Psoroptes ovis mange in Belgian Blue cattle: How to approach a multifactorial problem? Charlotte Sarre Dissertation submitted in fulfilment of the requirements for the degree of Doctor (PhD) in Veterinary Sciences 2015 Promoters: Prof. Dr. Edwin Claerebout Prof. Dr. Peter Geldhof Department of Virology, Parasitology and Immunology Faculty of Veterinary Medicine Ghent University 2 TABLE OF CONTENTS List of abbreviations ................................................................................................................ 5 CHAPTER 1 - Review on Psoroptes ovis ................................................................................ 9 1.1 Introduction ...................................................................................................................................... 11 1.2 Life cycle and epidemiology ............................................................................................................ 12 1.3 Pathogenesis and clinical signs ........................................................................................................ 18 1.4 Immune response against mites ....................................................................................................... 23 1.4.1 Introduction .............................................................................................................................. 23 1.4.2 Innate immunity against Psoroptes ovis in sheep and cattle .................................................... 25 1.4.3 Adaptive immunity against Psoroptes ovis in sheep and cattle ................................................ 28 1.4.4 Immunity during Sarcoptes scabiei infections .......................................................................... 33 1.4.4.1 Innate immunity against Sarcoptes scabiei ...................................................................................... 34 1.4.4.2 Adaptive immunity against Sarcoptes scabiei ................................................................................. 35 1.5 Diagnosis of psoroptic mange in cattle ............................................................................................ 38 1.6 Treatment and prevention of psoroptic mange ................................................................................. 42 1.6.1 Treatment of psoroptic mange .................................................................................................. 42 1.6.2 Treatment failure ...................................................................................................................... 47 1.6.3 Prevention of psoroptic mange ................................................................................................. 48 1.6.4 Alternative treatment methods .................................................................................................. 49 1.7 References ........................................................................................................................................ 52 OBJECTIVES ........................................................................................................................ 67 CHAPTER 2 - Risk factors for Psoroptes ovis mange on Belgian Blue farms in Northern Belgium ................................................................................................................................... 71 2.1 Introduction ...................................................................................................................................... 73 2.2 Materials and methods ..................................................................................................................... 74 2.2.1 Cross-sectional questionnaire survey ....................................................................................... 74 2.2.2 Farm visits ................................................................................................................................ 74 2.2.3 Statistical analysis .................................................................................................................... 75 2.3 Results .............................................................................................................................................. 76 2.3.1 Questionnaire validation .......................................................................................................... 76 2.3.2 Prevalence of mange ................................................................................................................. 76 2.3.3 Applied management procedures .............................................................................................. 77 2.3.4 Risk analyses ............................................................................................................................. 78 2.3.4.1 Cross-sectional questionnaire survey ............................................................................................... 78 2.3.4.2 Farm visits ........................................................................................................................................ 79 2.4 Discussion ........................................................................................................................................ 80 2.5 References ........................................................................................................................................ 84 2.6 Annex 1 ............................................................................................................................................ 86 2.7 Annex 2 ............................................................................................................................................ 87 CHAPTER 3 - Evaluation of two intensive treatment schedules against Psoroptes ovis mange in Belgian Blue cattle ................................................................................................. 89 3.1 Introduction ...................................................................................................................................... 91 3.2 Materials and methods ..................................................................................................................... 92 3.3 Results .............................................................................................................................................. 95 3.4 Discussion ........................................................................................................................................ 98 3.5 References ...................................................................................................................................... 101 CHAPTER 4 - Comparative immune responses against Psoroptes ovis in two cattle breeds with different susceptibility to mange .................................................................... 103 4.1 Introduction .................................................................................................................................... 105 4.2 Materials and methods ................................................................................................................... 107 3 4.2.1 Animals and tissue collection ................................................................................................. 107 4.2.2 Psoroptes ovis antigen production .......................................................................................... 108 4.2.3 Histology, immunohistochemistry and cell counts ................................................................. 108 4.2.4 Quantitative real-time PCR .................................................................................................... 108 4.2.5 Cell proliferation assays ......................................................................................................... 111 4.2.6 Statistical analysis .................................................................................................................. 113 4.3 Results ............................................................................................................................................ 113 4.3.1 In vivo cutaneous immune response ....................................................................................... 113 4.3.2 In vitro immune response after PBMC re-stimulation ............................................................ 115 4.4 Discussion ...................................................................................................................................... 119 4.5 References ...................................................................................................................................... 123 CHAPTER 5 - General discussion ...................................................................................... 127 5.1 Environmental and parasite factors ................................................................................................ 129 5.1.1 Farm management .................................................................................................................. 129 5.1.2 Treatment protocols ................................................................................................................ 130 5.1.3 Mite strains ............................................................................................................................. 131 5.2 Host related factors .......................................................................................................................