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At least 1,567 records · Page 87Linked to original sources
PubMed2001

Monticellia ophisterni n. sp. (Cestoda: Monticelliidae) from the swamp-eel Ophisternon aenigmaticum (Synbranchiformes) from Mexico.

Monticellia ophisterni n. sp. is described from the swamp-eel Ophisternon aenigmaticum Rosen and Greenwood (Synbranchiformes: Synbranchidae) from Lake Catemaco, Veracruz, Mexico. The new species is placed into Monticellia because of the cortical position of the testes, ovary, and uterus. It differs from other Monticellia species (with the exception of Monticellia magna (Rego, Santos and Silva, 1974)) in the position of longitudinal musculature that crosses the vitelline follicles, making them paramuscular. The new species can be distinguished from M. magna--which possesses a similar number of testes (107-139), paramuscular vitelline follicles, and numerous gland cells distributed between the apex of the scolex and suckers--in the position of the genital pore (8-21% vs. 19-27%), in the presence of a weak internal longitudinal musculature, in the arrangement of the testes in the median field, and in the absence of a vaginal sphincter. This is the first proteocephalidean tapeworm reported from a synbranchid fish and the first species of Monticellia found in North America.

Animals↗
PubMed2002

Effects of concurrent infections on Hymenolepis diminuta (Cestoda) and Moniliformis dubius (Acanthocephala). I. General effects and comparison with crowding. 1961.

Hymenolepis diminuta developing in the presence of Moniliformis dubius are lighter, shorter, have a lower average weight:length ratio, and are limited to the posterior part of the intra-intestinal range they occupy in single infections. M. dubius in the concurrent infections are lighter, possibly shorter, have a lower average weight:length ratio, and tend to attach further anterior than in single infections. No effects were noted on the percent recovery of either helminth. Highly significant regressions of the wet weight, length, and weight:length ratio of H. diminuta and M. dubius on the number of larvae administered in single infections have been demonstrated. The weight and length of the H. diminuta, and the weight and weight:length ratios of the M. dubius, from concurrent infections were significantly lower than values predicted for single-species infections with a comparable number of worms. In crowded single-species infections, the distribution of attachment points of the H. diminuta is extended to include the anterior three-fourths of the intestine; in concurrent infections the tapeworms are limited to the posterior part of this range. Under crowded conditions, the M. dubius extend their linear intestinal distribution only slightly, all of the acanthocephalans attaching in the anterior half of the small intestine; in concurrent infections the acanthocephalans tend to be limited to the anterior part of this range. The distributional limitations in concurrent infections and the similarities between the effects of concurrent infection and crowding suggest that similar mechanisms, i.e., competition, possibly for carbohydrate, may be involved in the production of the effects of concurrent infection.

Acanthocephala↗
PubMed2002

Identification of life cycle stages of Cyathocephalus truncatus (Cestoda: spathebothriidea) using molecular techniques.

Morphological identification of tapeworm species at larval stages (procercoids and cysticercoids) is often difficult because few diagnostic characters are available. In the present study, a molecular approach (sequencing of partial 18S rDNA gene) was used to evaluate the genetic similarity between adult specimens of Cyathocephalus truncatus (Pallas, 1871) (Cestoda: Spathebothriidea) found in fish, its definitive host, and procercoids of the same species recovered from amphipod, Echinogammarus stammeri (Karaman, 1931). Furthermore, cestode cysticercoids of uncertain species were found in the amphipod's hemocoel. The sequences obtained from adults and procercoids were identical, and even very similar to those of C. truncatus available in GenBank, whereas the sequences obtained from cysticercoids differed significantly from those of adults and procercoids, indicating that these larvae belong to another species; later it was demonstrated that they were cysticercoids of Microsomacanthus pachycephala (Linstow, 1972), a cestode of the Hymenolepididae (Cyclophyllidea). The results of this investigation show that the comparison of nucleotide sequence data may avoid misclassification of developmental stages of parasites, which use the same intermediate host.

Animals↗
PubMed2002

Gastrointestinal helminths of ponies in Louisiana: a comparison of species currently prevalent with those present 20 years ago.

A survey in Louisiana of gastrointestinal helminths recovered at necropsy from 117 ponies with minimal exposure to anthelmintics between 1989 and 2000 is compared with a survey conducted 20 yr earlier in the same region. An objective of this study was to determine whether species diversity has been affected by the advent and use of the macrocyclic lactone (ML) parasiticides and by the increased anthelmintic pressure on the helminth species infecting the general equine population. Twenty-six cyathostome species and 8 strongyle species were recovered. Two cyathostome species that were not found before, Cylicostephanus asymetricus and C. bidentatus, and 1 species of large strongyle, Oesophagodontus robustus, were added to the list of species found in Louisiana. All cyathostome and large strongyle species found previously were still present. But prevalences and intensities were significantly reduced for almost all large and small strongyle species. Prevalences and intensities of Oxyuris equi adults and larvae were reduced, whereas the prevalence of Parascaris equorum remained constant. The tapeworm Paranoplocephala mamillana was added to the list of parasite species found in Louisiana. Anoplocephala perfoliata remained the most common cestode. This species was found at the same level of intensity but increased slightly in prevalence. Anoplocephala magna was found less frequently than previously. The overall diversity of species remained reatively unchanged. The reasons for the differences in intensity and prevalence of strongyles between these 2 periods are unknown but might be related to the development and use of the broad-spectrum ML anthelmintics in the intervening period, a difference in the population of equids surveyed, different techniques used to identify the parasites, or differences in numbers of parasites identified (or to all).

Animals↗
PubMed2003

STAT-6 is an absolute requirement for murine rejection of Hymenolepis diminuta.

Infection with helminth parasites typically evokes a T helper 2-cell response in the mammalian host. Interleukin (IL)-4 and IL-13 are important in the rapid expulsion of parasitic nematodes, with the absence of either cytokine being compensated for by the other. However, the IL-4 and IL-13 common signaling molecule, signal transducer and activator of transcription 6 (STAT-6) appears to be mandatory for the spontaneous expulsion of enteric helminths. Mice genetically deficient in IL-4, IL-13, or STAT-6 were infected with the cestode Hymenolepis diminuta and worm infectivity and jejunal goblet cell responses assessed 12-18 days postinfection (PI). Only the STAT-6 knockout (KO) animals harbored adult worms; neither gravid adult nor stunted H. diminuta was obtained from the infected IL-4 KO or IL-13 KO mice > or = 12 days PI. Also, the establishment of worms in the intestine of STAT-6 KO animals was associated with a reduced goblet cell response. These findings support the hypothesis that increased mucin production is an important part of the host response to tapeworm infection and that functional STAT-6 signaling may be an absolute requirement for the rejection of intestinal cestodes and thus, helminth parasites in general.

Animals↗
PubMed2003

In situ detection of antigenic glycoproteins in Taenia solium metacestodes.

Taenia solium has a complex life cycle. Its cysticercus can lodge in the brain, causing neurocysticercosis (NCC), and the adult tapeworm's survival in the intestine results in taeniasis. In this study, the in situ detection of previously described glycoprotein antigens used for serological diagnosis of NCC and the detection of other glycoconjugates was explored in cysticerci and the surrounding porcine tissue to understand their potential role in pathogenesis. Immunohistochemistry with an antiserum specific for glycoprotein antigens rich in N-linked carbohydrates and in situ histochemistry with a battery of lectins that have affinity to a variety of glycoconjugates were performed. The glycoconjugates rich in N-linked carbohydrates were detected in the vesicular fluid and tegument of the vesicular membrane and scolex, where the parasite has direct contact with the host tissues during cysticercosis and taeniasis, respectively. Additionally, as the inflammatory response progressed, the parasite's antigenic glycoproteins were also detected in the cytoplasm of inflammatory cells in the surrounding granuloma. In contrast, the spiral canal tegument, which will be exposed to intestinal enzymes in taeniasis, had N-acetyl-galactosamine-rich mucins. Thus, the differential saccharidic composition in T. solium metacestode structures may be important for the survival of the parasite in different host sites.

Animals↗
PubMed2004

Five new species of Pedibothrium (Tetraphyllidea: Onchobothriidae) from the tawny nurse shark, Nebrius ferrugineus, in the Pacific Ocean.

The spiral intestines of 7 Tawny nurse sharks (Nebrius ferrugineus; Rhincodontidae) from Australia and French Polynesia were examined for tapeworms. These sharks hosted 5 new species of Pedibothrium. The 5 species were prepared for light and scanning electron microscopy. Whereas 3 of the species exhibit the bipronged hooks typical of members of Pedibothrium, 1 species was found to possess tiny unipronged hooks or to lack some, or all, hooks, and all individuals of the fifth species appeared to lack bothridial hooks entirely. Nonetheless, the otherwise remarkable similarities between these species and the species of Pedibothrium bearing bipronged hooks were considered to be sufficient to justify the placement of these 2 species in this genus. All 5 species possess proglottid features typical of Pedibothrium, including a uterus that extends anteriorly only to the level of the cirrus sac and a cirrus sac that is bent anteriorly and is crossed by the vagina. All 5 species also exhibit uniloculated bothridia. Of particular note was the fact that all 5 species exhibit bladelike spinitrichs with elongated distal tips, a form of microthrix currently known only from species of Pedibothrium. As a consequence, these species were treated as possessing modified hooks or as having lost hooks. The diagnoses of Pedibothrium and Onchobothriidae were emended to include these species. Each of the 5 new species bears a strong resemblance to 1 or more species of Pedibothrium hosted by a species of rhincodontid shark other than N. ferrugineus. Much of Southwell's type and voucher material of Pedibothrium was located and used to verify the identity of Pedibothrium kerkhami and many of the hosts from which Southwell's material of Pedibothrium was collected. This material suggests that P. kerkhami parasitizes Stegostoma fasciatum and not N. ferrugineus.

Animals↗
PubMed2003

Cestodes of cestodes of Peruvian freshwater stingrays.

Adult tetraphyllidean tapeworms (Platyhelminthes: Eucestoda) from the spiral intestines of 3 species of potamotrygonid stingrays (Paratrygon aiereba, Potamotrygon castexi, and Portamotrygon motoro) in the Madre de Dios river in Peru were found to host numerous cysts embedded in their parenchymal tissues. Histological sections of the cysts revealed the presence of a scolex bearing 4 suckers and an unarmed apical organ consistent with larval stages of both Cyclophyllidea and Proteocephalidea. To further elucidate their identities, partial 28S ribosomal DNA (rDNA) sequences were characterized from 3 cysts and 4 adult Rhinebothrium spp. 'host' worms and screened against all available cestode 28S rDNA data. Initial BLAST screening and subsequent alignment ruled out the possibility that the cysts were cyclophyllidean, and the cyst and adult sequences were thus aligned together with all available lecanicephalidean, litobothriidean, proteocephalidean, and tetraphyllidean sequences. Sequences from all 3 cysts were identical, and phylogenetic analysis clearly placed them among derived members of the Proteocephalidea, although no exact match was found. Sequences from the adult host worms formed 2 identical pairs and grouped together with other tetraphyllidean species from rays. These results are compared with records of hyperparasites of South American catfish cestodes. This is the first confirmed record of a proteocephalidean cestode parasitizing a tetraphyllidean cestode.

Animals↗
PubMed2003

Taxonomic status of Choanoscolex lamothei García-Prieto, 1990 (Cestoda: Proteocephalidea) using morphological and molecular evidence.

The taxonomic status of Choanoscolex lamothei, a proteocephalidean tapeworm described from the catfish Ictalurus meridionalis (= I. furcatus) from Oaxaca, Mexico, was evaluated on the basis of morphological examination of types and freshly collected specimens from the type host and partial sequences of the large subunit (28S) ribosomal DNA. This study revealed that C. lamothei is a species of Megathylacoides (Proteocephalidae: Corallobothriinae) because of the medullary position of the genitalia (entirely cortical in Choanoscolex), the presence of semispherical sphincters on the suckers, a follicular ovary, and the alternating position of the vagina. Megathylacoides lamothei n. comb. differs from congeneric species in lacking an apical organ and in the number (130-208) of testes. Molecular data confirm the position of M. lamothei within Megathylacoides, which contains species parasitizing ictalurid fishes in North America.

Animals↗
PubMed2003

Is the prevalence of Taenia taeniaeformis in Microtus arvalis dependent on population density?

Populations of common voles Microtus arvalis were studied as hosts of the tapeworm Taenia taeniaeformis during a 14-yr survey. They were monitored in spring, summer, and autumn in a pastoral ecosystem in eastern France. A total of 7,574 voles were sampled during 2 multiannual population fluctuations. A third fluctuation was sampled during the increase phase only. Overall prevalence was lowest in summer (0.6%), increased by 3 times in autumn (1.5%) and a further 5 times in spring (7.8%). Analysis of prevalence, based on 7,384 voles, by multiple logistic regression revealed that extrinsic factors such as season and intrinsic factors such as host age and host density have a combined effect. In the longer term, host age and host density were positively associated with prevalence in summer. Host density was strongly associated with autumn prevalence. There was no association between the fluctuation phase and prevalence. The study shows that a long timescale (here a multiannual survey) is necessary to demonstrate the positive effect of host density on the prevalence of this indirectly transmitted parasite. The demonstration of this relationship depends on the rodents being intermediate rather than definitive hosts.

Age Factors↗
PubMed2004

Reinvestigation of spermiogenesis in the proteocephalidean cestode Proteocephalus longicollis (Zeder, 1800).

The reinvestigation of spermiogenesis in the proteocephalidean cestode Proteocephalus longicollis (Zeder, 1800) provides new details that were not described previously for this species. The 2 centrioles with roots are oriented at the first tangential to the long axis of the nucleus in a differentiation zone. They come to be arranged in the same plane only when a single intercentriolar body (ICB) appears between them. The ICB had been described previously as consisting of a number of dense elements (Swiderski, 1985) but, in the present study, appeared as a single, electron-dense plate. Also new for this species is the observation of 2 arching membranes that appear at the base of the differentiation zone only when the 2 flagella rotate toward the median cytoplasmic protrusion. Moreover, the formation of a crested body is described for the first time in P. longicollis. The present data support the suggestion that the process of spermiogenesis in proteocephalidean tapeworms corresponds in most features to that observed in some members of the unrelated tetraphyllidean clades, the Onchobothriidae and Phyllobothriidae. This may represent more evidence regarding the close relationship between tetraphyllidean and proteocephalidean cestodes, but existing information is fragmentary and controversial in some characters.

Animals↗
PubMed2004

The Hymenolepis diminuta-golden hamster (Mesocricetus auratus) model for the evaluation of gastrointestinal anticestode activity.

A novel laboratory anticestode assay was developed using Hymenolepis diminuta in the hamster. The commercial anticestode compounds, praziquantel, bunamidine, and niclosamide were active against patent infections of Hymenolepis diminuta in golden hamsters (Mesocricetus auratus) when given orally at 3.125, 100, and 200 mg/kg, respectively. The gastrointestinal nematode anthelmintics, cambendazole and mebendazole, were active at 50 mg/kg. Rafoxanide (fasciolicide) was active at 25 mg/kg, the lowest level tested. The coccidiostat, nicarbazin, was active at experimental levels (800 mg/kg and up). The anthelmintic-ectoparasiticide (endectocide), ivermectin, was inactive against the tapeworm at 0.5 mg/kg, as expected.

Administration, Oral↗
PubMed2005

Systematics of Mesocestoides (Cestoda: Mesocestoididae): evaluation of molecular and morphological variation among isolates.

A hypothesis-based framework was used to test if 3 genetic strains of Mesocestoides (clades A, B, and C) are distinct evolutionary lineages, thereby supporting their delimitation as species. For comparative purposes, 3 established cestode species, Taenia pisiformis, Taenia serialis, and Taenia crassiceps were assessed using the same methods. Sequence data from mitochondrial rDNA (12S) and the second internal transcribed spacer of nuclear rDNA (ITS-2) revealed derived (autapomorphic) characters for lineages representing clade A (n = 6 autapomorphies), clade B (n = 4), and clade C (n = 9) as well as T. pisiformis (n = 15) and T. serialis (n = 12). Furthermore, multivariate analysis of morphological data revealed significant differences among the 3 genetic strains of Mesocestoides and between T. pisiformis and T. serialis. The level of phenotypic variation within evolutionary lineages of Mesocestoides and Taenia spp. tapeworms was similar. Results from this study support recognizing Mesocestoides clades A, B, and C as separate species, and provide evidence that clade B and Mesocestoides vogae are conspecific.

Animals↗
PubMed2003

Seasonal and yearly population dynamics of two exotic helminths, Camallanus coti (Nematoda) and Bothriocephalus acheilognathi (Cestoda), parasitizing exotic fishes in Waianu Stream, O'ahu, Hawaii.

Exotic poeciliid fishes introduced into Hawaiian freshwaters are responsible for the introduction of several exotic parasites, of which the most important are Camallanus cotti and Bothriocephalus acheilognathi in terms of potential disease threat to native stream fishes. This roundworm and tapeworm are the most prevalent and abundant freshwater fish helminths in Hawaiian streams. This study examined the seasonal and yearly population structure of C. cotti and B. acheilognathi to determine if the tropical Hawaiian environment characterized by low climatic variability permits continuous opportunities for parasite transmission regardless of time of year. Camallanus cotti displayed seasonal differences in prevalence and mean abundance, whereas B. acheilognathi did not. Camallanus cotti prevalence and mean abundance were higher in the Hawaiian summer (47.7%, 0.79) than in winter (25.8%, 0.36). A seasonal relationship of C. cotti levels is likely explained by extensive rains associated with the Hawaiian winter season, which may act to decrease parasite transmission by flushing infected poeciliid hosts, intermediate copepod hosts, and possibly free-living infective worm stages downstream. Bothriocephalus acheilognathi displayed low prevalence and mean abundance in both summer (4.0%, 0.06) and winter (6.5%, 0.07), and it may be difficult to detect seasonal changes due to these low levels. Camallanus cotti prevalence and mean abundance remained relatively constant from the summer of 1995 to the summer of 1999, indicating that levels of this roundworm are stable in Waianu Stream. Whereas B. acheilognathi prevalence and mean abundance were low during the summer of 1995 and the summer of 1997, a dramatic peak in prevalence and mean abundance was observed in the summer of 1998 (41.2%, 1.06), with levels decreasing sharply in the summer of 1999 (4.4%, 0.07). It appears that B. acheilognathi also is present in stable populations at low levels, even though levels rose sharply during a single year.

Animals↗
PubMed1997

Isolation and characterisation of mRNA encoding the salmon- and chicken-II type gonadotrophin-releasing hormones in the teleost fish Rutilus rutilus (Cyprinidae).

The complementary DNAs (cDNA) encoding the [Trp7,Leu8]-gonadotrophin-releasing hormone (salmon-type GnRH; sGnRH:GeneBank accession no. u60667) and the [His5,Trp7,Tyr8]-GnRH (chicken-II-type GnRH; cGnRH-II: GeneBank accession no. u60668) precursor in the roach (Rutilus rutilus) were isolated and sequenced following reverse transcription and rapid amplification of cDNA ends (RACE). The sGnRH and cGnRH-II precursor cDNAs consisted of 439 and 628 bp, and included open reading frames of 282 and 255 bp respectively. The structures of the encoded peptides were the same as GnRHs previously identified in other vertebrates. The sGnRH and cGnRH-II precursor cDNAs, including the non-coding regions, had 88.6 and 79.9% identity respectively, to those identified in goldfish (Carassius auratus). However, significant similarity was not observed between the non-coding regions of the GnRH cDNAs of Cyprinidae and other fish. The presumed third exon, encoding partial sGnRH associated peptide (GAP) of roach, demonstrated significant nucleotide and amino acid similarity with the appropriate regions in the goldfish, but not with other species, and this may indicate functional differences of GAP between different families of fish. cGnRH-II precursor cDNAs from roach had relatively high nucleotide similarity across this GnRH variant. Cladistic analysis classified the sGnRH and cGnRH-II precursor cDNAs into three and two groups respectively. However, the divergence between nucleotide sequences within the sGnRH variant was greater than those encoding the cGnRH-II precursors. Consistent with the consensus developed from previous studies, Northern blot analysis demonstrated that expression of sGnRH and cGnRH-II was restricted to the olfactory bulbs and midbrain of roach respectively. This work forms the basis for further study on the mechanisms by which the tapeworm, Ligula intestinalis, interacts with the pituitary-gonadal axis of its fish host.

Amino Acid Sequence↗
PubMed1991

Effects of wastewater irrigation of pastures on the health of farm animals and humans.

Wastewater recycling and reuse through agricultural irrigation can provide an economical means of preventing pollution of surface water sources, while conserving water resources and valuable nutrients for increased crop production and grazing pastures. With proper methods of wastewater treatment, health risks to farmers and farm animals as well as to the public who consume agricultural produce can be prevented. The possibility of transmission of the beef tapeworm Taenia saginata, Salmonella sp. and Mycobacteria sp. to farm animals grazing on wastewater-irrigated pasture is evaluated. While such transmission is possible when raw, untreated wastewater is used for irrigation, the risk is greatly reduced and essentially eliminated with effluent treated to meet the new World Health Organisation (WHO) recommended microbial guidelines for effluent. These guidelines call for one or less helminth eggs per litre and a mean of 1,000 faecal coliform bacteria per 100 ml. In warm climates and where land is available, one of the most economical methods of achieving this standard is the use of multi-cell stabilisation ponds designed for a 25-day detention period. In colder climates and where land is a limiting factor of wastewater treatment, conventional secondary biological treatment followed by disinfection can also be applied to meet this standard.

Agriculture↗
PubMed1997

Risk and the food safety chain: animal health, public health and the environment.

Food safety related to the consumption of animal-derived protein encompasses a wide variety of production and processing procedures which begins with the farm and inputs to the animals on the farm (e.g. feed and water) and includes the environment in which animals are reared. Hazards may be physical, artificial or naturally-occurring chemicals, organisms which cannot reproduce outside a specified life-cycle (e.g., parasites such as tapeworm in pigs) or viruses. Other microbes reproduce in the gastrointestinal tract of food animals as well as on the surface of food and in the environment. Methods of risk assessment for physical and chemical hazards have been used for many years. However, with microbial pathogens which can survive and grow on meat, in soil, water or other media, risk assessment methods are at the early stages of development. Due to the broad habitat range, the role of microbial pathogens in the food safety of meat, poultry, fruit and vegetables is important. The use of antibiotics in livestock species may accelerate the development of antibiotic-resistant strains of microbial pathogens, potentially complicating treatment for both animals and humans. The authors discuss the food chain, risk analysis and hazard analysis and critical control points in relation to foodborne pathogens, and introduce general strategies for improving pathogen control on the farm.

Animals↗
PubMed1997

Public health risks of ostrich and crocodile meat.

This paper discusses the infectious agents and chemical substances potentially capable of contaminating the meat of ostriches and crocodiles and which thus pose a danger to human handlers and consumers. For ostrich meat, there is no danger from Crimean-Congo haemorrhagic fever or spongiform encephalopathy. Contamination of ostrich meat with salmonellae, chlamydia, pasteurellae, mycobacteria and erysipelas might be possible, but has never been reported. No parasites are known which could be transmitted through ostrich meat to human consumers. Residues from growth hormones, antibiotics and acaricides are potential public health hazards. For crocodile meat, there is a distinct possibility of contamination with salmonellae, depending on housing, feed, slaughter technique and hygiene practices under which the animal is reared. Chlamydial infections are common on some crocodile farms in southern Africa. Mycobacteriosis is extremely rare. Tapeworm cysts have been found in crocodile meat in two cases only. Trichinellosis has been reported on several crocodile farms in Zimbabwe. A generalised coccidiosis with invasion of organs and tissues has been seen in several species of crocodiles, but should present no danger to consumers.

Alligators and Crocodiles↗