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PubMed1997

Basic and applied immunology in cestode infections: from Hymenolepis to Taenia and Echinococcus.

In larval cestode infections, it is well established that the intermediate mammalian host infected with egg-derived metacestodes in the tissue becomes completely immune to reinfection with eggs, whereas autoinfection has been conceived to occur in Hymenolepis nana/mouse (and human) and Taenia solium/human systems when these hosts are initially infected with metacestode-derived adult tapeworms in the lumen. In this review paper, the first topic is immunobiology of H. nana/mouse system on the reinfection immunity in order to get critical information as to how the initially ingested parasite (eggs or metacestodes) can develop into adult worms and how autoinfection does or does not occur in immunocompetent mice, since H. nana can complete its whole life cycle in the mouse intestinal tissue and lumen. When mice are infected with eggs (= oncospheres) of H. nana, they become immune to challenge infections with eggs within a few days (early response) and with cysticercoids within two weeks (late response). The initially established adult worms are expelled later (worm expulsion response). When mice are infected with cysticercoids, either derived from beetles or mice, they become immune to challenge infection with cysticercoids but not with eggs. Therefore, autoinfection occurs in the intestinal tissue for the establishment of cysticercoids in the tissue but never occurs in the intestinal lumen for the establishment of adult worms in immunocompetent mice. The second topic is vaccination trial against challenge infection with eggs of Asian Taenia in pigs. Pigs vaccinated with frozen oncospheres of Asian Taenia from Taiwan or Korea or T. saginata showed very strong resistance, whereas pigs vaccinated with those of T. solium showed partial resistance only. It is suggested that Asian Taenia is much closer to T. saginata than T. solium from the immunobiological viewpoint. The third topic is immunodiagnosis of echinococcosis and cysticercosis. Immunoblot analysis has revealed that Em18 (18 kDa component of crude antigens of Echinococcus multilocularis protoscolex) and glycoproteins of T. solium cysticerci are highly specific or unique to alveolar echinococcosis and cysticercosis, respectively. The fourth topic is discussion on miscellaneous prospects including laboratory animal models for echinococcosis and cysticercosis.

Animals↗
PubMed1997

Echinococcus granulosus myophilin--relationship with protein homologues containing "calponin-motifs".

Myophilin, a smooth-muscle protein of the tapeworm Echinococcus granulosus, was recently postulated to be a member of the calponin family of proteins. A detailed genetic analysis revealed that 17 proteins had significant homology with the amino-acid sequence of the N-terminal region of myophilin and/or possessed one or more "calponin-motifs". Comparison of the amino-acid sequences of the N-terminus showed that the homologous proteins clustered into distinct groups based on the number of calponin-motifs. The calponin-motif of myophilin was genetically more similar to that present in the muscle protein mp20 of Drosophila melanogaster than to those in any other homologous proteins of vertebrates. The existence of a distinct motif which is "conserved" in other proteins across a range of species suggests an important functional role for the motif.

Amino Acid Sequence↗
PubMed1997

The Interplay between Patency, Microsomal Na(+)/K(+) ATPase Activity and Juvenile Hormone, in Tenebrio molitor Parasitized by Hymenolepsis diminuta.

Beetles infected with metacestodes of the rat tapeworm, Hymenolepis diminuta, exhibit reduced fecundity, due to alterations in vitellogenesis. Follicle cell patency is retarded and inefficient vitellogenin uptake ensues. Here, we have reassessed patency and its stimulation by JH III at day 3 post-infection, when the most detrimental changes are observed in other ovarian processes. In Rhodnius prolixus, patency is believed to be brought about by the action of a JH-dependent membrane-bound Na(+)/K(+) ATPase (EC 3.6.1.3); however, this had not been established in Tenebrio molitor. Therefore, the properties of the enzyme, with respect to optimal assay conditions and juvenile hormone dependency, are reported. Maximal stimulation occurred between 50 and 500 nM JH III, a range over which greatest increases in patency were also observed. In infected insects, a 35% reduction in Na(+)/K(+) ATPase activity was noted, but exposure to 50 nM JH III is sufficient for stimulation to a specific activity 89% that of JH-treated controls. In a similar fashion, patency in infected insects is reduced, but can be 'rescued' by 50 nM JH III. Moreover, in the absence of exogenous hormone, patency in infected beetles can be elevated to control levels after in vitro culture (6 h), with exchange of medium every 2 h. The possibility that such reversible decreases in enzyme activity and patency are caused by a JH binding inhibitor molecule is discussed. Copyright 1997 Elsevier Science Ltd. All rights reserved

Journal Article↗
PubMed1999

Spermatophore production and spermatheca content in Tenebrio molitor infected with Hymenolepis diminuta.

Male and female Tenebrio molitor act as intermediate hosts for metacestodes of the rat tapeworm, Hymenolepis diminuta. It is known that the bean-shaped accessory glands of infected males exhibit an extended growth period and are significantly larger than those from noninfected males by day 10 after emergence. We wished to determine whether more material is transferred from these glands into the spermatophores. Here we report that the protein content and trehalase activity of spermatophores produced by bean-shaped accessory glands from infected males is elevated. However, protein transferred to the female spermatheca during mating was not affected by the infection status of the male. No evidence of transfer of trehalase to the spermatheca was detected but spermatheca from virgin, infected females contained significantly greater trehalase activity than those from noninfected females.

Journal Article↗
PubMed1997

Current views on geographic distribution and modes of infection of neurohelminthic diseases.

Neurohelminthiases are more prevalent in geographic areas where environmental factors and poor sanitary conditions favor the parasitism between man and animals. In recent years, population shifts and rapid transport have facilitated the spread of certain helminthic diseases from endemic to non-endemic areas. Although many helminthic parasites are known to cause various human diseases afflicting many millions of people in the world, neurohelminthiases are often not diagnosed because they have been unrecognized by clinicians or confirmatory diagnostic tests are not easily available. Paragonimiasis and schistosomiasis (fluke diseases) are endemic in Asia, Africa and Central America; lesions in the central nervous system (CNS) due to ectopic parasitism of the preadult and adult flukes produce various clinical features that often mimic other diseases. In most cestodiasis (tapeworm disease), the adult worm that lodges in the alimentary tract does not involve the CNS; however, the larvae often enter the nervous system by migration or by metastasis via the systemic circulation, where they cause cystic lesions. Cysticercosis is the most common CNS helminthic infection especially in endemic areas where the parasitism between man and pigs is maintained. In other cestodiases, infections to man are often caused by ingestion of food or water contaminated with feces of the definitive hosts (mammals or man). Nematodes (roundworms) generally enter the CNS by ectopic migration of the infective larvae (larva migrans); the routes of infection to man vary with species of the nematodes, and the animal hosts they infest. Angiostrongylus cantonensis is a neurotropic nematode that requires the CNS of mammalian hosts for its growth; the third-stage larvae frequently invade skeletal muscles and the nervous system. Strongyloides, a gastrointestinal nematode, is known to cause CNS involvement in immunosuppressed patients. Recently, some nematodes heretofore unknown to cause human parasitism have been recognized as the causative agents of CNS infections.

Africa↗
PubMed1984

William Osler and Arthur Conan Doyle versus the antivivisectionists: some lessons from history for today.

Reaction against vivisection for research reached its height in the last two decades of the 19th century and the first two of the 20th, and a resurgence began in the 1960s. Antivivisectionism was and is related, in part, to emphasis on humanitarian sentiments. Two humanitarian physicians defended vivisection as essential. Dr. Arthur Conan Doyle in 1886 justified the killing of rabbits to relieve human suffering from hydrophobia. In 1910, he objected to the antihuman campaign of the antivivisectionists. Dr. William Osler reacted similarly to the threat to vivisection. He gave emphatic evidence to investigative committees in the United States in 1900 and in Britain in 1907. Osler also performed vivisection. His experimentation included studies of pig typhoid and tapeworm cysts in pigs and of the fate of india ink injected into the lungs of kittens. Osler and Conan Doyle were but two of the many prominent physicians who helped stem the tide of antivivisection legislation near the turn of the century. A review of the elements that fostered antivivisectionism in the society of their time is relevant in understanding and reacting to similar sentiments in the present era.

Animals↗
PubMed1999

Neurocysticercosis in pregnancy: a case initially diagnosed as eclampsia.

BACKGROUND: Neurocysticercosis is an infection of the central nervous system with the pork tapeworm's cysticercus. CASE: A 21-year-old Hispanic primigravida presented at 33 weeks' gestation with acute onset of mental status changes preceded by headaches and emesis. She was transferred comatose to our institution with a diagnosis of postictal state secondary to eclampsia. Upon arrival, the patient developed anisocoria, papilledema, posturing, and hypertension. Neuroimaging showed an intraventricular cyst. The patient was treated with ventriculostomy, induction of labor, postdelivery shunting, albendazole, and prednisone. CONCLUSION: Neurocysticercosis should be considered in the differential diagnosis of pregnant patients with coma and/or seizures, especially if the patient has emigrated from or traveled to an endemic area. Albendazole, with shunt procedure, is the treatment of choice for intraventricular neurocysticercosis.

Adult↗
PubMed2000

African Cucurbita pepo L.: properties of seed and variability in fatty acid composition of seed oil.

Pumpkin (Cucurbita pepo) seeds are used locally in Eritrea to treat tapeworm. Seeds were found to be rich in oil (approximately 35%), protein (38%), alpha-tocoferols (3 mg/100 g) and carbohydrate content (approximately 37%). The physico-chemical properties and fatty acid composition of the seed oil were examined. The four dominant fatty acids found are: palmitic C16:0 (13.3%), stearic C18:0 (8.0%), oleic C18:1 (29.0%) and linoleic C18:2 (47.0%). The oil contains an appreciable amount of unsaturated fatty acids (78.0%) and found to be a rich source of linoleic acid (47.0%). Within the three localities of the study, variations exist in seed properties and the fatty acid composition of the oil.

Cucurbitaceae↗
PubMedDate not supplied

Resurgence of cases of epileptic seizures and burns associated with cysticercosis in Assologaima, Jayawijaya, Irian Jaya, Indonesia, 1991-95.

Historically, neurocysticercosis (NCC) caused by the larval stage, cysticercus or cysticerci, of the pork tapeworm Taenia solium was recognized in Paniai District, western Irian Jaya Province, Indonesia, in the early 1970s. In the 1990s, we observed a rapid increase in the number of cases of epileptic seizures and burns in Assologaima Sub-District, Jayawijaya District, eastern Irian Jaya. There were totals of 1120 new cases of burns and 293 new cases of epileptic seizures during 1991-95 in Assologaima where the number of inhabitants was 15,939. Histopathological examination of resected cysts from patients and a pig revealed that they were cysticerci of T. solium. DNA analysis of these cysts revealed that the nucleotide sequences of 391 base-pair fragments of the mitochondrial cytochrome c oxidase subunit 1 gene were exactly the same in those from patients and the pig. Although 3 of 391 base-pair fragments might differ from that of T. solium reported previously, there were no differences in the amino-acid sequences. Approximately 67% and 65% of persons with epileptic seizures and with subcutaneous nodules, respectively, showed antibody responses highly specific to cysticercosis. Therefore, most cases of epileptic seizures and burns were considered to be associated with cysticercosis in Irian Jaya.

Adolescent↗
PubMedDate not supplied

Mass treatment against human taeniasis for the control of cysticercosis: a population-based intervention study.

An intervention study with mass treatment against taeniasis to prevent neurocysticercosis due to Taenia solium in a rural community in Mexico was performed in 1991-96. Information and biological samples were obtained at the beginning of the study, at 6 months and at 42 months after mass treatment with praziquantel at a single dose of 5 mg/kg. Prevalence rates of taeniasis were measured by the detection of Taenia coproantigens and Taenia eggs in faeces; neurocysticercosis was suggested by clinical data and by serum antibodies in humans and also in swine. A reduction of 53% after 6 months and of 56% after 42 months for human taeniasis was seen after treatment. Late-onset general seizures decreased 70%. Anti-cysticercus antibodies in the human population were reduced by 75% after 42 months. Antibodies in pigs also showed a significant reduction of 55% after 6 months. In conclusion, an impact of mass chemotherapy against taeniasis to control cysticercosis in the short and long term was demonstrated. Praziquantel for tapeworm treatment should not be given at doses lower than 10 mg/kg. Late-onset convulsive crisis and specific antibodies are good indicators of neurocysticercosis and of exposure to the parasite, respectively.

Adolescent↗
PubMed2002

The molecular epidemiology of Echinococcus granulosus and cystic hydatid disease.

It is now generally recognized that the dog tapeworm Echinococcus granulosus, the cause of cystic hydatid disease, exhibits substantial genetic diversity. This variability has important implications for the design and development of vaccines, diagnostic reagents and drugs effective against this parasite. The paper describes various deoxyribonucleic acid-based approaches that have been used for accurate identification of these genetic variants and their application in molecular epidemiological surveys of cystic hydatid disease in different geographical settings.

Animals↗
PubMed2004

Cysticercosis: imported and autochthonous infections in Kuwait.

Intracerebral and non-central nervous system (non-CNS) cysticercosis caused by the larval pork tapeworm Taenia solium was diagnosed in patients in an Islamic state. The mode of transmission and challenges in diagnosis are highlighted. Sixteen patients with neurocysticercosis and six with non-CNS lesions were diagnosed by imaging studies (computerized tomography [CT]/magnetic resonance imaging [MRI]) and serology (ELISA and/or enzyme-linked immunoelectrotransfer blot assay [EITB]). Four of 55 family members, including servants, tested for antibodies were positive by the EITB and ELISA. Only one of these sera tested for antibodies to adult T. solium was positive: that of the cook, the probable source of the infection. We postulate a similar mode of transmission in the other Kuwaitis. Evaluation of several commercially available ELISA kits showed they were of poor specificity. Even in countries where pork consumption is proscribed by religious laws, physicians should include cysticercosis in their differential diagnosis in patients with neurological symptoms or non-CNS lesions, especially in non-endemic countries with a large expatriate population such as Kuwait. In children particularly, and in this region, suspected tuberculous lesions on CT must be investigated to rule out cysticerci by a more diligent use of the sensitive and specific EITB assay. Failure to understand the local epidemiology leads to empirical, inappropriate and prolonged therapy for chronic disease.

Adolescent↗
PubMedDate not supplied

Mass chemotherapy for intestinal Taenia solium infection: effect on prevalence in humans and pigs.

Mass treatment of the human population with niclosamide was carried out in 2 villages in rural Guatemala where Taenia solium was endemic, to determine how this would affect the epidemiology of the parasite. Intestinal taeniasis was diagnosed by microscopy and coproantigen testing, and porcine cysticercosis by a specific Western blot. Before mass treatment, the prevalence of human taeniasis was 3.5%; 10 months after treatment it was 1%, a significant decrease (P < 10(-4)). All tapeworms that could be identified to the species level were T. solium. Similarly, the seroprevalence of antibodies to cysticercosis in pigs declined from 55% before treatment to 7% 10 months after treatment, once again a significant decrease (P < 10(-6)). These effects were seen in both villages. The possible use of mass chemotherapy as a tool in the control of T. solium is discussed.

Animals↗
PubMed2003

Human cystic and alveolar echinococcoses as indication to liver transplantation.

The human cystic and alveolar echinococcoses are zoonotic diseases caused by larval stages of the tapeworms Echinococcus granulosus and E multilocularis. In man the liver form of the diseases develops most frequently. Recent epidemiological data indicate that the distribution of E multilocularis in the central Europe is wider than was previously anticipated; more cases of human alveococcosis during the last years have also been noted in Poland. In the present paper we analyzed several cases of human echinococcoses from Poland with respect to diagnosis and treatment as well as the indications for liver transplantation.

Adult↗
PubMed2001

Adhesive secretions in the Platyhelminthes.

This review is the first to draw together knowledge about bioadhesives secreted by a group of parasites. Mechanisms of mechanical attachment are well known among parasites, but some can also attach to host surfaces by chemical means using a thin layer of adhesive material secreted at the parasite-host interface. Attachment by adhesives to living surfaces has not been studied in detail previously. A significant volume of research has determined much about the chemistry and nature of bioadhesives secreted by various marine macroinvertebrates from different phyla for attachment to inert substrates. Mussels and barnacles are sessile and adhere permanently, whereas starfish display temporary but firm adhesion during locomotion, feeding and burrowing. We focus on the Platyhelminthes that comprises the largely free-living Turbellaria and the wholly parasitic Monogenea, Cestoda, Digenea and Aspidogastrea. The term tissue adhesion is introduced to describe attachment by adhesives to epithelial surfaces such as fish epidermis and the lining of the vertebrate gut. These living layers regenerate rapidly, secrete mucus, are a site for immune activity and are therefore especially hostile environments for organisms that inhabit them, presenting a significant challenge for adhesion. Not all platyhelminths adhere to living surfaces and types of adhesion to inert substrates by the free-living turbellarians are also reviewed. Tissue adhesion is particularly well exemplified by monopisthocotylean monogeneans, parasites that are especially mobile as larvae, juveniles and adults on the epidermis of the body and gill surfaces of fish. These monogeneans secrete adhesives from the anterior end when they move from site to site, but some have secondarily developed adhesives at the posterior end to supplement or replace mechanical attachment by hooks and/or by suction. The temporary but tenacious anterior adhesives of monogeneans display remarkable properties of instant attachment to and detachment from their host fish surfaces. In contrast to the mobility of turbellarians and monopisthocotylean monogeneans and the simplicity of their direct life cycles, the largely endoparasitic Cestoda and Digenea are considered to be less mobile as adults. The complex cestode and digenean life cycles, involving intermediate hosts, place different demands on their various stages. Diverse, mostly anterior, gland cells in larvae, metacestodes and adults of the true tapeworms (Eucestoda), and in larval and adult Gyrocotylidea and Amphilinidea are reviewed. Conspicuous gland cells, mostly but not exclusively at the anterior end, in miracidia, cercariae and adults of digeneans and in cotylocidia and adults of aspidogastreans are also reviewed. Unlike turbellarians and monogeneans, accounts of unequivocal adhesive secretions in the Cestoda, but especially in the Digenea and Aspidogastrea, are relatively rare. The primary purpose of many conspicuous glands in the different stages of these mostly endoparasitic flatworms is for penetration into, or escape from, different hosts in their life cycle. We provide a detailed review of current knowledge about adhesion (in the sense of a thin layer of chemical material) in the Platyhelminthes including uses among eggs, larval, juvenile and adult stages. Information on structure, morphology and ultrastructure of the various adhesive systems that have been described is reviewed. Application of the 'duo gland' model is discussed. Comparisons are made between the little that is known about the chemistry of flatworm adhesives and the significant knowledge of the chemical nature of other invertebrate bioadhesives, especially those from marine macroinvertebrates. The potential importance of adhesives in parasitism is discussed. (ABSTRACT TRUNCATED)

Animals↗
PubMed2002

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.

Animals↗
PubMed2006

Control of Taenia solium cysticercosis/taeniosis.

Cysticercosis is emerging as a serious public health and agricultural problem in many poorer countries of Latin America, Africa, and Asia. Caused by the pork tapeworm, Taenia solium, this zoonotic disease forms larval cysts in humans and pigs that can lead to epilepsy and death in humans, reduces the market value of pigs and makes pork unsafe to eat. It occurs where pigs range freely, sanitation is poor, and meat inspection is absent or inadequate, and is thus strongly associated with poverty and smallholder farming. Although theoretically easy to control and declared eradicable cysticercosis remains neglected in most endemic countries due to lack of information and awareness about the extent of the problem, suitable diagnostic and management capacity, and appropriate prevention and control strategies. Human neurocysticercosis occurs when the larval cysts develop in the brain. It is considered to be the most common parasitic infection of the human nervous system and the most frequent preventable cause of epilepsy in the developing world. Thus far the infection has not been eliminated from any region by a specific program, and no national control programs are yet in place. We consider the tools available for combating cysticercosis and suggest simple packages of interventions, which can be conducted utilizing existing services and structures in the endemic countries to provide appropriate and sustainable control of the disease.

Animals↗
PubMed1983

Hydatidosis and cysticercosis: the dynamics of transmission.

The infective pattern of taeniids in their intermediate hosts is determined by the complex interaction of parasite- and host-related factors. Many of these have been examined in this review, but particular emphasis has been placed on environmental factors that affect the free-living egg. While number, infectivity and distribution of eggs are among the important factors determining the infective pattern, the dynamics of this aspect of transmission have been previously neglected. The biotic potential of the large taeniid tapeworms is enormous. Eggs deposited on pasture are subjected to the microclimatic effects of the environment. They seem to tolerate a relatively wide temperature range. Heat down to -30 degrees C. However, they are rapidly killed by low humidity at all temperatures. Under more favourable conditions, they have finite life spans largely determined by the environmental temperature. At deposition, the egg population seems to be at various stages of maturity. Immature eggs appear to be able to mature under suitable environmental conditions and to become infective. They then age, and their infectivity to the intermediate host declines. At the population level, the changes in infectivity with time are determined by the relative stages of maturity within the egg population and the temperatures that it experiences. Under certain circumstances the infectivity of a given population may increase temporarily. The movements and defaecation habits of the definitive host determine the primary site of egg deposition. However, evidence is accumulating that considerable dispersion occurs almost immediately afterwards. Eggs have been shown to disperse up to 80 m within 10 days and there are indications that small numbers travel much further. Intermediate hosts, such as cattle and sheep, generally avoid grazing areas contaminated with faeces. Thus, dispersal enhances the chance of the eggs being ingested. The combination of high biotic potential and long-range dispersal means that individual infected definitive hosts can be responsible for infecting intermediate hosts over a very wide area. Although various possible agents have been suggested, the mechanisms responsible for disseminating eggs are still uncertain.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗