Animal Sciences 3170 Animal Diseases

ASC 3170 Host – Pathogen Interaction Management System Specific Diseases

Tissue Specific Diseases

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My Contact Joe Hogan Phone

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

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)Nutritional 2)Metabolic 3)Trauma 4)Toxic Materials 5)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 Host Environment 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

Interaction dynamic

Host Parasite Interaction CommensalismNo harm No benefit

Host Parasite Interaction ParasitismOne 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 10 8

ID 50 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

LD 50 Lethal Dose 50 Number of organisms or toxin required to cause death in 50% of the test animals –Specified time –Specified route

LD 50 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 normal flora population # of cells in human body

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

Due to exposure

Defense mechanisms 1. Physical 2. Cellular 3. Immunological 4. Non-specific

Physical Factors - Site Specific Respiratory Gastro-intestinal Uro-genital Mammary

INVADING HOST

Transmission of Pathogens 1) Airborne 2) Direct contact 3) Food/H 2 O borne 4) 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

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