coenurus cerebralis isolated from Yaan city were 0-1.4% for pcox1, 0-1.0% for 12S rRNA and 0-2.1% for ITS. In Hunan province, variations were 0-1.0%, 0-1.5% and 0-3.3% for corresponding genes for non-coenurus cerebralis isolated from Changsha city, while variations of T.multiceps isolates from Xiangxi autonomous prefecture were 0-1.0%, 0-1.1% and 0-3.4% for pcox1, 12S rRNA and ITS, respectively. Phylogenetic analysis based on pcox1 sequences indicated that all cerebral and noncerebral metacestodes belong to T.multiceps. These results provide reference values for future molecular epidemiological and biological study on T.multiceps in dogs and intermediate hosts.

Clinical validation of molecular markers of macrocyclic lactone resistance in Dirofilaria immitis

Prophylaxis with macrocyclic lactone (ML) endectocides is the primary strategy for heartworm control. Recent evidence has confirmed that ML-resistant Dirofilaria immitis isolates have evolved. Comparison of genomes of ML-resistant isolates show they are genetically distinct from wild-type populations. Previously, we identified single nucleotide polymorphisms (SNPs) that are correlated with phenotypic ML resistance. Since reliable in vitro assays are not available to detect ML resistance in L3 or microfilarial stages, the failure to reduce microfilaraemia in infected dogs treated with an ML has been proposed as a surrogate clinical assay for this purpose. The goal of our study was to validate the genotype-phenotype correlation between SNPs associated with ML resistance and failure to reduce microfilaraemia following ML treatment and to identify a minimal number of SNPs that could be used to confirm ML resistance. In this study, 29 participating veterinary clinics received a total of 148 kits containing supplies for blood collection, dosing and prepaid shipping. Patients recruited after a diagnosis of heartworm infection were treated with a single standard dose of Advantage Multi® and a blood sample taken pre- and approximately 2-4 weeks post-treatment. Each sample was processed by performing a modified Knott's Test followed by isolation of microfilariae, genomic DNA extraction and MiSeq sequencing of regions encompassing 10 SNP sites highly correlated with ML resistance. We observed significant correlation of SNP loci frequencies with the ML microfilaricidal response phenotype. Although all predictive SNP combination models performed well, a 2-SNP model was superior to other models tested. The predictive ability of these markers for ML-resistant heartworms should be further evaluated in clinical and epidemiological contexts.

A study of the impact of DNA helical rise on protein-DNA interaction

Nucleosomes are not uniformly distributed along DNA and their positioning (termed "nucleosomal landscape") can be derived using data available for several genomes. In this study we analyzed DNA helical rise profiles through a tetranucleotide code, and we defined the nucleosomal landscape of several sequences forming dinucleosomes and of the sequences of huntingtin, myotonic dystrophy type 1 and fragile mental retardation 2 genes, which contained several repeated sequences. We also analyzed the profiles of some sequences interacting with transcription factors or with RNA polymerase II. In the genomes of Cenorhabditis elegans, Mus musculus and Homo sapiens we found profiles with extremely low helical rise values, characteristic of nucleosome free regions. We defined these regions as "holes" and found that their presence correlates with lamina associated domains sequences. Altogether, this study shows that DNA helical rise profile may have a role in gene expression modulation and in shaping chromosomal structure.