Integrated transcriptomic and proteomic analyses of plerocercoid and adult Spirometra mansoni reveal potential important pathways in the development of the medical tapeworm

BACKGROUND

Spirometra mansoni can parasitize animals and humans through food and water, causing parasitic zoonosis. Knowledge of the developmental process of S. mansoni is crucial for effective treatment; thus, it is important to characterize differential and specific proteins and pathways associated with parasite development.

METHODS

In this study, we performed a comparative proteomic analysis of the plerocercoid and adult stages using a tandem mass tag-based quantitative proteomic approach. Additionally, integrated transcriptomic and proteomic analyses were conducted to obtain the full protein expression profiles of different life cycle stages of the tapeworm.

RESULTS

Approximately 1166 differentially expressed proteins (DEPs) were identified in adults versus plerocercoids, of which 641 DEPs were upregulated and 525 were downregulated. Gene Ontology (GO), Clusters of Orthologous groups (COG) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses indicated that most DEPs related to genetic information processing and metabolism of energy in adults seem to be more activated. In the plerocercoid stage, compared to metabolism, genetic information processing appears more dynamic. Protein-protein interaction (PPI) revealed six key proteins (phosphomannomutase, glutathione transferase, malate dehydrogenase, cytoplasmic, 40S ribosomal protein S15, ribosomal protein L15 and 60S acidic ribosomal protein P2) that may play active roles in the growth and development of S. mansoni. Finally, the combination of transcriptomic and proteomic data suggested that three pathways (ubiquitin-mediated proteolysis, phagosome and spliceosome) and five proteins closely related to these pathways might have a significant influence in S. mansoni.

CONCLUSIONS

These findings contribute to increasing the knowledge on the protein expression profiles of S. mansoni and provide new insights into functional studies on the molecular mechanisms of the neglected medical tapeworm.

Cerebral sparganosis masquerading brain neoplasm: A rare incidental case

Sparganosis is a parasitic infection caused by plerocercoid larvae of the genera Spirometra. Cerebral sparganosis is one of its most serious complications wherein clinical and imaging findings may pose diagnostic challenge. Here we present a case of cerebral sparganosis which mimicked as brain tumour on clinicoradiological examination. The case is reported in view of its rarity in India and the need for awareness of the entity.

Proteomic and Immunological Identification of Diagnostic Antigens from Spirometra erinaceieuropaei Plerocercoid

Human sparganosis is a food-borne parasitic disease caused by the plerocercoids of Spirometra species. Clinical diagnosis of sparganosis is crucial for effective treatment, thus it is important to identify sensitive and specific antigens of plerocercoids. The aim of the current study was to identify and characterize the immunogenic proteins of Spirometra erinaceieuropaei plerocercoids that were recognized by patient sera. Crude soluble extract of the plerocercoids were separated using 2-dimensional gel electrophoresis coupled with immunoblot and mass spectrometry analysis. Based on immunoblotting patterns and mass spectrometry results, 8 antigenic proteins were identified from the plerocercoid. Among the proteins, cysteine protease protein might be developed as an antigen for diagnosis of sparganosis.

[Prevalence of Spirometra mansoni infections in hosts in Jiangsu Province]

OBJECTIVE

To investigate the prevalence of Spirometra mansoni infections in hosts in Jiangsu Province, so as to provide the scientific basis for the management of sparganosis mansoni.

METHODS

From 2018 to 2019, nine counties (cities, districts) were randomly selected from Jiangsu Province as the survey sites, and 100 healthy individuals were randomly selected to perform the serological test of S. mansoni infections and the detection of S. mansoni eggs. The procercoids were detected in the intermediate host Cyclops, and the S. mansoni eggs were identified in the stool samples of the definitive hosts cats and dogs.

RESULTS

The prevalence of S. mansoni human infections was 0 (0/900) in the 9 survey sites of Jiangsu Province, and the sero-prevalence of the specific IgG antibody against S. mansoni was 1.22% (11/900). The positive rate of procercoids was 0.33% (3/900) in Cyclops. In addition, the S. mansoni egg-positive rate was 1.48% (2/135) in cats and dogs.

CONCLUSIONS

Sparganosis mansoni is prevalent in Jiangsu Province. Health education pertaining to the damages of sparganosis mansoni and the route of S. mansoni infections should be improved.

Human Sparganosis in Korea

BACKGROUND

Sparganosis is a larval cestodiasis caused by the plerocercoid of Spirometra spp. Since the first description of human sparganosis in 1924, several hundred cases have been reported in Korea. However, systematic approaches for literature surveys of Korean sparganosis have seldom appeared.

METHODS

We searched publicly available databases such as PubMed, Research Information Sharing Service, and Korea Medical Citation Index with relevant Medical Subject Headings.

RESULTS

At least 438 Korean sparganosis cases have been described from 1924 to 2015. Preoperative diagnosis has been significantly increased since the 1980s due to popularization of serological and imaging diagnostics. Cases were largely detected from fifth decades in general, but cerebral sparganosis was detected in relatively young age groups (third and fourth decades). Sparganosis was prevalent in men (75.9%). Consumption of frog/snake and drinking unfiltered water were found in 63.4% and 16.9% of patients, respectively. Most frequently affected sites were subcutaneous tissues (49.9%), followed by the central nervous system (36.2%). Involvements of visceral organs (7.6%), ocular regions (3.6%), and muscles (2.7%) were noticed. In women, breast sparganosis constituted a large proportion (34.2%). Sparganosis associated with immunocompromised patients has recently been reported.

CONCLUSION

Sparganosis has been continuously reported in Korea during the past 90 years, although its incidence has decreased during the last 20 years. The disease is mostly characterized by subcutaneous nodule, but infection of the worm in vital organs often results in serious illness. Continuous awareness is warranted to monitor sparganosis occurrence and associated clinical consequences.

[Ocular infestation by plerocercoid of Spirometra mansonoides: first case report in Peru]

Plerocercoidosis is a parasitic zoonosis caused by plerocercoid larvae of the genus Spirometra. The larvae migrate through the intestinal wall tissue, by subcutaneous route and can reach different areas of the body like the head, the brain and the eye socket. A case is reported of a 45 year-old man from the Peruvian Amazon with burning sensation associated with conjunctival edema and hemorrhage in the outer eye border of the right eye for eleven months. A localized worm in the right orbital cavity was observed, which was extracted. Morphological and histopathological studies identified it as Spirometra mansonoides localized in the eye, which is the first case reported in Peru.

[Effect of physicochemical factors on infectivity of Spirometra mansoni plerocercoid]

OBJECTIVE

To observe the effect of different physicochemical factors on the infectivity of Spirometra mansoni plerocercoids.

METHODS

The muscle samples with plerocercoids taken from Rana nigromaculata (about 1 cm3 each piece) were treated with different temperature (-20 degrees C, 4 degrees C, 37 degrees C and 56 degrees C) or different concentrations of ethanol (20%, 30%, 40%, 50% and 60%) for 1, 2 or 3 h, or soaked in ginger juice, vinegar (total acid concentration of 4.5%, pH 3.05) or soy sauce (containing 19.3% NaCl) for 3, 6, 12 or 24 h. The muscle with plerocercoids treated with normal saline under 20 degrees C served as control. 30 plerocercoids were used under each condition and fed to 10 mice averagely (3 larvae/mouse). Another 20 plerocercoids with frog meat were comminuted for 3 min then fed to 10 mice. One week later, the mice were sacrificed to collect the parasitic plerocercoids and the number of positive mice and plerocercoids was recorded.

RESULTS

None of the mice fed with plerocercoids treated under -20 degrees C for 2 h was infected. All the mice fed with plerocercoids treated under 56 degrees C for 2 h and 3 h were infected. The percentage of infective plerocercoids was 60% (18/30) and 43% (13/30), respectively, considerably lower than those of the control (90%, 27/30) (P < 0.05). None of the mice fed with plerocercoids soaked in 60% ethanol for 2 h was infected. All the mice fed with plerocercoids soaked in 60% ethanol for 1 h, or in 50% ethanol for 2 h or 3 h were infected. The percentage of infective plerocercoids was 60% (18/30), 57% (17/30), and 50% (15/30), respectively, considerably lower than those of the control (93%, 28/30) (P<0.05). None of the mice fed with plerocercoids soaked in vinegar for 24 h, or soy sauce for 6 h was infected. The infectivity of the plerocercoids treated by ginger juice for 24 h was similar to the control (P>0.05). Among the ten mice fed with comminuted frog meat with plerocercoids, five were infected with 6 plerocercoids.

CONCLUSION

Treatment with -20 degrees C or 60% ethanol for 2 h, soy sauce for 6 h, or vinegar for 24 h can destroy the infectivity of plerocercoids in 1 cm3 frog muscle.

Cerebral sparganosis: A case report

Sparganosis is a rare parasitic infection in humans caused by a larval cestode of the genus Spirometra. Spargana invade muscle, subcutaneous tissue, the eye, urogenital, and abdominal viscera, but the central nervous system (CNS) is not a frequent site of invasion. Here, we describe an 18-year-old patient with cerebral sparganosis and review data from other cases reported in the medical literature.

Parasitic lesion of the insula suggesting cerebral sparganosis: case report

Cerebral sparganosis, a parasitic disease, rarely produces a chronic active inflammatory response in the brain. Clinically and radiographically the process may mimic a neoplasm. We report a 30-year-old man who underwent surgical exploration for a mass in the insular cortex. Histology revealed a densely fibrotic mass heavily infiltrated with plasma cells and lymphocytes, in which were embedded parasitic forms consistent with sparganosis. We describe the MRI appearances and pathologic features. Intracranial mass lesions secondary to sparganosis must be considered in patients with a history of travel to endemic areas, especially Asia.

Cutaneous sparganosis in France: the second case described from Europe. Case report

The first case of sparganosis is reported from France. The patient, a 21-year-old man, presented with a subcutaneous lump on the chest, and the diagnosis was made on histological examination after needle biopsy. He achieved a complete recovery.

Hepatotrophic activity in mouse serum infected with plerocercoids of Spirometra erinacei

To investigate the mechanism by which liver weight increases during plerocercoid infections as well as the possible existence of a hepatocyte-growth-factor (HGF)-like substance in the serum of mice infected with Spirometra erinacei plerocercoids, liver DNA synthesis was measured in vivo and in vitro. Infection with S. erinacei plerocercoids significantly stimulated DNA synthesis in mouse parenchymal hepatocytes prior to the increase in liver weight, at least partly by stimulating the induction of the salvage pathways of pyrimidine biosynthesis. Furthermore, infected mouse serum directly stimulated DNA synthesis in cultured mouse parenchymal hepatocytes. These results suggest that an HGF-like substance is present in the serum of mice infected with S. erinacei plerocercoids.

in a domestic cat in India

Adult Spirometra sp. were found in an experimental cat. This is the first report from northern India. It is suggested that this infection may have resulted from the feeding of raw fish offal.

Analysis of derivatized ceramides and neutral glycosphingolipids by high-performance tandem mass spectrometry

Microscale reduction of ceramides and neutral glycosphingolipids has been evaluated as a means of improving their analysis by fast atom bombardment mass spectrometry, alone and in combination with tandem mass spectrometry. Reduction (conversion of the amide to an amine) of native ceramides and glycosphingolipids containing one to three sugars yields derivatives that show significant signal enhancement. This sensitivity increase allows the acquisition of normal and tandem fast atom bombardment mass spectra from a submicrogram amount of sample. Concomitant permethylation is required for glycosphingolipids that contain more than three sugars. Collision induced dissociation mass spectra of protonated molecular ions, recorded on a four sector instrument, show improved fragmentation allowing the simultaneous characterization of both the ceramide and carbohydrate portions of glycosphingolipids. The reductions are carried out at the nanogram to microgram level with borane, reacting the solid sample with condensed reagent vapor. The borane reduction method has been adapted for this class of substances by adding an oxidation step in order to convert unsaturated lipids to hydroxylated derivatives by oxidation of the resulting organoborane. This approach, used in conjunction with tandem mass spectrometry, allows the determination of olefinic bond location. Labeled derivatives have been prepared by reacting the substrates with trideuterioborane and were used to ascertain the fragmentations and localize olefinic bonds. The collision induced fragmentation of reduced ceramides and neutral glycosphingolipids is only weakly affected by the presence of additional functionalities, such as methoxyl (after permethylation) and hydroxyl groups (resulting from hydroboration and oxidation), a characteristic which facilitates interpretation of the spectra of unknown compounds.

The growth factor from plerocercoid larvae of the tapeworm, Spirometra mansonoides, stimulates growth but is not diabetogenic

A factor produced by plerocercoids of the tapeworm Spirometra mansonoides is similar to human growth hormone (hGH) in that it stimulates body growth, binds to hGH receptors, cross-reacts with anti-hGH antibodies, and has lactogenic and insulin-like activities. The purpose of this study was to determine whether plerocercoid growth factor (PGF) is similar to hGH in expressing diabetogenic activity in the genetically obese (ob/ob) mouse. To determine an effective dose for use in the obese mice, the ability of daily injections of PGF to stimulate growth of phenotypically normal mice of the same strain was assessed in a 10-day weight gain assay. Injections of PGF stimulated a dose-dependent weight gain (r = 0.83) and 25 ng eq/day of PGF stimulated a response not significantly different from that produced by 100 micrograms of bovine growth hormone/day. Diabetogenicity was assessed using fasting blood glucose and glucose tolerance tests in obese mice that had been injected for 3 days with saline, hGH, or PGF. Human growth hormone caused a significant increase (P less than 0.005) in fasting blood glucose and glucose tolerance of the obese mice was impaired (P less than 0.01). All of the doses of PGF used to test diabetogenicity in the obese mice were at least twice that required to stimulate a maximal growth response in normal mice, yet none of the doses of PGF increased fasting blood glucose or decreased glucose tolerance. These results show that PGF was a potent growth stimulant but was not diabetogenic.

Insulin-like effects in the rat of the purified growth factor from Spirometra mansonoides plerocercoids

The acute effects of injections of the human growth hormone-like factor purified from plerocercoids of the tapeworm Spirometra mansonoides on carbohydrate, lipid, and protein metabolisms were determined in intact rats. Male rats were injected ip with saline, insulin, or various doses of partially purified PGF. The rats injected with insulin had significantly reduced serum glucose concentrations but no dose of PGF caused a change in serum glucose levels. Insulin and PGF stimulated [14C]glucose and [14C]leucine oxidation to 14CO2 in adipose tissue and muscle and increased incorporation of both [14C]glucose carbons into lipids and [14C]leucine into protein in fat and muscle. The responses to PGF were dose-dependent and persisted after 3 hr of incubation in vitro. Injections of naloxone prior to injecting PGF to block the stress response did not prevent the stimulation of insulin-like responses by PGF. Therefore, PGF has intrinsic insulin-like activities in normal male rats.

Carbohydrate metabolism in intact golden hamsters infected with plerocercoids of Spirometra erinacei (Cestoda: Diphyllobothriidae)

This study was performed to investigate the mechanism involved in a decrease in the serum glucose of golden hamsters infected with plerocercoids of Spirometra erinacei. The concentration of glucagon, the activity of glucose-6-phosphatase in the liver, and the in vivo incorporation of 2-deoxy-D-[1,2-3H]glucose into various organs increased in plerocercoid-infected hamsters compared with controls. Furthermore, the serum from the plerocercoid-infected hamsters enhanced the in vitro incorporation of [U-14C]glucose into adipose tissues, compared with control serum. The serum levels of immunoreactive insulin and somatomedin associated with nonsuppressible insulin-like activity in experimental animals, however, were not significantly different from those in controls. Therefore, we conclude that the decrease in serum glucose associated with plerocercoid infection is not the result of a decrease in gluconeogenesis, but the result of an increased utilization of glucose in the peripheral tissues.

Cerebral sparganosis

Cerebral sparganosis is caused by the migrating larva of Spirometra mansonoides. Only seven cases have been reported worldwide. We here report the second known case in the United States. Including our case, ages ranged from 24 to 46 years. Men and women were equally affected. Headache, convulsions, focal neurologic signs, and peripheral eosinophilia were common. CT often revealed an enhancing mass. Surgical resection of the parasitic granuloma gave excellent results. often revealed an enhancing mass. Surgical resection of the parasitic granuloma gave excellent results.

Lipid metabolism in golden hamsters infected with plerocercoids of Spirometra erinacei (Cestoda: Pseudophyllidea)

Golden hamsters infected with Spirometra erinacei plerocercoids develop a hypertriglyceridaemia characterized by an increase in very low-density lipoprotein. Acyl-CoA synthetase activity, the rate of fatty acid synthesis in the liver and triglyceride production studies showed that the activation and synthesis of fatty acid and production of triglyceride in plerocercoid-infected hamsters were not significantly different from the controls. Lipase activity in post-heparin plasma was found to be suppressed in plerocercoid-infected golden hamsters. The presence of plerocercoids also resulted in a significant reduction in serum thyroxine, but the hypertriglyceridaemia associated with plerocercoid infection was not reversed by injecting the infected hamsters with 2 micrograms/day doses of L-thyroxine. The levels of serum immunoreactive insulin in plerocercoid-infected hamsters were not significantly different from the controls. We conclude that the hypertriglyceridaemia, associated with plerocercoid infection in hamsters, results predominantly from a suppression of triglyceride degradation, and that the suppression of lipase activity is probably not the result of hypothyroidism or the lack of insulin, but the result of secretion of growth hormone-like substances.

Some biochemical effects of the growth hormone analogue produced by plerocercoids of the tapeworm Spirometra mansonoides on carbohydrate metabolism of adipose tissue from normal, diabetic, and hypophysectomized rats

Plerocercoids of Spirometra mansonoides produce a functional analogue of mammalian growth hormone (GH). Plerocercoid growth factor (PGF) mimics the growth-promoting actions of GH, but has not been shown to duplicate all of the actions reported for GH. The purpose of this study was to determine the effects of plerocercoid infection (chronic PGF treatment) on glucose metabolism of adipose tissue and to compare the effects to those elicited by insulin and GH in intact, diabetic, and hypophysectomized male rats. Groups of rats were constantly exposed to PGF (via plerocercoid infection) or injected twice daily with bovine GH, insulin, or saline for 10 days. Basal oxidation rates of [U-14C]glucose to 14CO2 in adipose tissue segments were measured in vitro immediately after tissue removal. Other aliquots of adipose tissue were preincubated in hormone-free medium for 3 hr prior to testing the ability of the tissue to respond to insulin or human GH (hGH) added in vitro. Adipose tissue from PGF-treated intact and hypophysectomized rats had significantly elevated basal glucose oxidation rates, and the tissue was sensitive to further stimulation by insulin or hGH. The results obtained with intact and hypophysectomized rats were essentially the same, indicating that the effects of PGF were not due to suppression of endogenous GH. The basal glucose oxidation rate in adipose tissue from diabetic rats was stimulated (P less than 0.01) by PGF, but the tissue was not sensitive to insulin added in vitro. Furthermore, PGF had no effect on body growth or blood glucose concentrations of diabetic rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Insulin-like effects of fatty acid synthesis in liver of hamsters infected with plerocercoids of the tapeworm, Spirometra mansonoides

Elevated serum lipids are associated with infections of laboratory rodents with plerocercoids of Spirometra mansonoides. The effect of infection with these larval tapeworms on triglyceride degradation and hepatic de novo fatty acid synthesis was investigated in Syrian hamsters. Serum lipoprotein electrophoresis revealed a consistent elevation in very low density lipoproteins in the infected animals. Lipoprotein lipase activity was enhanced in the infected animals. After seven days of plerocercoid infection the activity of acetyl-CoA carboxylase (E.C. 6.4.1.2) was significantly elevated after 6, 12 and 18 hours of fasting. Fatty acid synthetase was significantly increased after 0, 6, 12, 18 and 24 hours of fasting. Therefore, a chronic insulin-like activity on lipid metabolism of hamsters is associated with plerocercoid infection.

Effects of Spirometra erinacei plerocercoids on the growth of Snell dwarf mice

Snell normal and dwarf mice were infected with Spirometra erinacei plerocercoids collected in Japan, to investigate the relationship between the growth-promoting effects of plerocercoids and the growth hormone releasing factor and the somatostatin--growth hormone--somatomedin axis in the host. Infection with plerocercoids caused increases in body weight and weights of muscle, liver, spleen and heart in the normal male mice, and increases in the head--body length, body weight and weights of muscle, liver, spleen, kidney and heart in the normal female mice, but did not increase the weight of the fat pad. Infection with plerocercoids caused increases in body weights and weights of muscle, liver and spleen in the male dwarf mice, and increases in the head--body length, body weight and weights of muscle, liver, spleen and kidney in the female dwarf mice. These observations suggest that plerocercoids promote the growth of dwarf mice as well as normal mice. As the dwarfism of Snell mice is due to a defective anterior pituitary gland, it seems that plerocercoids do not stimulate secretion of growth hormone from the pituitary. Accordingly, it seems to be more probable that the larvae secrete a growth hormone-like substance.

Delay of puberty onset in males due to suppression of growth hormone

Infection with Spirometra mansonoides at 22 days of age was associated with delayed sexual maturation in the male rat. Balanopreputial separation occurred at 46.7 +/- 0.8 days in controls and at 50.6 +/- 0.9 days in worm-treated rats (p less than 0.02). This was accompanied by a delay in the normal prepubertal testicular and seminal vesicle weight increases. LH remained normal but serum FSH was depressed as early as 25 days of age. The castration response in worm-treated rats was comparable to that of controls, when the FSH levels were normalized as percentages of resting level. The LH response to castration was diminished. The acute FSH and LH response to GnRH was normal and pituitary stores of gonadotrophin, as estimated by radioimmunoassayable concentrations of FSH and LH, were normal. It can be concluded that puberty onset in males is not linked to body weight gain pe se, and that the absence of endogenous GH secretion affects both sexual maturation and gonadotrophin secretion in the prepubertal period.

Biological effects of Spirometra erinacei plerocercoids in several species of rodents

Observations were made of the biological effects on infection with plerocercoids of Spirometra erinacei on normal female Snell mice, male chinese hamsters, golden hamsters, normal and hypox rats. Plerocercoid infection caused the strongest growth-promoting effect on normal Snell mice. In mice, this effect appears to be independent of strain. Chinese hamsters infected with these larvae showed similar growth. The infected normal rats and golden hamsters, however, showed a weight increase in the skeletal muscle only, while the hypox rats exhibited no effect at all. The elevation in the concentration of serum triglyceride was observed in all the animals investigated except for rats. Golden hamsters, in particular, exhibited a marked increase in the concentration of serum free fatty acids and total cholesterol. There was close correlation between the concentrations of serum triglyceride and free fatty acids, and the regression coefficient of the resulting linear regression equation for the experimentals was higher than that for the controls. This suggests that serum triglyceride results from an increased concentration of serum free fatty acids derived from stimulated lipolysis. The total cholesterol concentration in the serum decreased in chinese hamsters infected with larvae. The serum glucose concentration increased in normal Snell mice but decreased in chinese and golden hamsters. No difference in glycerol and free fatty acid concentration was observed in infected animals except for golden hamsters.

Spirometra mansonoides: effects of plerocercoid infection on glycogen deposition in rats

The effects of infection with plerocercoids of Spirometra mansonoides on tissue glycogen deposition of rats was determined. Hypophysectomized rats infected for two days had higher liver glycogen concentrations than controls and this effect was greatest after one week. Elevated liver glycogen associated with plerocercoid infection was observed in fed animals both at the beginning and at the end of the light period as well as after an overnight fast. Glycogen phosphorylase (1,4 alpha D glucan: orthophosphate alpha glucosyltransferase EC 2.4.1.1.) was inhibited but glucose-6-phosphatase (EC 3.1.3.9) was unaffected in the livers of infected hypophysectomized rats. While this effect is similar to actions of both growth hormone and insulin, plerocercoid infection had no influence on glycogen of cardiac or skeletal muscle at any time. Plerocercoid infection had no effect on the glycogen concentration of any tissue of intact rats.

The lipogenic effect of the growth factor produced by plerocercoids of the tapeworm, Spirometra mansonoides, is not the result of hypothyroidism

Plerocercoid larvae of the tapeworm, Spirometra mansonoides produce a growth hormone-like factor that stimulates body growth of a variety of normal and hormone-deficient animals. Plerocercoid infection (15 per hamster) stimulated an increase in body weight, and markedly suppressed pituitary weight and growth hormone (GH) concentrations of serum and pituitaries of Syrian hamsters. The suppression of serum GH persisted for at least 4 mo after the initiation of infection. The presence of plerocercoids also resulted in a significant reduction (30-50%) in serum thyroxine (T4). The pronounced lipogenic effect associated with plerocercoid infection was not reversed by injection of the infected hamsters with high (10 or 20 micrograms/day) or low (1 or 2 micrograms/day) doses of L-thyroxine. These results suggest that the plerocercoid growth factor may function in a manner similar to high levels of endogenous GH by activating the feedback system that inhibits pituitary secretion of both GH and TSH. Whereas hypothyroidism may be associated with hyperlipidemia the resultant hypothyroid state induced by plerocercoid infection does not explain the hypertriglyceridemia and hypercholesterolemia which were a consistent observation in plerocercoid-infected hamsters.

Immunological aspects associated with suppression of hormone levels in rats infected with plerocercoids of Spirometra mansonoides (Cestoda)

The effect of the plerocercoid larvae of Spirometra mansonoides on hormone levels and the immune system of intact and hypophysectomized (Hx) rats was studied. Intact rats exhibited a decrease in serum growth hormone (GH) and thyroxine (T4) concentrations and a suppression of the humoral immune response 2 wk postinfection. At 4 and 9 wk postinfection, hormone concentrations and the humoral immune response returned to normal levels in the rats. When rats were infected with plerocercoids and then received daily injections for 2 wk of either GH or T4, the immune response returned to normal in the T4-injected, but not the GH-injected animals. Plerocercoid infection had no effect on the humoral immune response of Hx rats. The results of the present study suggest that PGF may act via an endocrine pathway to suppress the host's immune response enabling the parasite's survival in this host.

Chemotherapeutic effects of 4-isothiocyanato-4'-nitrodiphenylamine (C9333-Go/CGP 4540) on infections with Nematospiroides dubius, Hymenolepis diminuta, Hymenolepis nana and Spirometra mansonoides

4-Isothiocyanato-4'-nitrodiphenylamine possessed anthelmintic activity against Nippostrongylus dubius and Hymenolepis nana in mice and H. diminuta in rats as determined by both egg counts and recovery of parasites at autopsy. No activity was detected against the cestode. Spirometra mansonoides, in cats.

Cestode zoonoses of aquatic animals

The cestode zoonoses of Diphyllobothrium, and Spirometra and Sparganosis are discussed from the point of view of their transmission and epidemiology.