The ruddy turnstone, Arenaria interpres interpres, a new definitive host for Gynaecotyla squatarolae (Digenea: Microphallidae)

The ruddy turnstone, Arenaria interpres interpres, a migratory Korean bird, was proved to be a natural definitive host for Gynaecotyla squatarolae (Digenea: Microphallidae). The ruddy turnstone was found dead at the seashore of Okgueup, Gunsan-si, Jeollabuk-do. The intestinal tract was examined, and 98 unknown flukes were recovered. The worms were 600 284 micrometer in size, and had 2 ventral suckers. The seminal vesicle was large, the genital atrium was prominent, and the average egg size was 20 12.5 micrometer. Based on these results, the worms were identified as G. squatarolae. This is the first report on the ruddy turnstone as a natural definitive host of G. squatarolae in the Republic of Korea.     

Gymnophallid digenean Parvatrema duboisi uses Manila clam as the first and second intermediate host

To identify the metacercariae of a gymnophallid trematode in the Manila clam Ruditapes philippinarum from the Ariake Sea, experimental infection and molecular analysis were conducted. Based on the morphology of adult worms obtained from experimentally infected mice, the parasite was identified as Parvatrema duboisi. Comparison of internal transcribed spacer (ITS) region of ribosomal DNA (rDNA) sequences for metacercariae and sporocysts from Manila clams and adult worms collected from wild wigeon Anas penelope showed minor differences ranging from 0 to 0.8%. These data strongly suggest that in the Ariake Sea, the parasite has a lifecycle using the Manila clam as the first and second intermediate hosts and wigeon as the definitive host.     

Gynaecotyla squatarolae (Digenea: Microphallidae) from rats experimentally infected with metacercariae from the shore crab, Macrophthalmus dilatatus

Metacercariae of Gynaecotyla squatarolae (Digenea: Microphallidae) were discovered from the shore crab, Macrophthalmus dilatatus, purchased at a market in a coastal town of Taean-Eup, Chungcheongnam-do, Republic of Korea. Their adult flukes were confirmed by experimental infection of rats. The metacercariae of G. squatarolae were elliptical (391.1 x 362.5 micrometer), and the excysted metacercariae had progenetic genital organs, including the ovary and testes. To obtain adult flukes, 6 Sprague-Dawley rats were fed 500 metacercariae each, and killed at days 2, 4, and 6 post-infection. The adult flukes were identified as G. squatarolae (Yamaguti, 1934) Yamaguti, 1939, based on morphological characters, including 2 ventral suckers (1 large and 1 small), a large genital atrium equipped with the cirrus and the metraterm, separated male and female genital pores, a transversely long cirrus pouch, and extensive vitelline follicles. In the present study, it has been first proven that the shore crab M. dilatatus is a second intermediate host for G. squatarolae in the Republic of Korea.     

Concomitant and protective immunity in mice exposed to repeated infections with Echinostoma malayanum

Concomitant immunity and its consequence against infection play roles in regulating worm burdens in helminthiasis. Under natural conditions, this immunity is generated by exposure to repeated low dose or trickle infection. In this study, concomitant immunity was induced in mice exposed repeatedly to infection with Echinostoma malayanum and its protective effect on a challenge infection evaluated. A profile of worm burden from exposure to 10 metacercariae/mouse/week rose rapidly during the first 2 weeks reaching a plateau from week 3 to 8 post infection. Based on a cumulative dose of infection, worm recoveries were around 75% in the first 2 weeks, dropped to 50% at week 3 and 19% at week 8. After week 2, adult worm burden was constant and no juvenile worms were found after week 3 of the experiment. To examine the effect of resistance against reinfection, mice in the experimental group were primarily infected with 10 metacercariae/week for 5 weeks, treated with praziquantel and were challenged with 75 metacercariae/animal. The number of worms recovered from the experimental groups was significantly lower than that from naïve control groups beginning from 24 h to 28 days post challenge. The worms in the experimental group showed growth retardation and the proportion of adult worms was lower than that in the control animals especially during the first 3 weeks of the experiment. Parasite fecundity was also suppressed compared with that in the control group. The selective effects of protective immunity on establishment, growth, and fecundity of challenged worms affected the population dynamics of E. malayanum which is a similar phenomenon to concomitant immunity in schistosomiasis.     

Discovery of Maritrema obstipum (Digenea: Microphallidae) from migratory birds in Korea

Adults of Maritrema obstipum (Digenea: Microphallidae) were found in the intestines of 4 species of migratory birds, including the sanderling (Crocethia alba), Kentish plover (Charadrius alexandrines), Mongolian plover (Charadrius mongolus), and red-necked stint (Calidris ruficollis), collected from Yubu Island, Chungcheongnam-do, Korea. The worms of were 451 × 265 μm in size, and were easily identifiable as Maritrema species by the presence of the cirrus sac, and the ring-like distribution of the vitellaria. More specifically, the ejaculatory duct curved posteromedially, and the 2 parts of vitelline follicles were found to be distinct at the posterior end. The eggs were brown-colored, and 19.8 × 12.3 μm in size. All these findings implicated M. obstipum as the pertinent species of the worms. Beside these, adult worms of Gynaecotyla squatarolae, Parvatrema duboisi, and Acanthoparyphium sp. were also discovered. This is the first report establishing migratory birds as the natural definitive hosts for M. obstipum.     

Human infections of fish-borne trematodes in Vietnam: prevalence and molecular specific identification at an endemic commune in Nam Dinh province

The prevalence of fish-borne trematodes in humans and their molecular identification was investigated in the Rang Dong commune of Nam Dinh province, Vietnam, between January 2009 and December 2010. A total of 405 people in this commune were interviewed on the habit of eating raw fish and all of their stool samples were collected using the Kato-Katz technique for examination of the presence of fish-borne trematodes. The worms (and eggs) were first morphologically examined, counted, described and identified, then the representative isolates were subjected for molecular species confirmation. A total of 385 adult flukes collected from 10 patients were morphologically identified to species and defined as Clonorchis sinensis (14.58%) in Opisthorchiidae family, Haplorchis taichui (32.29%), Haplorchis pumilio (52.08%) and Centrocestus formosanus (1.04%) in Heterophyidae family. A high rate (77.8%) of the interviewees was found to have the habit of eating raw fish. This habit was attributed to the high infection rate of fish-borne trematode in humans (22.72%; OR = 2.486). The infection rate of fish-borne trematodes in males was higher (29.3%) than that in females (16.0%) and increased by age, reaching the highest in the patients aged 40–59 years (28.2–28.7%). The infection intensity of fish-borne trematode was found light (336 EPG). Adult flukes were collected from a group of the patients with the highest intensity of infection and subjected to molecular and phylogenetic analysis using a portion (326 bp) of mitochondrial cox1. Phylogenetic tree inferred from cox1 sequences using sequence data for 34 isolates of opisthorchid, heterophyid, fasciolid, paragonimid, schistosomid trematodes and taeniid cestodes revealed that they are distinct groups. The newly collected with the known clonorchid and heterophyid isolates form the well defined taxonomic groups, respectively, confirming that C. sinensis and Haplorchis spp. (H. pumilio and H. taichui) were among the collected samples.     

Multiple near-identical genotypes of Schistosoma japonicum can occur in snails and have implications for population-genetic analyses

We genotyped (using 16 or 17 microsatellite loci) numerous adult Schistosoma japonicum raised in rabbits exposed to pooled cercariae from small numbers of naturally infected snails from several localities in China. As expected, duplicate multi-locus genotypes (MLGs) were found among these worms. Additionally, many more MLGs, often near-identical, were found than snails used as sources of cercariae. Explanations for these results include (i) genotyping errors, (ii) development within each infected snail of multiple sibling miracidia and (iii) somatic mutation producing genetically varied cercariae from a single miracidium. To control for genotyping errors we re-analysed samples from many individual worms, including repeating the initial PCR. Explanations invoking the development of multiple sibling miracidia within a single snail are not likely to be correct because almost all duplicate MLGs fell within same-sex clusters in a principal coordinates analysis. We would expect both sexes to be represented in a multi-miracidium infection. In addition, we exposed several snails to infection by a single miracidium. One such snail, via an experimentally infected mouse, yielded 48 adult worms. The presence of at least nine near-identical MLGs among these worms was confirmed by re-genotyping. We regard somatic mutation as the most likely explanation for our results. The implications of multiple MLGs for population-genetic studies in S. japonicum are discussed.     

Dioctophyme renale (Nematoda: Dioctophymatoidea) in the abdominal cavity of Rattus norvegicus in Japan

We collected 24 brown rats, Rattus norvegicus, in Kanagawa Prefecture in Japan and found one rat harboring a dioctophymatid nematode. A single male and a female worm were recovered from the abdominal cavity and were identified as Dioctophyme renale based on morphologic features and a BLAST DNA sequence analysis. We describe the morphological features of the adult worms and eggs from this extremely rare case of D. renale infection in a brown rat.     

Studies with Brugia pahangi. I. Parasitological observations on primary infections of cats (Felis catus)

The large majority of cats given a single inoculation of third stage larvae of Brugia pahangi became microfilaraemic. Some cats had microfilariae in their blood 53 or 54 days after infection and most had become positive before 72 days after infection. In the majority of cats microfilarial counts remained very steady between 2 and 10 microfilariae per mm³ for long periods. At autopsy 10·7% of the infective larvae injected were recovered as adult worms. The recovery of adult worms was directly related to the number of larvae injected. The microfilarial level did not increase significantly with an increase in the number of adult worms.     

Spontaneous worm expulsion and intestinal IgA response in mice infected by Vampirolepis nana

The expulsion of the gastrointestinal parasite Vampirolepis nana was examined in different mouse strains and in immunosuppressed mice infected to different degrees with eggs and cysticercoids. To investigate the immunological mechanism that regulates expulsion, surface-bound mouse immunoglobulins were examined on adult worms. The time to spontaneous expulsion of worms was dependent on strain (C57BL, BDF(1), B6C3F(1)相似文献   

Tegumental ultrastructure of adult Gynaecotyla squatarolae (Digenea: Microphallidae)

Gynaecotyla squatarolae (Digenea: Microphallidae) adult flukes were recovered from experimental chicks at day 4-6 post-infection and their tegumental ultrastructure was observed with a scanning electron microscopy. They were pyriform in shape, and their anterior halves were concaved ventrally. The whole body surface was covered with tegumental spines, which were wide and 16-17 digitated between oral and ventral suckers. The density of spines and number of digits decreased posteriorly. The oral sucker was subterminal and the excretory pore was at the posterior end of the worm. Two ventral suckers were similar in appearance and protruded near midline of the worm. The genital atrium was dextral to the small ventral sucker. The dorsal surface was covered with tegumental spines, but the spines were sparser than on the ventral surface. On the middle portion of the dorsal surface, a small opening presumed to be the Laurer's canal was seen. From these findings, it has been confirmed that the adult G. squatarolae has unique characteristics in the surface ultrastructure.     

Development of the reproductive system of Echinostoma paraensei in Mesocricetus auratus analyzed by light and confocal scanning laser microscopy

This study was performed to gain insight into the maturation of the reproductive system of Echinostoma paraensei worms grown in an early infection of Mesocricetus auratus. Hamsters were infected with 100 metacercariae and necropsied on days 3, 5, 7, 10 and 14 post infection (dpi). Recovered flukes stained with hydrochloric carmine were preserved as whole mounts and analyzed by light and confocal scanning laser microscopy. The average worm recovery was 43.7 per host. Images of the male and female reproductive systems were taken. The ovary and anterior and posterior testis were evidenced on day 3, while the ootype and cirrus sac were present on day 5. Confocal imaging showed primordium testis and ovary as a cluster of primordial cells from day 3 onward. The testes, ovary, cirrus sac and uterus organs were already present during the first week of life. The two testes were seen as individual structures on 7 dpi while the cirrus sac and vitelline glands were in development. The ovary was connected to the uterus while the ootype was adjacent to it. Both testes were larger than the ovary, showing cells at different stages of development, but with few bundles of functional spermatozoa in 10 day-old worms. On day 14, eggs and spermatozoa were seen in the uterus and seminal vesicle, respectively, while oocytes appeared in the ootype as fertilized eggs. We conclude that the reproductive system of E. paraensei was functional on 14 dpi in the hamsters.     

An imported human case of hookworm infection with worms in the rectum]

An imported case of rectal hookworm infection was diagnosed by stool examination and recovery of adult worms from the rectal mucosa by sigmoidoscopy. The chief complaints of a patient were diarrhea, abdominal pain and weight loss for about 1 month after returning from his travel abroad to the Southeast Asia. Leukocytosis(16,750/microliters) and peripheral eosinophilia(33.7%) were noticed without anemia. Typical hookworm eggs were detected by stool examination, and 3 worms were collected by sigmoidoscopy from rectal mucosa of this patient. Those worms were confirmed as adult worms of Ancylostoma duodenale(male:1, female:2) based on their morphological characteristics. The symptoms were relieved after treatment with anthelmintics. This case was considered as one of the imported parasitic infections in Korea, and a rare case of hookworm infection on human rectal mucosa.     

Formation of <Emphasis Type="Italic">Yersinia pseudotuberculosis</Emphasis> biofilms on multiple surfaces on <Emphasis Type="Italic">Caenorhabditis elegans</Emphasis>

Summary A liquid-based assay was used to evaluate the ability of Yersinia pseudotuberculosis to form a bacterial biofilm on the nematode Caenorhabditis elegans. After 3 days of incubation in the liquid assay a biofilm was clearly visible by light microscopy on both the head and vulva region of the worms. At times, the biofilm formation on the vulva appeared to prevent the laying of eggs by the adult hermaphrodite; the eggs would later hatch inside of the worm. One possible explanation for the biofilm formation observed on the vulva may be the increased motion of the cuticle surrounding the vulva when the worm is immersed in a liquid culture. This is the first report of biofilm formation on the vulva of C. elegans.     

Molecular characterization of Echinococcus isolates indicates goats as reservoir for Echinococcus canadensis G6 genotype in Neuquén, Patagonia Argentina

Human cystic echinococcosis is a highly endemic zoonotic disease in the province of Neuquén, Patagonia Argentina, although a hydatid control programme has been carried out since 1970. Human infection due to Echinococcus canadensis (G6 genotype) is frequent in Neuquén. However, the reservoir for this species remains undetermined in a region where camels are absent. We investigated the fertility, viability and molecular epidemiology of hydatid cysts obtained from local goats, pigs and sheep in order to identify the possible reservoirs of E. canadensis (G6). We also analyzed isolates from infected dogs. A total of 67 isolates were identified by the DNA sequencing of the mitochondrial cytochrome c oxidase subunit 1 gene. Cysts from sheep (n = 16), goats (n = 23) and pigs (n = 18) and adult worms from 10 infected dogs were analyzed. The fertility of the hydatid cysts was 78.6%; 90.4% and 94.4% for sheep, goats and pigs, respectively. We detected E. canadensis (G6) in 21 of 23 goat samples and in 1 dog isolate, E. canadensis (G7) in all the pig isolates, E. granulosus sensu stricto (G3) in 1 sheep and the G1 genotype in 15 sheep, 2 goats and 9 dog samples. The G1 haplotypes included the common sheep strain sequence and 2 microvariants of this sequence. E. granulosus sensu stricto (G3) is described for the first time in South America. We conclude that goats act as reservoir for E. canadensis (G6) in Neuquén, and that control strategies may have to be adapted to local molecular epidemiology to improve the control of parasite transmission.     

RNA interference targeting cathepsin B of the carcinogenic liver fluke, Opisthorchis viverrini

Functional genomics have not been reported for Opisthorchis viverrini or the related fish-borne fluke, Clonorchis sinensis. Here we describe the introduction by square wave electroporation of Cy3-labeled small RNA into adult O. viverrini worms. Adult flukes were subjected to square wave electroporation employing a single pulse for 20 ms of 125 V in the presence of 50 μg/ml of Cy3-siRNA. The parasites tolerated this manipulation and, at 24 and 48 h after electroporation, fluorescence from the Cy3-siRNA was evident throughout the parenchyma of the worms, with strong fluorescence evident in the guts and reproductive organs of the adult worms. Second, other worms were treated using the same electroporation settings with double stranded RNA targeting an endogenous papain-like cysteine protease, cathepsin B. This manipulation resulted in a significant reduction in specific mRNA levels encoding cathepsin B, and a significant reduction in cathepsin B activity against the diagnostic peptide, Z-Arg-Arg-AMC. This appears to be the first report of introduction of reporter genes into O. viverrini and the first report of experimental RNA interference (RNAi) in this fluke. The findings indicated the presence of an intact RNAi pathway in these parasites which, in turn, provides an opportunity to probe gene functions in this neglected tropical disease pathogen.     

Survey for zoonotic liver and intestinal trematode metacercariae in cultured and wild fish in An Giang Province, Vietnam

Although Vietnam has a high risk of fishborne zoonotic trematode (FZT) infections for humans, little information exists on the epidemiology of these infections in the country's fish. Because of the importance of cultured catfish and snakehead production in An Giang province, a major production area in the Mekong Delta of Vietnam, a survey for FZTs was carried out in randomly selected fish farms between June 2005 and March 2006. For comparison, wild fish from the same area were also surveyed. A total of 852 cultured fish from 4 districts were collected and examined by pepsin digestion to determine their FZT infection status. In Tra catfish, the prevalence of all types of metacercariae was 2.6%, of which the prevalence of Haplorchis pumilio was 0.7%. The overall prevalence of metacercariae in wild fish was 30.6%, of which 10.3% harbored zoonotic species: H. pumilio (2.8%) and Procerovum sp. (5.6%). The prevalence of Opisthorchis metacercariae, which were diagnosed as O. viverrini, was 1.9%. No metacercariae were found in cultured snakehead fish, although wild-caught snakehead fish had a FZT prevalence of 10.3%: 5.1% were O. viverrini 2.6% H. pumilio and 2.6% were Procerovum sp. These are the first reports of H. pumilio, Procerovum sp., and O. viverrini metacercariae in Vietnamese fish. These results indicate that consumption of improperly prepared fish represents a significant risk of acquiring FZTs in this south Vietnam region.     

Isolation of Onchocerca gibsoni tissue from frozen nodules for biochemical use

A new procedure is described which enables gram quantities of adult Onchocerca tissue to be isolated from frozen connective tissue nodules, thus minimizing the risk of enzymatic degradation. Bovine connective tissue nodules containing adult Onchocerca gibsoni worms were obtained from Australia frozen at −70°C and sectioned while still frozen into 3 mm thick slabs. The sections were thawed immediately before use, worm segments removed, rinsed, pelleted, and flash frozen in liquid nitrogen. Quality of the isolated material was demonstrated by the presence of an intact adult epicuticle as determined by electron microscopy, and by the presence of viable uterine larvae and cells. This procedure is applicable to other nodule-forming worms such as Onchocerca volvulus and is suitable for investigations which require the isolation of labile molecules or those present in minute quantities.     

Schistosoma mansoni: In vitro schistosomicidal activity of piplartine

Schistosomiasis is one of the world’s greatly neglected tropical diseases, and its control is largely dependent on a single drug, praziquantel. Here, we report the in vitro effect of piplartine, an amide isolated from Piper tuberculatum (Piperaceae), on Schistosoma mansoni adult worms. A piplartine concentration of 15.8 μM reduced the motor activity of worms and caused their death within 24 h in a RPMI 1640 medium. Similarly, the highest sub-lethal concentration of piplartine (6.3 μM) caused a 75% reduction in egg production in spite of coupling. Additionally, piplartine induced morphological changes on the tegument, and a quantitative analysis carried out by confocal microscopy revealed an extensive tegumental destruction and damage in the tubercles. This damage was dose-dependent in the range of 15.8–630.2 μM. At doses higher than 157.6 μM, piplartine induced morphological changes in the oral and ventral sucker regions of the worms. It is the first time that the schistosomicidal activity has been reported for piplartine.