Key aspects of Infectious Diseases Flashcards
Microbes: smallest to largest
Prions Viruses Bacteria Fungi Protozoa Multicellular parasites
Microorganism
An organism that is so small that it is microscopic (invisible to the naked eye)
Types of organism
Pathogenic and non-pathogenic
Pathogenic microorganisms
Pathogens
Microorganism that can cause disease upon colonization of host
Obligate pathogen
Microorganism which must infect host and cause disease in order to multiply and be transmitted from one host to another (myobacterium tuberculosis)
Facultative pathogen
Microorganism which can infect and multiply in hosts but is also capable of multiplying in environment (e. coli)
Opportunistic pathogen
Microorganism which does not ordinarily cause disease but which, under certain conditions (impaired immunity) becomes pathogenic (HIV)
Infectious disease triangle
Susceptible host
Pathogen
Environment
Susceptible host (disease triangle)
Breed, age, sex, genotype
Physiology and susceptibility
Immune response
Pathogen (disease triangle)
Pathogenicity
Dispersal efficiency
Survival efficiency
Innoculation dose
Environment (disease triangle)
Abiotic and biotic factors Housing management Population density Sanitation Nutrition Prevention
Disease
disorder of structure or function in the host that adversely impacts the host and is not simply result of physical injury
Infectious diseases
Diseases cause by pathogenic microorganisms (bacteria, viruses, parasites, fungi, prions) some are communicable
Communicable
They can be spread directly or indirectly from one animal to another
Etiology
study of the cause of disease
Infection
the invasion and multiplication of pathogens in an individual or population
Non-diseased state - risk and exposure factors - susceptibility to the disease - biological evidence of infection - clinical illness - progression of disease - recovery or death
Koch’s postulate
Healthy -> RBCs -> causitive agent absent
Diseased -> RBC (with agent) -> causitive agent present -> injected into healthy -> diseased
Causative agent present
Five periods of infectious disease
Incubation Prodromal Illness Decline Convalescence
Exposure Outcomes
No infection Carrier Sub-clinical infection - immunity -carrier -non-immunity Clinical infection -immunity -carrier -non-immunity -death
Why does animal health matter
Animal health is an engin of growth for vulnerable communities
Feeding a growing population relies on healthy animals
Human lives and livelyhoods dependant on healthy animals
Controlling animal disease protects our health
