Principle of Infectious Diseases

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Principle of Infectious Diseases

• By Xavia Hutchinson Bri Smith

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Objective

• Students will learn the infectious disease
  causing agents.
• Students will know how to treat infectious
  diseases.
• Students will learn Kochs postulates.

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Starter Question

• What type of infectious diseases do you know that
  animals can get?

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Vocab

• Anthrax a bacterial infection within the skin,
  intestines, and respiratory system.
• Vector organism that transmits disease.
• Prokaryotic cells without membrane bound
  organelles.
• Anemia low in red blood cells.
• Systemic affecting entire body.

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Vocab cont.

• Lyme Disease bacterial infection that is in
  humans and animals that can cause symptoms such
  as fatigue and joint pains.
• Antimicrobial agent that hinders the growth or
  kills microorganism.
• Bacteriostatic agent that slows the rate of
  growth in bacteria.
• Antiseptic germicides that can be used on the
  skin of animals.
• Disinfectants germicides that are too harsh to
  be used on skin but can be used on inanimate
  objects or surfaces.

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Background info of Kochs postulates

• Why was Kochs postulates made?
• Anthrax outbreak in 2001 caused German physician
  Robert Koch to investigate why certain diseases
  were occurring.
• What did Koch study?
• Anthrax in cattle.

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Foundation of Kochs Postulate

• The infectious agent should be detectable in sick
  animals but not healthy animals.
• It should be possible to isolate and culture the
  organism.
• Organisms taken from the culture and introduced
  into a healthy animal should cause the same
  disease.
• The same organism should be isolated from the
  second animal.

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What did Kochs postulate do

• Helped establish germ theory
• Understanding infectious diseases

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Causes of Infectious Diseases

• Microorganisms (An organism of microscopic or
  submicroscopic size)
• May be a single cell or multicellular organism
• Microorganisms are very diverse
• Microorganism live in all types of environments,
  all around the world

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Disease Agents

• Traditionally, infectious diseases are divided
  into four classes of agents
• Bacteria
• Viruses
• Fungi
• Parasites

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Bacteria

• One celled prokaryotic organisms
• They are affected by the environment
• There is good bacteria and bad bacteria
  (pathogens)
• Pathogens (signs of disease)
• when a deadly bacteria invades a host it
  multiplies, during this incubation stage pathogen
  numbers increase rapidly.

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Bacteria cont.

• Endo/Exo toxins (These toxins help in the result
  of the signs of diseases.)
• Exotoxins are proteins produced and released by
  secretion.
• Endotoxins is the cell wall of the bacteria that
  is only released after the bacteria dies.
• Prodomal phase
• stage in disease when first signs of illness
  occurs, in this short period of time symptoms are
  physically present, then quickly progress into a
  more severe stage.
• Classifying bacteria is an ongoing process
• gram-positive gram-negative etc.

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Bacterial Infections

• Strangles
• Commonly found in Horses
• Bacteria (streptococcus equi)
• Symptoms (anorexia, fever, nasal discharge)
• Wooden tongue
• Commonly found in Cow and Sheep
• Bacteria (actinobacillus lignieresi)
• Symptoms (inflammation of tongue or lymph nodes)
• Kennel Cough
• Commonly found in Canines
• Bacteria (bordetella bronchiseptica)
• Symptoms ( dry cough anorexia)

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Viruses

• A virus is an infective agent that typically
  consists of a nucleic acid molecule in a protein
  coat, and is able to multiply only within the
  living cells of a host.
• Process of infection
• Virus locates host cell and attaches itself to it
• Viruses can be specific in the host/host cells it
  infects
• Virus penetrates
• Virus uses either DNA or RNA to multiply inside
  the host.

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Viruses cont.

• Virus then releases lysosomes that will destroy
  the host cells
• The assembled viruses are then released out the
  host and wait for their next host.
• Some viruses require a vector (an organism, such
  as a mosquito or tick, that carries
  disease-causing microorganisms) to transmit
  themselves from one host to another

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Viral Infections

• Equine Influenza
• Commonly found in Horses
• Virus (Equine influenza virus)
• Symptoms (fever, cough, nasal discharge)
• Shipping fever
• Commonly found in Cows
• Virus (IBR)
• Symptoms (high fever, ocular discharge, severe
  pneumonia)
• Feline Leukemia
• Commonly found in Cats
• Virus (retrovirus)
• Symptoms (weight loss, anemia, tumors)

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Fungi

• Fungi are eukaryotic cells with cell walls
• Fungi gain nutrients by absorbing nutrients from
  their surroundings
• Fungi are spore producers (spores provide the
  ability to spread the organism to other areas)
• Fungi can affect animals in several ways

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Fungi cont.

• Infects outer layer of the body (skin, hair/fur,
  nails/claws)
• Infects the internal organs then spreads to other
  regions of the body (systemic)
• Infects food sources (indirectly infecting
  animals)

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Fungal Infections

• Valley Fever
• Commonly found in Cats Dogs
• Fungus (coccidiodes immitis)
• Symptoms (lumps abscesses)
• Ringworm
• Affects all species
• Fungus (microsporum sp.)
• Symptoms (hair loss, crusting, flaking)
• Histoplasmosis
• Commonly found in Cats Dogs
• Fungus (histoplasma capsulatum)
• Symptoms (respiratory infection, weight loss,
  diarrhea)

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Parasites

• Single celled organisms or Large arthropods
• Parasites can be internal or external
• Parasites use their host as a source of nutrients
  and protection
• Parasites have complex life cycles allowing them
  to survive and infect others

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Parasites cont.

• Full life cycles require more than one host
• Animal that carries the adult parasite is called
  the definitive host
• Animal that carries immature stage of parasite,
  such as larvae, is called the intermediate host
• External parasites are called arthropods
• mites
• ticks
• fleas

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Parasitic Infections

• Hookworms
• Commonly in Cats Dogs
• Parasite (anclyostoma sp.)
• Symptoms (diarrhea, anemia, anorexia)
• Strongylosis
• Commonly found in Horses
• Parasite (strongylus sp.)
• Symptoms (colic, diarrhea, weight loss)
• Heart worm
• Commonly found in Dogs
• Parasite (dirofilaria immitis)
• Symptoms (coughing, fluid in abdomen, cardiac
  failure)

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Treatments

• Many chemicals exist to hinder growth or kill
  these infectious disease agents
• Antimicrobial Antibiotic
• Antibiotics are capable of killing bacteria NOT
  viruses
• Antimicrobials
• Bacteriostatic (an antibiotic that only slows the
  rate of growth of bacteria)
• Antiseptics (used on animals skin)
• Disinfectants (used only on inanimate objects)

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Clinical Practice

• Culturing is a technique used to isolate and
  identify microorganism
• Proper sampling and handling
• Sample added to medium for growth
• Incubation in proper temperatures
• Specific time period
• Antibiotic sensitivity tests performed
• Analysis of results

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Treatments

• Anthelmintic is a process used to identify the
  animals who need to be treated for parasitic
  infections
• Anthelmintic process
• Animals are evaluated by the color of its mucous
  membrane
• Color chart compares mucous membrane with the
  color conjunctiva of the eyes
• Animals with the palest mucous membranes are then
  treated

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Treatments Clinical Practice

• Supportive Treatment (supplementing vital
  nutrients and care to lame animals)
• Fluids given to animals lacking in water
• Tubes connected to the stomach to pump food into
  the body