Morphology Of Adult Worms Research Articles

Morphological and Molecular Characterization of Paragonimus skrjabini Complex from Yunnan, China: A Brief Report

PurposeTo perform environmental sampling and molecular identification of Paragonimus in endemic regions, which may help in minimizing transmission among humans.MethodsMountain crabs from the genus Potamiscus were collected and the encysted metacercariae were extracted and subjected to morphological identification, followed by animal inoculation in Sprague–Dawley (SD) rats. After 112 days of infection, animals were killed and adult worms were extracted from lungs and muscles. The morphology of adult worms was characterized by microscopy and molecular identification was done by polymerase chain reaction, followed by sequencing of cox1 and ITS2 genes. Phylogenetic analysis was done by maximum parsimony method.ResultsA total of 447 crabs were captured from the streams of Tongchang Town, Jinping County, Yunnan Province, China. The infection rate was found to be 41% (186 out of 447 crabs). The metacercariae of Paragonimus skrjabini was identified by the characteristics round or spherical encysted form measuring 410 to 460 × 400 to 460 µm. After animal infection in SD rats, adults were presumptively confirmed to be P. skrjabini, which was also confirmed by gene amplification and sequence analysis of cox1 and ITS2 regions. Paragonimus skrjabini clustered with previously reported P. skrjabini from Yunnan and Vietnam. The confidence values of their branches were > 95%. Phylogenetic analysis of the ITS2 region revealed two distinct clusters with distinct geographical grouping. Phylogenetic analysis with the combined data sets reiterated the geographical grouping with P. skrjabini from Yunnan clustering with strains from Vietnam.ConclusionMetacercariae of P. skrjabini was discovered in freshwater crabs in Yunnan province, China, and the strains were phylogenetically related to P. skrjabini from Vietnam.

Invalidation of Diphyllobothrium hottai (Cestoda: Diphyllobothriidae) based on morphological and molecular phylogenetic analyses

Diphyllobothrium hottai Yazaki, Fukumoto & Abe, 1988 was described based on the morphology of adult worms recovered from golden hamsters that had been experimentally infected with plerocercoids obtained from Japanese surf smelts (Hypomesus pretiosus japonicus) and olive rainbow smelts (Osmerus eperlanus mordax). Although D. hottai was considered to be distinct from Diphyllobothrium ditremum (Creplin, 1825), their taxonomic relationship requires further clarification. In our study, D. hottai and D. ditremum obtained from hamsters experimentally infected with plerocercoids isolated from Japanese surf smelts were compared using morphological and molecular methods. The criterion usually used to differentiate between D. hottai and D. ditremum is the difference in the angle between the long axis of the cirrus sac and that of the seminal vesicle. However, we found variation of the angle within the same individual and, one specimen showed both of the different angles that were supposedly unique to each of the species. Furthermore, phylogenetic analysis of the complete sequences of the mitochondrial cytochrome c oxidase subunit 1 and cytochrome b genes revealed that both species were genetically indistinguishable. Therefore, D. hottai is considered to be a junior synonym of D. ditremum.

PARAGONIMUS KERBERTI N.SP. (DIGENEA, PARAGONIMIDAE), PARASITE OF CARNIVORES IN CAMEROON

Paragonimus kerberti n.sp. (hitherto undescribed) is reported from the lungs of artificially infected cat (Felis catus Linnaeus, 1758) from Cameroon. Its description is based on the morphology of adult worms but also, on the dimension of fresh, living eggs released from experimentally infected cats (in the metraterm of mature worms, or laid by living worm), length of prepatent period and duration of eggs incubation.

PARAGONIMUS GONDWANENSIS N. SP. (DIGENEA, PARAGONIMIDAE), PARASITE OF MAMMALS (HUMANS AND CARNIVORES) IN CAMEROON

Paragonimus gondwanensis n. sp. (hitherto undescribed) is reported from the lungs of naturally infected cat (Felis catus Linnaeus, 1758) and civet [Civettictis civetta (Schreber, 1776)] from Cameroon. Its description is based on the morphology of adult worms but also, on the dimension of fresh, living eggs released from naturally and experimentally infected cats and hospitalized patients (in the metraterm of worms, emitted in the beginning of prepatent period and laid by living worm), length of prepatent period and duration of eggs incubation. The presence of this species in human patients is confirmed

Molecular Characterization of a Tetraspanin from the Human Liver Fluke, Opisthorchis viverrini

BackgroundThe human liver fluke, Opisthorchis viverrini, is designated as a group 1 carcinogen, and is the major risk factor for cholangiocarcinoma in endemic countries throughout Southeast Asia. Proteins in the excretory-secretory products and tegumental surface membranes of the fluke have been proposed to play pivotal roles in parasite survival in the host, and subsequent pathogenesis. These macromolecules are therefore valid targets for the development of vaccines and new drugs to control the infection. Tetraspanins (TSP) are prominent components of the tegument of blood flukes where they are essential for tegument formation, are directly exposed to the immune system, and are major targets for a schistosomiasis vaccine. We propose that similar molecules in the surface membranes of O. viverrini are integral to tegument biogenesis and will be efficacious vaccine antigens.Methodology/Principal FindingsThe cDNA sequence encoding O. viverrini tetraspanin-1 (Ov-TSP-1) was identified and cloned. The Ov-tsp-1gene was isolated from a cDNA library. Ov-tsp-1 mRNA was expressed most highly in metacercariae and eggs, and to a lesser extent in juvenile and adult worms. Immunolocalization with adult flukes confirmed that Ov-TSP-1 was expressed in the tegument and eggs in utero. Western blot analysis of rOv-TSP-1 probed with sera from O. viverrini-infected humans and hamsters indicated that both hosts raise antibody responses against the native TSP. Using RNA interference we silenced the expression level of Ov-tsp-1 mRNA in adult flukes by up to 72% by 10 days after delivery of dsRNA. Ultrastructural morphology of adult worms treated with Ov-tsp-1 dsRNA displayed a distinctly vacuolated and thinner tegument compared with controls.Conclusions/SignificanceThis is the first report of a tetraspanin from the tegument of a liver fluke. Our data imply that tetraspanins play important structural roles in the development of the tegument in the adult fluke. Potential uses of O. viverrini tetraspanins as novel interventions are discussed.

Assessment of Akodon cursor (Rodentia, Sigmodontinae) as permissive host to Schistosoma mansoni infection: morphology of adult worms

AbstractThe natural infection with parasitic helminths is common in wild rodent populations. Once such interactions are better understood in the laboratory, it will be more feasible to extend the findings to infected hosts in nature. The flukes recovered from laboratory-infected Akodon cursor at 63 days post-infection were stained with hydrochloric carmine and individually mounted on glass slide as whole-mounts. Light and laser scanning confocal microscopy studies of adult male and female Schistosoma mansoni are reported. The parasites were examined morphologically and biometrically, which was obtained in a digital system for image analysis. Parameters used were: tegument thickness, digestive, excretory and reproductive systems. The overall conclusion of this experiment is that the morphological features of adult worm were similar to laboratory mice. It has been confirmed that the grass mouse is a permissive host to S. mansoni infection.

Morphological and molecular characterization of Paragonimus westermani in northeastern India

Evidence for the presence of lung flukes of the Paragonimus westermani in India remains scant. In particular, evidence based on morphology of adult worms is lacking. Metacercariae of the genus Paragonimus, recovered from crabs in two regions of northeastern India, were raised to adulthood in laboratory rats. Morphologically, these worms appear to be P. westermani. DNA sequences from the second internal transcribed spacer (ITS2) and a portion of the ribosomal large subunit gene (28S) of the nuclear ribosomal RNA gene repeat, as well as fragments of the mitochondrial cytochrome c oxidase subunit 1 ( cox1) and NADH dehydrogenase subunit 1 ( nad1) genes, all supported this identification. Molecular phylogenetic methods were used for studying the relatedness of these Indian flukes with counterparts from southeast and far-east Asia. Molecular data showed that Indian representatives of the P. westermani complex represent a distinct lineage. It is unclear whether the Indian form can cause disease in humans as some members of the complex do elsewhere.

Suppression of mRNAs Encoding Tegument Tetraspanins from Schistosoma mansoni Results in Impaired Tegument Turnover

Schistosomes express a family of integral membrane proteins, called tetraspanins (TSPs), in the outer surface membranes of the tegument. Two of these tetraspanins, Sm-TSP-1 and Sm-TSP-2, confer protection as vaccines in mice, and individuals who are naturally resistant to S. mansoni infection mount a strong IgG response to Sm-TSP-2. To determine their functions in the tegument of S. mansoni we used RNA interference to silence expression of Sm-tsp-1 and Sm-tsp-2 mRNAs. Soaking of parasites in Sm-tsp dsRNAs resulted in 61% (p = 0.009) and 74% (p = 0.009) reductions in Sm-tsp-1 and Sm-tsp-2 transcription levels, respectively, in adult worms, and 67%–75% (p = 0.011) and 69%–89% (p = 0.004) reductions in Sm-tsp-1 and Sm-tsp-2 transcription levels, respectively, in schistosomula compared to worms treated with irrelevant control (luciferase) dsRNA. Ultrastructural morphology of adult worms treated in vitro with Sm-tsp-2 dsRNA displayed a distinctly vacuolated and thinner tegument compared with controls. Schistosomula exposed in vitro to Sm-tsp-2 dsRNA had a significantly thinner and more vacuolated tegument, and morphology consistent with a failure of tegumentary invaginations to close. Injection of mice with schistosomula that had been electroporated with Sm-tsp-1 and Sm-tsp-2 dsRNAs resulted in 61% (p = 0.005) and 83% (p = 0.002) reductions in the numbers of parasites recovered from the mesenteries four weeks later when compared to dsRNA-treated controls. These results imply that tetraspanins play important structural roles impacting tegument development, maturation or stability.

Lymphatic dwelling filarioid nematodes in reindeerRangifer tarandus tarandus, (Cervidae) in Finland, identified asRumenfilaria andersoniLankester & Snider, 1982 (Nematoda: Onchocercidae: Splendidofilariinae)

A filarioid nematode inhabiting the lymphatic vessels of the subserosal rumen and mesenteries associated with a high prevalence of its microfilariae in peripheral blood was observed in Finnish reindeer (Rangifer tarandus tarandus) in 2004 and 2006. Adult specimens were collected by dissecting lymphatic vessels from slaughtered animals, where some of the nematodes were seen through the wall of the dilated vessels as thin white winding threads obscuring the vessel. The morphology of adult worms and microfilaria is described based on light and scanning electron microscopy. These filariae belong to the subfamily Splendidofilariinae of the Onchocercidae and resemble Rumenfilaria andersoni, recovered from different host and localization, the ruminal veins of Alces alces in Canada. Comparison of paratypes of this species revealed only minor differences which were not sufficient to separate the filarioid parasitic in R. tarandus in Finland and we identify the nematode as R. andersoni. However, the findings suggest two different parasite populations. The finalizing of this taxonomic question in the future requires an integrated approach, in which the DNA-based and morphological identifications are consistent.

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.

Parasitological and morphological characteristics of Brazilian strains of Schistosoma mansoni in Mus musculus

Aiming to determine parasitological and morphological differences between Brazilian strains (CMO, CM and BE) of Schistosoma mansoni the following parameters were studied: prepatent period, kinetics of egg releasing in feces, intestinal oogram, infectivity and the morphology of adult worms. No statistical difference (p>0.05) was found regarding the mean prepatent period (44 and 46 days) and infectivity (26% and 29%). All strains showed a higher concentration of trapped eggs in the small intestine than large intestine (p<0.05). All characteristics of the reproductive system and suckers of male worms presented significant differences (p<0.05). CMO strain was smaller in all measurements. Females showed significant differences (p<0.05) in the larger diameter of the eggs, in the area and perimeter of the spine egg and in the oral sucker area. We conclude that differences in strains can be expressed even when the strains have been cycled for several generations under laboratory conditions.

Thelazia lacrymalis (Nematoda, Spirurida, Thelaziidae): report in a horse in Germany and contribution to the morphology of adult worms.

Thelazia lacrymalis (Nematoda, Spirurida, Thelaziidae): report in a horse in Germany and contribution to the morphology of adult worms.

Variations in egg size of Trichuris trichiura.

In patients infected with Trichuris trichiura, large eggs as well as more typical eggs were frequently found in the feces; these large eggs have been attributed to human infection by T. vulpis. To clarify whether the female worms laying the large eggs were T. trichiura or T. vulpis, we examined the morphology of adult worms and the size of whipworm eggs obtained from a patient and from several domestic dogs. Adult female T. trichiura worms were easily and quickly distinguished from those of T. vulpis by their convoluted vaginal tracts and uteri. Eggs obtained from the uteri of T. trichiura were of two sizes, with approximately 80% being of the smaller variety (57 X 26 microns) and 20%, the larger (78 X 30 microns). These percentages were about equal to those found the feces of the patient. T. vulpis uterine eggs were slightly larger (82 X 39 microns) than the large eggs of T. trichiura. The distribution of the 2 populations of eggs in 30 adult female T. trichiura was as follows: 1 worm had only large eggs, 14 had only the typical smaller eggs, and 15 had both varieties in their uteri.

Identification of Stellantchamus falcatus Metacercariae encysted in mullets in Korea.

A group of metacercariae encysted in the flesh of Mugil sp. were identified to be Stellantchasmus falcatus by the morphology of adult worms obtained experimentally. It is confirmed that mullets serve as a second intermediate host of this heterophyid fluke in Korea.

肉食獣に寄生する条虫&lt;I&gt;Mesocestoides paucitesticulus&lt;/I&gt;の形態

The precise morphology of adult worms, tetrathyridia and eggs ofMesocestoides paucitesticuluswas observed macroscopically and histologically. It was useful for discriminating this species fromM. lineatusandM. litteratus.

Comparative Development of Temperate Zone and Arctic Isolates of Trichinella spiralis in the White Mouse

Experiments were conducted in white mice to compare infectivity, morphology, and developmental capacity of Trichinella spiralis isolated from laboratory animals in Michigan and North Carolina (temperate zone isolates) and those from a polar bear and an Alaskan dog (arctic isolates). Subsequent to a passage in guinea pigs and mice, each of 10 mice was inoculated with a single dose of 500 larvae of a particular isolate. Five mice infected with an isolate were killed 8 days after infection. Significantly greater numbers of adult worms were recovered from mice infected with the temperate zone isolates than from mice given the arctic isolates. Thirty days postinfection, significantly greater numbers of larvae were found in the skeletal muscles of the remaining mice infected with the temperate zone isolates than were found in mice infected with the arctic isolates. There were no differences between the temperate zone and the arctic isolates in morphology of adult worms or in the size of the cysts found in the diaphragms. Four consecutive passages of T. spiralis in white mice resulted in increased infectivity of all isolates. Variations in infectivity of Trichinella spiralis that are associated with different geographical regions have been reported by several workers. Nelson and Mukundi (1963) reported that a strain of T. spiralis from Kenya had little infectivity to rats and domestic pigs. Kozar and Kozar (1965) found that T. spiralis from Kenya had less infectivity and pathogenicity for mice and rats than did a strain from Poland. Nelson et al. (1966) found that T. spiralis from Kenya and from Alaska had little infectivity for rats. Recently, Read and Schiller (1969) reported that rats, hamsters, and mice were relatively refractory to T. spiralis from Alaska. Rappaport (1943a, b), on the other hand, found no morphological or biological differences among three strains of T. spiralis, two of human origin and one of suilline origin. The following study was made to determine if differences in infectivity and morphology exist between our temperate zone and arctic isolates of T. spiralis. MATERIALS AND METHODS The temperate zone isolates originated from 2 sources. One isolate from a human infection had Received for publication 30 December 1969. * Paper No. N.S. 710, published with the approval of the director, Wisconsin Agricultural Experiment Station. t Present address: Agricultural Research and Development Department, Pfizer Inc., Terre Haute, Indiana 47808. been maintained since 1938 in mice and rats at the Michigan laboratory of Dr. S. E. Could. The other isolate from a pig had been maintained since 1936 in rats and mice at the laboratory of Dr. J. E. Larsh, Jr., in North Carolina. Infected muscle tissue of a polar bear and an Alaskan dog, sent by Dr. R. L. Rausch, were the sources of the 2 arctic isolates of T. spiralis. After receipt of the original materials, infected muscle tissue of each isolate was fed separately to guinea pigs. Infective larvae were recovered from the skeletal musculature of guinea pigs following pepsin-HCl digestion. An additional passage in mice of each isolate was required, since the number of larvae recovered from guinea pigs was insufficient to carry out the planned experiments.

The Status of the Genera Acanthatrium Faust, 1919, and Prosthodendrium dollfus, 1931 (Trematoda: Lecithodendriidae)

In a recent paper, Etges (1960) reviewed briefly the lecithodendriid genera, Acanthatrium Faust, 1919, and Prosthodendrium Dollfus, 1931. In this paper the suppression of Acanthatrium as a generic synonym of Prosthodendrium, as stated by Yamaguti (1958), and the use of both names as in the revised genus Prosthodendrium were accepted. Yamaguti referred to Dubois' (1955) revision of subgenera (note plural) in a footnote (op. cit., p. 821). Further study by the writer reveals that Dubois (1955) treated only members of the subgenus Prosthodendrium and did not revise the subgenus Acanthatrium. Moreover, the suppression of Acanthatrium Faust, 1919, in favor of Prosthodendrium Dollfus, 1931, (apparently by Yamaguti) has violated the law of priority. The present note is intended to clarify the systematics of the Acanthatrium-Prosthodendrium complex. The reader is referred to the discussion by Etges (1960) supporting the unigeneric concept of this complex. Comparisons of life histories and morphology of adult worms show the Acanthatrium Skarbilovich, 1948, and Prosthodendrium Dollfus, 1937, to be congeneric. The current basis for separating these is the presence (Acanthatrium) or absence (Prosthodendrium) of spines on the wall of the genital atrium; however, as will be pointed out below, this feature is not clear-cut and definite, but forms a graded series. The illustrations below depict the graded sequence of genital atrium and atrial spine development in selected members of these subgenera. Phylogenetic significance of this sequence is not intended by the writer. Figure 1 shows the minute, unarmed form of genital atrium found in Prosthodendrium swansoni Macy, 1936; in fact, a definite atrium is not mentioned by Macy (1936) in his diagnosis of P. swansoni. Figure 2 shows the small atrium of P. naviculum Macy, 1936, in which minute papillae are found; this condition is seen to be intermediate between typical Prosthodendrium and Acanthatrium species. Figure 3 shows the larger atrium of Acanthatrium oligacanthum Cheng, 1957, armed with only 9 minute spines, 0.0026 mm long. Figures 4 through 8 indicate gradual enlargement and complication of the genital atrium, and increase in the number and length of atrial spines, culminating in the elaborate structure seen in A. alicatai Macy, 1940 (fig. 8), which has numerous broad spines 0.026 mm long, and the atrium divided into 3 distinct muscular pockets. This gradual sequence further indicates the difficulty of clearly defining these 2 groups on a generic level. Evidence presented and cited above indicates Yamaguti (1958) to be correct in placing all members of this complex in one genus. Yet, since most members of the group clearly lack or possess atrial spines, the Acanthatrium and Prosthodendriumn do have practical value to the systematist, and the writer agrees with Yamaguti in their utilization. It is evident, however, that since Acanthatrium Faust,

The Life History of Diphyllobothrium Mansonoides Mueller, 1935, and Some Considerations with Regard to Sparganosis in the United States 1

Summary 1. The procercoid develops in Cyclops leuckarti, C. viridis, C. bicuspidatus, and becomes infective in from 18 to 21 days. 2. Mice of various species are found regularly susceptible to oral infection. Guinea pigs, rats, rabbits, birds, cats, and monkeys are generally resistant to oral infection with procercoids. 3. Certain hosts, generally resistant to oral infection, such as the rat, cat, etc., can be infected by hypodermic injection of the procercoids. 4. Resistance appears to be of two types. That occurring in rats appears to be located in the alimentary canal since they cannot be infected orally but can be infected by injection. That in frogs and birds appears to lie in the tissues themselves since they cannot be infected even by injection. 5. The morphology of adult worms raised from spargana from various intermediate hosts is constant and typical. 6. The definitive hosts are the cat, bobcat, and occasionally the dog. 7. Infection in the cat with the adult worm produces marked emaciation, anemia, nervousness, and permanent stunting. 8. Cats which have been long infected develop a resistance to the parasite which shows itself in diminished egg production, impaired viability of the eggs produced, and marked diminution in size of the worms. 9. Mice infected with spargana pass through an acute stage, lasting about 2 months, during which time the coat is rough, the eyes inflamed, and emaciation apparent. Mice surviving this stage pass into a chronic condition and resume normal appearance. 10. The rat does not show external signs of infection. In this host the spargana are smaller, and their heads usually surrounded by a bloody area. 11. In monkeys, infected by injection, no signs are apparent during the first 2 months. After this period, however, elephantiasis of the affected part may develop. The swellings are filled with a slimy gelatinous mass. 12. In all hosts the migration of spargana is attended by extensive tissue damage and pathology. 13. Experiments on transplanting spargana suggest the possibility that the mouse and snake strains of D. mansonoides may be separate. 14. D. mansonoides differs from mansoni in that it does not infect frogs, rabbits or birds, and appears to thrive better in the cat as a definitive host than in the dog. 15. D. mansonoides appears to be worthy of consideration as a probable cause of sparganosis in man in this country. Over a large section of the country, man must be continually exposed to infection wherever drinking water from natural sources is used. 16. The sparganum does not undergo asexual reproduction or proliferation in the tissues.