DOCSLIB.ORG

Lecture 5: Emerging Parasitic Helminths Part 2: Tissue Nematodes

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Lecture 5: Emerging Parasitic Helminths Part 2: Tissue Nematodes Readings-Nematodes • Ch. 11 (pp. 290, 291-93, 295 [box 11.1], 304 [box 11.2]) • Lecture 5: Emerging Parasitic Ch.14 (p. 375, 367 [table 14.1]) Helminths part 2: Tissue Nematodes Matt Tucker, M.S., MSPH [email protected] HSC4933 Emerging Infectious Diseases HSC4933. Emerging Infectious Diseases 2 Monsters Inside Me Learning Objectives • Toxocariasis, larva migrans (Toxocara canis, dog hookworm): • Understand how visceral larval migrans, cutaneous larval migrans, and ocular larval migrans can occur Background: • Know basic attributes of tissue nematodes and be able to distinguish http://animal.discovery.com/invertebrates/monsters-inside- these nematodes from each other and also from other types of me/toxocariasis-toxocara-roundworm/ nematodes • Understand life cycles of tissue nematodes, noting similarities and Videos: http://animal.discovery.com/videos/monsters-inside- significant difference me-toxocariasis.html • Know infective stages, various hosts involved in a particular cycle • Be familiar with diagnostic criteria, epidemiology, pathogenicity, http://animal.discovery.com/videos/monsters-inside-me- &treatment toxocara-parasite.html • Identify locations in world where certain parasites exist • Note drugs (always available) that are used to treat parasites • Describe factors of tissue nematodes that can make them emerging infectious diseases • Be familiar with Dracunculiasis and status of eradication HSC4933. Emerging Infectious Diseases 3 HSC4933. Emerging Infectious Diseases 4 Lecture 5: On the Menu Problems with other hookworms • Cutaneous larva migrans or Visceral Tissue Nematodes larva migrans • Hookworms of other animals • Cutaneous Larva Migrans frequently fail to penetrate the human dermis (and beyond). • Visceral Larva Migrans – Ancylostoma braziliense (most common- in Gulf Coast and tropics), • Gnathostoma spp. Ancylostoma caninum, Ancylostoma “creeping eruption” ceylanicum, • Trichinella spiralis • They migrate through the epidermis leaving typical tracks • Dracunculus medinensis • Eosinophilic enteritis-emerging problem in Australia HSC4933. Emerging Infectious Diseases 5 HSC4933. Emerging Infectious Diseases 6 1 Visceral Larva Migrans (VLM) • Caused by juveniles of several species of nematodes that gain entry to improper host • Larvae begin tissue migration, but become arrested and migrate throughout body • Toxocara canis, Toxocara cati • Ascaris suum No maturation to adults http://www.cdc.gov/mmwr/preview/mmwrht ml/mm5649a2.htm HSC4933. Emerging Infectious Diseases 7 HSC4933. Emerging Infectious Diseases 8 Toxocara canis T. canis life cycle • Dog roundworm – Transmitted maternal-fetal • Infects very high % puppies • Distributed worldwide • Worms release massive amounts of eggs that are environmentally stable • Causes VLM, OLM • Albendazole+inflammatory drugs HSC4933. Emerging Infectious Diseases 9 HSC4933. Emerging Infectious Diseases 10 Diseases Gnathostoma spp. • VLM – Larvae invade multiple tissues (liver, heart, lungs, • G. spinigerum brain, muscle) and cause fever, anorexia, weight • Transmitted in Asia, especially Thailand and loss, cough, rashes, hepatosplenomegaly Japan; recently emerged as an important – Death can occur rarely, by severe cardiac, human parasite in Mexico pulmonary or neurologic involvement. • Humans infected by eating undercooked • OLM fish or poultry containing third-stage – Larvae produce various ophthalmologic lesions, larvae, or by drinking water containing sometimes misdiagnosed as retinoblastoma infected copepods – Often occurs in older children or young adults, • Disease due to migrating, immature worms with only rare eosinophilia or visceral manifestations. • Emerging imported infections • Dx: For both VLM and OLM, the diagnosis rests • Adults and larvae have numerous spines for on clinical signs, history of exposure to puppies, encysting in host tissue laboratory findings, and detection of antibodies Note collar of spines of to Toxocara. adult worm, used for – Remember, no eggs in stool sticking in host tissue HSC4933. Emerging Infectious Diseases 11 HSC4933. Emerging Infectious Diseases 12 2 Gnathostoma spp. Gnathostomiasis and Tx • Within 24-48 h of ingestion of larvae, patients may develop fever, vomiting, epigastric pain. • Migration in the subcutaneous tissues causes intermittent, migratory, painful, pruritic swellings (cutaneous larva migrans). • Migration to other tissues (visceral larva migrans) can result in ocular involvement, more serious manifestations such as eosinophilic meningitis with myeloencephalitis. • Removal and identification of the worm is both diagnostic and therapeutic. • Tx: Surgical removal or combination with albendazole or ivermectin HSC4933. Emerging Infectious Diseases 13 HSC4933. Emerging Infectious Diseases 14 Mexico: An emerging problem Trichinosis (Trichinellosis) • First case of clinical • Zoonotic infections gnathostomiasis was reported in • Humans are accidental, dead-end hosts Mexico in 1970 • Multiple species of Trichinella infect humans • Over 1,000 cases reported along depending on climate and reservoir hosts Gulf/Pacific Coasts from 1980- • T. spiralis, T. pseudospiralis, T. nativa, T. nelsoni, 1996 T. britovi – 1993-1997: 98 cases in Acapulco • T. spiralis is comopoliltan, most pathogenic • Linked to eating ceviche • Emerging in China, Russia, other European • Mass production and commercial countries distribution of tilapia has been – In 2008, morbidity due to trichinellosis doubled implicated in Russia: 312 cases in 2008 vs. 155 in 2007. – 779 human cases in EU Member States during 2007 HSC4933. Emerging Infectious Diseases 15 HSC4933. Emerging Infectious Diseases 16 Various Life Cycles of Trichinella spp. T. spiralis Life Cycle Domestic cycle • Domestic pigs are considered the dominant reservoir host, but there are many different typical hosts throughout the world Infection is maintained Sylvatic (wild animal) cycles primarily in rats and other rodents which may • Temperate regions (carrion and live be eaten by other prey): pig, wild boar, horse, dog, animals such as pigs and bear, fox bears. • Arctic regions (carcasses): polar bear, walrus, wolf, fox • Tropical regions (carcasses): wharthog, hyena HSC4933. Emerging Infectious Diseases 17 18 3 T. spiralis Distribution Nurse Cell Complex • Larvae encysted in striated muscle • Subversion and redirection of host cell activities – Alteration of gene expression of host cell from contractile fiber to cell that nourishes worm – Synthesis of collagen by neighboring fibroblasts encloses nurse cell • Juveniles absorb nutrients while in nurse cell and increase 1mm in 4-8 weeks, infective to hosts • Juveniles enter developmental arrest and live for years • Emerging in China, Russia, other European countries • Calcification of nurse cell and worms by host – In 2008, morbidity due to trichinellosis doubled in Russia: 312 cases in 2008 reactions vs. 155 in 2007. • 779 human cases in EU Member States during 2007 • Lithuania, June 2009: outbreak due to wild boar meat sausages -affected 107 people HSC4933. Emerging Infectious Diseases 20 Disease Trichinosis Dx and Tx • The first few days of the infection • Dx based on symptoms of stage of life cycle and are characterized by larvae in feces, blood, other secretions gastroenteritis associated with diarrhea, abdominal pain, • Muscle biopsy for larvae, PCR, antibody vomiting. detection • Pathology is due to migrating • Steroids are used for infections with severe newborn larvae as they randomly symptoms penetrate cells (e.g., brain, liver, • Mebendazole or albendazole can be used to kidney, heart) in their search for treat infections in the intestines striated skeletal muscle cells. • Treatment should begin as soon as possible and – Fever and myalgia, bilateral the decision to treat is based upon symptoms, Immature larva periorbital edema, and petechial exposure to raw or undercooked meat, and from biopsy hemorrhage laboratory test results. • Heavy infection results in – No specific treatment for trichinosis once the generalized edema, larvae have invaded the muscles cardiomyopathies and CNS abnormalities HSC4933. Emerging Infectious Diseases 21 HSC4933. Emerging Infectious Diseases 22 Prevention Outbreak: Crazy turtles • In July 2008, four teaching hospitals in northern Taiwan reported 8 patients in • Curing (salting), drying, smoking, or 2 groups with fever, myalgias, and eosinophilia of unknown cause developed microwaving meat does not consistently kill after they shared a common food source in May 2008. – Group A: 20 Taiwanese, participated in a festive meal at a Japanese food restaurant, and infective worms. were served raw meat, blood, liver, and eggs of 3 of 5 soft-shelled turtles – Group B: A group of 3 Japanese customers was served the other 2 turtles • Cook meat products until the juices run clear • Extensive serologic testing for helminths by ELISA, hits against Trichinella spp. or to an internal temperature of 170⁰F. • The incubation period, clinical features, and laboratory findings in this outbreak were similar to those of other reported trichinosis outbreaks • Freeze pork less than 6 inches thick for 20 days associated with eating mammals – T. papuae and T. zimbabwensis are the most likely parasites causing this outbreak at 5⁰F to kill any worms. because of their ability to infect mammals and reptiles. • Serum specimens from 6 of the 8 case-patients reacted most strongly to the • Cook wild game meat thoroughly-harder to kill 53-kDa recombinant protein of T. papuae. worms than in pork. • Significance: – Not yet determined how
Load more

Recommended publications
  • Gnathostoma Spinigerum Was Positive
    Department Medicine Diagnostic Centre Swiss TPH Winter Symposium 2017 Helminth Infection – from Transmission to Control Sushi Worms – Diagnostic Challenges Beatrice Nickel Fish-borne helminth infections Consumption of raw or undercooked fish - Anisakis spp. infections - Gnathostoma spp. infections Case 1 • 32 year old man • Admitted to hospital with severe gastric pain • Abdominal pain below ribs since a week, vomiting • Low-grade fever • Physical examination: moderate abdominal tenderness • Laboratory results: mild leucocytosis • Patient revealed to have eaten sushi recently • Upper gastrointestinal endoscopy was performed Carmo J, et al. BMJ Case Rep 2017. doi:10.1136/bcr-2016-218857 Case 1 Endoscopy revealed 2-3 cm long helminth Nematode firmly attached to / Endoscopic removal of larva with penetrating gastric mucosa a Roth net Carmo J, et al. BMJ Case Rep 2017. doi:10.1136/bcr-2016-218857 Anisakiasis Human parasitic infection of gastrointestinal tract by • herring worm, Anisakis spp. (A.simplex, A.physeteris) • cod worm, Pseudoterranova spp. (P. decipiens) Consumption of raw or undercooked seafood containing infectious larvae Highest incidence in countries where consumption of raw or marinated fish dishes are common: • Japan (sashimi, sushi) • Scandinavia (cod liver) • Netherlands (maatjes herrings) • Spain (anchovies) • South America (ceviche) Source: http://parasitewonders.blogspot.ch Life Cycle of Anisakis simplex (L1-L2 larvae) L3 larvae L2 larvae L3 larvae Source: Adapted to Audicana et al, TRENDS in Parasitology Vol.18 No. 1 January 2002 Symptoms Within few hours of ingestion, the larvae try to penetrate the gastric/intestinal wall • acute gastric pain or abdominal pain • low-grade fever • nausea, vomiting • allergic reaction possible, urticaria • local inflammation Invasion of the third-stage larvae into gut wall can lead to eosinophilic granuloma, ulcer or even perforation.
    [Show full text]
  • The Functional Parasitic Worm Secretome: Mapping the Place of Onchocerca Volvulus Excretory Secretory Products
    pathogens Review The Functional Parasitic Worm Secretome: Mapping the Place of Onchocerca volvulus Excretory Secretory Products Luc Vanhamme 1,*, Jacob Souopgui 1 , Stephen Ghogomu 2 and Ferdinand Ngale Njume 1,2 1 Department of Molecular Biology, Institute of Biology and Molecular Medicine, IBMM, Université Libre de Bruxelles, Rue des Professeurs Jeener et Brachet 12, 6041 Gosselies, Belgium; [email protected] (J.S.); [email protected] (F.N.N.) 2 Molecular and Cell Biology Laboratory, Biotechnology Unit, University of Buea, Buea P.O Box 63, Cameroon; [email protected] * Correspondence: [email protected] Received: 28 October 2020; Accepted: 18 November 2020; Published: 23 November 2020 Abstract: Nematodes constitute a very successful phylum, especially in terms of parasitism. Inside their mammalian hosts, parasitic nematodes mainly dwell in the digestive tract (geohelminths) or in the vascular system (filariae). One of their main characteristics is their long sojourn inside the body where they are accessible to the immune system. Several strategies are used by parasites in order to counteract the immune attacks. One of them is the expression of molecules interfering with the function of the immune system. Excretory-secretory products (ESPs) pertain to this category. This is, however, not their only biological function, as they seem also involved in other mechanisms such as pathogenicity or parasitic cycle (molting, for example). Wewill mainly focus on filariae ESPs with an emphasis on data available regarding Onchocerca volvulus, but we will also refer to a few relevant/illustrative examples related to other worm categories when necessary (geohelminth nematodes, trematodes or cestodes).
    [Show full text]
  • Whatyourdrmaynottellyouabou
    What Your Doctor May Not Tell You About Parasites First published in Great Britain in 2015 by Health For The People Ltd. Tel: 0800 310 21 21 [email protected] www.hompes-method.com www.h-pylori-symptoms.com Copyright © 2015 David Hompes, Health For The People Ltd. David Hompes asserts the moral right to be identified as the author of this work. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise without the prior permission of the publishers. HEALTH DISCLAIMER The information in this book is not intended to diagnose, treat, cure or prevent any disease, nor should it replace a one-to-one relationship with your physician. You should always seek consultation with a qualified medical practitioner before commencing any protocol contained herein. This book is sold subject to the condition that it shall not, by way of trade or otherwise, be lent, resold, hired out or otherwise circulated without the publisher’s prior consent in any form of binding or cover other than that in which it is published and without a similar condition including this condition being imposed upon the subsequent purchaser. British Library Cataloguing in Publication Data. 2 What Your Doctor May Not Tell You About Parasites Contents Introduction 5-13 1 What is a Parasite? 14-26 2 Where are Parasites to be found? 27-33 3 Why doesn’t the Medical System fully acknowledge 34-38 Parasites? 4 How on earth do you acquire Parasites?
    [Show full text]
  • MIM3 Draft Press Release Final Docx
    FOR IMMEDIATE RELEASE CONTACT: Tahli Kouperstein, (240) 662-2221 [email protected] EXPECT THE UNEXPECTED IN AN ALL-NEW SEASON OF ANIMAL PLANET’S MONSTERS INSIDE ME -- On October 5, Season Three Shares the Gruesome and Deadly Stories Of Parasites Living Within Us -- (Silver Spring, Md.) – Just because a parasite is not a bear, tiger or some other large predator, that doesn’t mean it can’t be as deadly…if not more so. MONSTERS INSIDE ME returns on Friday, October 5, at 8 PM (ET/PT), retelling the real-life, harrowing dramas of people infected by deadly parasites as doctors and scientists try to unravel each case before it’s too late. MONSTERS INSIDE ME reveals what happens to unsuspecting victims when the smallest creatures turn out to be the biggest monsters. Parasites are organisms that live on or in another species, which then serve as hosts from which the parasite gains nutrients. Failing to recognize or incorrectly diagnosing a parasite can wreak havoc and sometimes cause death. This season, MONSTERS INSIDE ME features stories about people who are harboring tapeworms, flesh-eating diseases, the bubonic plague, rabies, rat-bite fever, a brain-eating amoeba and more. The series also chronicles accounts of victims who suffer from objects that mistakenly are left in them during surgery. • When Kiera, from Springfield, Ohio, experiences severe headaches, she is rushed to the emergency room. Initially, doctors perform a spinal tap and suspect meningitis. After an MRI is performed, doctors realize she might have a teratoma, a tumor that is composed of cells from other organs, which can grow hair, teeth and even eyes.
    [Show full text]
  • Combination Anthelmintic Treatment for Persistent Ancylostoma Caninum Ova Shedding in Greyhounds
    CASE SERIES Combination Anthelmintic Treatment for Persistent Ancylostoma caninum Ova Shedding in Greyhounds Lindie B. Hess, BS, Laurie M. Millward, DVM, Adam Rudinsky DVM, Emily Vincent, BS, Antoinette Marsh, PhD ABSTRACT Ancylostoma caninum is a nematode of the canine gastrointestinal tract commonly referred to as hookworm. This study involved eight privately owned adult greyhounds presenting with persistent A. caninum ova shedding despite previous deworming treatments. The dogs received a combination treatment protocol comprising topical moxidectin, followed by pyrantel/febantel/praziquantel within 24 hr. At 7–10 days posttreatment, a fecal examination monitored for parasite ova. Dogs remained on the monthly combination treatment protocol until they ceased shedding detectable ova. The dogs then received only the monthly topical moxidectin maintenance treatment. The dogs remained in the study for 5–14 mo with periodical fecal examinations performed. During the study, three dogs reverted to positive fecal ova status, with two being associated with client noncompliance. Reinstitution of the combination treatment protocol resulted in no detectable ova. Use of monthly doses of combination pyrantel, febantel and moxidectin appears to be an effective treatment for nonresponsive or persistent A. caninum ova shedding. Follow-up fecal examinations were important for verifying the presence or absence of ova shedding despite the use of anthelmintic treatment. Limitations of the current study include small sample size, inclusion of only privately owned greyhounds, and client compliance with fecal collection and animal care. (JAmAnimHospAssoc2019; 55:---–---. DOI 10.5326/ JAAHA-MS-6904) Introduction include the following: moxidectina,b, milbemycin oximec, fenben- Ancylostoma caninum is a nematode of the canine gastrointestinal dazoled, and/or pyrantel-containing productse,f.
    [Show full text]
  • Molecular Identification of the Etiological Agent of Human
    Jpn. J. Infect. Dis., 73, 44–50, 2020 Original Article Molecular Identification of the Etiological Agent of Human Gnathostomiasis in an Endemic Area of Mexico Sylvia Paz Díaz-Camacho1, Jesús Ricardo Parra-Unda2, Julián Ríos-Sicairos2, and Francisco Delgado-Vargas2* 1Research Unit in Environment and Health, Autonomous University of Occident, Sinaloa; and 2Public Health Research Unit "Dra. Kaethe Willms", School of Chemical and Biological Sciences, Autonomous University of Sinaloa, University city, Culiacan, Sinaloa, Mexico SUMMARY: Human gnathostomiasis, which is endemic in Mexico, is a worldwide health concern. It is mainly caused by the consumption of raw or insufficiently cooked fish containing the advanced third-stage larvae (AL3A) of Gnathostoma species. The diagnosis of gnathostomiasis is based on epidemiological surveys and immunological diagnostic tests. When a larva is recovered, the species can be identified by molecular techniques. Polymerase chain reaction (PCR) amplification of the second internal transcription spacer (ITS-2) is useful to identify nematode species, including Gnathostoma species. This study aims to develop a duplex-PCR amplification method of the ITS-2 region to differentiate between the Gnathostoma binucleatum and G. turgidum parasites that coexist in the same endemic area, as well as to identify the Gnathostoma larvae recovered from the biopsies of two gnathostomiasis patients from Sinaloa, Mexico. The duplex PCR established based on the ITS- 2 sequence showed that the length of the amplicons was 321 bp for G. binucleatum and 226 bp for G. turgidum. The amplicons from the AL3A of both patients were 321 bp. Furthermore, the length and composition of these amplicons were identical to those deposited in GenBank as G.
    [Show full text]
  • Gnathostomiasis: an Emerging Imported Disease David A.J
    RESEARCH Gnathostomiasis: An Emerging Imported Disease David A.J. Moore,* Janice McCroddan,† Paron Dekumyoy,‡ and Peter L. Chiodini† As the scope of international travel expands, an ous complication of central nervous system involvement increasing number of travelers are coming into contact with (4). This form is manifested by painful radiculopathy, helminthic parasites rarely seen outside the tropics. As a which can lead to paraplegia, sometimes following an result, the occurrence of Gnathostoma spinigerum infection acute (eosinophilic) meningitic illness. leading to the clinical syndrome gnathostomiasis is increas- We describe a series of patients in whom G. spinigerum ing. In areas where Gnathostoma is not endemic, few cli- nicians are familiar with this disease. To highlight this infection was diagnosed at the Hospital for Tropical underdiagnosed parasitic infection, we describe a case Diseases, London; they were treated over a 12-month peri- series of patients with gnathostomiasis who were treated od. Four illustrative case histories are described in detail. during a 12-month period at the Hospital for Tropical This case series represents a small proportion of gnathos- Diseases, London. tomiasis patients receiving medical care in the United Kingdom, in whom this uncommon parasitic infection is mostly undiagnosed. he ease of international travel in the 21st century has resulted in persons from Europe and other western T Methods countries traveling to distant areas of the world and return- The case notes of patients in whom gnathostomiasis ing with an increasing array of parasitic infections rarely was diagnosed at the Hospital for Tropical Diseases were seen in more temperate zones. One example is infection reviewed retrospectively for clinical symptoms and confir- with Gnathostoma spinigerum, which is acquired by eating uncooked food infected with the larval third stage of the helminth; such foods typically include fish, shrimp, crab, crayfish, frog, or chicken.
    [Show full text]
  • Proceedings of the Helminthological Society of Washington 51(2) 1984
    Volume 51 July 1984 PROCEEDINGS ^ of of Washington '- f, V-i -: ;fx A semiannual journal of research devoted to Helminthohgy and all branches of Parasitology Supported in part by the -•>"""- v, H. Ransom Memorial 'Tryst Fund : CONTENTS -j<:'.:,! •</••• VV V,:'I,,--.. Y~v MEASURES, LENA N., AND Roy C. ANDERSON. Hybridization of Obeliscoides cuniculi r\ XGraybill, 1923) Graybill, ,1924 jand Obeliscoides,cuniculi multistriatus Measures and Anderson, 1983 .........:....... .., :....„......!"......... _ x. iXJ-v- 179 YATES, JON A., AND ROBERT C. LOWRIE, JR. Development of Yatesia hydrochoerus "•! (Nematoda: Filarioidea) to the Infective Stage in-Ixqdid Ticks r... 187 HUIZINGA, HARRY W., AND WILLARD O. GRANATH, JR. -Seasonal ^prevalence of. Chandlerellaquiscali (Onehocercidae: Filarioidea) in Braih, of the Common Grackle " '~. (Quiscdlus quisculd versicolor) '.'.. ;:,„..;.......„.;....• :..: „'.:„.'.J_^.4-~-~-~-<-.ii -, **-. 191 ^PLATT, THOMAS R. Evolution of the Elaphostrongylinae (Nematoda: Metastrongy- X. lojdfea: Protostrongylidae) Parasites of Cervids,(Mammalia) ...,., v.. 196 PLATT, THOMAS R., AND W. JM. SAMUEL. Modex of Entry of First-Stage Larvae ofr _^ ^ Parelaphostrongylus odocoilei^Nematoda: vMefastrongyloidea) into Four Species of Terrestrial Gastropods .....:;.. ....^:...... ./:... .; _.... ..,.....;. .-: 205 THRELFALL, WILLIAM, AND JUAN CARVAJAL. Heliconema pjammobatidus sp. n. (Nematoda: Physalbpteridae) from a Skate,> Psammobatis lima (Chondrichthyes: ; ''•• \^ Rajidae), Taken in Chile _... .„ ;,.....„.......„..,.......;. ,...^.J::...^..,....:.....~L.:.....,
    [Show full text]
  • A Study of Learning Gains and Attitudes in Biology Using an Emerging Disease Model in Teaching Ecology
    A Study of Learning Gains and Attitudes in Biology Using an Emerging Disease Model in Teaching Ecology Susan Chabot CATALySES, Summer 2017 Science Teacher/Department Chair Lemon Bay High School Englewood, Florida [email protected] Abstract Lemon Bay High School (LBHS) is a mid-sized suburban public high school on the southwest coast of Florida in Charlotte County. Although we have a robust honors and advance placement (AP) science program, the number of general students taking additional science classes is small. We have recognized this trend and account dwindling general science enrollment to the shift in biology instruction that followed the state induction of the biology end-of-course exam (EOC). All students must pass biology and take (not pass) the biology EOC to receive a high school diploma. Instruction in preparation for changing biology standards and focus over the last 15 years has drastically altered the delivery of biology content. Although currently more emphasis is placed on project-based/thematic learning units, teachers of biology have been forced to rely on direct instruction methods in order to complete the necessary material for this state-mandated test. The shift has been away from depth of understanding and scientific thinking skills to quick-coverage of material in the hopes students will recall some vocabulary and concepts during the biology end-of-course exam. With stagnant test scores in general biology classes and waning appreciation for the sciences, the belief is that student attitudes and science content understanding will improve through the integration of thematic, project-based learning units that incorporate emerging pathogens, disease, and biology content standards.
    [Show full text]
  • Hookworm (Ancylostomiasis)
    Hookworm (ancylostomiasis) Hookworm (ancylostomiasis) rev Jan 2018 BASIC EPIDEMIOLOGY Infectious Agent Hookworm is a soil transmitted helminth. Human infections are caused by the nematode parasites Necator americanus and Ancylostoma duodenale. Transmission Transmission primarily occurs via direct contact with fecal contaminated soil. Soil becomes contaminated with eggs shed in the feces of an individual infected with hookworm. The eggs must incubate in the soil for several days before they become infectious and are able to be transmitted to another person. Oral transmission can sometimes occur from consuming improperly washed food grown or exposed to fecal contaminated soil. Transmission can also occur (rarely) between a mother and her fetus/infant via infected placental or mammary tissue. Incubation Period Eggs must incubate in the soil for 5-10 days before they mature into infectious filariform larvae that can penetrate the skin. Within the first 10 days following penetration of the skin filariform larvae will migrate to the lungs and occasionally cause respiratory symptoms. Three to five weeks after skin penetration the larvae will migrate to the intestinal tract where they will mature into an adult worm. Adult worms may live in the intestine for 1-5 years depending on the species. Communicability Human to human transmission of hookworm does NOT occur because part of the worm’s life cycle must be completed in soil before becoming infectious. However, vertical transmission of dormant filariform larvae can occur between a mother and neonate via contaminated breast milk. These dormant filariform larvae can remain within in a host for months to years. Soil contamination is perpetuated by fecal contamination from infected individuals who can shed eggs in feces for several years after infection.
    [Show full text]
  • Taenia Solium Transmission in a Rural Community in ·Honduras: an Examination of Risk Factors and Knowledge
    Taenia solium Transmission in a Rural Community in ·Honduras: An Examination of Risk Factors and Knowledge by Haiyan Pang Faculty of Applied Health Sciences Brock University A thesis submitted for completion of the Master of Science Degree Haiyan Pang © 2004 lAMES A GIBSON LIBRARY . BROCK UNIVERSITY sr. CAtHARINES· ON Abstract Taenia soliurn taeniasis and cysticercosis are recognized as a major public health problem in Latin America. T. soliurn transmission not only affects the health of the individual, but also social and economic development, perpetuating the cycle of poverty. To determine prevalence rates, population knowledge and risk factors associated with transmission, anepidemiological study was undertaken in the rural community of Jalaca. Two standardized questionnaires were used to collect epidemiological and T. soli urn general knowledge data. Kato-Katz technique and an immunoblot assay (EITB) were used to determine taeniasis and seroprevalence, respectively. In total, 139 individuals belonging to 56 households participated in the study. Household characteristics were consistent with conditions of poverty of rural Honduras: 21.4% had no toilet or latrines, 19.6% had earthen floor, and 51.8% lacked indoor tap water. Pigs were raised in 46.4% of households, of which 70% allowed their pigs roaming freely. A human seroprevalence rate of 18.7% and a taeniasis prevalence rate of 2.4% were found. Only four persons answered correctly 2: 6 out of ten T. soliurn knowledge questions, for an average passing score of 2.9%. In general, a serious gap exists in knowledge regarding how humans acquire the infections, especially neurocysticercosis was identified. After regression analysis, the ability to recognize adult tapeworms and awareness of the clinical importance of taeniasis, were found to be significant risk factors for T.
    [Show full text]
  • Studies Show That Fecal Dx Antigen Tests Allow for Earlier Detection of More Intestinal Parasites
    Research update Studies show that Fecal Dx antigen tests allow for earlier detection of more intestinal parasites Antigen detection is commonly used today to diagnose Results heartworm and Giardia infections, and now it is available for In the 1,156 field fecal samples for the roundworm and hookworm additional parasites. IDEXX Reference Laboratories, as a leader study and the 1,000 field fecal samples for the whipworm study, in pet healthcare innovation, has developed immunoassays for egg-positive roundworm, hookworm, and whipworm results were the detection of hookworm, roundworm, and whipworm antigens noted in 23, 13, and 27 samples, respectively. In contrast, 26, 19, in feces of dogs and cats. These antigens are secreted from the and 35 samples were antigen positive for roundworm, hookworm, adult worm and are not present in their eggs, which allows for and whipworm. The T. canis ELISA detected T. cati coproantigen in detection of prepatent stages as well as the ability to overcome the feline samples. Fecal antigens detected more infections than did challenges of intermittent egg laying. Earlier detection during the fecal flotation. prepatent period will also reduce the frequency of environmental contamination with potentially infectious eggs. Roundworm Hookworm Whipworm Two recent papers describing the performance of the Fecal Dx™ antigen tests, enzyme-linked immunosorbent assays (ELISAs) Fecal flotation 23 13 27 developed by IDEXX for coproantigen detection of Trichuris vulpis, positive Ancylostoma caninum and Toxocara canis in dogs and Toxocara cati in cats, are summarized below. Fecal Dx antigen 26 19 35 • Enzyme-linked immunosorbent assay for coproantigen detection test positive of Trichuris vulpis in dogs1 • Enzyme-linked immunosorbent assays for coproantigen Table 1.
    [Show full text]