DOCSLIB.ORG

Be Aware of Schistosomiasis

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Be Aware of Schistosomiasis Be Aware of Schistosomiasis INTERNATIONAL ASSOCIATION FOR MEDICAL ASSISTANCE 2012 EDITION TO TRAVELLERS For updates go to www.iamat.org IAMAT [email protected] www.iamat.org @IAMAT_Travel IAMATHealth Be Aware of Schistosomiasis THE HELPFUL DATEBOOK snails belonging to the genus Bulinus, which serve as the specific It is noon, the skies are clear, it is unbearably hot and a caravan snakes hosts to the larval stages of the Schistosoma haematobium worm. its way across the Sahara. Twenty-eight people on camelback are heading towards the oasis named El Mamoun. They are tourists The Snail – The Innocent Creature Nurturing Infection participating in ‘La Saharienne’, a popular excursion conducted twice The eggs of the worm are eliminated via the urine of those infected. weekly across the desert of southern Tunisia by an international travel When an egg reaches freshwater, it hatches rapidly – see picture of the club. In the boundless Sahara, they were living a fascinating life-cycle of the human schistosomes (1). The ensuing larva (an experience, their senses thrilled by the majestic grandeur of the immature form of life called miracidium) is an oval shaped organism desert. After hours of riding, they reached the oasis and were dazzled clothed with minute cilia (2) swimming in search of the Bulinus snail. to see a clear pond fed by a bubbling spring. The idea of jumping into The miracidium [Gr.: meirákon = young form of life] is attracted by the the cool water to relieve the intense heat must have been exciting. snail’s mucous secretion and burrows into the soft tissue of the There was a momentary pause at the pond’s edge to test the water, mollusc (e). Once inside, the miracidium transforms itself into an then the tourists waded in. Although they had been warned never to elongated, thin walled sack called mother sporocyst [Gr.: sporá = wade or bathe in the freshwater in the tropics, the cool water was sowing, seed; kústis = sack] (3), which gives rise to about four irresistible after travelling for so long under the scorching sun. The hundred daughter sporocysts (4). Each one forms within its cavity advice given at home was forgotten in the momentary relief of the numerous fork-tailed cercariae [Gr.: kerkos = tail], representing the refreshing oasis pond. early stages of maturing worms. A single miracidium may produce Milan – five months later. A pathologist was examining a vaginal thousands of cercariae in only six weeks and this production may biopsy of a young woman suspected of having cancer. Under the carry on in the snail for months. microscope, he was amazed to see some peculiar worm eggs. There The water in the pond of El Mamoun was teeming with this kind of was no doubt in his mind that these were not the common worm eggs microscopic life when our tourists arrived at the oasis. Previous visits routinely seen in his work, but the eggs of the flatworm called to the oasis by Bedouins had left the pond infected, a legacy of the Schistosoma haematobium. disease for the tourists to contract. The eggs of this worm damage the urinary and genital tracts which Like divers jumping from their boats, the cercariae, stimulated by the become inflamed and scarred. The disease, called schistosomiasis bright light and the high temperature of the day, abandon the snails to (bilharziasis), is a languishing, debilitating illness which saps the attack humans. Seen under the microscope they look like miniature physical and mental energies of its victims. tadpoles, with a pear shaped buoy and a long tail terminating in a y- It was clear to him that this young woman must have spent some shaped fork which acts as a propeller to move the organism through time in Africa or the Middle East where this type of worm is prevalent. the water (5). They are now swimming in a desparate race against When interviewed she confirmed that she had been in Africa, time, searching for a human host to ensure their survival. They will die participating in one of the excursions organized by the club. within 48 hours if the search fails. The young woman was not a cancer victim at all, but had contracted Attracted by the oily secretion lubricating the human body, they schistosomiasis while swimming in the oasis pond. When attach themselves with their oral suckers to the skin. They do not need investigators began to fear that other members of her group might also to find a wound or break in the skin since they secrete an enzyme be infected, her date book came to their aid. Many of her companions which splits the ‘cement’ holding the cells of the skin together (6). As had exchanged addresses with this attractive young lady, and soon as the cercariae start to penetrate the outer layers, they shed eventually all members of the group were contacted and examined. their tails (7) and burrow a tunnel through the epidermis (skin). The toll was heavy – out of 28 persons, nine were added to the long list of travellers infected at El Mamoun. Humans – The Sexual Life of the Worm The tail-less cercariae, now called schistosomulae, then reach the THE LIFE OF THE FLATWORM lymph vessels which drain into the two major veins, allowing the How did it happen? The swimmers hadn’t noticed among the vegetation schistosomulae of both sexes to reach first the lungs and then the liver, at the edge of the pond the presence of minute snails so small that a where they mature and mate. dozen would easily fit into a teaspoon. In some ponds and rivers as The worms have a rounded and elongated appearance. In the many as 1,000 can be found in a square meter. They are the freshwater animal kingdom they are placed under the group Platyhelmintes (Gr.: 1 platús = broad; élmis = worm). They are greyish-white in color and completely surrounding the eggs forming granulomas (L.: granulum = measure between 1/2 and 1 inch (1.2-2.5cm) in length and have two small grain) in the bladder tissue. Within about a month the eggs die suction discs for adhesion and feeding. They belong to the family of and their shells calcify into rigid structures forming polyps, nodules, flukes or Trematoda (Gr.: tre–ma = hole) and are commonly called and ulcers. Slowly these are replaced by fibrous scar tissue, making ‘blood flukes’ because they live in the blood vessels of mammals. The the bladder wall rigid and thicker causing constriction especially on name for their genus, Schistosoma (Gr.: schistós = cleft, split; soma = the lower portion of the ureters (the tubes carrying urine from the body), indicates their difference from all other flukes: They are not kidneys to the bladder) impairing the outflow of urine. This produces hermaphroditic, but have two sexes – male and female. When they back pressure, dilating the ureters and reducing the functioning of the mate, the edges of the larger male worm fold over to form a groove to kidneys. Finally the accumulation of body wastes in the blood poisons hold the slender and longer female close to him (8). Then, tightly the human body resulting in death. embraced, they leave the liver, swimming against the flow of the venous blood, to settle in the blood vessels surrounding the bladder THE FLATWORM IN HUMANS and the adjacent organs in the genito-urinary system. Of the thousands of different species of flatworms living as parasites The reason? Since the only way to ensure the survival of the species in practically every kind of vertebrate, only six are responsible for the is to get the eggs into freshwater, the worms live close to the natural human disease schistosomiasis. Each species has a specific openings of the human body – the bladder or the openings of the intermediate host a suitable species of freshwater snail, in which the reproductive organs – so that the eggs can easily escape to the larva undergoes further development: outside. • Schistosoma haematobium lives in the blood vessels of the bladder The human body doesn’t suspect their presence because the and genitalia. The eggs, characterized by a terminal spike (d), are worms disguise themselves with a coating of protein similar to that of passed with urine. The intermediate host snail belongs to the genus the host. This coating fools the human’s defense system, which Bulinus which has a conical shaped shell, dark grey in color otherwise would fight off foreign particles. Undisturbed, the worms measuring about 1cm in length (d1). The infection caused by may live for years producing an incredible number of eggs. S. haematobium is found in Africa (including the island of Madagascar), the Middle East, the islands of Madagascar, and in the The Eggs – The Quest for Freedom state of Maharashtra in India. The eggs, which are oval-shaped with a spike protruding from one end • Schistosoma mansoni lives in the blood vessels surrounding the (Schistosoma haematobium), are deposited in large numbers in the large bowel. The eggs, which have a lateral spine (c), are passed tissue of the bladder. Some reach the innermost part through the with the stools. The intermediate host belongs to the genus tiniest of blood vessels. They are now only separated from the urine by Biomphalaria, a snail with a flat disc-shaped shell (c1), dusky brown a thin layer of tissue, which they pierce with the spike to allow them to or reddish in color with a diameter of 7-22mm. The infection caused fall into the urine. When the eggs are eliminated from the bladder and by S. mansoni is endemic in Africa (including the island of reach fresh water, they will hatch into miracidia, search out the snails, Madagascar), the Arabian peninsula, Brazil, Suriname, Venezuela, and start the cycle anew.
Load more

Recommended publications
  • Schistosomiasis
    MODULE \ Schistosomiasis For the Ethiopian Health Center Team Laikemariam Kassa; Anteneh Omer; Wutet Tafesse; Tadele Taye; Fekadu Kebebew, M.D.; and Abdi Beker Haramaya University In collaboration with the Ethiopia Public Health Training Initiative, The Carter Center, the Ethiopia Ministry of Health, and the Ethiopia Ministry of Education January 2005 Funded under USAID Cooperative Agreement No. 663-A-00-00-0358-00. Produced in collaboration with the Ethiopia Public Health Training Initiative, The Carter Center, the Ethiopia Ministry of Health, and the Ethiopia Ministry of Education. Important Guidelines for Printing and Photocopying Limited permission is granted free of charge to print or photocopy all pages of this publication for educational, not-for-profit use by health care workers, students or faculty. All copies must retain all author credits and copyright notices included in the original document. Under no circumstances is it permissible to sell or distribute on a commercial basis, or to claim authorship of, copies of material reproduced from this publication. ©2005 by Laikemariam Kassa, Anteneh Omer, Wutet Tafesse, Tadele Taye, Fekadu Kebebew, and Abdi Beker All rights reserved. Except as expressly provided above, no part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage and retrieval system, without written permission of the author or authors. This material is intended for educational use only by practicing health care workers or students and faculty in a health care field. ACKNOWLEDGMENTS The authors are grateful to The Carter Center and its staffs for the financial, material, and moral support without which it would have been impossible to develop this module.
    [Show full text]
  • First Morphogenetic Analysis of Parasite Eggs from Schistosomiasis
    First morphogenetic analysis of parasite eggs from Schistosomiasis haematobium infected sub-Saharan migrants in Spain and proposal for a new standardised study methodology Marta Reguera-Gomez, M Valero, M Carmen Oliver-Chiva, Alejandra de Elias-Escribano, Patricio Artigas, M Cabeza-Barrera, Joaquín Salas-Coronas, Jérôme Boissier, Santiago Mas-Coma, M Dolores Bargues To cite this version: Marta Reguera-Gomez, M Valero, M Carmen Oliver-Chiva, Alejandra de Elias-Escribano, Patricio Artigas, et al.. First morphogenetic analysis of parasite eggs from Schistosomiasis haematobium infected sub-Saharan migrants in Spain and proposal for a new standardised study methodology. Acta Tropica, Elsevier, 2021, 223, pp.106075. 10.1016/j.actatropica.2021.106075. hal-03332420 HAL Id: hal-03332420 https://hal.archives-ouvertes.fr/hal-03332420 Submitted on 2 Sep 2021 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. First morphogenetic analysis of parasite eggs from Schistosomiasis haematobium infected sub-Saharan migrants in Spain and proposal for a new standardised study methodology Marta Reguera-Gomez a, M. Adela Valero a,*, M. Carmen Oliver-Chiva a, Alejandra de Elias-Escribano a, Patricio Artigas a, M. Isabel Cabeza-Barrera b, Joaquín Salas- Coronas b, Jérôme Boissierc, Santiago Mas-Coma a, M.
    [Show full text]
  • Pocket Guide to Clinical Microbiology
    4TH EDITION Pocket Guide to Clinical Microbiology Christopher D. Doern 4TH EDITION POCKET GUIDE TO Clinical Microbiology 4TH EDITION POCKET GUIDE TO Clinical Microbiology Christopher D. Doern, PhD, D(ABMM) Assistant Professor, Pathology Director of Clinical Microbiology Virginia Commonwealth University Health System Medical College of Virginia Campus Washington, DC Copyright © 2018 Amer i can Society for Microbiology. All rights re served. No part of this publi ca tion may be re pro duced or trans mit ted in whole or in part or re used in any form or by any means, elec tronic or me chan i cal, in clud ing pho to copy ing and re cord ing, or by any in for ma tion stor age and re trieval sys tem, with out per mis sion in writ ing from the pub lish er. Disclaimer: To the best of the pub lish er’s knowl edge, this pub li ca tion pro­ vi des in for ma tion con cern ing the sub ject mat ter cov ered that is ac cu rate as of the date of pub li ca tion. The pub lisher is not pro vid ing le gal, med i cal, or other pro fes sional ser vices. Any ref er ence herein to any spe cific com mer cial prod ucts, pro ce dures, or ser vices by trade name, trade mark, man u fac turer, or oth er wise does not con sti tute or im ply en dorse ment, rec om men da tion, or fa vored sta tus by the Ameri can Society for Microbiology (ASM).
    [Show full text]
  • Schistosoma-Associated Salmonella Resist Antibiotics Via Specific Fimbrial
    Barnhill et al. Parasites & Vectors 2011, 4:123 http://www.parasitesandvectors.com/content/4/1/123 RESEARCH Open Access Schistosoma-associated Salmonella resist antibiotics via specific fimbrial attachments to the flatworm Alison E Barnhill, Ekaterina Novozhilova, Tim A Day* and Steve A Carlson Abstract Background: Schistosomes are parasitic helminths that infect humans through dermo-invasion while in contaminated water. Salmonella are also a common water-borne human pathogen that infects the gastrointestinal tract via the oral route. Both pathogens eventually enter the systemic circulation as part of their respective disease processes. Concurrent Schistosoma-Salmonella infections are common and are complicated by the bacteria adhering to adult schistosomes present in the mesenteric vasculature. This interaction provides a refuge in which the bacterium can putatively evade antibiotic therapy and anthelmintic monotherapy can lead to a massive release of occult Salmonella. Results: Using a novel antibiotic protection assay, our results reveal that Schistosoma-associated Salmonella are refractory to eight different antibiotics commonly used to treat salmonellosis. The efficacy of these antibiotics was decreased by a factor of 4 to 16 due to this association. Salmonella binding to schistosomes occurs via a specific fimbrial protein (FimH) present on the surface on the bacterium. This same fimbrial protein confers the ability of Salmonella to bind to mammalian cells. Conclusions: Salmonella can evade certain antibiotics by binding to Schistosoma. As a result, effective bactericidal concentrations of antibiotics are unfortunately above the achievable therapeutic levels of the drugs in co-infected individuals. Salmonella-Schistosoma binding is analogous to the adherence of Salmonella to cells lining the mammalian intestine.
    [Show full text]
  • Evolution of the Schistosomes (Digenea: Schistosomatoidea): the Origin of Dioecy and Colonization of the Venous System
    University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Faculty Publications from the Harold W. Manter Laboratory of Parasitology Parasitology, Harold W. Manter Laboratory of 12-1997 Evolution of the Schistosomes (Digenea: Schistosomatoidea): The Origin of Dioecy and Colonization of the Venous System Thomas R. Platt St. Mary's College Daniel R. Brooks University of Toronto, [email protected] Follow this and additional works at: https://digitalcommons.unl.edu/parasitologyfacpubs Part of the Parasitology Commons Platt, Thomas R. and Brooks, Daniel R., "Evolution of the Schistosomes (Digenea: Schistosomatoidea): The Origin of Dioecy and Colonization of the Venous System" (1997). Faculty Publications from the Harold W. Manter Laboratory of Parasitology. 229. https://digitalcommons.unl.edu/parasitologyfacpubs/229 This Article is brought to you for free and open access by the Parasitology, Harold W. Manter Laboratory of at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Faculty Publications from the Harold W. Manter Laboratory of Parasitology by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. J. Parasitol., 83(6), 1997 p. 1035-1044 ? American Society of Parasitologists 1997 EVOLUTIONOF THE SCHISTOSOMES(DIGENEA: SCHISTOSOMATOIDEA): THE ORIGINOF DIOECYAND COLONIZATIONOF THE VENOUS SYSTEM Thomas R. Platt and Daniel R. Brookst Department of Biology, Saint Mary's College, Notre Dame, Indiana 46556 ABSTRACT: Trematodesof the family Schistosomatidaeare
    [Show full text]
  • Neglected Tropical Diseases
    Neglected Tropical Diseases David Mabey London School of Hygiene & Tropical Medicine Disease Control strategy Elimination target Schistosomiasis MDA, health education, sanitation, snail control Yes (in some countries) Onchocerciasis MDA, (vector control) Yes (in Americas) Lymphatic filariasis MDA, vector control Yes (as a PH problem) Trachoma MDA, water and sanitation, health education Yes (as a PH problem) Yaws MDA Yes Soil transmitted helminths MDA No Guinea worm Safe water, health education Yes African trypanosomiasis Case finding and treatment, (vector control) Yes (T.b. gambiense) Visceral leishmaniasis Case finding and treatment Yes (subcontinent) Leprosy Case finding and treatment Yes Cysticercosis Sanitation, meat inspection, vaccination of pigs No Echinococcosis Abattoir control, treatment of dogs, education No Fascioliasis Treatment of sheep, health education No Chagas disease Vector control, blood screening Yes (some countries) Buruli ulcer Case finding and treatment No Rabies Vaccination of dogs, health education No Dengue Vector control No 35 year old English man • Unwell for 3 days • Fever • Cough • Itchy rash • Holiday in Malawi for 2 weeks • Returned 5 weeks ago • What else would you like to know? Travel History is important Where exactly has the patient been? • Which countries? • Rural or urban? • Dates of travel, when did symptoms begin? What exactly has the patient been doing? • New sexual partner(s)? • Fresh water contact? • Exposure to sick people? Immunisations before travel? Malaria prophylaxis? Any other medication
    [Show full text]
  • Lecture 18 Feb 24 Shisto.Pdf
    Digeneans: All life cycles involve a mollusc and a vertebrate All life cycles are similar but different All life cycles are a variation of one theme. Adult-egg-miracidium-[black box of sprorocyst/rediae] Cercariae leave snail (usually): 1) penetrate host (definitive or intermediate) 2) encyst on vegetation Among human parasitic diseases, schistosomiasis (sometimes called bilharziasis) ranks second behind malaria in terms of socio-economic and public health importance in tropical and subtropical areas. The disease is endemic in 74 developing countries, infecting more than 200 million people in rural agricultural and peri-urban areas. Of these, 20 million suffer severe consequences from the disease and 120 million are symptomatic. In many areas, schistosomiasis infects a large proportion of under-14 children. An estimated 500-600 million people worldwide are at risk from the disease Globally, about 120 million of the 200 million infected people are estimated to be symptomatic, and 20 million are thought to suffer severe consequences of the infection. Yearly, 20,000 deaths are estimated to be associated with schistosomiasis. This mortality is mostly due to bladder cancer or renal failure associated with urinary schistosomiasis and to liver fibrosis and portal hypertension associated with intestinal schistosomiasis. Biogeography The major forms of human schistosomiasis are caused by five species of water- borne flatworm, or blood flukes, called schistosomes: Schistosoma mansoni causes intestinal schistosomiasis and is prevalent in 52 countries and territories of Africa, Caribbean, the Eastern Mediterranean and South America Schistosoma japonicum/Schistosoma mekongi cause intestinal schistosomiasis and are prevalent in 7 African countries and the Pacific region Schistosoma intercalatum is found in ten African countries Schistosoma haematobium causes urinary schistosomiasis and affects 54 countries in Africa and the Eastern Mediterranean.
    [Show full text]
  • Recent Progress in the Development of Liver Fluke and Blood Fluke Vaccines
    Review Recent Progress in the Development of Liver Fluke and Blood Fluke Vaccines Donald P. McManus Molecular Parasitology Laboratory, Infectious Diseases Program, QIMR Berghofer Medical Research Institute, Brisbane 4006, Australia; [email protected]; Tel.: +61-(41)-8744006 Received: 24 August 2020; Accepted: 18 September 2020; Published: 22 September 2020 Abstract: Liver flukes (Fasciola spp., Opisthorchis spp., Clonorchis sinensis) and blood flukes (Schistosoma spp.) are parasitic helminths causing neglected tropical diseases that result in substantial morbidity afflicting millions globally. Affecting the world’s poorest people, fasciolosis, opisthorchiasis, clonorchiasis and schistosomiasis cause severe disability; hinder growth, productivity and cognitive development; and can end in death. Children are often disproportionately affected. F. hepatica and F. gigantica are also the most important trematode flukes parasitising ruminants and cause substantial economic losses annually. Mass drug administration (MDA) programs for the control of these liver and blood fluke infections are in place in a number of countries but treatment coverage is often low, re-infection rates are high and drug compliance and effectiveness can vary. Furthermore, the spectre of drug resistance is ever-present, so MDA is not effective or sustainable long term. Vaccination would provide an invaluable tool to achieve lasting control leading to elimination. This review summarises the status currently of vaccine development, identifies some of the major scientific targets for progression and briefly discusses future innovations that may provide effective protective immunity against these helminth parasites and the diseases they cause. Keywords: Fasciola; Opisthorchis; Clonorchis; Schistosoma; fasciolosis; opisthorchiasis; clonorchiasis; schistosomiasis; vaccine; vaccination 1. Introduction This article provides an overview of recent progress in the development of vaccines against digenetic trematodes which parasitise the liver (Fasciola hepatica, F.
    [Show full text]
  • Praziquantel Treatment in Trematode and Cestode Infections: an Update
    Review Article Infection & http://dx.doi.org/10.3947/ic.2013.45.1.32 Infect Chemother 2013;45(1):32-43 Chemotherapy pISSN 2093-2340 · eISSN 2092-6448 Praziquantel Treatment in Trematode and Cestode Infections: An Update Jong-Yil Chai Department of Parasitology and Tropical Medicine, Seoul National University College of Medicine, Seoul, Korea Status and emerging issues in the use of praziquantel for treatment of human trematode and cestode infections are briefly reviewed. Since praziquantel was first introduced as a broadspectrum anthelmintic in 1975, innumerable articles describ- ing its successful use in the treatment of the majority of human-infecting trematodes and cestodes have been published. The target trematode and cestode diseases include schistosomiasis, clonorchiasis and opisthorchiasis, paragonimiasis, het- erophyidiasis, echinostomiasis, fasciolopsiasis, neodiplostomiasis, gymnophalloidiasis, taeniases, diphyllobothriasis, hyme- nolepiasis, and cysticercosis. However, Fasciola hepatica and Fasciola gigantica infections are refractory to praziquantel, for which triclabendazole, an alternative drug, is necessary. In addition, larval cestode infections, particularly hydatid disease and sparganosis, are not successfully treated by praziquantel. The precise mechanism of action of praziquantel is still poorly understood. There are also emerging problems with praziquantel treatment, which include the appearance of drug resis- tance in the treatment of Schistosoma mansoni and possibly Schistosoma japonicum, along with allergic or hypersensitivity
    [Show full text]
  • Be Aware of Schistosomiasis | 2015 1 Fig
    From our Whitepaper Files: Be Aware of > See companion document Schistosomiasis World Schistosomiasis 2015 Edition Risk Chart Canada 67 Mowat Avenue, Suite 036 Toronto, Ontario M6K 3E3 (416) 652-0137 USA 1623 Military Road, #279 Niagara Falls, New York 14304-1745 (716) 754-4883 New Zealand 206 Papanui Road Christchurch 5 www.iamat.org | [email protected] | Twitter @IAMAT_Travel | Facebook IAMATHealth THE HELPFUL DATEBOOK It was clear to him that this young woman must It’s noon, the skies are clear, it is unbearably have spent some time in Africa or the Middle hot and a caravan snakes its way across the East where this type of worm is prevalent. When Sahara. Twenty-eight people on camelback are interviewed she confirmed that she had been heading towards the oasis named El Mamoun. in Africa, participating in one of the excursions They are tourists participating in ‘La Sahari- organized by the club. enne’, a popular excursion conducted twice weekly across the desert of southern Tunisia The young woman did not have cancer at all, by an international travel club. In the bound- but had contracted schistosomiasis while less Sahara, they were living a fascinating swimming in the oasis pond. When investiga- experience, their senses thrilled by the majestic tors began to fear that other members of her grandeur of the desert. After hours of riding, group might also be infected, her date book they reached the oasis and were dazzled to see came to their aid. Many of her companions had Fig. 1 Biomphalaria fresh-water snail. a clear pond fed by a bubbling spring.
    [Show full text]
  • Phylogeny of Seven Bulinus Species Originating from Endemic Areas In
    Zein-Eddine et al. BMC Evolutionary Biology (2014) 14:271 DOI 10.1186/s12862-014-0271-3 RESEARCH ARTICLE Open Access Phylogeny of seven Bulinus species originating from endemic areas in three African countries, in relation to the human blood fluke Schistosoma haematobium Rima Zein-Eddine1*, Félicité Flore Djuikwo-Teukeng1,2, Mustafa Al-Jawhari3, Bruno Senghor4, Tine Huyse5 and Gilles Dreyfuss1 Abstract Background: Snails species belonging to the genus Bulinus (Planorbidae) serve as intermediate host for flukes belonging to the genus Schistosoma (Digenea, Platyhelminthes). Despite its importance in the transmission of these parasites, the evolutionary history of this genus is still obscure. In the present study, we used the partial mitochondrial cytochrome oxidase subunit I (cox1) gene, and the nuclear ribosomal ITS, 18S and 28S genes to investigate the haplotype diversity and phylogeny of seven Bulinus species originating from three endemic countries in Africa (Cameroon, Senegal and Egypt). Results: The cox1 region showed much more variation than the ribosomal markers within Bulinus sequences. High levels of genetic diversity were detected at all loci in the seven studied species, with clear segregation between individuals and appearance of different haplotypes, even within same species from the same locality. Sequences clustered into two lineages; (A) groups Bulinus truncatus, B. tropicus, B. globosus and B. umbilicatus; while (B) groups B. forskalii, B. senegalensis and B. camerunensis. Interesting patterns emerge regarding schistosome susceptibility: Bulinus species with lower genetic diversity are predicted to have higher infection prevalence than those with greater diversity in host susceptibility. Conclusion: The results reported in this study are very important since a detailed understanding of the population genetic structure of Bulinus is essential to understand the epidemiology of many schistosome parasites.
    [Show full text]
  • TREMATODES Blood Species
    Lecturer : Nerran K.F.AL- Rubaey Practical parasites Lab - 13 - TREMATODES Blood Species : 1- Schistosoma mansoni : Common Name ( Manson, s Blood Fluke) Causes Intestinal Schistosomiasis . 2- Schistosoma japonicum :Common Name ( Blood Fluke ) Causes Intestinal Schistosomiasis . 3- Schistosoma haematobium : Common Name ( Bladder Fluke ) Causes Urinary Schistosomiasis. Eggs : The average Schistosoma eggs is comprised of developed miracidium , these eggs are oval in shape and the presence of lateral or terminal spines distinguishes the egg of one species from the other species . Figure ( 1- 1 ) : Egg of Schistosoma mansoni *It, s have large lateral spine and developed miracidium . 1 PDF created with pdfFactory trial version www.pdffactory.com Figure ( 1- 2 ) : Egg of Schistosoma japonicum *It, s have small lateral spine and developed miracidium . Figure ( 1- 3 ) : Egg of Schistosoma haematobium *It, s have large terminal spine and developed miracidium . Adults : The adults of Schistosoma sp.are the only trematodes that have separate sexes . Unlike the other adult trematode , the Schistosomes are rounder in appearance . Although the typical female measures 2 cm in length and the male measures 1.5 cm in length , the male has the capability to almost completely surround the female during copulation . 2 PDF created with pdfFactory trial version www.pdffactory.com Figure ( 1- 4 ) : Schistosomes in copula. ( The Life cycle of Schistosoma sp.) 3 PDF created with pdfFactory trial version www.pdffactory.com Notes *Diagnostic stage is :egg * Infective stage is : cercaria * Final host is : human * Intermediate is : snail Table ( 1 ): Differentiation between Schistosoma sp. Properties Schistosoma Schistosoma Schistosoma mansoni japonicum haematobium 1- natural habitat Adult live in vein Adult live in vein of Adult live in vein of of large intestine small intestine urinary bladder 2- male (No.
    [Show full text]