The Experts below are selected from a list of 2799 Experts worldwide ranked by ideXlab platform

Seth E Oneal - One of the best experts on this subject based on the ideXlab platform.

  • spatial relationship between taenia solium Tapeworm carriers and necropsy cyst burden in pigs
    PLOS Neglected Tropical Diseases, 2017
    Co-Authors: Ian W Pray, Ricardo Gamboa, Viterbo Ayvar, Claudio Muro, Luz M Moyano, Victor Benavides, Robert H Flecker, Seth E Oneal
    Abstract:

    Background Taenia solium, a parasite that affects humans and pigs, is the leading cause of preventable epilepsy in the developing world. Geographic hotspots of pigs testing positive for serologic markers of T. solium exposure have been observed surrounding the locations of human Tapeworm carriers. This clustered pattern of seropositivity in endemic areas formed the basis for geographically targeted control interventions, which have been effective at reducing transmission. In this study, we further explore the spatial relationship between human Tapeworm carriers and infected pigs using necroscopic examination as a quantitative gold-standard diagnostic to detect viable T. solium cyst Infection in pigs. Methodology/principal findings We performed necroscopic examinations on pigs from 7 villages in northern Peru to determine the number of viable T. solium cysts in each pig. Participating humans in the study villages were tested for T. solium Tapeworm Infection (i.e., taeniasis) with an ELISA coproantigen assay, and the distances from each pig to its nearest human Tapeworm carrier were calculated. We assessed the relationship between proximity to a Tapeworm carrier and the prevalence of light, moderate, and heavy cyst burden in pigs. The prevalence of pig Infection was greatest within 50 meters of a Tapeworm carrier and decreased monotonically as distance increased. Pigs living less than 50 meters from a human Tapeworm carrier were 4.6 times more likely to be infected with at least one cyst than more distant pigs. Heavier cyst burdens, however, were not more strongly associated with proximity to Tapeworm carriers than light cyst burdens. Conclusion/significance Our study shows that human Tapeworm carriers and pigs with viable T. solium cyst Infection are geographically correlated in endemic areas. This finding supports control strategies that treat humans and pigs based on their proximity to other infected individuals. We did not, however, find sufficient evidence that heavier cyst burdens in pigs would serve as improved targets for geographically focused control interventions.

  • geographic correlation between Tapeworm carriers and heavily infected cysticercotic pigs
    PLOS Neglected Tropical Diseases, 2012
    Co-Authors: Seth E Oneal, Victor C. W. Tsang, Silvia Rodriguez, Robert H Gilman, Viterbo Ayvar, Patricia P Wilkins, Luz Maria Moyano, Guillermo Gonzalvez, Andre Diaz
    Abstract:

    Background: Neurocysticercosis is a leading cause of preventable epilepsy in the developing world. Sustainable community-based interventions are urgently needed to control transmission of the causative parasite, Taenia solium. We examined the geospatial relationship between live pigs with visible cysticercotic cysts on their tongues and humans with adult intestinal Tapeworm Infection (taeniasis) in a rural village in northern Peru. The objective was to determine whether tongue-positive pigs could indicate high-risk geographic foci for taeniasis to guide targeted screening efforts. This approach could offer significant benefit compared to mass intervention. Methods: We recorded geographic coordinates of all village houses, collected stool samples from all consenting villagers, and collected blood and examined tongues of all village pigs. Stool samples were processed by enzyme-linked immunosorbent assay (ELISA) for presence of Taenia sp. coproantigens indicative of active taeniasis; serum was processed by enzyme-linked immunoelectrotransfer blot for antibodies against T. solium cysticercosis (EITB LLGP) and T. solium taeniasis (EITB rES33). Findings: Of 548 pigs, 256 (46.7%) were positive for antibodies against cysticercosis on EITB LLGP. Of 402 fecal samples, 6 (1.5%) were positive for the presence of Taenia sp. coproantigens. The proportion of coproantigen-positive individuals differed significantly between residents living within 100-meters of a tongue-positive pig (4/79, 5.1%) and residents living .100 meters from a tongue-positive pig (2/323, 0.6%) (p=0.02). The prevalence of taeniasis was .8 times higher among residents living within 100 meters of a tongue-positive pig compared to residents living outside this range (adjusted PR 8.1, 95% CI 1.4–47.0). Conclusions: Tongue-positive pigs in endemic communities can indicate geospatial foci in which the risk for taeniasis is increased. Targeted screening or presumptive treatment for taeniasis within these high-risk foci may be an effective and practical control intervention for rural endemic areas.

  • taenia solium Tapeworm Infection oregon 2006 2009
    Emerging Infectious Diseases, 2011
    Co-Authors: Seth E Oneal, Patricia P Wilkins, John Noh, William E Keene, William E Lambert, James C Anderson, Jennifer Compton Luman, John M Townes
    Abstract:

    Neurocysticercosis (NCC) is a parasitic disease caused by central nervous system Infection with Taenia solium larval cysts. It is the most common helminthic Infection of the central nervous system and a leading cause of acquired epilepsy in Latin America, Southeast Asia, and central Africa (1,2). The disease also is increasingly of clinical and public health concern in the United States, primarily in immigrants and travelers from cysticercosis-endemic regions (3–5). Cysticercosis is acquired through fecal–oral transmission of Tapeworm eggs shed in the feces of a human carrying intestinal Tapeworms. Ingested eggs release oncospheres, which invade the intestinal mucosa and disseminate throughout the body to form larval cysts. NCC occurs when cysts develop in the central nervous system and is the primary source of illness and death (6). The Tapeworm’s complete life cycle occurs in regions with poor sanitary infrastructure, where foraging pigs have access to human feces. Most NCC cases in the United States probably were acquired in cysticercosis-endemic areas by immigrants or travelers who entered the United States already infected with cysts (3). However, immigrants and travelers also can harbor intestinal Tapeworms, and domestic transmission of NCC does occur (7,8). Few states require reporting of cysticercosis; thus, population-based epidemiologic data in the United States are limited. Even in jurisdictions that require reporting, the clinical nature of NCC diagnosis complicates surveillance efforts because no single laboratory test definitively establishes the diagnosis. Surveillance therefore relies on clinician or institutional reporting. In 1989, California became the first state to require reporting; 112 cysticercosis cases were reported during the first year, for a crude annual incidence of 1.5 cases per 100,000 Hispanics (9). A retrospective case-series from Oregon based on hospital discharge diagnoses during 1995–2000 estimated an annual incidence of 0.2 cases per 100,000 general population and 3.1 cases per 100,000 Hispanics (10). In 5 cases, no exposure to a cysticercosis-endemic area was documented, which suggests the possibility of local transmission. Oregon adopted administrative rules for T. solium reporting in 2002 after the coroner’s examination implicated hydrocephalus secondary to obstructing ventricular cysts in 2 unexplained deaths (10). However, no subsequent efforts were undertaken to stimulate passive reporting or to actively find unreported cases. As a result, only 7 NCC cases, all in Hispanics, were reported to public health officials during the first 5 years of reporting. Oregon has a rapidly growing Hispanic population, which currently represents 11% of the total population. Approximately half of all Oregon Hispanics report birth outside the United States (11). In the context of an increasing population at risk, the small number of passively reported cases suggests inadequate surveillance. Identification and treatment of Tapeworm carriers in the United States could prevent additional NCC cases. However, intestinal Tapeworm Infection produces few symptoms, and the prevalence is typically <1%–2%, even in regions where cysticercosis is endemic (12). During the 1980s, Los Angeles (LA) County, California, adopted a program of screening for Tapeworm carriers with some success. By screening household members of NCC case-patients using light microscopy on fecal samples, the county identified an intestinal Tapeworm carrier in 7% of its overall investigations and in 22% of investigations involving domestically acquired NCC (13). Improved screening methods have been developed in the interim, including an ELISA for Taenia sp. coproantigens in feces and an enzyme-linked immunoelectrotransfer blot (EITB) for serum antibodies against T. solium Tapeworm (14,15). Serologic methods are desirable because they are specific to T. solium intestinal Infection and highly sensitive (99%) and avoid the collection and processing of potentially infectious feces (15). Our objective was to evaluate the utility of public health surveillance for T. solium Infection in Oregon. We implemented population-based active surveillance to determine the incidence of cysticercosis. We also piloted screening specifically for additional T. solium Infection among affected households by using a combination of symptom screening, laboratory analysis of fecal and serum specimens, and radiographic imaging.

Robert H Gilman - One of the best experts on this subject based on the ideXlab platform.

  • taeniasis and cysticercosis
    2018
    Co-Authors: Jo Hendersonfrost, Robert H Gilman
    Abstract:

    Cestodes, or Tapeworms, vary greatly in size and behavior but have similar morphology consisting of a head, called a scolex, a neck, and a worm body, called a strobila, which is formed by body segments called proglottids. T. saginata, T. solium, and T. asiatica. The life cycles of these Taenia species are similar. As definitive host, humans acquire intestinal Infection with these cestodes by ingestion of undercooked meat—pork in the case of T. solium and T. asiatica and beef in the case of T. saginata—containing encysted larvae termed cysticercus. This Tapeworm Infection is called taeniasis. As intermediate host, humans acquire tissue Infection of cysticerci by ingestion of T. solium eggs. After ingestion, the eggs mature into metacestodes, which are infective larvae capable of encysting in tissues. This Infection is called cysticercosis. T. solium is the only species known to cause significant human pathology; most commonly larvae encyst in the central nervous system (CNS), which is called neurocysticercosis. T. saginata and T. asiatica are similar morphologically and closely related genetically. They cause limited pathology in humans but significant economic losses in the livestock industry.

  • taenia solium Infection in peru a collaboration between peace corps volunteers and researchers in a community based study
    PLOS ONE, 2014
    Co-Authors: Nathaniel S Watts, Manuela Verastegui, Monica Pajuelo, Taryn Clark, Mariacristina I Loader, Charles R Sterling, Jon S Friedland, Robert H Gilman
    Abstract:

    Background Neurocysticercosis is a leading cause of seizures and epilepsy in most of the world, and it occurs when Taenia solium larval cysts infect the central nervous system. T. solium Tapeworm Infection is endemic in much of Peru, but there are scarce data on the prevalence in many rural highland communities where it is likely to be hyper-endemic. Peace Corps Volunteers live and work in these communities; however, to our knowledge, they have not been used to facilitate public health research. Materials and Methods We utilized Peace Corps Volunteers to estimate the prevalence of T. solium Tapeworm Infection in seven rural communities in northern Peru. A convenience non-random sampling frame was used. Peace Corps Volunteers facilitated the collection of stool samples (N = 2,328), which were analyzed by sedimentation and microscopy. Niclosamide treatment and purgation preceded species identification, which was done by PCR-REA. Results Taenia sp. egg-positive stool samples were found in three of the seven communities we surveyed. The overall prevalence of Taenia sp. egg positivity was 2.1% (49/2,328) (95% CI = 1.6–2.8%) with prevalence up to 4.3% (42/977) (95% CI = 3.1–5.8%) by community. All 34 of the specimens tested by PCR-REA were T. solium. The overall prevalence of T. solium Tapeworm Infection was 1.5% (34/2,328) (95% CI = 1.0–2.0%). Prevalence up to 2.9% (28/977) (95% CI = 1.9–4.1%) by community was observed. Conclusion/Significance This study recorded high T. solium Tapeworm prevalence, and identified hyper-endemic rural communities. It demonstrates that synergy between researchers and Peace Corps Volunteers can be an effective means to conducting large-scale, community-based studies in remote areas of Peru.

  • geographic correlation between Tapeworm carriers and heavily infected cysticercotic pigs
    PLOS Neglected Tropical Diseases, 2012
    Co-Authors: Seth E Oneal, Victor C. W. Tsang, Silvia Rodriguez, Robert H Gilman, Viterbo Ayvar, Patricia P Wilkins, Luz Maria Moyano, Guillermo Gonzalvez, Andre Diaz
    Abstract:

    Background: Neurocysticercosis is a leading cause of preventable epilepsy in the developing world. Sustainable community-based interventions are urgently needed to control transmission of the causative parasite, Taenia solium. We examined the geospatial relationship between live pigs with visible cysticercotic cysts on their tongues and humans with adult intestinal Tapeworm Infection (taeniasis) in a rural village in northern Peru. The objective was to determine whether tongue-positive pigs could indicate high-risk geographic foci for taeniasis to guide targeted screening efforts. This approach could offer significant benefit compared to mass intervention. Methods: We recorded geographic coordinates of all village houses, collected stool samples from all consenting villagers, and collected blood and examined tongues of all village pigs. Stool samples were processed by enzyme-linked immunosorbent assay (ELISA) for presence of Taenia sp. coproantigens indicative of active taeniasis; serum was processed by enzyme-linked immunoelectrotransfer blot for antibodies against T. solium cysticercosis (EITB LLGP) and T. solium taeniasis (EITB rES33). Findings: Of 548 pigs, 256 (46.7%) were positive for antibodies against cysticercosis on EITB LLGP. Of 402 fecal samples, 6 (1.5%) were positive for the presence of Taenia sp. coproantigens. The proportion of coproantigen-positive individuals differed significantly between residents living within 100-meters of a tongue-positive pig (4/79, 5.1%) and residents living .100 meters from a tongue-positive pig (2/323, 0.6%) (p=0.02). The prevalence of taeniasis was .8 times higher among residents living within 100 meters of a tongue-positive pig compared to residents living outside this range (adjusted PR 8.1, 95% CI 1.4–47.0). Conclusions: Tongue-positive pigs in endemic communities can indicate geospatial foci in which the risk for taeniasis is increased. Targeted screening or presumptive treatment for taeniasis within these high-risk foci may be an effective and practical control intervention for rural endemic areas.

  • characterization cloning and expression of two diagnostic antigens for taenia solium Tapeworm Infection
    Journal of Parasitology, 2004
    Co-Authors: Min Z Levine, Hector H Garcia, Robert H Gilman, Patricia P Wilkins, Armando E Gonzalez, William S Lane, John M Asara, Kathy Hancock, Victor C. W. Tsang
    Abstract:

    Adult and larval stages of Taenia solium cause 2 diseases in humans, i.e., taeniasis and cysticercosis, respectively. Diagnosis and treatment of taeniasis are the ultimate means to eliminate cysticercosis. A serological taeniasis diagnostic test has been developed for laboratory use. However, recombinant forms of the taeniasis diagnostic proteins are required to overcome the limited supply of native proteins and allow the development of a low-cost and field-applicable test with high sensitivity and specificity. Using 2-dimensional electrophoresis of T. solium excretory and secretory (TSES) products from hamster adult Tapeworm in vitro cultures, we have identified 5 T. solium–specific protein spots, with molecular weights of 33 kDa (protein isoelectrofocusing point [pI]: 5.6, 5.3, 5.1) and 38 kDa (pI: 4.6, 4.5). Protein sequencing and molecular cloning of these proteins showed that although endowed with different pIs, the proteins with the same molecular weights shared the same protein backbone, named TSES...

Derek M Mckay - One of the best experts on this subject based on the ideXlab platform.

  • murine model of chemically induced colitis protective effect of Tapeworm Infection in a neutralizing anti il 10 antibody blocks the
    2013
    Co-Authors: Derek M Mckay, Meaghan M Hunter, Arthur Wang, Christina L Hirota
    Abstract:

    Derek M. McKayMeaghan M. Hunter, Arthur Wang, Christina L. Hirota andhttp://www.jimmunol.org/content/174/11/7368J Immunol€2005; 174:7368-7375; ;Referenceshttp://www.jimmunol.org/content/174/11/7368.full#ref-list-1This article cites 41 articles, 13 of which you can access for free at: Subscriptionshttp://jimmunol.org/subscriptionsInformation about subscribing to The Journal of Immunology is online at: Permissionshttp://www.aai.org/ji/copyright.htmlSubmit copyright permission requests at: Email Alertshttp://jimmunol.org/cgi/alerts/etocReceive free email-alerts when new articles cite this article. Sign up at:

  • neutralizing anti il 10 antibody blocks the protective effect of Tapeworm Infection in a murine model of chemically induced colitis
    Journal of Immunology, 2005
    Co-Authors: Meaghan M Hunter, Arthur Wang, Christina L Hirota, Derek M Mckay
    Abstract:

    There is increasing evidence that parasitic helminth Infection has the ability to ameliorate other disease conditions. In this study the ability of the rat Tapeworm, Hymenolepis diminuta, to modulate dinitrobenzene sulfonic acid (DNBS)-induced colitis in mice is assessed. Mice receiving DNBS (3 mg intrarectally) developed colitis by 72 h after treatment. Mice infected 8 days before DNBS with five H. diminuta larvae were significantly protected from the colitis, as gauged by reduced clinical disease, histological damage scores, and myeloperoxidase levels. This anticolitic effect was dependent on a viable Infection and helminth rejection, because no benefit was observed in mice given killed larvae or in infected STAT6 knockout mice or rats, neither of which eliminate H. diminuta. The anticolitic effect of H. diminuta was associated with increased colonic IL-10 mRNA and stimulated splenocytes from H. diminuta- plus DNBS-treated mice produced more IL-10 than splenocytes from DNBS-only treated mice. Coadministration of an anti-IL-10 Ab blocked the anticolitic effect of prophylactic H. diminuta Infection. Also, mice infected 48 h after DNBS treatment showed an enhanced recovery response. Finally, using a model of OVA hypersensitivity, we found no evidence of concomitant H. diminuta Infection enhancing enteric responsiveness to subsequent ex vivo OVA challenge. The data show that a viable Infection of H. diminuta in a nonpermissive system exerts a profound anticolitic effect (both prophylactically and as a treatment) that is mediated at least in part via IL-10 and does not predispose to enhanced sensitivity to bystander proteins.

Guiyun Yan - One of the best experts on this subject based on the ideXlab platform.

  • quantitative trait loci for susceptibility to Tapeworm Infection in the red flour beetle
    Genetics, 2003
    Co-Authors: Daibin Zhong, Aditi Pai, Guiyun Yan
    Abstract:

    Parasites have profound effects on host ecology and evolution, and the effects of parasites on host ecology are often influenced by the magnitude of host susceptibility to parasites. Many parasites have complex life cycles that require intermediate hosts for their transmission, but little is known about the genetic basis of the intermediate host's susceptibility to these parasites. This study examined the genetic basis of susceptibility to a Tapeworm ( Hymenolepis diminuta ) in the red flour beetle ( Tribolium castaneum ) that serves as an intermediate host in its transmission. Quantitative trait loci (QTL) mapping experiments were conducted with two independent segregating populations using amplified fragment length polymorphism (AFLP) markers and randomly amplified polymorphic DNA (RAPD) markers. A total of five QTL that significantly affected beetle susceptibility were identified in the two reciprocal crosses. Two common QTL on linkage groups 3 and 6 were identified in both crosses with similar effects on the phenotype, and three QTL were unique to each cross. In one cross, the three main QTL accounted for 29% of the total phenotypic variance and digenic epistasis explained 39% of the variance. In the second cross, the four main QTL explained 62% of the variance and digenic epistasis accounted for only 5% of the variance. The actions of these QTL were either overdominance or underdominance. Our results suggest that the polygenic nature of beetle susceptibility to the parasites and epistasis are important genetic mechanisms for the maintenance of variation within or among beetle strains in susceptibility to Tapeworm Infection.

  • effects of Tapeworm Infection on male reproductive success and mating vigor in the red flour beetle tribolium castaneum
    Journal of Parasitology, 2003
    Co-Authors: Aditi Pai, Guiyun Yan
    Abstract:

    Parasites may exert negative effects on host survivorship and reproductive success. The effects of parasites on female host fitness have been well documented; however, the effects of parasites on the reproductive success of male hosts and particularly the underlying mechanisms that alter male fitness are not well understood. Previous studies demonstrated that Infection by rat Tapeworm (Hymenolepis diminuta) reduced the fitness of male red flour beetles (Tribolium castaneum) in an environment of female mate choice and strong male–male competition. The present study determined the role of female mate choice and male insemination capacity on observed fitness reduction of male beetles by the Tapeworm parasites. We found that infected males showed reduced mating vigor and consequently inseminated fewer females than did uninfected males. Specifically, Tapeworm Infection reduced the number of offspring sired by a male by 14–22% even when male–male competition and female mate choice were absent. Further, the inse...

  • consequences of larval Tapeworm Infection for the fitness of the intermediate hosts flour beetles tribolium spp
    Canadian Journal of Zoology, 1997
    Co-Authors: Guiyun Yan
    Abstract:

    The problem of the effect of parasites on the fitness of their hosts is central to understanding the ecological and evolutionary consequences of parasitism. This study examined the consequences of Infection with a Tapeworm parasite, Hymenolepis diminuta, on the fitness of its intermediate hosts, Tribolium castaneum and T. confusum, and the correlation between host fitness and Infection intensity. Fitness was measured as the proportion of offspring contributed by a focal individual in a test population, using beetle body colors as genetic markers. Thus, this fitness measurement estimated the overall effects on various fitness components affected by parasites, except the beetles' susceptibility to predation by definitive hosts or to parasitism by other parasites. Three different methods of Infection were used to produce various levels of parasite intensity. Overall, the Tapeworm Infection significantly reduced the beetles' fitness, by 9–16% for T. confusum and 29–32% for T. castaneum, and parasite-induced f...

  • influence of Tapeworm Infection on the production of aggregation pheromone and defensive compounds in tribolium castaneum
    Journal of Parasitology, 1996
    Co-Authors: Guiyun Yan, Thomas W Phillips
    Abstract:

    Recent studies suggest that parasites affect host development, reproduction, and behavior through alterations of host hormones and pheromones, or other hormone-triggered biochemical events. We previously reported that Hymenolepis diminuta Infection affects surface-seeking and cannibalism behaviors, and reduces male sperm precedence of Tribolium castaneum beetles. This study examined the quantitative effects of H. diminuta on the production of aggregation pheromone and 3 defensive compounds in male T. castaneum beetles, using 2 wild-caught, geographically distinct T. castaneum strains. For the c-Madison strain, infected beetles exhibited a 2- to 22-fold increase in defensive compounds; conversely, no changes were observed in strain c-Africa. Parasite Infection did not significantly influence aggregation pheromone secretion in either strain. Because defensive compounds function as repellents or deterrents to other insects, parasite-induced increases in the secretion of defensive compounds may be a physiologic clue for the behavioral changes in infected T. castaneum beetles. Significant among-strain variation in defensive compound production seen in infected beetles suggests that caution is needed before generalizing about changes in volatile production and in host behavior induced by a parasite.

  • BEHAVIORAL CHANGES IN TRIBOLIUM BEETLES INFECTED WITH A Tapeworm: VARIATION IN EFFECTS BETWEEN BEETLE SPECIES AND AMONG GENETIC STRAINS
    The American Naturalist, 1994
    Co-Authors: Guiyun Yan, Lori Stevens, Jos. J. Schall
    Abstract:

    We report behavioral alterations induced by Tapeworm (Hymenolepis diminuta) Infection in several genetic strains of two species of flour beetles, Tribolium, under two Infection levels in a laboratory environment. Under a high level of Infection, Tribolium castaneum (strain cSM) shows decreased emigration and surface-seeking behavior and increased cannibalism. In contrast Tribolium confusum (strain b+) shows increased emigration and surface-seeking behavior, and cannibalism is not significantly changed. Under a low level of Infection, emigration is not affected in any of the 11 genetic strains examined. Prevalence of parasitism is positively associated with emigration rate. Different genetic strains of T. confusum exhibited different susceptibility to Tapeworm Infection, suggesting intraspecific genetic variation in susceptibility to Infection. This genetic basis may reflect past differences in selection resulting from different Infection histories and suggests susceptibility to Infection could evolve as a...

John Adams Oaks - One of the best experts on this subject based on the ideXlab platform.

  • hymenolepis diminuta mucosal mastocytosis and intestinal smooth muscle hypertrophy occur in Tapeworm infected rats
    Experimental Parasitology, 1998
    Co-Authors: Michael B. Dwinell, Paul Bass, Ruth M Wise, John Adams Oaks
    Abstract:

    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.

  • Tapeworm Infection decreases intestinal transit and enteric aerobic bacterial populations
    American Journal of Physiology-gastrointestinal and Liver Physiology, 1997
    Co-Authors: Michael B. Dwinell, D. M. Schaefer, Paul Bass, John Adams Oaks
    Abstract:

    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.

  • Intestinal myoelectric alterations in rats chronically infected with the Tapeworm Hymenolepis diminuta
    American Journal of Physiology-gastrointestinal and Liver Physiology, 1994
    Co-Authors: Michael B. Dwinell, Paul Bass, John Adams Oaks
    Abstract:

    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.