Animal Sciences 3170 Animal Diseases ASC 3170 • Host – Pathogen Interaction • Management • System Specific Diseases Tissue Specific Diseases TEXT • None • Supplemental Reading • Website – http://www.oardc.ohio-state.edu/as413/ My Contact • Joe Hogan [email protected] • Phone 330-263-3801 Tentative Exam Schedule • See syllabus Quizzes & Homework • Announced – no pop quizzes • No make-up quizzes • No make-up homeworks Make-up Exams • Discretion of Hogan Final Grade % Final Grade Two hourly exams Quizzes and Homework Final Exam 50% 25% 25% Terminology • • • • Pandemics/Epidemic/Endemics Antibodies/Antibiotics Virus/Bacteria/Fungi/Protoza Host Defense – Cellular – Immunity – Innate – Induced Terminology Confusion Disease • Specific disorder or illness Latin meaning • Disease – “Not at ease” Disease • Infectious – Living agent • Non-infectious – Nonliving agent Non Infectious Disease 1) 2) 3) 4) 5) Nutritional Metabolic Trauma Toxic Materials Congenital Defects Infectious Disease • Agents infect/invest Infectious Agents • Bacteria • Virus • Protozoa • Fungi • Parasites Infectious Disease Process • Enter host • Multiply • Evade host defenses • Harm host The Holy Triangle Environment Host Pathogen Infectious Diseases • Contagious – Animal to animal transfer • Non contagious – Environmental to animal transfer Transmission • Direct – Cough – Aerosol – Touch Transmission • Indirect – Vectors – Fomites Vector • organism that transmits a particular disease or parasite from one animal to another Fomites • inanimate objects that transmits a particular disease or parasite from one animal to another Fomites “demics” • Relating to population or area Epidemic • Rate of disease in a population greater than expected Endemic • Disease is maintained at a relatively constant rate in the population without the need for external input Pandemic • Epidemic of worldwide (large geographical area) distribution J.M. Helfrich 1995 Host Parasite Host Parasite • Interaction dynamic Host Parasite Interaction Commensalism • No harm • No benefit Host Parasite Interaction Parasitism • One lives @ expense of other PARASITES - HOST • Successful Parasites co-evolve with Host Host Parasite Interaction Mutualism – both benefit Objective of pathogens • Reproduce Pathogenicity • Capacity to infect Virulence • Degree of pathogenicity ID • Infectious dose = minimal # of pathogens needed to establish a disease. – Pathogen specific – Range 1 to 108 ID50 • Infectious Dose 50 • Gold standard for virulence • Number of organisms required to produce an infection in 50% of the test animals – Specified time – Specified route LD50 • Lethal Dose 50 • Number of organisms or toxin required to cause death in 50% of the test animals – Specified time – Specified route LD50 Toxin Pathogen Types • May change category – Host – Life Cycle – Environment Obligate Pathogens • Associated only with disease Opportunistic or Potential Pathogens • Normal flora • Disease when host compromised Human Normal Flora Bacterial # of cells in normal human flora body population Pathogen Assault Pathogenic Microbes • Frontal assault – Short incubation – Rapid clinical signs – Intimate transmission Pathogenic Microbes • Stealth assaults – Incubation lengthy – Slow onset of signs – Environmental transmission HOST Host • Final Host – Parasite reaches sexual maturity or replicates Host • Intermediate Host – Essential – Temporary environment for development Host • Reservoir Host – Harbors pathogens that infect others HOST DEFENSES Innate Defenses • Inherent to host Innate = Intrinsic • No Prior Exposure Needed Host Defenses • Inducible Defenses Inducible Defenses • Due to exposure Defense mechanisms 1. 2. 3. 4. Physical Cellular Immunological Non-specific Physical Factors - Site Specific Respiratory Gastro-intestinal Uro-genital Mammary INVADING HOST Transmission of Pathogens 1) 2) 3) 4) Airborne Direct contact Food/H2O borne Arthropod borne Attachment/Adherence Specific site on host cells Defenses Against Adherence pH Secretions Normal flora Flushing pH Mouth Urine Stomach pH Secretory Products Antibody Enzymes Iron chelators Anti-toxins Gut Dermal Vagina Normal Flora Occupies attachment sites Produce by-products that are competitive Model for Commensals Flushing Action Urinary tract Mammary gland Nasal secretion Bacterial Attachment Factors Proteins Glycocaylx Bacteria Counter with Pili Upper Respiratory Nasal hairs Turbulence Mucous • Drain • Swallow • Cililiary esculator Rabbit Lung Cilia Upper Respiratory Tree Dermal Cell turnover pH Proteins/lipids Intestinal Attachment GO HOME!