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PubMedDate not supplied

Fine structure of buccal cavity and esophagus in Toxocara canis (Nematoda, Ascarididae) infective larvae.

The ultrastructure of the alimentary tract of Toxocara canis infective larvae, with emphasis on the buccal cavity and vestibular-esophageal region, is described. The buccal opening which extends to the vestibule is lined by a thick cuticle. Between the buccal opening and the vestibule there are three cuticular projections which might function either as a valve or for grinding food. Cells associated with the triradiate vestibule show an elaborate system of narrowed cytoplasmic lamellae differentiated in the apical part of the cells. The possible osmoregulatory function of these cells is discussed. Active secretory gland cells are present in the esophagus: the dorsal gland is located behind the muscular esophageal tract, the others are placed at the posterior region of the esophagus. They have an intracytoplasmic cistern which opens through a secretory duct into the esophageal lumen. The secretion produced by these cells might be used to facilitate the migration of the larva; it could represent the material with antigenic properties.

Animals↗
PubMed1990

The in vitro adherence of murine eosinophils, neutrophils and non-induced and induced macrophages to infective larvae of Toxocara canis (Nematoda, Ascarididae).

Infective larvae of the parasite nematode Toxocara canis were incubated in vitro with murine eosinophils, neutrophils and non-induced and induced macrophages. The interactions between the different types of cells and the worms were observed in the presence or absence of immune mouse serum and/or complement. Cells showed considerable differences in the manner, duration and outcome of this interaction. Despite the adhesion of cells to the larvae of T. canis, there was no evidence of damage to the worms. Scanning and transmission electron microscopic observations suggest that the cells adhere to the cuticular surface via an electron-dense material. This material might play a protective role against the helmintotoxic capacity of the inflammatory cells.

Animals↗
PubMed1994

Visceral larva migrans in mice experimentally infected with Baylisascaris transfuga (Ascarididae: Nematoda).

Laboratory bred albino mice, weighing 20 to 25 g, were orally infected with 2000 Baylisascaris transfuga infective eggs each. Mice were randomly chosen and sacrificed on days 1, 2, 3, 10, 15, 24 and 70 post-infection. Samples of intestine, mesenteric lymph nodes, liver, lungs, heart, spleen, kidneys, uterus, brain and skeletal muscles were collected and processed for conventional histopathology. In the early infection the major necropsy findings were focal haemorrhages on the intestinal wall, liver, lungs and brain. Histologically, larvae were found in haemorrhagic areas. In the subacute-chronic infection white nodules were scattered through all the examined organs, except the brain. Histologically, the white nodules corresponded to granulomas containing larvae surrounded by lymphocytes, eosinophil leukocytes and macrophages. The migration of B. transfuga larvae in spleen, kidneys and uterus of infected mice appears to have not been reported by previous workers. The possible role of B. transfuga larvae in the Visceral Larva Migrans syndrome is discussed.

Animals↗
PubMed2005

Survey on helminthofauna in pheasants from Eastern Europe.

In order to assess the parasitological status in imported pheasants, 51 birds (Phasianus colchicus) coming from Poland and Rumania and used in Italy in repopulation interventions for hunting purposes were examined. From each animal the trachea, oesophagus, crop and intestine were collected and examined for the presence of nematodes. The examination of the oesophagi and crops of 5 birds revealed the presence of parasites pertaining to the family Capillariidae: Eucoleus contortus was found in all of the 5 animals, E. annulatus was present along with the previous parasite in one animal coming from Poland. The examination of the tracheae revealed the presence of Syngamus trachea in 5 animals (9.80%). Adult or larval stages of Heterakis gallinarum (37.25% of birds) and Capillariidae (35.29%) were found in the intestinal tracts. Aonchotheca caudinflata was detected only in one bird coming from Poland; the capillarids found in all of the remaining pheasants exhibited morphological characteristics referable to Capillaria phasianina, a species never reported in Italy. The release of game from foreign countries, therefore, may always constitute a risk for the autochthonous one due to the spread of new parasitic infections.

Animals↗
PubMed2003

Diffuse retinochoroiditis due to Baylisascaris procyonis in Monglian gerbils.

Baylisascaris procyonis, raccoon roundworm, causes a severe retinal lesion in humans. The lesion is termed as diffuse unilateral subacute neuroretinitis (DUSN). To understand the pathogenesis of B. procyonis in gerbils, we inoculated 17 embryonated eggs/g body weight of B. procyonis into 15 male Mongolian gerbils, Merionis ungiculatus, and monitored their fundi with an ophthalmoscope. Six of 15 gerbils (40%) showed severe retinitis with a sinuous track due to larval movement. The lesions extended across nearly half of the affected fundi. Histopathological examination revealed perivasculitis in the optic disk region, inflammatory proliferation of the pigment cells, and vitreitis in most cases. These findings were similar to those in human cases of DUSN, suggesting that gerbils might be a useful model for understanding the pathogenesis of B. procyonis infection in humans.

Animals↗
PubMed2006

Helminths of pond-reared walleye from Wisconsin.

One hundred extended growth walleye fingerlings, Sander vitreus (Percidae), collected on 6 October 2004, from 1 rearing pond at the Lake Mills State Fish Hatchery in Lake Mills, Wisconsin, were examined for parasites. Diplostomum sp. (Trematoda: Diplostomatidae), Contracaecum sp. (Nematoda: Anisakidae), Bothriocephalus cuspidatus (Cestoda: Bothriocephalidae), and Proteocephalus sp. (Cestoda: Proteocephalidae) were the only parasites found. The first 3 species occurred as larval stages. Diplostomum sp. and Contracaecum sp. had similar prevalences, mean intensities, and mean abundances (72%, 2.2, and 1.6 and 71%, 2.1, 1.5, respectively) in walleye fingerlings. A headlamp technique used by the Wisconsin Department of Natural Resources personnel generated a prevalence of Diplostomum sp. in the lens that overestimated the prevalence of Diplostomum sp. found in a random subsample of 100 fingerlings examined with a microscope. Proteocephalus sp. and B. cuspidatus infected 14 and 12 fingerlings, respectively.

Animals↗
PubMed2005

Baylisascariasis.

The raccoon roundworm, Baylisascaris procyonis, is the most common and widespread cause of clinical larva migrans in animals. In addition, it is increasingly recognized as a cause of devastating or fatal neural larva migrans in infants and young children and ocular larva migrans in adults. Humans become infected by accidentally ingesting infective B. procyonis eggs from raccoon latrines or articles contaminated with their feces. Two features distinguish B. procyonis from other helminthes that cause larva migrans: (i) its aggressive somatic migration and invasion of the central nervous system and (ii) the continued growth of larvae to a large size within the central nervous system. Typically, B. procyonis neural larva migrans presents as acute fulminant eosinophilic meningoencephalitis. Once invasion of the central nervous system has occurred, the prognosis is grave with or without treatment. To date, despite anthelmintic treatment of cases of B. procyonis neural larva migrans, there are no documented neurologically intact survivors. Epidemiologic study of human cases of neural larva migrans demonstrate that contact with raccoon feces or an environment contaminated by infective eggs and geophagia or pica are the most important risk factors for infection. In many regions of the United States, increasingly large populations of raccoons, with high rates of B. procyonis infection, live in close proximity to humans. Although documented cases of human baylisascariasis remain relatively uncommon, widespread contamination of the domestic environment by infected raccoons suggests that the risk of exposure and human infection is probably substantial. In the absence of early diagnosis or effective treatment, prevention of infection is the most important public health measure.

Animals↗
PubMed2005

Prevalence of anisakin nematodes in fish from Southern Baltic Sea.

Nematodes from the superfamily Ascaridoidea (families Anisakidae and Raphidascarididae) are worldwide distributed parasites. Their live cycles include many species of water invertebrates and teleostean fish as intermediate hosts, and fish, sea mammals or fish-eating birds being definitive hosts. Humans can be infected with some of these parasites after consumption of raw or wrongly processed fish. The parasitological investigations of fish (herring, cod and flatfish) from southern Baltic (ICES 24-26) provided in the years 80 and 90 showed their infection with larvae of several anisakid species: Anisakis simplex s. str., Contracaecum osculatum C and Hysterothylacium auctum. Sporadically Pseudoterranova decipiens and Raphidascaris acus were also found. Larvae of Anisakis simplex were noted mainly in herrings, C. osculatum primarily in cods and H. auctum in flounders. Additionally, preserved herrings (marinated, smoked) were also investigated and sporadically live larvae of A. simplex were found. The main etiological agent of human anisakidosis worldwide is A. simplex. Although the live cycle of this nematode cannot be completed in the Baltic Sea--this nematode is brought to the Baltic by infected herring migrating from the North Sea for spawning in coastal waters of the Southern Baltic--the prevalence and intensity of infection with larvae of this nematode species were the highest in fish investigated by us. The results obtained suggest the possibility of the human infection with A. simplex larvae in Poland.

Animals↗
PubMed2000

Natural transfer of helminths of marine origin to freshwater fishes with observations on the development of Diphyllobothrium alascense.

Infective stages of helminths of 5 species that occur as adults in marine mammals were found in burbot, Lota lota (L.) (Gadidae), from the lower Kuskokwim River (southwestern Alaska): Diphyllobothrium alascense Rausch et Williamson, 1958; Pyramicocephalus phocarum (Fabricius, 1780); Corynosoma strumosum (Rudolphi, 1801); Corynosoma semerme (Forsell, 1904); and Pseudoterranova decipiens (Krabbe, 1878). Some larval stages were obtained also from smelt, Osmerus mordax dentex Steindachner, an anadromous fish important as prey of burbot. Burbot, which are freshwater fish, could become paratenic hosts of those helminths by means of at least 3 interactions: by consuming marine fishes in brackish waters at river mouths, by feeding on marine fishes that enter lower reaches of rivers, or by preying on anadromous fishes as they migrate up rivers. Consumption of burbot by people may result in infection by helminths of marine origin; of those recorded, only P. decipiens may be significantly pathogenic. Attempts to rear P. phocarum in dogs were unsuccessful. Plerocercoids of D. alascense, of very small size and found only in the gastric lumen of burbot, readily infected dogs. For study of their development, strobilae were obtained at intervals of 48 hr to 32 days postinfection. In heavy infections, some strobilae developed slowly, while others underwent rapid development.

Acanthocephala↗
PubMed1998

Role of Leptodora kindti (Cladocera: Leptodoridae) in the life cycle of Raphidascaris biwakoensis (Nematoda: Anisakidae), a fish parasite in Lake Biwa, Japan.

Advanced third-stage larvae (body length 2.92 to 5.49 mm) of the fish nematode Raphidascaris biwakoensis Fujita, 1928 were found as frequent parasites of the leptodorid cladoceran Leptodora kindti (Focke) in Lake Biwa, southern Honshu, Japan, in July 1995. This is the first confirmed record of the L3 of this nematode species from an invertebrate host, showing that L. kindti may serve as a true intermediate host to R. biwakoensis, probably in addition to lower aquatic vertebrates. The high degree of prevalence of the nematode larvae in L. kindti in Lake Biwa indicates that this plankton crustacean is an important source of infection with R. biwakoensis for fish definitive and paratenic hosts.

Animals↗
PubMed1976

Epizootiology of an outbreak of cerebrospinal nematodiasis in cottontail rabbits and woodchucks.

An epizootic of cerebrospinal nematodiasis in cottontail rabbits (Sylvilagus floridanus) and woodchucks (Marmota monax) caused by Baylisascaris procyonis larvae followed the establishment of an ascarid-infected raccoon (Procyon lotor) population in a woodlot. Five of seven raccoons examined from the woodlot harbored ascarids, with one heavily infected animal shedding approximately 27,500 eggs per gram of feces. A laboratory-reared cottontail rabbit developed neurologic disease due to larval migration 80 days after infection with B. procyonis eggs from the raccoons.

Animals↗
PubMed1983

Fatal cerebrospinal disease caused by Baylisascaris procyonis in domestic rabbits.

Infection with Baylisascaris procyonis, the common roundworm of raccoons, was found to be the cause of an epizootic of fatal CNS disease in domestic rabbits (Oryctolagus cuniculus). Clinical signs included torticollis, ataxia, tremors, and falling. Gross lesions were limited to white, raised nodules (1 to 1.5 mm) on the epicardium, endocardium, and liver serosa, and they were found to be larval granulomas. Microscopic lesions included multifocal myocarditis, multifocal hemorrhagic tracks and associated necrosis and inflammation in the liver, multifocal eosinophilic myositis, focal nephritis, and mild interstitial pneumonia; larval granulomas were seen in the heart, liver, lung, and mandibular salivary gland. Lesions in the brain consisted of multifocal areas of necrosis and inflammation in the cerebrum, cerebellum, midbrain, and medulla, with accompanying perivascular leukocyte aggregates and neuronal and axonal degeneration. Large numbers of large ascarid larvae were seen in the brain. Epidemiologically, infection was linked to the use of contaminated straw from a barn used by raccoons. On the basis of this study as well as that of similar studies, it was concluded that barn use and contamination by raccoons may be an important source of infection of animals and possibly man with this parasite.

Animals↗
PubMed2002

The effect of an experimental infection of the nematode Heterakis gallinarum on hand-reared grey partridges Perdix perdix.

We compared 26 hand-reared grey partridges given an experimental infection of the caecal nematode Heterakis gallinarum with 26 uninfected ones. Under laboratory conditions after 91 days, there were no measurable clinical effects of the infection. We found no effect of treatment on the amount of food eaten or on caecal dropping production. However, treated birds, in particular females, developed slightly lower body mass (around 2%) compared to the controls. At post-mortem examination, we found a positive relationship between breast muscle mass and the number of worms collected from the caeca of treated birds. Treated birds with no worms when examined had smaller breast muscle mass (4.6%) compared to the uninfected control birds. These results are largely different to those found in a similar study that documented significant negative impacts on most of these factors in 8 infected birds compared to 6 controls. Its findings were used in a published model to support a hypothesis that H. gallinarum maintained in the environment by common pheasants, the primary host for this worm, could negatively affect wild grey partridge productivity and survival. In the same model our data would not support this hypothesis. Possible explanations for the different results from the 2 experiments are discussed. Together they suggest that only in certain, as yet unidentified circumstances, could experimental H. gallinarum infections have deleterious effects on hand-reared grey partridges.

Animals↗
PubMed2000

Raccoon roundworm (Baylisascaris procyonis) encephalitis: case report and field investigation.

Baylisascaris procyonis is a common and widespread parasite of raccoons in the United States and Canada. With large raccoon populations occurring in many areas, the potential risk of human infection with B procyonis is high. We report a case of severe raccoon roundworm (B procyonis) encephalitis in a young child to illustrate the unique clinical, diagnostic, and treatment aspects, as well as public health concerns of B procyonis infection. Acute and convalescent serum and cerebrospinal fluid samples from the patient were tested for antibodies against B procyonis to assist in documenting infection. An extensive field survey of the patient's residence and the surrounding community was performed to investigate raccoon abundance and to determine the extent of raccoon fecal contamination and B procyonis eggs in the environment. The patient evidenced serologic conversion, and the field investigation demonstrated a raccoon population far in excess of anything previously reported. There was abundant evidence of B procyonis eggs associated with numerous sites of raccoon defecation around the patient's residence and elsewhere in the community. Because B procyonis can produce such severe central nervous system disease in young children, it is important that pediatricians are familiar with this infection. The public should be made aware of the hazards associated with raccoons and B procyonis to hopefully prevent future cases of B procyonis infection.

Animals↗
PubMed1996

Larval anisakids (Nematoda: Ascaridoidea) in horse mackerel (Trachurus trachurus) from the fish market in Granada (Spain).

Horse mackerel (Trachurus trachurus) from the fish market in Granada, South Spain, were surveyed for anisakid nematodes. The fish came from fishing ports all over the country. Larval anisakids were found in 39.4% of the fish examined. In all, 26.1% were infected with third-stage larvae (L3s) of Anisakis simplex; 0.3%, with A. physeteris L3s; 31.1%, with Hysterothylacium aduncum L3s; and 1.7%, with fourth-stage larvae (L4s) of Hysterothylacium sp. Horse mackerel from Mediterranean Sea coast ports (South and Southeast Spain) had the lowest levels of infection and those from Cantabrian Sea coast ports (North Spain) had the highest levels. Variations in infection levels with host size (age) and season of capture were surveyed.

Animals↗
PubMed2002

The trouble with sealworms (Pseudoterranova decipiens species complex, Nematoda): a review.

Sealworms or codworms, larvae of ascaridoid nematodes belonging to the Pseudoterranova decipiens species complex, infect the flesh of numerous species of marine and euryhaline fish, and have proven a chronic and costly cosmetic problem for seafood processors. Moreover, the parasite may cause abdominal discomfort in humans when consumed in raw, undercooked or lightly marinated fish. In this review, the phylogeny, life cycle and distributions of sealworms are discussed along with biotic and abiotic factors which may influence distributions of these parasites in their intermediate and final hosts. Also considered here are efforts to control the problem through commercial fishing practices, fish processing technology, and the reduction of infection parameters in marine fish populations by biological means. Ironically, concern over sealworm problem has subsided in some fisheries in recent years, not as a result of falling infection parameters in fish stocks or innovations in processing technology, but as a consequence of declines in abundance and size of groundfish.

Animals↗
PubMed2004

The occurrence of Contracaecum sp. larvae (Nematoda: Anisakidae) in the catfish Clarias gariepinus (Burchell) from Lake Chivero, Zimbabwe.

Clarias gariepinus were collected from Lake Chivero, Zimbabwe, and examined for nematode parasites from November 2000 to May 2002. Of the 202 specimens collected, 42.6% were infected with third-stage larvae of Contracaecum sp. in the body cavity. The intensity of the infection was 1-7 worms per fish (mean intensity = 2.2). Seasonal variation in the prevalence of the parasite was not obvious and there was no significant difference in the prevalence of infection between males and females (chi 2 = 2.228; P > 0.05). No significant relationship between host size and prevalence was established. There was also no significant relationship between intensity and the body condition factor (r = 0.11; P > 0.05). The low parasite prevalence may have been caused by the disruption of the infection cycle since piscivorous birds, which are the final hosts of the parasite, do not feed on C. garieplnus in Lake Chivero.

Animals↗