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Production and characterization of monoclonal antibodies against excretory/secretory products of adult Echinococcus granulosus, and their application to coproantigen detection.

Two IgM murine monoclonal antibodies (MAbs), EgC1 and EgC3, were produced against the excretory/secretory (E/S) products of Echinococcus granulosus adult worms. Immunoblotting revealed that both predominantly recognized a 50 kDa antigen in the somatic extract and an 85 kDa component in the E/S products. Immunolocalization showed that both MAbs reacted with the tegument of the parasite, and additionally EgC3 reacted with parenchyma and the tegument lining the external surface of the reproductive organs. A coproantigen capture ELISA was developed using a rabbit polyclonal antibody against E/S products from adult tapeworms as catching antibodies, and each one of MAbs as detecting antibody. The assays detected seven out of eight (EgC1), and eight out of eight (EgC3) experimentally infected dogs (worm burdens ranging from 61 to 57,500), using heat-treated samples obtained at prepatent period, and none (n=8) of helminth-free samples. Time course analysis showed that, after a 12-25 days lag, coproantigen levels rose above cut off O.D. values and typically peaked around 30 days post-infection (DPI) at the end of the experiment. One dog experimentally infected with Taenia hydatigena metacestodes was slightly detected as positive at different time points after 30 DPI. Both MAbs showed a similar pattern of recognition, but T. hydatigena antigens were undetectable for a longer period, and reached lower O.D. values with EgC1. Interestingly, fecal samples from two experimentally infected dogs with Echinococcus multilocularis were not recognized by the EgC1 assay, suggesting a potential value as species-specific diagnostic tool.

Animals↗

Genetic variation in Taenia solium.

Neurocysticercosis is a major zoonotic larval cestode infection that has a worldwide distribution and is of significant public health importance. Knowledge of the genetic structure of Taenia solium can be applied to the epidemiology and transmission of this disease, since genetic variants may differ in infectivity and pathogenicity. Molecular epidemiological approaches can also enable detailed studies of transmission. On a global scale, mitochondrial markers have differentiated between T. solium isolates from Asia and isolates from Africa/Latin America. Intraspecific variation in T. solium has been detected to some extent, using RAPD markers to differentiate between T. solium populations from different regions within Mexico. Markers currently available for T. solium have not been used to analyse genetic variation at the community or local level. The development of highly polymorphic markers such as microsatellites in T. solium can provide the means to examine genetic heterogeneity of tapeworm infection at the household, community and regional level. Preliminary studies suggest it is possible to analyse population genetic variation in communities using a range of polymorphic markers.

Animals↗

Transmission dynamics of Taenia solium and potential for pig-to-pig transmission.

Taenia solium taeniasis/cysticercosis is one of few potentially eradicable infectious diseases and is the target of control programs in several countries. The larval stage of this zoonotic cestode invades the human brain and is responsible for most cases of adult-onset epilepsy in the world. Our current understanding of the life cycle implicates humans as the only definitive host and tapeworm carrier, and thus the sole source of infective eggs that are responsible for cysticercosis in both human and pigs through oral-faecal transmission. Here we review transmission dynamics of porcine cysticercosis including an alternative pig-to-pig route of transmission, previously not suspected to exist. Second-hand transmission of T. solium eggs could explain the overdispersed pattern of porcine cysticercosis, with few pigs harbouring heavy parasite burdens and many more harbouring small numbers of parasites.

Animals↗

WHO classification of alveolar echinococcosis: principles and application.

Alveolar echinococcosis is caused by the larval stage of the fox tapeworm (Echinococcus multilocularis) and is frequently diagnosed as a space occupying lesion in the liver. The growth pattern resembles that of a malignant tumor with infiltration throughout the liver, spreading into neighbouring organs and metastases formation in distant organs. Thus, one of the prevailing differential diagnoses is liver cancer. Guided by the Tumor-Node-Metastasis (TNM) system of liver cancer, the European Network for Concerted Surveillance of Alveolar Echinococcosis and the WHO Informal Working Group on Echinococcosis proposed a clinical classification for alveolar echinococcosis. It was designated as PNM system (P = parasitic mass in the liver, N = involvement of neighbouring organs, and M = metastasis). As for TNM in oncology, single PNM categories were combined into four stages, I to IV. The system was developed by a retrospective analysis of 97 patients' records from two treatment centers (Besançon/France and Ulm/Germany). Recently, this WHO classification was applied to 222 patients in 4 clinical centers around the world (Besançon/France, n = 26; Urumqi/China, n = 46; Sapporo/Japan, n = 58; and Ulm/Germany, n = 92). All patients could be classified who had been diagnosed in the period from January 1998 to June 2005. The stage grouping indicated center differences, but appeared to segregate patients according to various treatment regimens. The WHO classification not only serves as a tool for the international standardization of disease manifestation but also aids to evaluate the outcome of a chosen diagnostic and treatment procedure in different treatment centers in Europe and Asia.

Animals↗

Taeniasis/cysticercosis trend worldwide and rationale for control.

Pig production has increased significantly worldwide in recent years. Small-scale pig husbandry has become a popular source of income in rural and resource-poor communities in most of developing countries. A parallel increase of human Taenia carrier and human cysticercosis is expected but detailed data are not available. However, Taenia solium is considered responsible for over 10% of acute case admission to the neurological ward of countries where it is endemic. The control strategy that seems at the moment more promising is a combination of the different tools available and includes the identification of areas at high risk and the presumptive treatment of the suspected cases and their families. This active finding and treatment of probable tapeworm carriers should be accompanied by health education and control swine cysticercosis. WHO invites all endemic countries to recognize the importance of taeniasis/cysticercosis control and to collect epidemiological data and to adopt policies and strategies for its control.

Animals↗

Phylogeny of Taenia: Species definitions and origins of human parasites.

Phylogeny is fundamental as it constrains explanations about history and forms our foundation for recognizing and diagnosing species. In the absence of such a framework taxonomists historically relied on intuitive processes, personal judgment and authority, often embracing a typological view of species that disregarded otherwise unequivocal historical and biological criteria. Species of Taenia are among the most characteristic tapeworms infecting carnivores and humans as definitive hosts and indeed Taeniidae is unique among the Eucestoda in requiring 2 obligate mammalian hosts for transmission; a high percentage (>80%) of life cycles have been completely elucidated among the approximately 45 species and nominal subspecies of Taenia. Until recently there had been no comprehensive attempts at reconstruction of a phylogeny among these important parasites. Such analyses have allowed us to explore the origins and evolution of those independent species of Taenia that occur in humans (T. saginata, T. asiatica, and T. solium) and to understand the ecological and historical processes serving as determinants of biogeography and host-association. These studies supported the status of T. asiatica as a valid species and diagnosed a relationship as the sister-species of T. saginata. These conclusions contrasted with a diversity of opinions that would subsume T. asiatica as a subspecies. Recognition of a species constitutes a specific and testable hypothesis, is not an arbitrary decision and is most appropriately assessed in the context of phylogenetic or historical data. Considering macrospecies, a process has been outlined by Brooks and McLennan [Brooks DR, McLennan DA. The nature of diversity: an evolutionary voyage of discovery. University of Chicago Press: Chicago; 2002] as follows: (1) Discovery: a systematist describes the species; (2) Phylogenetic reconstruction; (3) Evaluation I: do sister-species show geographical overlap-are they sympatric or allopatric (use phylogeny+geographical distributions)? (4) Evaluation II: are sister-species reproductively isolated based on information from natural history, ecology and reproductive biology? Species may be viewed in the context of microevolutionary and macroevolutionary processes. For instance, microspecies are defined in ecological time and involve populations and contemporary process that are potentially reversible (reticulate). In contrast, macrospecies as exemplified by T. saginata and T. asiatica are divergent lineages resulting from processes in evolutionary time where an ancestor has undergone a permanent split that is non-reversible (non-reticulate). Applying these criteria in evaluation of T. saginata and T. asiatica, it becomes clear that in evolutionary time these represent historical lineages with independent spatial and temporal trajectories, having separated from a common ancestor near 0.78 to 1.71 MYBP in Africa, or Eurasia. In ecological time, sympatry, reproductive isolation, and differences in life history evident for T. saginata and T. asiatica as observed in China, and perhaps other regions of Southeast Asia, further serve to validate these taeniids.

Animals↗

Taeniasis/cysticercosis in Papua (Irian Jaya), Indonesia.

Reports showed that an important parasitic zoonotic disease caused by Taenia solium, Taenia saginata and Taenia asiatica is found endemic in several areas of Indonesia including Papua, Bali and North Sumatra. At present it is known that the highest prevalence of taeniasis/cysticercosis in Indonesia, caused by T. solium is among the indigenous communities in Papua (formerly Irian Jaya). In the early 1970s, 8-9% of stool samples from the Enarotali hospital, Paniai District (Irian Jaya) were found positive with Taenia eggs. The samples were from members of the Ekari (Kapauku) ethnic group. Stool samples from the Moni ethnic group, living east of surrounding lakes, were egg negative. Cysticerci of T. solium were discovered in pigs. During the years 1973-1976 cases of burns increased and were ultimately found to be primarily associated with epileptic seizures induced by neurocysticercosis cases. Among 257 cases of burns, 88 cases (62.8%) were suffering from epileptic seizures before or during hospitalization. In the year 1981 T. solium seropositive persons were mostly (16%) found in the endemic Obano village. In 1997 the parasite was discovered in Jayawijaya District, which is located approximately 250 km east of Paniai District. During 1991-1995, a local health center in Assologaima, Jayawijaya District reported 1120 new cases with burns and a further 293 new cases of epileptic seizures among 15,939 inhabitants. The histopathologic appearance and mitochondrial DNA analysis found the cysts to be similar to those of T. solium from other regions of the world. Sensitive and specific serological diagnostic methods were used and improved. Cysticerci were detected in dogs, as well as in pigs. A coproantigen test for detection of adult tapeworms in patients was carried out. Medical treatment with praziquantel for taeniasis and albendazole for cysticercosis (with prednisone and sodium phenytoin treatment in cases with neurocysticercosis) was undertaken. Lifestyle, religion, and socioeconomic aspects are important issues in the perpetuation and enhancing the endemicity of T. solium taeniasis and cysticercosis in Papua, Indonesia.

Animals↗

Imaging aspects and non-surgical interventional treatment in human alveolar echinococcosis.

Alveolar echinococcosis (AE) of the liver caused by the metacestode of the fox tapeworm Echinococcus multilocularis is characterized by a multivesicular structure surrounded by an extensive fibro-inflammatory host reaction. The lesions behave like a slow-growing liver cancer, without sharp limits between the parasitic tissue and the liver parenchyma. Invasion of biliary and vascular walls is another hallmark of this severe disease. Moreover, the poor vascularization of the parasitic mass often leads to necrosis in the central part of the lesion. This explains why liver abscess due to superimposed bacterial infection of the necrotic area may occur in this disease. Currently, a range of imaging techniques can be used at the different stages of management of AE. For diagnosis, ultrasonography remains the first line examination. For a more accurate disease evaluation, aiming to guide the surgical strategy, computerized tomography, Magnetic Resonance (MR) imaging, including cholangio-MR imaging are of importance, providing useful complementary information. More recently, Positive-Emission Tomography using [18F] fluoro-deoxyglucose has been developed for the follow-up of inoperable AE patients under long-term benzimidazoles therapy. This approach seems very promising to assess inflammatory activity and thereby to indirectly depict parasitic activity. Non-surgical interventional procedures, mainly percutaneous biliary and/or centro-parasitic abscesses drainages, are currently a major aspect in the care of incurable AE patients and have largely contributed to the improvement of survival in this situation during the past 20 years. They may also be used as a bridge before a curative surgical procedure in symptomatic patients presenting a life-threatening bacterial and/or fungal infection. It is also very useful in inoperable patients to overcome similar infectious episodes.

Animals↗

Exploratory spatial relative risk mapping.

The many faces of disease mapping include maps of disease case locations, regional counts of cases, and disease risk. Another approach is that of mapping the relative risk. Previous methods to map the relative risk were based on regression models of relative risk, given information about geographical locations and established risk factors. However, spatial epidemiological investigations are often exploratory with limited knowledge about the putative risk factors. Indeed, often the primary motivation for the analysis is to identify unknown geographically varying risk factors. An exploratory approach to mapping the spatial relative risk is to scale the risk map using the background risk in the unexposed (or less-exposed) population. Exposure to unknown spatial risk factors is defined via specific cluster analysis. Identification of spatial disease clusters separates the population into those inside and those outside high risk areas (the exposed and unexposed populations). This exploratory approach to relative risk mapping gives the investigator an impression about the importance and geographical distribution of the unknown spatial risk factors. Two examples illustrate the exploratory relative risk mapping approach using a spatial point data set on pseudorabies in pig-herds and a regional count data set on small fox tapeworm infections in red foxes.

Animals↗

Spatial spreading of Echinococcus multilocularis in Red foxes (Vulpes vulpes) across nation borders in Western Europe.

The occurrence of the fox tapeworm Echinococcus multilocularis in Red foxes was studied in Belgium and a neighbouring region in The Netherlands. A total number of 1202 foxes were analysed (1018 in Belgium and 184 in The Netherlands) of which 179 were infected with E. multilocularis (164 in Belgium and 15 in The Netherlands). Further, the spatial distribution of infection among sampled foxes was analysed with an ellipsoidal gradient, demonstrating a decreasing prevalence in northwestern direction. Using this gradient, we showed that the spatial patterns of infection in Belgium and the neighbouring region in The Netherlands correspond, indicating a continuous distribution of E. multilocularis across the nation borders. Part of the Belgian data allowed investigating temporal changes in the spatial distribution of E. multilocularis. This revealed a northwestern spread of E. multilocularis.

Animals↗

Wilderness in the city: the urbanization of Echinococcus multilocularis.

A distinct increase in fox populations, particularly in urban areas, has been observed in Europe. This is of particular concern in endemic regions of the small fox tapeworm Echinococcus multilocularis, the aetiological agent of human alveolar echinococcosis. Novel tools have facilitated the investigation of the ecology of urban foxes and have demonstrated the urban wildlife cycle of E. multilocularis. Such studies are essential for estimating the risk of transmission to humans and to determine the basics for the development of control strategies.

Animals↗

Coexistence of salivary gland cysticercosis with squamous cell carcinoma of the mandible.

Cysticercosis is a parasitic infestation caused by the pork tapeworm larval stage, Cysticercus cellulosae. The majority of the cases present in ocular, cerebral, and subcutaneous locations. We report the presence of cysticercosis inside the submandibular gland in association with squamous cell carcinoma of the inferior alveolar ramus of the mandible. To the best of our knowledge, this is the first case report documenting cysticercosis inside a salivary gland. A 65-year-old male presented with complaints of an ulcerative lesion on the inferior alveolar ramus present for 2 months. Histological examination revealed a keratinizing well-differentiated squamous cell carcinoma involving the alveolar margin and mandible. The histopathological examination of the submandibular gland revealed cysticercosis. This case emphasizes the importance of adequate sampling of all the tissues obtained for associated infectious disorders, more so in immunosuppressed patients, which will help the clinician to manage the case appropriately.

Aged↗

High prevalence of Taenia saginata taeniasis and status of Taenia solium cysticercosis in Bali, Indonesia, 2002-2004.

An epidemiological survey of taeniasis/cysticercosis was carried out in one semi-urban and two urban villages in three districts of Bali, Indonesia in 2002 and 2004. In total, 398 local people from 247 families were diagnosed by anamnesis and clinical examinations, and 60 residents were suspected to be taeniasis carriers. Among 60 suspected carriers, 56 persons expelled a total of 61 taeniid adult worms after praziquantel treatment. From 398 residents, 252 stool samples were available for analysis of taeniid eggs, coproantigens or copro-DNA for identification of taeniid species, and 311 serum samples were available for detection of antibodies against Taenia solium cysticercosis. Taeniasis prevalences were highly variable among three villages (1.1-27.5%), and only one case of cysticercosis due to T. solium infection was detected. All expelled tapeworms were confirmed to be Taenia saginata by mtDNA analysis. There was no Taenia asiatica human case in Bali. Case control analysis of 106 families chosen at random from 179 families in 2004 and another 106 families from non-endemic areas revealed that risk factors of T. saginata taeniasis for families were: level of education (P<0.01); consumption of beef lawar (P<0.01); and the source of lawar (P<0.01).

Adolescent↗

Improvement of the synthetic tri-peptide vaccine (S3Pvac) against porcine Taenia solium cysticercosis in search of a more effective, inexpensive and manageable vaccine.

Vaccination of pigs may curtail Taenia solium transmission by reducing the number of cysticerci, the precursors of adult intestinal tapeworms in humans. Several antigen preparations induce protection against porcine cysticercosis in experimental settings but only one subunit vaccine (S3Pvac) has been tested and proved effective in the field against naturally acquired disease. Besides improving of the vaccine's effectiveness, significant reductions in production costs and in the logistics of its administration are necessary for the feasibility of nationwide control programs. This review highlights the development of several versions of S3Pvac aimed to increase effectiveness, reduce costs and increase feasibility by novel delivery systems and alternative routes of administration.

Animals↗

Local and systemic immune responses to Echinococcus granulosus in experimentally infected dogs.

Local and systemic immune responses were studied in six dogs experimentally infected with the dog/sheep tapeworm Echinococcus granulosus. All dogs developed similar IgG antibody response to parasite antigens. In contrast, IgE and IgA responses differed widely. No relationship between IgA responses and parasite burden at the end of the infection were observed. Further, clear differences in the anti-parasite IgA response in serum as compared with specific IgA forming cells in mesenteric lymph nodes were observed within the same dog. An inverse association of anti-parasite IgE and parasite load seemed to be present, with the strongest IgE response in the one dog that had no worms in the intestine at the end of the experiment. No differences were observed in the numbers of intestinal mast cells and goblet cells among all infected dogs. However, the dog with no detectable parasite load had a marked reduction of detected mast cells in the submuscular and muscular layer of the mucosa. Our data give new insight into the immune response of dogs during E. granulosus infection and provide information that may be useful for the rational design of vaccines for the control of hydatid disease.

Animals↗

A multicenter evaluation of the effectiveness of Quest Gel (2% moxidectin) against parasites infecting equids.

Controlled trials with a common protocol were conducted in Idaho, Illinois and Tennessee to evaluate anthelmintic effectiveness of Quest Gel (QG; 2% moxidectin) against lumenal parasites in horses. Candidate horses were required to have naturally acquired nematode infections, as confirmed by presence of strongylid eggs in feces. At each site, 24 equids were blocked on the basis of pretreatment strongyle fecal egg counts (EPG) and randomly assigned to treatments within blocks. Within each block of two animals, one received QG on Day 0 at a dosage of 0.4 mg moxidectin/kg b.w. and one was an untreated control. Body weights measured the day before treatment served as the basis for calculating treatment doses. Horses assigned to treatment with QG received the prescribed dose administered orally with the commercially packaged Sure Dial syringe. Horses were necropsied 12-14 days after treatment, and lumenal parasites and digesta were harvested separately from each of five organs, including the stomach, small intestine, cecum, ventral colon and dorsal colon. Parasites from stomachs and small intestines were identified to genus, species and stage. Micro- (i.e., < 1.5 cm) and macroparasites (i.e., > 1.5 cm) in aliquots from the cecum, ventral colon and dorsal colon were examined in aliquots of approximately 200 parasites until at least 600 parasites had been identified to genus, species and stage or until all parasites in the 5% aliquot were examined, whichever occurred first. Data were combined across sites and analyzed by mixed model analysis of variance to assess the fixed effect of treatment and random effects of site and block within site. Because QG does not contain a cestocide, efficacy of QG against tapeworms was not significant (P > 0.05). Based on geometric means, however, efficacy of QG was greater than 90% (P < 0.05) against 38 species and developmental stages of cyathostomes, strongyles, bots, larval pinworms and ascarids encountered in at least 6 of 36 control horses in the combined data set. None of the horses treated with moxidectin exhibited evidence of adverse effects. Study results demonstrate QG, administered to horses with naturally acquired endoparasite infections at a dosage of 0.4 mg moxidectin/kg b.w., was highly effective against a broad range of equine parasitic infections.

Analysis of Variance↗

Dose-confirmation studies of the cestocidal activity of pyrantel pamoate paste in horses.

Dose confirmation studies of the cestocidal activity of pyrantel pamoate paste were conducted at two sites in North America during 2001. Horses with naturally-acquired cestode infections were identified by detection of typical Anoplocephala spp. eggs in feces collected between 7 and 92 days prior to treatment. Twenty and 22 horses were enrolled at Site 1 (Urbana, IL) and Site 2 (Knoxville, TN), respectively. Candidate horses were acclimated to study conditions for 14 days, ranked by length of interval since coprologic confirmation, and allocated randomly to one of two treatment groups: (T1) pyrantel pamoate paste 13.2mg pyrantel base per kilogram body weight administered orally, and (T2) untreated controls. Individual doses of pyrantel pamoate paste were prepared on the basis of contemporaneous body weights and administered to Group T1 horses on Day 0. Trained personnel monitored the animals at regular intervals after treatment to detect potential adverse reactions. Horses were euthanatized and necropsied 10-12 days after treatment. The contents of the large and small intestines were collected, and the walls of each organ were rinsed with water and inspected. Attached cestodes were recovered and preserved in 10% formalin. The intestinal contents and rinsed ingesta were washed over a #10-mesh (2mm aperture) sieve and tapeworms were extracted and preserved. Recovered cestodes were counted and examined at 1-4x magnification for identification to genus and species. At Site 1, specimens of Anoplocephala perfoliata were recovered from seven of 10 control horses, and from one of 10 horses treated with pyrantel pamoate. Mean cestode numbers were 4.52 in the control group and 0.07 for treated horses. At Site 2, cestodes were found in 10 of 11 controls (mean 26.2) and in five of 11 horses (mean 1.2) treated with pyrantel pamoate. In both studies, Group T1 means were significantly lower than the control group (P<0.005). The calculated efficacies were 98.4 and 95.5% at Sites 1 and 2, respectively. In two dose-confirmation studies, a single, oral treatment of pyrantel pamoate paste (19.13% w/w pyrantel base) at 13.2mg/kg was >or=95.5% effective against A. perfoliata in naturally-infected horses.

Animals↗