View metadata, citation and similar papers at core.ac.uk brought to you by CORE Section of Veterinary Pathology and Parasitology provided by Helsingin yliopiston digitaalinen arkisto Department of Basic Veterinary Sciences Faculty of Veterinary Medicine University of Helsinki, Finland National Veterinary and Food Research Institute Helsinki, Finland National Food Agency Helsinki, Finland ENDEMIC TRICHINELLOSIS – EXPERIMENTAL AND EPIDEMIOLOGICAL STUDIES Leena Oivanen Academic dissertation to be presented, with the permission of the Faculty of Veterinary Medicine, University of Helsinki, for public criticism in Walter Auditorium, Faculty of Veterinary Medicine, Agnes Sjöbergin katu 2, Helsinki, on June 17th 2005 at 12 noon. Helsinki 2005 Supervisors Professor Antti Sukura Department of Basic Veterinary Sciences Faculty of Veterinary Medicine University of Helsinki Finland Professor Tuula Honkanen-Buzalski National Veterinary and Food Research Institute Helsinki Finland Reviewers Doctor Alvin Gajadhar Centre for Animal Parasitology Canadian Food Inspection Agency Saskatoon Saskatchewan Canada Docent Riitta Maijala Department of Food and Environmental Hygiene Faculty of Veterinary Medicine University of Helsinki Finland Opponent Professor Arvid Uggla Faculty of Veterinary Medicine and Animal Science Swedish University of Agricultural Sciences Uppsala Sweden ISBN 952-91-8846-3 (paperback) ISBN 952-10-2515-8 (PDF) Yliopistopaino Helsinki, 2005 2 CONTENTS 1. ABSTRACT .............................................................................................................................. 5 2. ABBREVIATIONS ................................................................................................................... 7 3. LIST OF ORIGINAL PUBLICATIONS.................................................................................. 9 4. INTRODUCTION .................................................................................................................... 10 5. REVIEW OF THE LITERATURE ........................................................................................... 11 5.1 History of trichinellosis ...................................................................................................... 11 5.2 Taxonomy ........................................................................................................................... 11 5.2.1 Species and genotypes .............................................................................................. 11 5.2.1.1 Trichinella spiralis ....................................................................................... 12 5.2.1.2 Trichinella nativa ......................................................................................... 13 5.2.1.3 Trichinella britovi ........................................................................................ 13 5.2.1.4 Trichinella nelsoni ........................................................................................ 13 5.2.1.5 Trichinella murrelli ...................................................................................... 14 5.2.1.6 Trichinella pseudospiralis ............................................................................ 14 5.2.1.7 Trichinella papuae ....................................................................................... 14 5.2.1.8 Trichinella zimbabwensis ............................................................................. 14 5.2.1.9 Genotypes of uncertain taxonomic status ................................................... 15 5.3 Life cycle and morphology ................................................................................................. 15 5.3.1 Life cycle .................................................................................................................. 15 5.3.2 Morphology of the parasite ..................................................................................... 17 5.4 Pathogenesis and clinical signs ............................................................................................ 18 5.4.1 Clinical signs .............................................................................................................18 5.4.2 Laboratory findings .................................................................................................. 19 5.4.3 Acquired immunity ................................................................................................... 19 5.4.4 Infective dose ............................................................................................................ 20 5.4.5 Trichinella species-specific pathogenicity in humans .............................................. 20 5.4.6 Host-specific pathogenicity ..................................................................................... 20 5.5 Therapy .............................................................................................................................. 21 5.5.1 Anthelmintic drugs ................................................................................................... 21 5.5.2 Immunosuppressive drugs and adjunct therapy ....................................................... 22 5.5.3 Prophylaxis ............................................................................................................... 22 5.6 Diagnostic methods ............................................................................................................ 22 5.6.1 Diagnostic methods in human medicine .................................................................... 22 5.6.1.1 Direct detection ........................................................................................... 22 5.6.1.2 Indirect detection ......................................................................................... 23 5.6.2 Diagnostic methods in veterinary medicine .............................................................. 23 5.6.2.1 Direct detection ........................................................................................... 23 5.6.2.2 Indirect detection ......................................................................................... 25 5.6.3 Species specification and genotyping ....................................................................... 27 5.6.3.1 Random amplified polymorphic DNA-PCR ............................................... 27 5.6.3.2 Multiplex PCR ............................................................................................ 28 5.6.3.3 Other molecular methods ............................................................................. 28 5.7 Epidemiology and distribution ........................................................................................... 28 5.7.1 Domestic and sylvatic cycles ................................................................................... 29 5.7.2 Climatic effects ......................................................................................................... 29 5.7.3 Other environmental factors ..................................................................................... 30 5.7.4 Host diversity ........................................................................................................... 30 5.7.5 Sources of domestic infections ................................................................................. 30 5.7.6 Epidemiology in Finland ........................................................................................... 31 3 5.7.7 Epidemiology in other European countries ............................................................... 34 5.7.8 Global epidemiology .................................................................................................. 37 5.8 Control of trichinellosis ...................................................................................................... 38 5.8.1 Trends and challenges of trichinellosis control ......................................................... 39 6. AIMS OF THE STUDY ........................................................................................................... 40 7. MATERIALS AND METHODS ............................................................................................. 41 7.1 Materials ............................................................................................................................. 41 7.1.1 Animals utilized for descriptive studies ................................................................... 41 7.1.2 Experimental animals ................................................................................................ 41 7.1.3 Experimental feeds and conditions in the Trichinella survival study ....................... 42 7.1.3.1 Silage ............................................................................................................ 43 7.1.3.2 Grained barley ............................................................................................. 43 7.1.3.3 Propionic acid-fermented feed ..................................................................... 43 7.1.3.4 Pasture simulation ....................................................................................... 43 7.2 Methods ............................................................................................................................. 43 7.2.1 Animal experiments .................................................................................................. 43 7.2.2 Artificial digestion ......................................................................................................44