Aus dem Zentrum für klinische Tiermedizin der Tierärztlichen Fakultät der Ludwig-Maximilians-Universität München Arbeit angefertigt unter der Leitung von Univ.-Prof. Dr. med. vet. Katrin Hartmann Tritrichomonas foetus in purebred cats in Germany: Prevalence, association with clinical signs, and determinants of infection Inaugural-Dissertation zur Erlangung der tiermedizinischen Doktorwürde der Tierärztlichen Fakultät der Ludwig-Maximilians-Universität München vorgelegt von Kirsten Alice Kühner aus Boston, USA München 2012 Gedruckt mit der Genehmigung der Tierärztlichen Fakultät der Ludwig-Maximilians-Universität München Dekan: Univ.-Prof. Dr. Braun Referent: Univ.-Prof. Dr. Hartmann Korreferent: Univ.-Prof. Dr. Zerbe Tag der Promotion: 11. Februar 2012 To my parents, with love and gratitude, for believing in me and teaching me to always reach for my dreams. To my beloved dogs Tris and Lizzy, for faithfully accompanying me throughout the long years of my veterinary education. Table of contents IV TABLE OF CONTENTS I. INTRODUCTION ...................................................................................... 1 II. LITERATURE REVIEW .......................................................................... 2 1. Tritrichomonas foetus ................................................................................2 1.1. Evolutionary background and taxonomic classification .......................2 1.2. Morphology ...........................................................................................3 1.3. Living environment and life cycle ........................................................4 1.4. Host range .............................................................................................5 1.4.1. Cattle ...............................................................................................5 1.4.2. Small ruminants ..............................................................................6 1.4.3. Swine ...............................................................................................6 1.4.4. Dogs ................................................................................................7 1.4.5. Humans ...........................................................................................7 1.4.6. Domestic cats ..................................................................................8 2. Trichomonosis in domestic cats ...............................................................8 2.1. Etiology and historical review ..............................................................8 2.2. Prevalence and geographic distribution ..............................................11 2.2.1. North America ...............................................................................11 2.2.2. Europe ...........................................................................................11 2.2.3. Asia and Australia .........................................................................12 2.3. Epidemiology ......................................................................................13 2.3.1. Origin of feline infection ...............................................................13 2.3.2. Transmission .................................................................................15 2.3.3. Prevalence factors .........................................................................15 2.3.3.1. Signalment ................................................................................16 2.3.3.2. Housing situation ......................................................................17 2.4. Pathogenesis ........................................................................................18 2.4.1. Pathologic findings .......................................................................19 2.4.2. Parasite-specific mechanisms of pathogenicity ............................20 2.4.3. Host-specific determinants of infection ........................................21 2.5. Clinical findings ..................................................................................22 Table of contents V 2.6. Diagnostic methodology .....................................................................22 2.6.1. Direct faecal smear examination ...................................................23 2.6.2. Faecal culture ................................................................................24 2.6.3. Polymerase chain reaction.............................................................25 2.6.4. Histopathology ..............................................................................26 2.7. Treatment ............................................................................................26 2.7. Prognosis .............................................................................................28 III. PUBLICATION ........................................................................................ 29 IV. DISCUSSSION ......................................................................................... 38 1. Prevalence in Germany...........................................................................38 2. Detection methods ...................................................................................39 3. Clinical signs ............................................................................................41 3.1. Diarrhoea .............................................................................................41 3.1.1. Prevalence of T. foetus-associated diarrhoea ................................41 3.1.2. Association of diarrhoea with age .................................................42 3.1.3. Association of diarrhoea with enteroparasitic co-infections .........42 3.2. Other clinical signs ..............................................................................43 4. Determinants of infection .......................................................................44 4.1. Signalment ..........................................................................................44 4.1.1. Age ................................................................................................44 4.1.2. Breed .............................................................................................45 4.2. Co-infection with other enteroparasites ..............................................45 4.3. Environmental factors .........................................................................46 4.3.1. Housing density .............................................................................46 4.3.2. Management of litter boxes ...........................................................47 4.3.3. Proximity to livestock ...................................................................48 5. Conclusion ................................................................................................48 V. SUMMARY............................................................................................... 50 VI. ZUSAMMENFASSUNG ......................................................................... 52 VII. REFERENCES ......................................................................................... 54 VIII. ACKNOWLEDGEMENTS ..................................................................... 69 Abbreviations VI ABBREVIATIONS AIDS Acquired immune deficiency syndrome AUTf-1 specific feline Tritrichomonas foetus isolate BVSc Bachelor of Veterinary Science C cytosine D-1 specific bovine Tritrichomonas foetus isolate Dipl. ACVIM Diplomate of the American College of Veterinary Internal Medicine Dipl. ACVN Diplomate of the American College of Veterinary Nutrition Dipl. ECVIM-CA Diplomate of the European College of Veterinary Internal Medicine – Companion Animals DNA deoxyribonucleic acid Dr. Doctor Dr. med. vet. doctor medicinae veterinariae DVM Doctor of veterinary medicine et. al. and others (et alii) FeLV Feline leukemia virus FIV Feline immunodeficiency virus g gram GADPH glyceraldehyde 3-phosphate dehydrogenase GPA grade point average habil. Habilitatus ITS1 internal transcribed spacer region 1 ITS2 internal transcribed spacer region 2 kg kilogram L. Limacus µg Microgram µl microlitre mg milligram NFO Norwegian Forest P. Pentatrichomonas PCR polymerase chain reaction P p-value pH measure of the acidity of an aqueous solution PhD Philosophiae doctor Priv.-Doz. private lecturer (Privatdozent) Prof. Professor RNA ribonucleic acid rRNA ribosomal ribonucleic acid Abbreviations VII 5.8S rRNA non-coding component of the large eukaryotic ribosomal subunit 18S rRNA component of the small eukaryotic ribosomal subunit 16S rRNA component of the small prokaryotic ribosomal subunit S Svedberg S. Streptococcus T thymidine TFITS-F, TFITS-R specific primers used in PCR assay of Tritrichomonas foetus TFR3, TFR4 specific primer used in PCR assay of Tritrichomonas foetus T. felis Trichomonas felis T. hominis Trichomonas hominis T. foetus Tritrichomonas foetus TM Trademark TR7, TR8 specific primers used in the amplification of variable-length DNA repeats from the genome of trichomonads UK United Kingdom USA United States of America I. Introduction 1 I. INTRODUCTION Tritrichomonas foetus (T. foetus) is a single-celled protozoan that is well known as the causative agent of the economically devastating venereal trichomonosis in cattle (EMMERSON, 1932; RAE & CREWS, 2006). Recently this parasite has also been identified as an important pathogen in domestic cats (GOOKIN et al., 1999; LEVY et al., 2003). While T. foetus infects the bovine urogenital tract, leading to infertility,