Suppression of the growth and metastasis of mouse melanoma by Taenia crassiceps and Mesocestoides corti tapeworms

Cancer is still one of the leading causes of death, with an estimated 19.3 million new cases every year. Our paper presents the tumor-suppressing effect of Taenia crassiceps and Mesocestoides corti on B16F10 melanoma, the intraperitoneal application of which followed the experimental infection with these tapeworms, resulting in varying degrees of effectiveness in two strains of mice. In the case of M. corti-infected ICR mice, a strong tumor growth suppression occurred, which was accompanied by a significant reduction in the formation of distant metastases in the liver and lung. Tapeworm-infected C57BL/6J mice also showed a suppression of tumor growth and, in addition, the overall survival of infected C57BL/6J mice was significantly improved. Experiments with potential cross-reaction of melanoma and tapeworm antigens with respective specific antibodies, restimulation of spleen T cells, or the direct effect of tapeworm excretory-secretory products on melanoma cells in vitro could not explain the phenomenon. However, infections with T. crassiceps and M. corti increased the number of leukocytes possibly involved in anti-tumor immunity in the peritoneal cavity of both ICR and C57BL/6J mice. This study unveils the complex interplay between tapeworm infections, immune responses, and melanoma progression, emphasizing the need for further exploration of the mechanisms driving observed tumor-suppressive effects.

Evaluation of brain injury in goats naturally infected with Coenurus cerebralis; brain specific biomarkers, acute inflammation, and DNA oxidation

This investigate goals are to establish the utility of brain-specific biomarkers (GFAP and S100B) in vivo and to assess the brain damage in C. cerebralis-infected goats using histopathological and immunopathological methods. The animal material of the study consisted of 10 healthy and 20 Coenurus cerebralis infected female hair goats. Serum GFAP and S100B concentrations were measured to determine brain damage. Serum S100B (p < 0.037), GFAP (p < 0.012), urea (p < 0.045), GGT (p < 0.001) and ALT (p < 0.001) concentrations in the C.cerebralis group were significantly higher than the control group. There was no significant difference between the C.cerebralis group and the control group for hsTnI (p > 0.078), creatinine (p > 0.099) and CK-MB (p > 0.725). In the histopathological examination, pressure atrophy and related inflammatory changes were observed due to mechanical damage of the parasite. Immunohistochemical examinations revealed that the parasite stimulated inflammation with the expression of TNF-α and caused DNA damage with the expression of 8-OHdG. As a result, when the data collected for this study are assessed as a whole, it is thought that the use of brainspecific GFAP and S100B biomarkers may be beneficial in determining brain damage in naturally infected hair goats with C.cerebralis. Changes in the levels of brain-specific biomarkers contribute significantly to determining the prognosis of the disease in vivo. Measurement of GFAP and S100B concentrations from serum offers an important alternative to the CSF method.

Molecular phylogenetic identification and morphological characteristics of Raillietina echinobothrida (Cestoda: Cyclophyllidea: Davaineidae) in commercial chickens in North China

Raillietina echinobothrida (R. echinobothrida) is one of the most pathogenic and prevalent tapeworms threat to the commercial chickens in China. However, there is a lack of research on their molecular identification and morphological characteristics. This study explored the molecular identification markers for R. echinobothrida in North China based on 18s ribosomal RNA (18s rRNA) gene and the ribosomal DNA second internal transcribed spacer (ITS-2) gene. The BLAST results of 18s rRNA (1643 bp) and ITS-2 (564 bp) gene sequences showed that the isolated intestinal tapeworms were R. echinobothrida. Phylogenetic trees obtained by maximum likelihood (ML) or neighbor-joining (NJ) method revealed that the R. echinobothrida in North China had the closest evolutionary relationship with the species found on the Qinghai-Tibet plateau, China. Morphological observations by hematoxylin staining and scanning electron microscope showed four round suckers and a retractable rostellum on the spherical scolex of R. echinobothrida. Two rows of alternately arranged hooks distributed around the rostellum. There were 30-40 testes in each mature segment. A well-developed cirrus pouch lied outside the excretory duct of mature segment. The gravid segment contained 200-400 eggs and there was a well-developed oncosphere in each egg. In addition, abundant ultrastructural features in mature proglottid of R. echinobothrida in North China were identified by transmission electron microscopy. In conclusion, the present study established ways of molecular phylogenetic identification for R. echinobothrida based on 18s rRNA and ITS-2 gene, and identified the morphological and ultrastructural characteristics of R. echinobothrida in North China.

Suppression of inflammatory genes expression in the injured host intestinal wall during Mesocestoides vogae tetrathyridium larvae migration

Mesocestoides vogae is a cestode parasite of the family Mesocestoididae (order Cyclophyllidea). Its larvae, tetrathyridium, are approximately 1 mm long and 300 μm wide and infect a wide range of host species including humans. Tetrathyridium migrate through the intestinal wall to invade the peritoneal cavity. Despite intestinal penetration by such a large-sized parasite, symptomatic intestinal disorders are not common during the migration period. In this study, the dynamics of tetrathyridia migration and their pathogenicity towards intestinal tissues were examined in mice infected orally with these parasites. Most tetrathyridia were found to migrate through the intestinal wall, moving into the peritoneal cavity or liver 24 to 48 hours after the oral infections. Next, the pathogenicity of tetrathyridium in the intestinal wall was histopathologically evaluated, and tissue injury from tetrathyridium migration was confirmed. Inflammatory foci were observed as tetrathyridium migration tracks from 48 hours after oral infection; however, the number of inflammatory foci had decreased by half more than 48 hours later. Therefore, we examined the gene expression levels of the macrophage driving cytokine, IL-1β, and the eosinophil recruiting chemokine, CCL11, by quantitative reverse-transcriptase PCR. The expression levels of these genes in the infected group were significantly lower than those of the non-infected group at 48 hours post-infection. Although the immunomodulating ability of the excretory-secretory products released from tetrathyridium has been previously shown by in vitro assays, the significance of this ability in their lifecycle has remained unclear. In this study, we discovered that tetrathyridium causes temporal inflammation in the intestinal wall during penetration and large-scale migration in this organ, but tetrathyridium simultaneously suppresses the host’s inflammatory gene expression, might to be a strategy that reduces inflammatory responses and increases survival of the parasite.

Excretory-secretory (ES) products are released by parasitic helminths into their migration sites and/or the intestinal regions they inhabit where parasite and host immune responses interact. ES products are release by a wide range of parasitic helminths, some of which are known to modulate the host’s immune system. Some ES products from some cestode parasites are known to reduce the production of pro-inflammatory cytokines from artificially stimulated cells under in vitro conditions. However, the immunomodulatory properties of the ES products have only been observed with in vitro experimental models and the biological consequences of their potential ability to suppress the host’s immune system during the parasite’s lifecycle and how they affect host–parasite interactions await discovery. Our results show that tetrathyridium, the larval stage of the Mesocestoides vogae cestode, strongly inhibits the host’s inflammatory gene expression in the injured intestinal wall, and that the inflammatory hot-spots caused by larval migration disappear almost immediately after mice are orally infected with these parasites. The ability to suppress the host’s inflammatory gene expression when larvae migrate through and damage the host’s tissues is an effective survival strategy for M. vogae intestinal parasites.

Anoplocephala perfoliata Infection in Horses in Iceland: Investigation of Associations Between Intensity of Infection and Lesions

In Iceland, there is at least 1 horse for every 5 human inhabitants, mostly kept on uncultivated rangelands. Although the Icelandic horse is considered robust compared with other breeds, it is nevertheless susceptible to disease. Few studies have investigated the prevalence of intestinal parasites in horses in Iceland. The purpose of this study was to determine the prevalence of the tapeworm, Anoplocephala perfoliata, in horses in Iceland and to explore associations between intensity of infection and the severity of macroscopic pathological lesions in this population. In addition, the relationship between infection and geographical location in Iceland, horse age, and gender were investigated. The utility of a modified McMaster flotation method for identifying infected horses from fecal samples was also studied. The study sample consisted of 104 horses (aged 1-30 yr) slaughtered in 3 abattoirs in North and South Iceland during June and July 2016. The prevalence of A. perfoliata in the horses was 64.4%, with between 1-131 worms found in infected horses. The pathological changes in the horses associated with infection varied from mild (hyperemia in small areas) to severe (large ulcers and necrotic lesions coated with fibrin), and intensity of infection correlated with the size and type of pathological lesions in the intestines. No statistically significant associations between infection with A. perfoliata and geographical location, horse age, or horse gender were detected. The McMaster egg counting method used here was of very low sensitivity (7.4%) and was concluded to be inadequate for detection of A. perfoliata infection in horses. The prevalence of A. perfoliata in horses in Iceland in this study was found to be relatively high compared with results from many studies performed elsewhere in Europe. This may reflect the lack of treatment of horses in Iceland for this parasite, the environmental suitability for the intermediate mite host, and grazing management practices in Iceland. The high prevalence and association with pathology suggest that diagnosis of infection using a sensitive method, along with appropriate treatment, should be considered for horses in Iceland.

Dynamics and effects of Ligula intestinalis (L.) infection in the native fish Barbus callensis Valenciennes, 1842 in Algeria

The dynamics of the emergence, duration, and decline phases in epizootic cycles are well known for humans and some crops, but they are poorly understood for host-parasite systems in the wild. Parasites may be particularly insidious as they are often introduced unintentionally, simultaneously with their hosts, and later transferred to species in the new location. Here we investigate the epizootic dynamics of the tapeworm Ligula intestinalis in the Hamiz reservoir, Algeria, and explore its effects on the cyprinid fish Barbus callensis. Regular sampling was conducted from October 2005 to February 2008 with intermittent surveys carried out until 2010. Five percent of the 566 specimens of B. callensis that were caught were infected, with the maximum number of parasites found in spring. There was no obvious difference in weight between uninfected fish and infected ones, and infection did not affect fish condition. However, infected fish were significantly longer than uninfected fish and had inhibited gonad development. The proportion of infected fish caught was significantly higher in year 1 and by the second winter, infection collapsed to zero. The Ligula infection thus appeared to have minimal ecological effects and be of a temporary nature, thus exhibiting an epizootic cycle. Taken together, our data indicates that this infection declined or even failed during our study period. Failure may be due to the specific genetic strain of Ligula, but invasive carp may also have been influential in both the introduction and subsequent decline of this parasite.

Experimental cerebral and non-cerebral coenurosis in goats: A comparative study on the morphological and molecular characteristics of the parasite

This experimental study was conducted to test whether cerebral and non-cerebral forms of Coenurus cerebralis belong to one origin or they are originated from two different tape worms. In the first step of the study, two groups of dogs were orally infected with the protoscoleces of cerebral and non-cerebral cysts and four months after infection, the adult worms were collected and morphologically characterized. Then the obtained eggs from two groups of adult worms were orally inoculated to two groups of goats to trace the predilection sites and also to compare the morphological and molecular characteristics of the larval stage of the parasites. The results showed that, both cerebral and non-cerebral coenuri, produced morphologically similar worms in the experimentally infected dogs. We observed only non-cerebral coenurus cysts in two groups of experimentally infected goats and the morphological characteristics of the cysts of two different groups were also similar. The molecular findings also showed that the cysts of two groups were 100% identical to each other based on the CO1 and nad1 sequences. In conclusion, our morphological and molecular findings reinforce the evidence that Taenia multiceps is the single origin of both cerebral and non-cerebral form of C. cerebralis but in goats, the cysts show more tendency to non-cerebral organs.

Reservoir hosts for Gyrodactylus salaris may play a more significant role in epidemics than previously thought

BACKGROUND

Gyrodactylus salaris Malmberg, 1957 has had a devastating impact on wild Norwegian stocks of Atlantic salmon Salmo salar L., and it is the only Office International des Epizooties (OIE) listed parasitic pathogen of fish. The UK is presently recognised as G. salaris-free, and management plans for its containment and control are currently based on Scandinavian studies. The current study investigates the susceptibility of British salmonids to G. salaris, and determines whether, given the host isolation since the last glaciation and potential genetic differences, the populations under test would exhibit different levels of susceptibility, as illustrated by the parasite infection trajectory over time, from their Scandinavian counterparts.

METHODS

Populations of S. salar, brown trout Salmo trutta L., and grayling Thymallus thymallus (L.), raised from wild stock in UK government hatcheries, were flown to Norway and experimentally challenged with a known pathogenic strain of G. salaris. Each fish was lightly anaesthetised and marked with a unique tattoo for individual parasite counting. A single Norwegian population of S. salar from the River Lærdalselva was used as a control. Parasite numbers were assessed every seven days until day 48 and then every 14 days.

RESULTS

Gyrodactylus salaris regularly leads to high mortalities on infected juveniles S. salar. The number of G. salaris on British S. salar rose exponentially until the experiment was terminated at 33 days due to fish welfare concerns. The numbers of parasites on S. trutta and T. thymallus increased sharply, reaching a peak of infection on days 12 and 19 post-infection respectively, before declining to a constant low level of infection until the termination of the experiment at 110 days.

CONCLUSIONS

The ability of S. trutta and T. thymallus to carry an infection for long periods increases the window of exposure for these two hosts and the potential transfer of G. salaris to other susceptible hosts. This study demonstrates that G. salaris can persist on S. trutta for longer periods than previously thought, and that the role that S. trutta could play in disseminating G. salaris needs to be considered carefully and factored into management plans and epidemics across Europe.

Cerebral and non-cerebral coenurosis in small ruminants

Cerebral coenurosis is caused by Coenurus cerebralis, the larval stage of Taenia multiceps. The metacestode causes severe lesions in the brain and spinal cord of the intermediate host, so-called "gid" or "stagger" disease. Whereas, the non-cerebral coenurosis caused by Coenurus gaigeri, the larval stage of Taenia gaigeri, particularly affects goats. The cyst form of the Taenia gaigeri is found in intramuscular and subcutaneous tissues. The difference in the sequence of mitochondrial genes of cox1 and nadI and also other variations reported for clinical, morphological and pathological aspects in coenurosis lead to the hypothesis that there is genetic intraspecific variability within this species, such as in other members of the genus Taenia. Nevertheless, it has been shown that sheep and goats have been infected by both cerebral and non-cerebral coenurosis and it has been suggested that such cerebral and non-cerebral metacestodes may belong to different species of Taenia which are host specific for these hosts.

Using community surveillance data to differentiate between emerging and endemic amphibian diseases

We analyzed submission data from a wildlife care group during amphibian disease surveillance in Queensland, Australia. Between January 1999 and December 2004, 877 white-lipped tree frogs Litoria infrafrenata were classified according to origin, season and presenting category. At least 69% originated from urban Cairns, significantly more than from rural and remote areas. Total submissions increased during the early and late dry seasons compared with the early wet season. Frogs most commonly presented each year with injury, followed by 'other', sparganosis and irreversible emaciation of unknown aetiology. This is the first report of Spirometra erinacei infection in this species. A high prevalence (28%) of visible S. erinacei infection was found in emaciated frogs, but this was not statistically different from that in non-emaciated diseased frogs (25%). However, 14 emaciated specimens that were necropsied all had heavy S. erinacei infections, and the odds of visible sparganosis were statistically greater in emaciated frogs compared with injured, non-diseased frogs. We provide a detailed case definition for a new endemic disease manifesting as irreversible emaciation, for which S. erinacei may be the primary aetiological agent. The lack of significant spatial or temporal patterns in case presentation suggests that this is not a currently emerging disease. We show that community wildlife groups can play a valuable role in monitoring disease trends, particularly in urban areas, but identify a number of limitations associated with passive syndromic surveillance. We conclude that it is critical that professionals be involved in establishing syndromic case definitions, diagnostic pathology, complementary active disease surveillance, and data analysis and interpretation in all wildlife disease investigations.

Histopathological and ultrastructural studies of the tapeworm Monobothrium wageneri (Caryophyllidea) in the intestinal tract of tench Tinca tinca

Monobothrium wageneri is a monozoic caryophyllidean tapeworm of tench Tinca tinca. The pathological changes caused by this parasite within the intestinal tract of wild tench are described for the first time. Parasites were found attached to the anterior third of the intestine in tight clusters comprising up to 109 tapeworms. Infection was associated with the formation of raised inflammatory swellings surrounding the parasites. This host response, combined with the deep penetration of the scolex into the gut wall, formed a very firm seat of parasite attachment. Histopathological changes were characterised by a pronounced fibrogranulomatous lesion that extended through all layers of the intestine. This was accompanied by haemorrhage, oedema, necrosis and degeneration of the muscularis. A marked eosinophilic interface layer between the scolex of the tapeworm and gut wall indicated intimate host-parasite contact. Ultrastructural examinations revealed coniform spinitriches covering the neck and lateral sides of the scolex and capilliform filitriches present on the apical end of the scolex. Numerous glandular cytons (tegumental glands) were recorded throughout the scolex tegument. Large numbers of secretory granules discharged from the glands through a network of processes onto the scolex surface were consistent with distancing the cellular responses of the host. Observations of severe inflammatory lesions, partial intestinal occlusion and the potential for intestinal perforation represent important pathological changes that are consistent with loss of normal gut function. The lesions associated with the attachment of M. wageneri are more severe than those recorded for any other tapeworm of British freshwater fish.

Pathological and ecological host consequences of infection by an introduced fish parasite

The infection consequences of the introduced cestode fish parasite Bothriocephalus acheilognathi were studied in a cohort of wild, young-of-the-year common carp Cyprinus carpio that lacked co-evolution with the parasite. Within the cohort, parasite prevalence was 42% and parasite burdens were up to 12% body weight. Pathological changes within the intestinal tract of parasitized carp included distension of the gut wall, epithelial compression and degeneration, pressure necrosis and varied inflammatory changes. These were most pronounced in regions containing the largest proportion of mature proglottids. Although the body lengths of parasitized and non-parasitized fish were not significantly different, parasitized fish were of lower body condition and reduced weight compared to non-parasitized conspecifics. Stable isotope analysis (δ¹⁵N and δ¹³C) revealed trophic impacts associated with infection, particularly for δ¹⁵N where values for parasitized fish were significantly reduced as their parasite burden increased. In a controlled aquarium environment where the fish were fed ad libitum on an identical food source, there was no significant difference in values of δ¹⁵N and δ¹³C between parasitized and non-parasitized fish. The growth consequences remained, however, with parasitized fish growing significantly slower than non-parasitized fish, with their feeding rate (items s⁻¹) also significantly lower. Thus, infection by an introduced parasite had multiple pathological, ecological and trophic impacts on a host with no experience of the parasite.

Variation in the reproductive potential of Schistocephalus infected male sticklebacks is associated with 11-ketotestosterone titre

Parasites can impact host reproduction by interfering with host endocrine systems, but the adaptive nature of such effects is disputed. Schistocephalus solidus plerocercoids are parasites of three-spined sticklebacks Gasterosteus aculeatus that are often associated with impaired host reproduction. Here, we relate reproductive behavior and physiology to levels of the androgen 11-ketotestosterone (11KT) in naturally infected and non-infected male sticklebacks from two UK populations. In one population infected males harbored heavy infections and showed uniformly reduced 11KT titres and kidney spiggin (nesting glue protein) content compared to non-infected fish. However in a second population infection levels were more variable and males with smaller infections recorded 11KT and spiggin titres that overlapped those of non-infected fish; among infected males from this population 11KT and kidney spiggin also both correlated negatively with infection severity. Male reproductive behavior correlated closely with 11KT titre in both populations, and infected males with high 11KT levels exhibited normal reproductive behavior. Our results suggest that Schistocephalus infection per se does not block reproductive development in male sticklebacks, and that some male fish may have the ability to breed whilst infected. Our results are not consistent with the hypothesis that Schistocephalus adaptively castrates male hosts via endocrine disruption; rather they support the hypothesis that reproductive disruption is a side effect of the energetic costs of infection.

The response of intestinal mucous cells to the presence of enteric helminths: their distribution, histochemistry and fine structure

Histochemical and ultrastructural investigations were conducted on the mucous cells of the intestine of brown trout, Salmo trutta L., naturally infected with the cestode Cyathocephalus truncatus (Pallas, 1781) and the acanthocephalan Echinorhynchus truttae Shrank, 1788. A subpopulation of 45 S. trutta were examined of which 15 specimens harboured E. truttae, 15 of which were infected with C. truncatus and 15 fish, the control group, were uninfected. In histological sections, hyperplasia and hypertrophy of the mucous cells were evident at the site of parasite infection. Enhanced mucus secretion was also recorded in infected fish. The number of mucous cells close to the site of parasite attachment within the intestine was significantly higher than the number detected in uninfected individuals and in infected individuals at sites 1 cm or greater from the point of parasite attachment. There were no significant differences between the number of mucous cells found at the latter two sites. Alcian blue and periodic acid-Schiff's staining of representative histological sections revealed a significant increase in the number of mucous cells staining positively for acid glycoconjugates compared to the number of cells found in the intestines of uninfected S. trutta. In transmission electron microscopy sections, each mucous cell typically possessed an elongated, basally positioned nucleus. The cytoplasm was observed to possess numerous electron dense and lucent vesicles, in addition to well-developed rough endoplasmic reticulum, Golgi apparatus and a few round mitochondria.

Proliferative peritoneal and pleural cestodiasis in a cat caused by metacestodes of Mesocestoides sp. Anatomohistopathological findings and genetic identification

A 10-year-old female cat was brought to Istituto Zooprofilattico Sperimentale delle Regioni Lazio e Toscana for post-mortem examination. The animal used to live, together with 26 other cats, in the big terrace of an apartment at the 8th floor in Rome; and was always fed with industrial pet food. Anamnesis referred balance troubles, vomit and convulsions, during a couple of days, followed by sudden death. At necropsy, the cat presented mucoid rhinitis, purulent tracheitis, small areas of pneumonia, dark spots in the liver, catarrhal-hemorrhagic gastritis, fibrinous enteritis and meningeal hyperemia. Thoracic and abdominal cavities were completely invaded by hundreds of larval stages of cestodes. The same parasites were also included in nodules in pancreatic, lung and kidney parenchyma. Microscopic examination of parasites allowed their identification as larval stages (metacestodes) of cestodes of the genus Mesocestoides. The molecular genotyping of the metacestodes indicates a close relationship with members of the genus Mesocestoides, although a significant variation was found with respect to the available sequences of other species of the genus.

Parasitic pulmonary eosinophilia

Parasitic infections, although common in tropical and subtropical regions, are prevalent worldwide because of changing immigration patterns and in international travel. The burden of worm infection is enormous and the intensity of infection is usually high among the poor and in immunocompromised individuals. Pulmonary eosinophilia occurs in almost all metazoan infections. In the Western world, the most common infections are caused by Strongyloides, Ascaris, Toxocara, and Ancylostoma species. Most of the nematodes multiply within the human host and cause pulmonary eosinophilia during larval migration through the lungs. Despite larval migration through the lungs, there is usually no permanent lung damage. The result is an increased number of eosinophils in the airways or lung parenchyma with or without peripheral eosinophilia. Löffler's syndrome, visceral larva migrans, and tropical pulmonary eosinophilia are the most common infections that cause pulmonary eosinophilia. The most serious parasitic eosinophilic lung disease is tropical pulmonary eosinophilia, a disorder caused by the filarial worms Wuchereria bancrofti and Brugia malayi, in which cases have typically been reported to masquerade acute or refractory bronchial asthma. Increasing awareness, newer diagnostic techniques, preventative measures, and antiparasitic drugs are important in reducing the worldwide morbidity and mortality from parasitic helminths and protozoa. This review focuses on common and some uncommon causes of pulmonary parasitic eosinophilia and their manifestations, diagnosis, and management.

Praziquantel and liposomized glucan-treatment modulated liver fibrogenesis and mastocytosis in mice infected with Mesocestoides vogae (M. corti, Cestoda) tetrathyridia

Beta-glucans are immunomodulators able to activate innate immunity and to potentiate acquired immune reactions. We investigated the impact of co-administration of liposomized beta-glucan on the larvicidal effect of the anthelmintic praziquantel (PZQ) in the livers and peritoneal cavities in mice infected with Mesocestoides vogae (M. corti). Also, within 2 weeks following therapy (up to day 29 p.i.) we examined collagen synthesis in the livers of mice by means of biochemical determination of hydroxyproline concentration, total mast cell counts and cell proliferative capacity using immunohistochemical and radiometrical methods. After co-administration of liposomized glucan (LG) and PZQ efficacy (%) was significantly higher than after treatment with either compound alone, particularly in the peritoneal cavity compared to the liver. In comparison with the control, more intense collagenesis was found in the B-liver parts (high intensity of infection) and lowering of collagen content in the A-parts (very weak infection). This effect was strongest after LG treatment and co-administration of PZQ abolished the pro-fibrotic effect of LG. In all groups, mast cell counts were higher in the B-liver parts than in the A-parts and the dynamics of mastocytosis was profoundly modulated following therapy. Whereas the effect of PZQ was only moderate, early and very strong onset was seen after LG treatment. Administration of PZQ suppressed LG induced-elevation of mast cells counts in both liver parts. Using DNA S-phase markers (BrdU and 3H-thymidine) the proliferative capacity was shown to be associated with several kinds of liver cells. Therapy significantly stimulated [3H]-thymidine incorporation (cell proliferation) only in the A-parts over that in control, the most after LG administration. In summary (i) the anthelmintic effect of PZQ could be enhanced after simultaneous administration of the immunomodulator beta-glucan entrapped in a liposomal carrier, (ii) intense mastocytosis seen after treatment with LG seems to have a direct role in the glucan's pro-fibrotic activity and can be abolished after co-administration of PZQ in a time-dependent manner, (iii) the pattern of cell proliferation indicates that in the case of PZQ treatment, the reparative processes of liver parenchyma are enhanced in an inverse correlation with the intensity of infection.

Mode of attachment and lesions associated with trypanorhynch cestodes in the gastrointestinal tracts of two species of sharks collected from coastal waters of Borneo

Lesions associated with two species of tapeworms within the digestive tract of wild-caught specimens of the bull shark, Carcharhinus leucas, and the sicklefin weasel shark, Hemigaleus microstoma, from Malaysian Borneo are described. Portions of the glandular stomach and pyloric gut with parasites were removed and fixed in 10% formalin buffered in sea water. Whole mounts, histological sections of tissues with and without worms in situ, and scanning electron microscopy images of detached worms were examined. Both species of cestodes belonged to the trypanorhynch family Tentaculariidae. Heteronybelinia estigmena was found in large numbers parasitizing the pyloric gut of C. leucas; an unidentified tentaculariid was found in relatively small numbers in both the glandular stomach and pyloric gut of H. microstoma. Both species burrowed their scoleces deeply in the mucosa and attached via hooked tentacles and unciniform microtriches of the scolex. The lesions induced by the parasites were marked in both sharks and ranged from acute necrotizing to chronic granulomatous gastroenteritis. Regenerative hyperplasia and intestinal metaplasia of gastric epithelium were also present. The severity and character of pathology was causally linked to the intensity of infection, the attachment mode of the parasites, and to the anatomophysiological relationships within the gut of the host shark.

[Bilateral bone perforation caused by Coenurus cerebralis in a sheep: case report]

Coenurus cerebralis is a cestode located in the brain and spinal cord of sheep that causes atrophy and perforation of the brain. In this study, a skull perforation caused by Coenurus cerebralis was reported in a sheep.

[Comparative cytopathological and histopathological studies of sheep with suspected Coenurus cerebralis infection]

Cerebrospinal fluid (CSF) smears were compared with brain imprints and histopathological sections of sheep with suspected Coenurus cerebralis infection. There was an increase of eosinophils, neutrophils, lymphocytes, phagocytic and epithelial cells in CSF smears. Similarly, purulent eosinophilic or necrotic-granulomatous infections were observed in histopathologic sections. Cytological exfoliation was similar to histopathological details and it was concluded that CSF cytology is useful as a pre-method in diagnosis of Coenurus cerebralis infection.

Changes in the neuromodulators of the diffuse endocrine system of the alimentary canal of farmed rainbow trout, Oncorhynchus mykiss (Walbaum), naturally infected with Eubothrium crassum (Cestoda)

A histopathological and immunohistochemical study on the intestines of 45 specimens of farmed rainbow trout, Oncorhynchus mykiss (Walbaum), from Loch Awe, Scotland, revealed a number of cellular deviations in individuals naturally infected with the pseudophyllidean cestode Eubothrium crassum (Bloch, 1779). Twenty-five individuals (55.5%) were infected with an average worm burden of 18.84 +/- 4.06 (mean +/- SE) cestodes per host (range, 2-80 worms; total 471 worms). The cestodes, measuring an average 8.23 +/- 1.10 cm (mean +/- SE; range, 5.3-13.0 cm) in length, were found attached by their scolices to the mucosal lining of the distal portion of the pyloric caeca. Within the caeca, the strobila evoked a mild catarrhal enteritis, namely an enhanced mucus production with epithelial cellular desquamation, a leucocytic infiltration of the lamina propria-submucosa and vacuolization of the intestinal epithelial cells. Eosinophilic granular cells of the stratum granulosum exhibited granular depletion, while within the catarrh, the presence of a high number of rodlet cells was noticed. Immunohistochemically, the occurrence of E. crassum caused a significant reduction in the number of bombesin-, gastrin-releasing peptide and glucagon-like immunoreactive endocrine cells, but an increase in the relative densities of endocrine cells containing cholecystokinin-8- and gastrin-like substances. There were, however, no significant differences in the number of endocrine cells that were immunoreactive to secretin, neuropeptide Y and peptide histidine-isoleucine antisera in the digestive tracts of either the infected or non-infected O. mykiss.

Neuroparasitic infections: cestodes, trematodes, and protozoans

Parasitic infection of the nervous system can produce a variety of symptoms and signs. Because symptoms of infection are often mild or nonspecific, diagnosis can be difficult. Familiarity with basic epidemiological characteristics and distinguishing radiographic findings can increase the likelihood of detection and proper treatment of parasitic infection of the nervous system. This article discusses the clinical presentation, diagnosis, and treatment for some of the more common infections of the nervous system caused by cestodes, trematodes and protozoans: Echinococcus spp., Spirometra spp. (sparganosis), Paragonimus spp., Schistosoma spp., Trypanosoma spp., Naegleria fowlerii, Acanthamoeba histolytica, and Balamuthia mandrillaris.

Ultrastructure of the spermatozoon of Raillietina (Raillietina) baeri (Cyclophyllidea, Davaineidae) an intestinal parasite of the multimammate rat, Mastomys huberti (Rodentia, Muridae)

The mature Raillietina (Raillietina) baeri spermatozoon exhibits an apical cone of electron-dense material about 2.5 microm long and 0.5 microm wide and two helicoidal crest-like bodies roughly 100-125 nm thick. The latter are of different lengths, spiralized and stand in an angle of about 50 degrees with the spermatozoon axis. The axoneme is of the 9 + "1" pattern and does not reach the posterior extremity of the gamete. The nucleus is an electron-dense cord coiled in a spiral around the axoneme. The cytoplasm exhibits a posterior densification and contains few small electron-dense granules in regions I, II and V of the spermatozoon. In regions III and IV, it is divided into irregular compartments by walls of electron-dense material. The cortical microtubules are spiralized and make an angle of 40-50 degrees to the spermatozoon axis. In this work, we describe, for the first time, a spermatozoon of a davaineidaean cestode parasitic of mammals. This has enabled us to show a wide apical cone, which has never been described before in a cyclophyllidean species the spermatozoon of which has two crest-like bodies.

Clinical, cytological and molecular evidence of Mesocestoides sp. infection in a dog from Italy

A 12-year-old, 13 kg, mixed-breed male dog was referred for anorexia and depression. The dog showed discomfort on abdominal palpation. Abdominal ultrasound examination revealed multiple, small, round anechoic cystic structures. Cystic fluid obtained with fine needle aspiration contained several 2-4 mm white motile flecks. Microscopic examination of the fluid revealed numerous irregularly shaped organisms measuring several hundred microns to 3 mm, the morphology of which was suggestive of intact and fragmented acephalic metacestodes of the genus Mesocestoides sp. Molecular analysis confirmed that the peritoneal infection was caused by Mesocestoides sp.

Histopathological changes caused by the metacestodes of Neogryporhynchus cheilancristrotus (Wedl, 1855) in the gut of the gibel carp, Carassius gibelio

Metacestodes of Neogryporhynchus cheilancristrotus (Wedl, 1855) were found in the gut of some gibel carp (Carassius gibelio) specimens from a Hungarian water reservoir. Location of metacestodes in the freshly opened gut was marked with disseminated, red-coloured, pinhead-sized nodules in the anterior part of the intestine. In histological sections, metacestodes were found in a hole inside the propria layer of the intestinal folds. The worms were in direct contact with the host tissue without being encapsulated as a result of host reaction. In some specimens with extruded rostellum the rostellar hooks were bored into the host tissue and suckers grabbed pieces of the surrounding connective tissue. Around the worms, congested capillaries and formation of macrophages were seen in the lysed connective tissue.

Epidemiology, clinical manifestations and diagnosis of zoonotic cestode infections: an update

This paper reviews the literature on zoonotic cestode infections with specific reference to the years 1999-2003. The sources and prevalence of various zoonotic tapeworm infections caused by adult and larval stages of the genera Taenia, Echinococcus, Diphyllobothrium, Hymenolepis and Dipylidium continue to be an important cause of morbidity and mortality, not only in most underdeveloped countries but also in industrialized countries, particularly in rural areas or among immigrant groups from endemic areas. The review gives a detailed report on recent molecular epidemiological studies on the taxonomy and phylogenetic variations in Echinococcus granulosus, immunological tests and imaging techniques used in epidemiological surveys and clinical investigations of important adult and larval tapeworm infections of animals and humans. Larval stages or metacestodes of Taenia solium, Echinococcus spp. and pseudophyllidean tapeworms (Spirometra syn. Diphyllobothrium spp.) may reside in various tissues of their intermediate hosts, including humans. In particular, Cysticercus cellulosae (T. solium) and the larvae of E. granulosus, and E. multilocularis, which are predominantly located in the liver, lungs and central nervous system forming various types of cysts, lead to a complex of systemic diseases such as cysticercosis, cystic echinococcosis and alveolar echinococcosis, respectively. Relatively rare clinical manifestations are seen in the muscles, subcutaneous tissue, spleen, kidneys, bones and body cavities.

Cestode parasites: application of in vivo and in vitro models for studies on the host-parasite relationship

Cestode worms, commonly also known as 'flat' worms or tapeworms, are an important class of endoparasitic organisms. In order to complete their life cycle, they infect intermediate and definitive hosts in succession, through oral ingestion of eggs or larvae, respectively. Serious disease in humans or other mammalian hosts is mostly caused by the larval stages. Echinococcus spp. and Taenia spp. have been extensively investigated in the laboratory due to the fact that they represent important veterinary medical challenges and also cause grave diseases in humans. In contrast, Hymenolepis spp. and Mesocestoides spp. infections are relatively rare in humans, but these parasites have been extensively studied because their life cycle stages can be easily cultured in vitro, and can also be conveniently maintained in laboratory animal hosts. Thus they are more easily experimentally accessible, and represent important models for investigating the various aspects of cestode biology. This review will focus on in vitro and in vivo models which have been developed for studies on the host-parasite relationship during infection with Echinococcus, Taenia, Hymenolepis, Mesocestoides and Spirometra, and will cover the use of these models to investigate the morphology and ultrastructure of respective genera, the immunological relationship with the host and the development of vaccination approaches, as well as applications of these models for studies on parasite metabolism, physiology and gene expression. In addition, the use of these models in the development of chemotherapeutic measures against cestode infections is reviewed.

Spatial and temporal changes in prevalence of a cloacal cestode in wintering waterfowl along the Gulf Coast of Texas

The cloacal cestode Cloacotaenia megalops is one of the most common helminths of waterfowl. We investigated the effect of this parasite on the body condition of wintering waterfowl populations and compared prevalence among age-sex classes, over time and between habitat types on the upper Gulf Coast of Texas (USA) from October 1986-February 2000. Greater than 9,500 birds of 25 waterfowl species were examined for the parasite. There was no statistical difference (P > 0.05) in body condition between birds with and without the parasite. Average prevalence was lowest for geese (mean = 3.7%) versus 21 to 71% in duck species. Average prevalence was similar (P = 0.81) between diving ducks (mean = 46.9%) and puddle ducks (mean = 43.9%). Prevalence varied among age-sex classes and was related to sex rather than age. Variation among age-sex classes suggests differences in diet between sexes of duck species on the wintering grounds. There was no evidence for declining prevalence over the wintering period. Prevalence differed (P < 0.05) between collection sites, and thereby habitat types, for several species. Temporal trends indicate stable prevalence of C. megalops for diving ducks and increasing prevalence for puddle ducks. The increasing trend for puddle ducks may indicate declining habitat conditions resulting in increased exposure to the intermediate ostracod host.

Cecal rupture by Anoplocephala perfoliata infection in a thoroughbred horse in Seoul Race Park, South Korea

A 7-year-old Thoroughbred horse was admitted to the Equine Hospital, Korea Racing Association with signs of colic. Based on the size of impactions, the clinical signs, the results of abdominal paracentesis and medical treatment, the prognosis was poor. The horse died 3 hours later following hopeless discharge. At necropsy, the caecum and large colon were fully filled with fecal contents and there was a rupture (10 cm in dia) in the latero- ventral caecum. The mucosa of the ileo-caecal and caeco- colic valves appeared to the hyperemic, edematous and ulcerous. There were many tapeworms in the affected mucosa. Histopathologically, lesions included hyperaemia, a deep necrotic inflammatory lesion and ulcers in the mucosa and submucosa of ileo-caecal and caeco-colic valves. One hundred thirty four faecal samples were obtained from 16 stables and submitted to parasitic examination. A total of 4 genera of eggs were recovered: Stongylus spp (82.1%), Anoplocephala perfoliata (10.5%), Bovicola equi (0.7%) and Parascaris equorum (1.5%). The major findings in this study are the presence of A perfoliata and its suspected association with the colic which led into an eventual caecal rupture. This study indicates the needs for an epidemiological survey of colic that is associated with Anoplocephala.

Murine hypodense eosinophils induce tumour cell apoptosis by a granzyme B-dependent mechanism

PURPOSE

Eosinophils have been shown to potentiate anti-tumour cytotoxicity in both clinical and animal studies. The mechanism by which eosinophils induce tumour cell damage, however, has largely been speculative. The purpose of this study was to identify the mechanisms involved in eosinophil-induced tumour cell cytotoxicity.

METHODS

To investigate eosinophil cytotoxicity, eosinophils were isolated from the peritoneal cavity of Mesocestoides corti-infected BALB/c mice, and were separated into normodense (ND) and hypodense (HD) populations using discontinuous Percoll density gradient centrifugation. The tumoricidal activity of ND and HD eosinophils was assessed using the [51Cr]-release cytotoxicity assay (a measure of cytolytic activity) and the JAM assay (a measure of apoptotic activity). Investigation of apoptosis-inducing molecules in HD eosinophils was undertaken by RT-PCR. The calcium chelator EGTA, serine protease inhibitor aprotinin and a competitive substrate for granzyme B were used to assess the role of perforin and granzyme B in HD eosinophil killing.

RESULTS

Cytotoxic activity induced by HD eosinophils was significantly greater than that of ND eosinophils, and apoptosis was the principal killing mechanism. RT-PCR analysis revealed that HD eosinophils express mRNA for perforin, granzyme B and Fas ligand. Furthermore, HD eosinophil killing was markedly inhibited by EGTA, intracellular aprotinin and the granzyme B competitive substrate.

CONCLUSIONS

These data are consistent with a hypothesis that murine HD eosinophils elicit tumoricidal activity via a granzyme B-dependent mechanism.

Eosinophilia and helminthic infections

Among microbial agents, helminths are the most common cause of eosinophilia. An approach to the evaluation of a patient with eosinophilia is outlined, with particular emphasis on clues in the history, examination and routine laboratory data that can help with the diagnosis. Multiple helminthic infections have been associated with eosinophilia, and the characteristic modes of spread, clinical manifestations, diagnostic tests and therapeutic considerations of these infections are discussed.

Cestodiasis with intestinal diverticulosis in a lesser flamingo (Phoeniconaias minor)

An adult female lesser flamingo (Phoeniconaias minor), caught in the African Rift Valley in 1991 and subsequently housed at the Baltimore Zoo, died of severe visceral gout in 1996. Necropsy revealed a white, moderately firm, nodular lesion, 1 cm in diameter, in the serosal wall of the small intestine. Although it was initially thought to be a tumor or focal granuloma, histologic examination revealed multiple cestodes deeply embedded at the base of the crypts between the intestinal villi, with their massive scolices (up to 3.4 mm in diameter) distending these spaces into multiple diverticulae. The mucosal epithelium surrounding the scolices was severely attenuated. Around the diverticulae, in the submucosa and muscularis, was a mild to moderate lymphocytic reaction and mild fibrosis. The proximity of multiple scolices and extensive invasion of host tissue suggested that the infection occupied a preexisting lesion. The cestodes were cyclophyllids but were distinct from any species previously reported from flamingos. Helminths should be included in differential diagnoses for gastrointestinal nodules in flamingos.

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.

Pathological alterations caused by Anoplocephala perfoliata infection in the ileocaecal junction of equids

The pathological alterations caused by Anoplocephala perfoliata in the ileocaecal junction of 28 equids slaughtered in an abattoir in Madrid (Central Spain) are described. The lesions were scored in grades based on the intensity of the damage and were related to the tapeworm number observed. The first grade (grade I) of alterations consisted of a slight enteritis associated with focal erosions observed in 43% of parasitized animals with low parasitic burden (1-26 tapeworms). The second grade (grade II) was a focal pseudomembranous enteritis, present in the ileocaecal junctions of 36% infected animals with moderate to high burden (23-188 tapeworms), and the third grade (grade III) was a regional necrotizing enteritis, present in the animals (21%) with the highest burden (72-248 tapeworms). The possible role of the lesions caused by this parasite in the aetiology of colic is discussed.

Histopathological reactions of the blue shark, Prionace glauca, to postlarvae of Hepatoxylon trichiuri (Cestoda: Trypanorhyncha: Hepatoxylidae) in relationship to scolex morphology

Postlarvae of the cestode Hepatoxylon trichiuri (Holten, 1802) were found attached to the surface of viscera of Prionace glauca (Linnaeus, 1758) taken from Atlantic coastal waters off the south coast of Massachusetts, USA. Gross anatomy of the attachment site shows a quadripartite rim surrounding a deep pit with holes corresponding to the penetration site of each tentacle. Hyperplasia of the liver capsule into outgrowths at the attachment site conform to the attachment of the bothridia. The cuboidal epithelium of the liver capsule became columnar forming papillary outgrowths, with a dense fibrotic reaction beneath the attachment site and infiltration by leukocytes and pigment containing granulocytic cells. Blood sinusoids beneath the attachment site are greatly enlarged. Postlarvae attached to the surface of the epigonal organs of three blue sharks were not accompanied by reactions. SEM examination of the scolex of H. trichiuri postlarvae revealed fused pairs of bothridia within infolded muscular lateral rims, porose tegument devoid of microtriches and a bilateral plane of symmetry in the tentacular armature.

Reliability of coprological diagnosis of Anoplocephala perfoliata infection

Three coprological methods were tested to establish the reliability of in vivo diagnosis of Anoplocephala perfoliata. A total of 107 faecal samples were analyzed, and the presence of tapeworms were confirmed postmortem in 24 animals with burdens that ranged from 1 to 248 worms; most of them (71%) with less than 100 parasites. Best results were obtained with a combination of two sedimentation/flotation methods, detecting only half the parasitized animals (54% sensitivity). No relationship could be established between tapeworm burden and egg detection, but results indicate that coprological methods have a lower likelihood of diagnosing cestode infection when horses have less than 100 tapeworms.

Postmortem investigations on winter stranded sperm whales from the coasts of Belgium and The Netherlands

During winter 1994-95, four and three sperm whales (Physeter macrocephalus) were stranded along the Belgian and the Dutch coasts, respectively. Necropsies and tissue samplings were collected 24 hrs post mortem. Lesions on several whales included round and linear skin scars, ventral skin abrasions, acute skin ulcers, acute ulcerative stomatitides, acute to chronic external otitides, and passive visceral congestion. In addition, these sperm whales appeared to be debilitated with severe weight deficit, had blubber thickness reduction, the absence of abdominal fat, and the intestinal tracts were almost empty. Three categories of lesions and their possible relation with the stranding were evaluated. Cutaneous scars observed on the seven whales appeared to have no relation with the stranding. The poor body condition and acute integument ulcerative lesions were present before the stranding. Ventral skin abrasions and visceral passive congestion were caused by the strandings. Absence of food in the alimentary tracts, evidence of weight loss and blubber thickness reduction were compatible with an extended presence of the sperm whales in the North Sea, where adequate food is not available. This might lead to progressive weakness, predisposing the animals to secondary pathogens such as viral diseases. Finally, the coastal configuration of the southern North Sea makes it a trap for sperm whales which have entered the area during their wanderings.

The distribution of Anoplocephala perfoliata in the intestine of the horse and associated pathological changes

The intestinal tracts of 130 horses were examined for infection with Anoplocephala perfoliata at necropsy. Fifty horses (38.5%) harboured the tapeworm, and the site of attachment of each worm was recorded using predetermined anatomical landmarks. The worms were attached in four regions of the gastrointestinal tract: 17% of the worms were found at the ileocaecal junction, 81% on the caecal wall, 1.7% in the terminal ileum and 0.2% in the ventral colon. The severity of lesions produced at the sites of attachment was related to the number of worms attached. Due to the small area of the ileocaecal junction, worms at this site were attached in close proximity, resulting in more severe lesions. The major features of the lesions included ulceration, diphtheritic membranes and thickening of the mucosa, submucosa and lamina propria. There was an increase in the number of eosinophils and a decrease in the number of lymphocytes present at the sites of lesions.

The effect of Gyrodactylus salaris (Monogenea) on the epidermis of Atlantic salmon, Salmo salar, parr in the river Batnfjordselva, Norway

Skin morphology of Atlantic salmon, Salmo salar, parr infected with Gyrodactylus salaris was examined for 3 yr in the river Batnfjordselva in Norway and compared to that of uninfected salmon parr from a neighboring river. The epidermis of the infected population had more cell layers and was thicker than the epidermis of parr from the uninfected population. The number of mucous cells did not differ, and no seasonal changes in morphology of the epidermis were detected in either rivers. Intensity of G. salaris did not correlate to epidermal thickness, epidermal cell layers, or mucous cell concentration.

Ultrastructure of spermiogenesis and the spermatozoon of Nomimoscolex sp. (Cestoda, Proteocephalidea) intestinal parasite of Clarotes laticeps (Fish, Teleost) in Senegal

Spermiogenesis in Nomimoscolex sp. begins with the formation of a differentiation zone delimited at the front by arched membranes. It is bordered by cortical microtubules and contains two centrioles surmounted each by striated roots. The latter are linked together at their bases by a thin layer of electron-dense material. The two centrioles give each a flagellum that rotates and fuses with the median cytoplasmic extension. The nucleus elongates, becomes filiform and migrates between the axonemes in the cytoplasmic extension. During the nuclear migration, crested-like bodies form. After the migration of the nucleus, the old spermatid separates from the residual cytoplasm by strangulation of the ring of arched membranes. The mature spermatozoon of Nomimoscolex sp. lacks mitochondria, is filiform and tapered at both its extremities. Its anterior end exhibits an apical cone of electron-dense material and three crested-like bodies of unequal length coiled in a spiral on its periphery. The axoneme is of the 9 + 1' pattern. The cortical microtubules are parallel to the spermatozoon axis. The nucleus is a fibrous cord of partly condensed chromatin. The cytoplasm is slightly dense but contains many electron-dense granules in regions II and III of the spermatozoon. Crested-like bodies and striated roots linked together by an electron-dense material have never been reported during the spermiogenesis in a proteocephalidean. In addition we describe for the first time the existence of three crested-like bodies in the Proteocephalidea.