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Neurocysticercosis: current knowledge and advances.

Neurocysticercosis is the most common cause of acquired seizures worldwide. Most cases of this larval stage infection of the pork tapeworm Taenia solium occur in the developing world, although increasing numbers of cases are being recognized in the United States, particularly among Hispanic immigrants. The ability of the pathogen to persist for years within the host is the subject of immunologic and biochemical investigation. The major presenting symptom is seizures, although symptoms of obstructive hydrocephalus occur if cysts are located near the ventricles or in the subarachnoid spaces. Diagnosis is dependent on clinical, radiologic, and serologic data. Therapy with antiparasitic agents, especially albendazole, is effective in large burden disease or disease within sensitive neuraxis sites (the ventricles, the subarachnoid spaces). When patients with radiologically enhancing disease are given cysticidal therapy, there appears to be a reduction in seizure recurrences. Surgery is indicated for disease in selected anatomic sites. Long-term prevention requires attention to pork husbandry and general sanitation, including the potential use of mass human chemotherapy and porcine vaccination.

Brain Diseases↗

Cysticercosis.

Cysticercosis, the consequence of ingesting viable eggs of the porcine tapeworm Taenia solium, currently remains one of the most common human parasitic conditions worldwide. Although preventable by the proper disposal of human wastes, cysticercosis of the central nervous system (neurocysticercosis) accounts for a substantial proportion of cases of epilepsy and hydrocephalus among children and adults in many developing countries. Cases also occur in nonendemic regions, reflecting patterns of immigration from highly endemic countries, especially Mexico and other areas of Latin America. Antiparasitic treatment during active infections, using albendazole or praziquantel, can eradicate the parasite, may lower the risk of late complications, and potentially reduces the morbidity of acute disease. Considerable controversy persists regarding the role of antiparasitic therapy in neurocysticercosis, however. Persons with active parenchymal or extraparenchymal disease, defined by the neuroradiographic appearance of lesions, can be treated with albendazole, 15 mg/kg/d divided into two daily doses for 8 days. Patients with parenchymal disease who do not respond to albendazole can receive a second course of albendazole or praziquantel, 50 mg/kg/d divided into three daily doses for 15 days. Concurrent administration of dexamethasone in standard doses is usually required during the first several days of antiparasitic therapy to minimize the inflammation and cerebral edema associated with death of the parasites. Patients with intraventricular cysts and hydrocephalus require shunting and surgical removal of cysticerci. By contrast, persons with inactive lesions and seizures as a consequence of remote infections typically require only symptomatic therapy with standard anticonvulsants.

Journal Article↗

Reappearance of human diphyllobothriasis in a limited area of Lake Como, Italy.

BACKGROUND: Very few sporadic cases of autochthonous diphyllobothriasis have been reported in Italy during the past 20 years, probably due to the drastic decrease or disappearance of some fish species, mainly Perca fluviatilis L., known as the intermediate host of the infective larval stage of this tapeworm. However, increasing consumption of raw or undercooked fish during the last years as influenced by Oriental cuisine, played an important role in a number of new single cases of the infection or microepidemics. PATIENTS: We describe six cases which were diagnosed within a period of 4 months, which all originated from the area of Lake Como (Lombardy region). All subjects had previously eaten raw perch fillets. Four individuals complained of gastrointestinal signs and symptoms, whereas two were asymptomatic. DISCUSSION: Parasitological diagnosis was achieved in four cases by recovery of typical operculated eggs in stool specimens; in two others by morphological features of proglottids recovered from feces. Treatment with niclosamide, as a single oral dose, cured the infection in all subjects. This is the first report of this infection in Italy in the last 10 years.

Adolescent↗

Efficacy of low doses of praziquantel in taeniasis.

Early experimental studies suggested that doses of 1 to 5 mg of praziquantel (PZQ) per kg are effective against several intestinal cestodiases. The usually recommended single dose of PZQ in human taeniasis is 5 or 10 mg/kg. A study in T. saginata taeniasis showed a full efficacy at a dose of 2.5 mg/kg. A field study confirmed that a dose between 3.4 and 7.5 mg/kg was effective in expulsion T. solium tapeworms in man. A dose of 2.5 mg of PZQ per kg would be safer and more economical in population-oriented interventions aiming at control of T. solium taeniasis in man.

Animals↗

Observation of an organism found in patients with gestational trophoblastic disease and in patients with toxemia of pregnancy.

This is an initial descriptive report of observations of multiple forms of an organism found in patients with gestational trophoblastic disease and in patients with preeclampsia-eclampsia. The worm-like forms most frequently observed have an average length of 1.0 to 1.5 mm. Larva-like forms have an average length of 150 mu; primordial eggs and egg-like forms in developmental stages range from 7 to 43 mu in diameter; and sperm-like forms are 3.5 mu or slightly smaller in size. These forms have been observed in contact smears prepared from 3 ml samples of peripheral circulating blood from both groups of patients, from trophoblastic tumor tissue, from contact smears prepared from placentas of patients with preeclampsia-eclampsia, and from umbilical cord blood of infants delivered of patients with preeclampsia-eclampsia. The various forms of this organism share morphologic characteristics of several orders of helminths, i.e., hookworms, roundworms and tapeworms. The taxonomy of these forms has not yet been determined. Until the time of taxonomic classification, the various forms will be referred to as Hydatoxi lualba. We have experimental evidence that this organism has biologic activity in BALB/c mice and in beagle dogs.

Animals↗

tris(Hydroxymethyl)aminomethane: an artifact detected as an aminotetrose by gas chromatography/mass spectrometry.

The monosaccharide content of the ethanol-soluble moiety of crude polysaccharide fractions of the tapeworm Hymenolepis diminuta and the blood fluke Schistosoma mansoni was investigated by gas-liquid chromatography of alditol acetate derivatives. A prominent, unusual peak was found, and mass spectrometry suggested identification as an aminotetrose, a four-carbon aminosugar reported only once in the past 15 years [D. A. Cumming, C. G. Hellerquist, and O. Touster (1981) J. Biol. Chem. 256, 7723-7726]. The unknown molecule was found to be tris(hydroxymethyl)aminomethane (Tris), whose acetylated derivative has a mass spectrum identical to that of an aminotetrose. The source of the Tris was traced to buffers used in conjunction with polysaccharide isolation.

Amino Sugars↗

Hymenolepis nana: maturation in an immunosuppressed unnatural rat host.

When eggs of the dwarf tapeworm Hymenolepis nana, cycled exclusively and directly through mice for more than 10 years, were inoculated into previously uninfected inbred Fischer (F344) strain rats, they failed to mature in the rat intestinal lumen. Eggs of H. nana inoculated into the rat developed normally into cysticercoids (cysts) in the intestinal tissue, but thereafter failed to mature in the lumen except when the host was treated with cortisone acetate from the day of cyst maturation. The Fischer rat initially given eggs of H. nana became completely immune to egg challenge within 2 days of egg inoculation; no cysts derived from challenge eggs were found in the immunized rat. Immunosuppression, assessed by the success of cyst recovery in the tissue 4 days after egg challenge, had no promotive effect on the recovery of adult worms derived from eggs initially inoculated. Rats initially given eggs and immunosuppressed by cyclophosphamide or antithymocyte serum did not harbor any adult worms. Cortisone acetate treatment which was sufficient for eggs inoculated to mature (a total of 75 or even 200 mg, from Day 5 of egg inoculation) had no effects of immunosuppression, whereas cortisone acetate treatment which was sufficient for immunosuppression (a total of 150 mg from Day -2, two days prior to the initial egg inoculation) induced some adult formation as well. In addition, when mouse-derived cysts were inoculated into the rat instead of eggs, they also failed completely to mature even when the rat was treated with cyclophosphamide or antithymocyte serum.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Hymenolepis microstoma: mouse strain differences in resistance to a challenge infection.

Antibody responses and host resistance to the tapeworm, Hymenolepis microstoma, were investigated using AKR/J and C3HeB/FeJ strains of mice. AKR mice were significantly more resistant than controls to a secondary infection following exposure to a 3-, 21-, or 40-day primary infection. During a primary infection, intestinal anti-worm antibody responses measured by an enzyme-linked immunosorbent assay were elevated in the more resistant AKR strain, whereas serum antibody titers did not differ between the two strains. However, during a secondary infection, serum IgA titers were higher in AKR mice than C3H mice. Suppression of the serum IgA anti-worm response by oral administration of lipopolysaccharide also suppressed resistance to a secondary infection. Intraperitoneal immunization with worm antigen resulted in a minor degree of protection in AKR mice. This protection was associated with increased intestinal antibody titers compared to mice not demonstrating protection. These results suggest that the protective responses observed in AKR mice relative to C3H mice reflect differences in mucosal antibody responses to H.

Animals↗

Hymenolepis citelli (Cestoda) and Nematospiroides dubius (Nematoda): interspecific interaction in mice.

In mice concurrently infected with Hymenolepis citelli and Nematospiroides dubius, survival of the tapeworm was prolonged, and there was an impairment of the efferent arm of the response to the cestode. The immunological rejection of a six cysticercoid primary H. citelli infection was delayed by the N. dubius infection. The growth of the cestode was poorer in concurrently infected mice, and this effect was rapid, being evident within 4 days of the N. dubius infection. Maximum biomass in the controls was reached on Day 20, whereas in the concurrently infected mice it was reached on Day 25. The induction of acquired immunity to homologous H. citelli infection was suppressed, although the expression of a secondary response against homologous challenge was not abrogated in doubly infected mice. The results are discussed with reference to the immunodepressive effects the nematode is known to have on heterologous antigenic stimulation.

Animals↗

Hymenolepis diminuta: nuclear magnetic resonance analysis of the excretory products resulting from the metabolism of D-[13C6]glucose.

Excretory products of the tapeworm Hymenolepis diminuta, fed D-[13C6]glucose in vitro for 90 min, were studied using 1H and 13C nuclear magnetic resonance spectroscopy. Signals due to lactate, succinate, acetate, and alanine were identified in the spectra. Several differently labeled species were present for these metabolites; the variations of higher concentration were a consequence of metabolic factors while those of lower concentration could be accounted for by residual 12C in the glucose. The two major labeled lactates, U-13C and 2,3-13C2, were in the ratio 2:1, respectively, and the three major labeled succinates, 1,2,2'-13C3,2,2'-13C2, and U-13C, were present in the ratio 20:10:3, respectively. The different species of labeled end products are related to the overall glucose metabolism of H. diminuta.

Acetates↗

Taenia taeniaeformis: immunoperoxidase localization of metacestode culture product(s) in hyperplastic gastric mucosa.

Rats infected with the hepatic metacestode Taenia taeniaeformis develop an extraordinary gastric hyperplasia. Indirect immunoperoxidase staining localized larval in vitro excretory secretory product specifically in the supranuclear cytoplasm of the epithelial cells lining the pits and glands in the hyperplastic gastric mucosa. The accumulation of this substance in the stomach epithelial cells may be relevant to the gastric hyperplasia induced by tapeworm infection.

Animals↗

Hymenolepis diminuta: intestinal goblet cell response to infection in male C57 mice.

Intestinal goblet cell numbers in two regions of the small intestine (20-30% and 60-70% distance form the pylorus) of male, 6- to 8-week-old C57 mice have been monitored following a 5-cysticercoid infection of the rat tapeworm, Hymenolepis diminuta. Test and sham-infected control mice were autopsied 0, 4, 8, 10, 14, and 28 days postprimary infection (p-1 degree-i) and 2, 4, 5, 7, and 14 days postsecondary infection (p-2 degree-i), administered 28 days p-1 degree-i. Results show a statistically significant increase in the number of mucus-containing goblet cells in both regions of the intestine during primary and secondary infections. Peak goblet cell numbers occurred on Day 8 p-1 degree-i and Day 5 p-2 degree-i in the 20-30% region and on Day 10 p-1 degree-i and Day 5 p-2 degree-i in the 60-70% region. In both regions, cell numbers declined to control levels by Day 14 p-1 degree-i, but remained significantly above control values 14 days p-2 degree-i. The increase in cell numbers correlated with an increase in goblet cell theca size and observable amounts of luminal mucus. The same infection regime in mice treated with cortisone elicited no goblet cell response. Male Wistar rats given a 10-cysticercoid infection and autopsied on Day 0, Day 10, and 15 months p-i showed a statistically significant increase in mucus-containing goblet cells only in the 60-70% region of intestine 10 days p-i; however, the worm burden was not eliminated. The functional significance of these results is discussed in relation to host immunity and murine cestode rejection.

Animals↗

1H NMR study of metabolic alterations in the small intestine of rats infected with Hymenolepis diminuta.

1H NMR spectra of the duodenum, jejunum and ileum tissues of the small intestine of a rat showed metabolic gradients. 2. The concentrations of metabolites in these gut regions were altered by the presence of the tapeworm Hymenolepis diminuta. 3. In the infected duodenum there was significantly less glycogen, glucose and phosphocreatine/creatine, but significantly more lactate than in the corresponding controls. 4. Infected jejunum contained significantly less betaine but significantly more succinate, alanine and lactate. 5. Infected ileum had significantly less glycogen and taurine but significantly more alanine and lactate.

Animals↗

Characterization of cloned antigens of Taenia ovis.

Fusion proteins derived from recombinant clones of Escherichia coli carrying the pEX series of expression vectors with cDNA inserts of the tapeworm, Taenia ovis, were characterized by their antigenicity when administered to mice and sheep. Antisera derived from these hosts were shown to react with a number of T. ovis adult worm and oncospheral antigens in Western blots, and to bind to oncospheres and worm tissue in fluorescent antibody tests. Epitopes produced by two clones (designated T07 and T08) are found on several antigenic polypeptides of T. ovis and a related species T. hydatigena. Those produced by a third clone (T03) are specific to T. ovis. The immunological results were confirmed by Northern blotting of T. ovis and T. hydatigena RNA: RNA transcripts corresponding to T07 and T08 are found in both T. ovis and T. hydatigena, whereas RNA corresponding to T03 is found in T. ovis only. Cross reacting epitopes in fusion proteins from T07 and T08 appear to have different amino acid sequences, and T. ovis antigenic epitopes are shared by a number of polypeptides in and between adult worms and oncospheres.

Animals↗

Experimental infection of Thailand Taenia (Chiengmai strain) in domestic animals.

Twenty-five gravid proglottides of a Thailand Taenia were obtained from a patient in Chiengmai, Thailand, and brought to our laboratory. The tapeworm was determined to be T. saginata-like by counting uterine branches (mean number 16, range 12-19 on each side). The eggs from these proglottides remained infective under storage at room temperature for 14 days followed by refrigeration (4-8 degrees C) for 131 days. Eight Small-Ear-Miniature pigs and two Holstein calves were each fed with 3000 eggs and sacrificed 12-76 days afterwards. Six pigs became infected and 16 cysticerci were recovered from the livers. Thirteen degenerated/calcified cysticerci were also recovered from the livers of the two calves. More cysticerci were found in the liver parenchyma (55%) than on the liver surface (45%) of the infected animals. Measurements of length, width, diameters of protoscolex, rostellum and sucker and hooklet pattern show that Thailand Taenia is similar to Taenia from Taiwan, Korea and Indonesia but different from T. saginata and T. solium. These findings indicate that Thailand Taenia, Taiwan Taenia, Korea Taenia, and Indonesia Taenia may be of the same species or sub-species.

Animals↗

Poor efficacy of albendazole for the treatment of human taeniasis.

In order to evaluate the efficacy of albendazole for the treatment of taeniasis, regimens of 400 mg x 1 day, 800 mg x 2 days, 800 mg x 3 days, 1200 mg x 2 days, and 1200 mg x 3 days were compared. Of 66 cases treated and investigated 7-14 days after treatment, 52 were still expelling proglottids. Three months posttreatment, these cases were re-treated with atabrine at 1.2 g per case for males and 1.0 g per case for females. Fifty-seven patients expelled worms or parts of tapeworms. The nine negatives may represent the number cured by the treatment with albendazole. The cure rates with albendazole for various regimens were up to 50% for 800 mg x 3 days, 1200 mg x 2 days or 1200 mg x 3 days, 14.3% for 800 mg x 2 days, and 0% for 400 mg x 1 day or 800 mg x 1 day. This study shows that albendazole is not very effective in the treatment for taeniasis.

Adolescent↗

A nuclear magnetic resonance study of the glucose metabolism of Hymenolepis diminuta exposed to histamine and serotonin in vitro.

The direct effects of the inflammatory mediators, histamine (HI) and serotonin (SE), on the glucose metabolism of Hymenolepis diminuta in vitro were studied by analyzing the excretory products from culture media, containing D-1-13C-glucose and various concentrations of HI and/or SE, by 1H-nuclear magnetic resonance (n.m.r.) spectroscopy. The results revealed that HI markedly accelerated the glycolysis process by increasing the amount of lactate production. The increased glycolytic activity was reflected in a concentration-dependent increase in glucose uptake. Excretion of acetate was also stimulated by HI. A low concentration of SE significantly increased succinate, acetate and lactate excretions, whereas a high concentration had little effect on lactate production and significantly decreased succinate and acetate excretions. A combination of HI and SE treatment at a low concentration had no significant effect, but at a high concentration showed an additive effect, with an increase in lactate production, a decrease in succinate production and an increase in glucose uptake. Thus this work confirms that HI and SE directly influence, albeit differently, energy metabolism of the tapeworm H. diminuta.

Animals↗

Intestinal contractions and migration behaviour in Hymenolepis diminuta.

The aim of this study was to determine if intestinal contractions were important in the migration behaviour of the rat tapeworm Hymenolepis diminuta. The objectives were to investigate the intestinal motility responses of the host to a meal which initiates worm migration, and the worms' responses to an artificial peristaltic contraction. A 1 g glucose meal elicited a significant orad migration by H. diminuta in the small intestine of the rat host when compared to water-fed controls (P less than 0.05). The glucose meal also significantly increased the transit rate, and thus, frequency of intestinal contractions in the small intestine of the rat, when compared to water-fed controls (P less than 0.05). Application of a circumintestinal ligature (6.3 g) (simulating an intestinal peristaltic contraction) resulted in significant worm migration when the ligature was applied in regions containing the worm's strobila as compared to controls where loose ligatures were tied in regions containing the strobila, or to controls where tight ligatures were tied ahead of the worm's strobila. These results suggest that H. diminuta migrates in an orad direction in response to the mechanical pressure produced by intestinal contractions induced by host feeding. It is concluded that contractions of the small intestine are an important cue in the migration behaviour of this cestode.

Animals↗