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First evidence of the presence of microtriches in the Gyrocotylidea.

The Gyrocotylidea, a small and enigmatic group of intestinal parasites of chimaeras, has been considered to be related either to the Monogenea, or, more frequently, to the most primitive monozoic tapeworms (Cestoda), i.e., the Amphilinidea and Caryophyllidea. The present study, based on transmission electron microscopical observations of a species of Gyrocotyle from the rabbit fish, Chimaera monstrosa, in the North Atlantic, demonstrates for the first time the presence of microtriches as surface structures of gyrocotylideans. Because microtriches are considered to be an autapomorphy of tapeworms (Cestoda), in which they differ from other Neodermata (Monogenea and Trematoda), the present data represent another source of evidence in support of a close relationship between the gyrocotylideans and the tapeworms sensu stricto (Eucestoda). Simple morphology, small size, and shape uniformity of the microtriches of Gyrocotyle sp. may indicate they represent an original (plesiomorphic) form that then evolved in more derived cestode groups into a variety of types present mainly on the scolex. The microtriches of Gyrocotyle sp. resemble those found in caryophyllidean, spathebothriidean, pseudophyllidean, and trypanorhynch cestodes, which are considered to represent the most basal groups of the Eucestoda.

Animals↗

Anthelmintics.

This article describes the drugs used in helminthic infections and their therapeutic indications, mode of action, toxicity and other details of each of the recommended drugs, and discusses the nature and treatment of infection by helminths important in human medicine. Infestation due to the roundworms Enterobius vermicularis, Ascaris lumbricoides and the hookworms, Ancylostoma duodenale and Necator americanus can all be treated effectively with pyrantel pamoate. For Enterobius vermicularis, however, a newer drug, mebendazole, is equally as effective. The advantage of these drugs in the indicated circumstances is that they can be administered in a single dose. Unfortunately, pyrantel pamoate is not a panacea and in the case of Necator it is not as effective as in the other roundworms. In that situation the use of tetrachlorethylene is preferable. For treatment of Strongyloides stercoralis, and important human parasite, because it can become disseminated and lead to fatal infections in immunoincompetent hosts, the only effective drug is thiabendazole. In treatment of Trichuris trichiura infection, mebendazole, administered over a period of 3 days, is the most effective available drug. For the roundworms inhabiting tissues--either as aberrant infections of man or as the normal part of their life cycle in man--therapy tends to be largely non-specific. For example, in visceral larva migrans, caused by the dog roundworm Toxocara canis, only palliative therapy with systemic anti-inflammatory agents and corticosteroids may be helpful. Cutaneous larva migrans, caused by the dog hookworms Ancylostoma brasiliensis and Ancylostoma caninum, is also treated primarily with symptomatic measures, but there is a suggestion that thiabendazole may kill the larvae and thus be effective. Trichinella spiralis may cause severe, even fatal infections in man, but only symptomatic therapy can be offered. Therapy for filarial infections is regrettably complicated and not completely effective. Diethylcarbamazine remains the best available drug, but in some of these infections local surgical excision may also be used. It is important to bear in mind that release of antigens from dying or dead worms may cause systemic inflammatory and allergic reactions that may require therapy with corticosteroids. Therapy for Cestodes is achieved most effectively with niclosamide, but the antimicrobial agent paromomycin has also been effective. For the aberrant cestode infections of man, such as echinococcal cysts or Taenia solium cycticerci, treatment is surgical if the affected areas are accessible. Treatment of schistosomal infections is quite toxic and, therefore, it is mandatory to determine viability of the worms before recommending therapy. If therapy is required, then Schistosoma mansoni infections are treated with stibophen and S. japonicum with antimony potassium tartrate, taking care in both of these instances to watch for the early signs of antimony toxicity; therapy of S. haematobium infections is based on administration of niridazole...

Anthelmintics↗

Occurrence of Bothriocephalus acheilognathi in cyprinid fish from three lakes in the flood plain of the Yangtze River, China.

Cyprinid fish, Hemiculter leucisculus, Cultrichthys erythropterus and Culter dabryi, were sampled from Liangzi, Honghu and Tangxun lakes in the flood plain of the Yangtze River. The cestode Bothriocephalus acheilognathi Yamaguti, 1934 was found in the 3 lakes, but C. erythropterus sampled from Liangzi lake was found uninfected due probably to the small sample size. Findings of the cestode in the 3 lakes represent the first record of the parasite in the flood plain of the Yangtze River, indicating that B. acheilognathi may be distributed much wider in China than previously recognized.

Animals↗

Occurrence of Atractolytocestus huronensis (Cestoda, Caryophyllaeidae) in German pond-farmed common carp Cyprinus carpio.

Up to now, the caryophyllid cestode Atractolytocestus huronensis Anthony, 1958, a parasite of common carp, has attracted little attention in Germany. Based on recent publications from the Czech Republic and Hungary, it appears probable that this cestode may be increasingly common in Germany. There is a strong connection between the occurrence of A. huronensis and imports of common carp from the Czech Republic and southern Germany. Although in most cases no clinical alterations in parasitized carp have been observed, care should be taken to avoid further dissemination and to prevent possible losses in commercial pond farming.

Age Factors↗

Parasitism by helminths in the grey-sided vole (Clethrionomys rufocanus) in northern Finland: influence of density, habitat and sex of the host.

We have studied helminths from 532 grey-sided voles (Clethrionomys rufocanus) in two localities in northern Finland, representing different biogeographic zones, during 1978-1983. The helminth communities in the two study areas were similar, characterized by a small number of species (eight) compared to eastern Siberia and Japan, and by the dominance of a single anoplocephalid cestode Andrya kalelai. The prevalence of this helminth varied significantly among habitats, possibly because of differences in the distribution and abundance of the intermediate hosts, oribatid mites. Vole density did not explain the habitat differences in A. kalelai, nor did the prevalence of A. kalelai increase between 2 yr of sustained high density in the host population. A between-year increase in the prevalence of the larval cestode Taenia tenuicollis at Kilpisjärvi was probably due to a simultaneous increase in the abundance of its definitive hosts, mustelids. The prevalence of A. kalelai was always higher in males; no sexual differences were detected in the larval T. tenuicollis.

Animals↗

Influence of host weight, sex and reproductive status on helminth parasites of the wild rabbit, Oryctolagus cuniculus, in Navarra, Spain.

A study was carried out in Navarra (northern Spain) on the influence of the weight, sex and reproductive status (lactant, pregnant or lactant + pregnant females and testicular weight for males) of the wild rabbit (Oryctolagus cuniculus) on two cestodes species: Andrya cuniculi and Mosgovoyia ctenoides and four intestinal nematodes: Graphidium strigosum, Trichostrongylus retortaeformis, Nematodiroides zembrae and Dermatoxys hispaniensis. A significantly higher prevalence of A. cuniculi was detected in lactant + pregnant females compared with non-breeding females. Trichostrongylus retortaeformis and N. zembrae showed a significantly higher mean intensity in lactant and lactant + pregnant females than in non-reproductive females. Trichostrongylus retortaeformis presented a higher mean intensity in females than in males, and the mean intensity of the same parasite species was significantly lower in active and inactive males compared with lactant and lactant + pregnant females. There were no significant differences between sexes in the prevalence of helminth parasites. No significant correlation was detected between host weight and the intensity (of infection) of helminths studied. No significant differences in the prevalence and mean intensity of the two cestode species were observed in the three weight categories studied (kittens, juveniles and adults). The prevalence of G. strigosum and mean intensity of T. retortaeformis were significantly higher in older heavier animals than in juveniles.

Age Factors↗

Pulmonary cestodiasis in a cynomolgus monkey (Macaca fascicularis).

Cestodiasis in primates has been noted historically to occur quite frequently, although tissue damage and clinical signs may or may not be apparent. Larval cestodes, such as hydatid cysts or cysticercus cysts, are known to cause extensive tissue damage, while other larval cestodes, such as tetrathyridia, cause minimal damage to the host. This case history concerns an apparently healthy cynomolgus monkey that was part of a surgical study. During the study, all parameters were normal. The monkey died 3 hours postsurgery. The apparent cause of death was respiratory arrest. At necropsy, it was discovered there were 1- to 3-mm-diameter cysts, which on transection extruded 2- to 5-mm-long larvae. The larvae could not be positively identified; however, they resembled tetrathyridia of Mesocestoides sp.

Animals↗

A new species of Linstowia (Cestoda: Anoplocephalidae) from marsupials in Bolivia.

A new species of cestode of the genus Linstowia (Cestoda: Anoplocephalidae) is described from marsupials of the genera Thylamys and Monodelphis. The new species (Linstowia schmidti) differs from Linstowia iheringi Zschokke, 1904, in having a much smaller strobila and reduced number of proglottids, and in the distribution of the eggs in gravid proglottids. In Bolivia, cestodes of the genus Linstowia appear to have a restricted geographic distribution, occurring in marsupials only in southeastern Bolivia near the western margin of the Chaco. This host-parasite association may represent an ecological-historical relict.

Animals↗

[Helminthiasis, metabolic rates and cold resistance in the red-backed vole from a natural population].

Estimation of the standard metabolic rate (SMR), maximal oxygen consumption (MOC) and thermoregulation ability in males of red-backed vole (Clethrionomys rutilus Pallas, 1779) have shown that individuals infected with nematodes Heligmosomum mixtum, regardless of intensity of worm infection, had an increased level of oxygen consumption in the cold exposition, while the individuals infected with the cestodes Arostrilepis horrida, had a lover oxygen consumption than non-invaded individuals. Worm burden of A. horrida correlated negatively with MOC value in the hosts. Thermo-conductance of individuals infected with A. horrida was significantly lower than in ones infected with H. mixtum. Opposite effects of these two helminthes seems to be determined by the specificity of pathogenesis and different body mass of parasites. Total body mass of nematodes are usually less than 0.2% of the host body mass whereas the total body mass of cestodes may exceed 5% of the host body mass.

Animals↗

Parasites as probes for biodiversity.

Cestodes of the genus Linstowia, parasitic in marsupials, show patterns of coevolution and ancient historical-ecological connections. Correlated with the breakup of the austral landmasses (Gondwanaland) of the Neotropical and Australian regions from the Antarctic continent, the age of this host-parasite community is estimated to be between 60 and 70 million years old. Based on the data from the survey of parasites of mammals from throughout Bolivia and from the phylogenetic analysis of the cestodes, we urge the planners of biodiversity preserves in the neotropics to consider the Yungas of Bolivia as a region that supports an ancient ecological community worthy of consideration as a biopreserve.

Animals↗

[Hydrolytic activity of enzymes produced by symbiotic microflora and its role in digestion processes of bream and its intestinal parasite Caryophyllaeus laticeps (Cestoda, Caryopyllidea)].

Bacteria capable to secrete enzymes hydrolyzing proteins and carbohydrates proved to be associated with the digestive-transport surfaces of the bream intestine and tegument of cestode Caryophyllaeus laticeps. Apparently, the contribution of symbiotic digestion to the hydrolysis of polymers increases during active feeding of fishes, while at low feeding rate, bacteria can compete with the host and its parasite for the available monomers. Secretion of bacterial enzymes hydrolyzing both complex carbohydrates and disaccharides reduces the metabolic expenditures of the macroorganisms for the synthesis of their own hydrolases. Glucose resulting from hydrolytic activity of bacterial enzymes can be used by all members of the established community. While bacteria colonizing the digestive-transport surfaces of the host and parasite were generally similar, some specific features were also observed probably due to the structural peculiarities of the intestinal mucosa and cestode tegument.

Animals↗

Helminth position within the intestine of naturally infected pike (Esox lucius) relative to host stomach contents.

The positions of 3 cestode species, Triaenophorus crassus Forel, Triaenophorus nodulosus (Pallas), and Proteocephalus pinguis LaRue, and a nematode, Raphidascaris acus (Bloch), within the intestine of naturally infected pike (Esox lucius L.) were evaluated with respect to the presence or absence and state of digestion of host stomach contents. The positions of scolices and strobilae of the cestodes did not vary with respect to host stomach contents. By contrast, R. acus was anterior (near the stomach) when the stomach contained partially digested items, posterior when the stomach was empty, and in an intermediate position when the stomach contained only intact items. These results are interpreted as migration of R. acus, but not T. crassus, T. nodulosus, or P. pinguis, in response to feeding activity of the host. Adult and larval R. acus migrated, but the extent of migration was reduced in hosts harboring T. crassus, more so for larval than adult R. acus.

Animals↗

Dose titration and confirmation tests for determination of cesticidal efficacy of epsiprantel in dogs.

Fifty-five dogs, naturally infected with Taenia sp or Dipylidium caninum or both, were assigned to the following treatment groups for dose titration studies with epsiprantel: nonmedicated control dogs (n = 14), medicated dogs given a dosage of 2.75 mg/kg of body weight (n = 15), medicated dogs given a dosage of 5.5 mg/kg (n = 16), and medicated dogs given a dosage of 8.25 mg/kg (n = 10). Medication was given orally in a tablet formulation. Feces were examined for cestodes passed and the gastrointestinal tract was examined at necropsy for retained cestodes. Efficacy of epsiprantel was 92.9% against Taenia and 44.8% against Dipylidium for a dosage of 2.75 mg/kg, 100% against Taenia and 99.8% against Dipylidium for a dosage of 5.5 mg/kg, and 94.6% against Taenia and 100% against Dipylidium for a dosage of 8.25 mg/kg. For dose confirmation, 36 dogs naturally infected with Taenia sp or D caninum or both were allotted to 2 treatment groups: nonmedicated control dogs (n = 16) and dogs medicated with epsiprantel at a dosage of 5.5 mg/kg (n = 20). Efficacy was 100% for both Taenia sp and D caninum.

Animals↗

Food-borne parasitic infections--old stories and new facts.

A review is presented of food-borne parasitic infections. Parasitic infections with public health hazards both from conventional slaughter animals and from seafood (fish and shellfish) are discussed. The former category includes cysticercosis, echinococcosis, and trichinosis, the latter category covers various trematode, cestode, nematode, and possibly also protozoan infections. Examples of trematode infections are heterophyidiasis, transmitted to man by marine fish, and Paragonimus spp parasites, transmitted by crustaceans. Cestode infections include diphyllobothriasis transmitted by both fresh water fish and fish from brackish waters. Special attention is drawn to the condition known as sparganosis. Of the nematode infections, the eosinophilic granulomatous enteritis due to the genera Anisakis, Phocanema, and Contracaecum, transmitted to man by either marine fish or crustaceans, is mentioned. Two other nematode infections. Angiostrongylus cantonensis and Capillaria philippinensis, can also be transmitted to man by marine fish. Free living amoebae (a.o. Naegleria) may be transmitted to man via shellfish as vehicles. Apart from a possible direct effect of these parasites, chemical alterations in seafood resulting from the presence of parasites may also be deleterious to the consumer. Special attention is drawn to a newly developed serological detection method, the enzyme-linked immunosorbent assay, which makes detection of infection possible not only at the slaughterhouse but also at the farm or in large herds. Strategies to control parasitic infections both in conventional slaughter animals and in seafood are discussed.

Animals↗

Anthelmintic efficacy of febantel combined with praziquantel in dogs.

Ninety-four dogs were randomly assigned to 1 of 6 groups (5 treated and 1 untreated control) for evaluation of anthelmintic efficacy. Three anthelmintic formulations were studied: a febantel paste, a praziquantel paste, and a combination paste containing both active ingredients. Treated dogs were dosed once daily for 3 days. The minimal effective dosages in combination were established as 10 mg of febantel and 1 mg of praziquantel/kg of body weight. At those dosages for the combination, 99.5% to 100% of the major nematodes and cestodes identified (ie, Ancylostoma caninum, Trichuris vulpis, Toxocara canis, Dipylidium caninum, and Taenia pisiformis) were eliminated. Febantel paste (10 mg/kg) alone was ineffective against cestodes (14.2% elimination of Dipylidium caninum) and praziquantel paste (1 mg/kg) alone was ineffective (0% to 2.4% elimination) against nematodes.

Animals↗

Methyl 5(6)-4-2-pyridyl piperazino carbamoyl benzimidazole-2-carbamate--a new broad spectrum anthelmintic.

Methyl 5(6)-4-2-pyridyl piperazino carbamoyl benzimidazole-2-carbamate (CDRI Comp. 81-470) was tested against various nematode and cestode infections in different experimental and domestic animals. The compound showed 100% effectivity against adult of Ancylostoma ceylanicum (hookworm) in hamsters (6.25 mg/kg p.o. X 1), Nippostrongylus brasiliensis (trichostrongylid) in rats (100 mg/kg p.o. X 3), Hymenolepis nana (cestode) in rats (25 mg/kg p.o. X 1) and Syphacia obvelata (oxyurid) in mice (12.5 mg/kg p.o. X 3). It was also found highly effective against artificial and natural helminth parasites of higher animals. The compound removed all, A. caninum and A. ceylanicum (hookworms) and Toxocara sp. (ascarid) from dogs at a dose of 10 mg/kg p.o. X 3; A. tubaeformis (hookworm) and Toxocara sp. at 25 mg/kg p.o. X 3 and 2.5 mg/kg p.o. X 3 respectively from cats and Ascaridia galli (ascarid) at 10 mg/kg p.o. X 3 from fowl. The compound in doses of 1500 mg/kg by oral route and 1000 mg/kg by i.p. route did not cause any mortality or produce adverse effect in mice. The expanded anthelmintic action and large therapeutic index indicate compound's great anthelmintic potentiality.

Animals↗

[Therapeutic effect of paromomycin sulfate on the 13th case of Mesocestoides lineatus infection found in Japan].

Mesocestoides tapeworm is a common cestode in carnivorous mammals, but human infection with the tapeworm of this genus have been infrequent. We have recently observed the 13th case of human infection with Mesocestoides lineatus in Japan. A 35-year-old man living in Gifu prefecture was admitted to our University Hospital with chief complaints of general fatigue and discharge of cestode segments in his stool. The patient gave a history of drinking blood and eating the raw liver of a snake Agkistrodon halys for medicinal purposes as same as the previous cases of all reported in Japan. The segments were identified as those of M. lineatus. He was treated orally 3 g of paromomycin sulfate. Stool examination after treatment with paromomycin sulfate revealed no evidence of parasitism. The present case may be the 2nd to have been successfully treated with paramomycin sulfate and the 21st case of Mesocestoides tapeworm infection in man described in the literature.

Adult↗

Choanotaenia atopa n. sp. (Cestoda: Dilepididae) from a domestic cat in Kansas.

Choanotaenia atopa (Cestoda: Dilepididae) is described (host: domestic cat from the vicinity of Manhattan, Kansas); its natural host is presumed to be a rodent. Choanotaenia atopa is morphologically similar to cestodes of 6 species, all from rodents, formerly placed in the genus Rodentotaenia Matevosian, 1953, and subsequently removed to the genera Choanotaenia Railliet, 1986, or Monopylidium Fuhrmann, 1899. The systematic position of those cestodes is discussed; Monopylidium and Rodentotaenia are treated as synonyms of Choanotaenia. Choanotaenia atopa is distinguished by size and form of rostellar hooks, regularly alternating genital pores, and other characters in genital organs.

Animals↗