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At least 19 recordsLinked to original sources
PubMed1987

Tapeworms.

Dogs and cats become infected with tapeworms by ingesting intermediate hosts that contain encysted juvenile tapeworms called larvae. The dog or cat is said to be the definitive host because it shelters the sexually reproductive, egg-producing stage of the tapeworm. The intermediate hosts, which are vertebrates in the case of Taenia and Mesocestoides and insects in the case of Dipylidium and Hymenolepis, become infected by ingesting unhatched but infective tapeworm eggs discharged in the feces of the dog or cat. The relatively less common Diphyllobothrium and Spirometra tapeworms discharge eggs that are undeveloped when passed in the feces and must fall into water to undergo development to the coracidium stage. Diphyllobothrium and Spirometra may have two or three aquatic intermediate hosts in series. The first of these, a copepod, ingests the free-swimming coracidium or ciliated oncosphere that has hatched from the egg. The final intermediate host containing the larva (plerocercoid) infective for the dog or cat is an aquatic vertebrate (fish, frog, water snake). Thus, dogs and cats become infected with tapeworms by eating uncooked meat or fish or by ingesting certain insects. These intermediate hosts are infected with juvenile tapeworms called larvae, which are the infective form for the dog or cat. The intermediate hosts, in turn, become infected by ingesting tapeworm eggs discharged in the feces of the dog or cat or, in the case of Diphyllobothrium and Spirometra, by ingesting coracidia that have subsequently developed in and hatched from such eggs. By far the most common tapeworms of dogs and cats in North America are D. caninum, T. pisiformis, and T. hydatigena. Therefore, the most common sources of tapeworm infection are, respectively, fleas, wild rabbits, and the uncooked meat and offal of ruminants and swine. Whenever a dose of tapeworm remedy is administered or dispensed, the client should be informed of these potential sources of reinfection. There is considerable overlap in the spectra of activity of currently available cestocides. Mebendazole, fenbendazole, niclosamide, bunamidine, and praziquantel are all effective against Taenia spp. Bunamidine is the drug of choice against Spirometra, Diphyllobothrium, and Mesocestoides. Praziquantel is the drug of choice against Echinococcus and Dipylidium.

Animals↗
PubMed2001

Myoelectric response of the small intestine to the orad presence of the tapeworm Hymenolepis diminuta.

During its 24-hr migratory cycle in the small intestine, Hymenolepis diminuta is located in the orad part of the small intestine during the early morning hours and then in the caudad part of the small intestine during the late afternoon and early evening. During the later period, tapeworm-induced alterations of interdigestive myoelectric activity, a correlate of smooth muscle contraction or intestinal motility, are most intense in the ileal region. The hypothesis tested was that the tapeworm-induced changes in intestinal motility are local responses of the intestine responding to the close proximity of the lumenally positioned tapeworm and to the nutritional state of the host. The small intestine was monitored before and for 20 days after infection using electrodes implanted on the serosa of the small intestine. Myoelectric recordings were analyzed for the frequency of the normal patterns of interdigestive myoelectric spiking patterns and the altered myoelectric spiking related to tapeworm infection. During the morning hours, when the tapeworms are situated in the orad small intestine, no changes were observed during the normal myoelectric pattern of the digestive phase in any region of the intestine. When examined after the conversion of the digestive to interdigestive phase of motility, only on day 10 postinfection was the interdigestive phase significantly altered. It was concluded that the presence of the tapeworm in the orad small intestine during the satiety stage of the rat causes no changes in the electric events of the small intestine, with the exception of day 10 postinfection. Because tapeworms in the orad small intestine do not induce the tapeworm-altered myoelectric activity observed in the afternoon and evening with caudally positioned tapeworms, tapeworm-altered motility is not simply a response of the small intestine to the local presence of the tapeworm.

Animals↗
PubMed1996

[The effect of crowding tapeworms Hymenolepis diminuta based on proglottids in the period of intensified variability].

Tapeworms obtained 13 months after the administration to rats of cysticercoids Hymenolepis diminuta - WMS il1 measured in 3-6-specimen populations an average of 677.9 mm in length while in 23-26-specimen populations an average of 356.9 mm in length. Strobilas of an exclusively unilateral (right-sided) position of genital pores (PGP) appeared in 76.3%-79.8% of tapeworms of the investigated groups. In such tapeworms belonging to 23-26-specimen populations the frequency of occurrence of typical proglottids containing 1 testis on the poral side and 2 testes on the aporal side (1p2a) and type 0p3a proglottids averaging 86.5% and 6.8%, respectively, declines in comparison to the average frequency of occurrence of proglottids of this type in 3-6-specimen populations amounting to 87.8% and 8.8%, respectively. The frequency of occurrence of four-testes (1p3a) proglottids averaged 5.5% in tapeworms from the 23-26-specimen populations and was 4.0% higher than the 1.5% average in tapeworms from the 3-6-specimen populations, in spite of the fact that in a population with a higher number of specimens proglottids are smaller and, therefore, have less room for an additional number of these organs. In tapeworms with variable PGP type 2p1a proglottids constituted the most frequent deviation in each of investigated group of different infection intensity. Their average frequency of occurrence rose from 0.4%-0.5% in tapeworms with unilateral PGP to an average of 5.5%-5.9% in tapeworms with variable PGP. Close positive correlation was found in tapeworms with variable PGP between the frequency of occurrence of such changes and the frequency occurrence of type 2p1a proglottids in every of investigated group (P < 0.01, r = from +0.887, to +0.918).

Animals↗
PubMed1998

Hymenolepsis diminuta: mucosal mastocytosis and intestinal smooth muscle hypertrophy occur in tapeworm-infected rats.

The mechanisms mediating motility changes during noninvasive tapeworm infection have not been characterized. In contrast, host intestinal motility changes during invasive nematode infection are mediated by mucosal mast cells (MMC). The purpose of this study was to examine and the correlate onset of myoelectric alterations 8 days after initial tapeworm infection with changes in intestinal morphology, MMC numbers, and MMC secretory activity. Segments of the small intestine, the tapeworms normal habitat, along with stomach, colon, and bladder were taken from tapeworm-infected and control rats. Tissues were fixed and stained to identify MMC and for morphologic measurement. Tapeworm-infected and uninfected rats with chronically implanted intestinal electrodes were treated with ketotifen, a mast cell stabilizer, and in vivo myoelectric activity monitored. In tapeworm-infected rats, the muscularis externa, on day 20 postinfection, and crypts of Lieberkuhn, on day 26 postinfection, from the entire small intestine appeared thickened or deeper, respectively. Increased muscularis thickness was due to smooth muscle hypertrophy in both the circular and the longitudinal muscle layers. Mucosal mastocytosis was first observed on day 26 postinfection and occurred only in the ileum of tapeworm-infected rats. Pharmacologic stabilization of mast cells with ketotifen did not prevent onset of enteric myoelectric alterations during tapeworm infection. Stomach, colon, and bladder MMC numbers and tissue dimensions were not different between Hymenolepis diminuta-infected rats and uninfected controls. Initiation of myoelectric alterations 8 days after infection precedes and may be a contributing factor to the onset of both smooth muscle hypertrophy and mucosal mastocytosis. Taken together, our data indicate that mast cells are not an initiating factor nor chronic stimulus maintaining intestinal myoelectric alterations during H. diminuta infection.

Animals↗
PubMed1999

Hymenolepis diminuta: praziquantel removal of adult tapeworms is followed by apoptotic down-regulation of mucosal mastocytosis.

The rat tapeworm, Hymenolepis diminuta, induces mastocytosis, hypertrophy of enteric smooth muscle, alteration of enteric myoelectric activity, and slowed enteric transit of the rat host's intestine. This report examines the resolution of both tapeworm-induced mastocytosis and tissue changes during the period following removal of the tapeworm with Praziquantel (PZQ). The dynamics of the mucosal mast cell (MMC) population following removal of the tapeworms was assessed by histochemical identification of MMC and morphometric techniques. As a possible mechanism of MMC population regulation, MMC apoptosis was examined over the same experimental period using the in situ nick end labeling of fragmented DNA (TUNEL). Shifts in MMC numbers were correlated with functional and morphological changes of the intestine following removal of the adult-stage tapeworm. Ileal tissues from rats infected 32 days with H. diminuta (the beginning of plateau phase of tapeworm-induced chronic mastocytosis) were harvested 1, 2, 3, and 4 weeks after the PZQ treatment. Control ilea were obtained either from rats which were never infected and never treated with PZQ or from rats infected with H. diminuta for 32 days but not treated with PZQ. In order to detect MMC and apoptosis, tissue sections of ileum were doubled stained sequentially with Astra blue for MMC granules followed by a modification of the TUNEL technique. No alteration in MMC numbers were observed in PZQ-treated animals until 3 weeks after the removal of the tapeworms. The decline of MMC occurred in the mucosa and submucosa. MMC numbers first approached uninfected control levels at 4 weeks posttreatment. Coincident with the decline in mucosal MMC numbers, the rate of MMC entering apoptosis also declined. Simultaneously, ileal smooth muscle layers, hypertrophied by infection, and mucosal structures began the process of involution and atrophy. Apoptosis of MMC in the submucosa and muscularis mucosa was not detected. In conclusion, H. diminuta-elicited mastocytosis and increased thickness of both mucosa and muscularis externa do not begin a decline toward control values until 3 weeks after the parasites are gone and normal intestinal motility is restored. These data are consistent with the lack of MMC mediation of altered motility, and the decline in the rate of MMC apoptosis at 3 weeks post-PZQ suggests that apoptosis may play an important role in the involution of tapeworm-induced mastocytosis.

Animals↗
PubMed1997

Tapeworm infection decreases intestinal transit and enteric aerobic bacterial populations.

Intestinal myoelectric patterns in rats are altered after chronic luminal infection with the tapeworm Hymenolepis diminuta. This study evaluates whether these altered patterns were associated with changes in intestinal fluid transit and endogenous enteric microbe levels. Luminal transit, measured throughout the small intestine during the interdigestive state, was significantly decreased during tapeworm infection. Reduced transit was regional, occurring in the same location as that of the tapeworm and maximal myoelectric alterations. In other experimental systems, aerobic and anaerobic bacterial overgrowth is associated with decreased transit; however, reduced transit during tapeworm infection was unexpectedly associated with decreased numbers of aerobic bacteria, whereas anaerobic bacterial populations remained unchanged. The lack of overgrowing endogenous microflora suggests that overgrowth is not responsible for tapeworm-stimulated alterations in host myoelectric patterns. We speculate that a tapeworm secretion could be responsible for both transit and motility changes while delayed intestinal transit could prevent tapeworm expulsion, aid the tapeworms' migration, and contribute to the digestion and absorption of nutrients by hosts and/or parasites.

Animals↗
PubMed1998

Hymenolepis diminuta fractions but not previous tapeworm infection stimulate intestinal myoelectric alterations in vivo in the rat.

Infection of rats with the enteric, lumen-dwelling tapeworm Hymenolepis diminuta causes electric changes in host intestinal smooth muscle and decreased luminal transit. The mechanisms that stimulate host intestinal alterations during this nontissue invasive infection may include the tapeworm's biomass, its diurnal migratory behavior, a host immune-mediated response, or direct parasite stimulation of host motor activity. In vivo intestinal myoelectric activity was monitored to evaluate the following: (1) that reinfection with H. diminuta is influenced by host immune regulation and (2) that administration of tapeworm fractions to never-before-infected rats initiates an alteration of enteric smooth muscle activity. To address the first hypothesis, we determined that altered intestinal myoelectric activity patterns were no different and did not occur earlier in a second infection with H. diminuta than in a primary infection. The lack of either a change in myoelectric pattern or an earlier onset of intestinal myoelectric changes indicates that tapeworm-induced myoelectric activity is not anamnestically stimulated by host immunomodulatory mechanisms. Consistent with the second hypothesis, administration of either H. diminuta carcass homogenate or tegument-enriched fractions directly into the intestinal lumen of tapeworm-naive rats initiated myoelectric patterns previously characteristic of chronic H. diminuta infection. Additionally, the appearance of characteristic nonmigrating myoelectric patterns in uninfected rats administered tapeworm fractions indicates that a substance from H. diminuta acts as the triggering signal molecule for intestinal myoelectric alterations. These findings also indicate that neither the tapeworm's biomass nor its diurnal movement is required for initiation of H. diminuta-altered myoelectric patterns. We have shown that H. diminuta possess a signal molecule(s) that alters host enteric electric activity, and we suggest that these alterations may play an important role in the symbiotic rat-tapeworm interrelationship.

Action Potentials↗
PubMed2003

Seasonal occurrence of the tapeworm Proteocephalus longicollis and its transmission from copepod intermediate host to fish.

Seasonal occurrence in terms of prevalence, intensity of infection, abundance and density of the tapeworm Proteocephalus longicollis (Zeder, 1800) and its transmission between its intermediate host (Cyclops abyssorum prealpinus) and definitive host (common whitefish, Coregonus lavaretus) in Lake Annecy, an oligotrophic lake in the western part of the Alps, France, were studied in the period of 1998-2000. A copepod Cyclops abyssorum prealpinus (Kiefer, 1939), the dominant species among planktonic crustaceans in the lake, served as the only intermediate host for this parasite. Infection with plerocercoids was higher in adult copepods (predominantly females) than in copepodite stages IV and V. The prevalence rate of 25% found in C. abyssorum prealpinus females in June 1998 represents a unique infection rate of intermediate hosts with fish tapeworms in natural conditions. The final host, the common whitefish Coregonus lavaretus (L.), was heavily infected with P. longicollis throughout the year (prevalence 90%; mean abundance 40.3; maximum intensity of infection more than 500 tapeworms per fish); immature tapeworms predominated in all samples (P<0.01). Transmission of tapeworm larvae from copepods to the common whitefish took place most intensively in summer and autumn, and depended on seasonal changes in the density of the C. abyssorum prealpinus population, infection of this copepod with plerocercoids and their density in the lake. In addition, transmission efficiency also seems to be determined by the longevity of tapeworm larvae in the intermediate host, timing of predation of the fish host and rapid development of the parasite within this host during the summer period. Overall transmission potential of P. longicollis was low, with only about 9% of juvenile specimens reaching maturity in common whitefish.

Animals↗
PubMed2001

Intestinal regrowth is amplified after jejunal but not ileal resection during tapeworm infection in the rat.

The ileum possesses functions required by a healthy individual that are not fully supplanted by the duodenum or jejunum. Evidence suggests that the ileum may also be necessary to maintain an enteric parasite-host interaction. We hypothesized that the ileum is essential to the survival of the lumen-dwelling, rat tapeworm, H. diminuta. Male rats were divided into three groups: those with ileal or jejunal resections and nonresected controls. Half of each rat group was infected with the tapeworm. After jejunal resection, the weight but not length of intestinal remnant (duodenum + ileum) in infected rats returned to that of control, nonresected intestine 29 days after surgery and tapeworm numbers were fully maintained. In contrast, after ileal removal intestinal length and weight of the remaining duodenum and jejunum in infected rats were significantly decreased and tapeworm survival diminished. Data indicates that intestinal growth following resection is amplified by tapeworm infection when the ileum remains but diminished when the ileum is removed. Furthermore, loss of the ileum results in decreased infection intensity and dry weight of the tapeworm.

Animals↗
PubMed2005

Short report: evaluation of a self-detection tool for tapeworm carriers for use in public health.

The current study was designed to evaluate a tool for the self-identification of tapeworm carriers. Clinical and animal health care practitioners and schoolteachers were trained regarding the life cycle, risk factors, and control measures related to infection with Taenia solium. More than 120 small glass bottles with a few tapeworm segments fixed in formaldehyde and an instructional guide were distributed among all clinical practitioners (physicians and nurses) working in health centers. The guide contained 10 key points on how to ask questions about tapeworm infections. Information on taeniosis and cysticercosis was also provided to the general population via different media. Seven tapeworm carriers were recorded in the official epidemiology surveillance system the year previous to the study, compared with the year after the study, when 41 tapeworm carriers (37 Taenia saginata; 4 Taenia solium) were recorded. Six times more tapeworm carriers were notified after the study. All four persons with Taenia solium were treated, thereby eliminating the parasite and subsequently preventing any new cases of human and swine cysticercosis that might have arisen from them.

Anthelmintics↗
PubMed1991

Regional modulations in tegumental glucose transporter kinetics in the rat tapeworm.

Comparisons of glucose transporter kinetics in 8-day (Km = 0.34 mM, Vmax = 14 nmole.min-1.g-1), 10-day (Km = 0.46 mM, Vmax = 18 nmole.min-1.g-1), the first quartile of 17-day (Km = 0.51 mM, Vmax = 21 nmole.min-1.g-1), and the first quartile of 32-day (Km = 0.33 mM, Vmax = 39 nmole.min-1.g-1) rat tapeworms (Hymenolepis diminuta) suggest maximal velocities may vary with age. A gradient in glucose transporter density is suggested in the rat tapeworm by changes in the estimated transporter Vmax in the first through fourth quartiles. Alterations in the physiological efficiency (as indicated by the Vmax/Km ratio) and permeability (indicated by the unsaturated permeability-area product) of the glucose transporter were determined to be significantly greater in the first quartile than in other quartiles of 17-day hymenolepids. A similar trend was apparent in older (32-day) worms. In tapeworms maintained for 30 min in glucose-free medium, maximal velocities were highest in the anterior (first) quartile, and reductions were seen in successive second, third, and fourth quartiles. When worms were maintained in a medium containing 11 mM glucose, maximal velocities were about twofold greater, but the Vmax increased in each successive quartile. The apparent half-saturation constants, which indicate that concentration of external glucose at which half of the glucose transporter proteins are occupied, are reduced approximately 50% in tapeworms maintained in glucose-free medium. These studies demonstrate that regional differences exist in the glucose transporter of the rat tapeworm, analogous to the intestinal glucose gradient. Furthermore, substrate-induced modulations in the transporter may also exhibit independent regional variability.

Animals↗
PubMed1994

Intestinal myoelectric alterations in rats chronically infected with the tapeworm Hymenolepis diminuta.

This study determined that intestinal myoelectric activity was profoundly altered during a strictly luminal, chronic, tapeworm infection. Chronically implanted bipolar electrodes were attached to five sites on the serosal surface of the rat small intestine. One was placed on the duodenum, three on the jejunum, and the fifth on the ileum. Electromyographic recording in nonfasted unanesthetized animals was begun at day 5 postsurgery. All electromyographic recordings were analyzed for slow wave (SW) frequency, phase III frequency, duration of phase III, and percentage of SW with spike potentials. Three initial control recordings prior to infection confirmed the presence of normal interdigestive motility characterized by the three phases (I, II, III) of the migrating myoelectric complex (MMC). Two nonpropulsive myoelectric alterations were observed in infected animals: the repetitive bursts of action potentials (RBAP) and periods of sustained spike potentials (SSP). Myoelectric activity from infected animals indicated decreased cycling of the interdigestive MMC. RBAP and SSP were more prevalent in the distal small intestine corresponding to tapeworm location. The percent of spike potential activity indicated that there was a reversal in the spike potential gradient on the small intestine. The number of spike potentials was maximal in caudal and minimal in oral intestine. We propose that overall localized increases in myoelectric spike potential activity represent increased contractility and decreased propulsion triggered by the presence of the tapeworm. These motility changes were surprising, since the tapeworm Hymenolepis diminuta does not penetrate the intestinal mucosa. This interaction between parasite and host may prevent expulsion of the tapeworm from the small intestine.

Action Potentials↗