Principle of Infectious Diseases By: Xavia Hutchinson & Bri Smith

Objective:  Students will learn the infectious disease causing agents.  Students will know how to treat infectious diseases.  Students will learn Koch’s postulates.

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

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.

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.

Background info of Koch’s postulates:  Why was Koch’s 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.

Foundation of Koch’s 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.

What did Koch’s postulate do…  Helped establish germ theory  Understanding infectious diseases

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

Disease Agents:  Traditionally, infectious diseases are divided into four classes of agents:  Bacteria  Viruses  Fungi  Parasites

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.

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.

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)

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.

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

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)

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

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)

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)

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

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

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)

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)

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

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

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