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PATHOGENIC ORGANISM AND DISEASE TERMS Pathogen microorganism that produces disease A living organism of microscopic dimensions Not all microorganisms are pathogens The microorganism in the pictures is not a pathogen-does not produce a disease, in fact… PATHOGENIC ORGANISM AND DISEASE TERMS Disease deviation from normal infectious disease noninfectious disease contagious (communicable) disease iatrogenic disease idiopathic disease INFECTIOUS DISEASES 4 classes of agents (an agent is something that produces an effect) Bacterium/Bacteria Virus/Viruses Fungus/Fungi Parasites BACTERIA Is a living cell Prokaryote cell – No Nucleus Made up of cytoplasm, DNA, ribosomes, flagella BACTERIA Cocci _ round Staphylococci– round, clusters Streptococci- round, chains clostridium Rickettsia –rod shaped, small Anthrax Endospore – oval body inside, resistant Strangles Bacilli – rod shaped Skin infections, wounds, food poisoning Gram positive ehrlichia Spirochetes – spiral Leptospirosis STAPHYLOCOCCI Staphylococci (cocci means round) – round, clusters Skin infections, wounds, food poisoning MRSA Gram positive Have thick wall that takes a stain (purple) STREPTOCOCCI Streptococci-round, Gram positive Strangles Pinkeye Strep throat Necrotizing fasciitis Sepsis chains BACILLI Bacilli – rod shaped Anthrax E. coli Salmonella Listeria Clostridium E. COLI Gram negative Anaerobic Lower intestines CLOSTRIDIUM Gram positive rod shaped bacteria Anaerobic (lives without oxygen) Food poisoning Clostridium perfringens enterotoxin RICKETTSIA Gram Negative bacteria Intracellular parasites •Typhus •Rocky Mountain Spotted Tick Fever SPIROCHETTE Lyme disease Leptospirosis 1. EXAMPLES OF INFECTIOUS BACTERIAL DISEASES Swine Yersinia Cattle E Coli Mastitis Anthrax Canine Leptospirosis (Lepto) Ehrlichiosis (Tick Fever) Bordatella Bronchiseptica (kennel cough) Rabbit Horse Pasteurella (Snuffles) Tuleremia (vector-ticks, flies) Tetanus Strangles Cat Enteritis Cystitis BACTERIA Is a living cell Prokaryote cell – No Nucleus Made up of cytoplasm, DNA, ribosomes, flagella VIRUS Not a living cell! Made up of genetic material/ nucleic acid But are considered alive because they reproduce, grow, develop, adapt, use energy sources from their environment (DNA or RNA) enclosed in a protein shell All sorts of shapes but are extremely tiny/ cannot see with a regular microscope Viruses insert their genetic material into a living cell The cell becomes the virus’ host. The virus DNA/RNA becomes a part of the cells DNA so that during cell division the virus is being replicated and passed on. Eventually the virus’ DNA takes over, completely changes the host cell/ kills it’s host cell and continues to replicate and create lots more viruses What about Retroviruses (Feline Leukemia and FIV) constantly change/ difficult to treat VIRUS VS RETROVIRUS Virus tends to contain DNA which can be replicated Retrovirus contains RNA which must be transcripted (“converted”) into DNA. this process is not accurate “mistakes” are made in the process DNA constantly varies because of the mistakes Reason why retroviruses are harder to treat/ prevent HIV, FIV, Feline Leukemia 2. EXAMPLES OF INFECTIOUS VIRUSES Rabies - most warm blooded animals Dogs Parvovirus Distemper Horses West Nile Virus Equine Encephalomyelitis Cattle Bovine Viral Diarrhea (BVD) Cats Feline Panleukopenia Calicivirus Feline Leukemia Virus Feline Immunodeficiency Virus Comparison chart bacteria vs virus Bacteria Virus Ribosomes Present Absent Living attributes Living organism Opinions differ on whether viruses are a form of life or organic structures that interact with living organisms Number of cells Unicellular; one cell No cells; not living Structures DNA and RNA floating freely in cytoplasm. Has cell wall and cell membrane DNA or RNA enclosed inside a coat of protein. Treatment Antibiotics Vaccines prevent the spread and antiviral medications help to slow reproduction but can not stop it completely. Enzymes: Yes Yes, in some Nucleus No No Virulence Yes Yes Infection Localized Systemic Benefits: Some bacteria are beneficial Viruses are not beneficial. Reproduction Fission- a form of asexual reproduction Invades a host cell and takes over the cell causing it to make copies of the viral DNA/RNA. Destroys the host cell releasing new viruses. Size Larger (1000nm) Smaller (20 - 400nm) Cell wall Peptidoglycan/Lipopolysaccharide No cell wall.Protein coat present instead PRIONS Are proteins Not alive They do not have DNA or RNA They have an ability to reproduce Can cause inherited or transmissible diseases PRIONS Prion diseases are fatal and cause progressive, neurodegenerative problems literally, holes in the brain The brain resembles a sponge / diseases are called spongiform Examples of spongiform encephalopathies are…. 1) Scrapie….in sheep and goats 2) BSE ….”Mad Cow Disease” 3) Chronic Wasting Disease…wild deer and elk Transmitted by inherited disease, or ingested from tissue of infected animals (brain, spinal cord) FUNGUS Is a living cell… a “plant” type cell with a stronger protein wall (chitin) Plants have a cellulose wall (a “sugar”) Mold, yeast, mushroom Study of fungus is mycology Fungus “move” by growing 3. EXAMPLES OF INFECTIOUS FUNGI (MYCOSES) Dermatophytes (Ringworm) Require keratin for growth Thrush Coccidioidomycosis (Valley Fever) Blastomycosis (South East) Histoplasmosis Candida (yeast infection) BUDDING YEAST VALLEY FEVER Coccidioidomycosis (disease) Round fungus (Coccidioides Immitis) Lives in the soil Dormant during dry spells Develops as a mold with long filaments that break off into airborne spores when it rains The spores get into the air by disruption of soil (construction, earthquakes, farming, dust storms) 4. EXAMPLES OF INFECTIOUS PARASITES Heartworm (Dirofilaria immitis) Trichinella…Trichinosis Hookworm (Ancylostoma), Whipworm (Trichuris vulpis), Roundworm (Toxocara) Giardia (protozoan) Coccidiosis (protozoan) NONINFECTIOUS DISEASE CLASSIFICATIONS Classifying diseases helps aid the veterinarian in obtaining a diagnosis Helps the diagnostic process Clinical signs and symptoms could be the result of several different disorders Differential diagnosis-a list of possible causes of disease Rule Outs-ruling out possible causes of disease through diagnostic testing, observation, trial treatment Metabolic-disruption of normal chemical reactions Diabetes, hypothyroidism, hyperthyroidism, Cushings, Addisons Anomalies – Congenital Birth Defects Cleft palate, deaf, retinal dysplasia, dwarfism Degenerative – progressive, permanent, longterm deterioration DJD (osteoarthritis), Bovine Spongioform Encephalopathy (BSE) Trauma – Traumatic reticuloperitonitis, high rise syndrome, sucking chest wound, diaphragmatic hernia, peritonitis, prolapsed uterus Toxins - ingestion, inhalation, contact Antifreeze, misapplication of flea and tick products, warfarin (rat poison), toads, OTC medications, illegal drugs, plants Immune Immune Mediated Hemolytic Anemia (IMHA), System Lupus Erythematosus (SLE), Pruritis and Atopy (itchiness and hairloss) [allergies] Iatrogenic- a condition that develops as a result of treatment Hyperadrenocorticism (Cushings)- can be caused by treatment for a severe allergy problem Surgery-excision of Thyroid glad to treat hyperthyroidism in cats…parathyroid may also be removed causing iatrogenic hypoparathyroidism. Idiopathic- no explanation for underlying cause of the disease Idiopathic seizures Idiopathic renal hematuria Neoplasm - benign or malignant tumor Nutrition – Acute acidosis in ruminants, malnutrition, skeletal disease, hypoglycemia, obesity, iodine deficiency MADTIN M T metabolic A anomalie I D degenerative Trauma Toxins Immune Iatrogenic idiopathic N Neoplasm nutritional NONINFECTIOUS DISEASE CLASSIFICATIONS Metabolic-disruption of normal chemical reactions Anomalies – Congenital Birth Defects Traumatic reticuloperitonitis, high rise syndrome, sucking chest wound, diaphragmatic hernia, peritonitis, prolapsed uterus Toxins - ingestion, inhalation, contact DJD (osteoarthritis), Bovine Spongioform Encephalopathy (BSE) Trauma – Cleft palate, deaf, retinal dysplasia, dwarfism Degenerative – progressive, permanent, longterm deterioration Diabetes, hypothyroidism, hyperthyroidism, Cushings, Addisons Antifreeze, misapplication of flea and tick products, warfarin (rat poison), toads, OTC medications, illegal drugs, plants Immune Immune Mediated Hemolytic Anemia (IMHA), System Lupus Erythematosus (SLE) Pruritis and Atopy (itchiness and hairloss) [allergies] NONINFECTIOUS DISEASE CLASSIFICATIONS Iatrogenic- a condition that develops as a result of treatment Idiopathic- no explanation for underlying cause of the disease Hyperadrenocorticism (Cushings)- can be caused by treatment for a severe allergy problem Surgery-excision of Thyroid glad to treat hyperthyroidism in cats…parathyroid may also be removed causing iatrogenic hypoparathyroidism. Idiopathic seizures Idiopathic renal hematuria Neoplasm - benign or malignant tumor Nutrition – Acute acidosis in ruminants, malnutrition, skeletal disease, hypoglycemia, obesity, iodine deficiency 3 SEIZURE CASES Seizure Case 1: A 3 month old male toy poodle. The dog is strictly a house dog and does not run free, In addition to the seizures, it has had intermittent diarrhea and is quite thin. Differential Diagnosis (DfDx): Developmental Disorder- brain malformation Hypoglycemia-could be secondary to poor diet, diarrhea, intestinal parasites Head Trauma- not likely with indoor dog Toxins-potential for ingesting medications or illegal drugs, chocolate Infectious causes of encephalitis- Distemper Idiopathic epilepsy-very unlikely due to age of dog Seizure Case 2: A 2 ½ year old male golden retreiver. This dog is in excellent physical condition and has been eating well. This dog is free to roam the neighborhood and recently had one episode of vomiting and one episode where it was limping and stiff. DfDx: Idiopathic epilepsy-this is high on the list because of age and breed of dog at the onset of seizures. Head Trauma-the recent limping and stiffness raises this possibility Toxins- the list is long, but possibilities include insecticides, chocolate Liver Disease-definitely needs to be ruled out but dog has been doing well otherwise Infectious Encephalitis Seizure Case 3: A 14 year old female schnauzer. This dog had its first seizure and since that time has not been acting normal. There has been some weight loss and a poor appetitie, and the owners feel the dog can no longer see. The dog is strictly an indoor dog with no history of trauma. DfDx: Metabolic Disease-liver dx, hypogylcemia (insulinoma in the pancreas), Diabetes Neoplasia- the age of the dog, the blindness, lack of normalcy after the seizure make this a high likelihood Ideopathic epilepsy-very unlikely with the age of the animal