Health and Disease. Dr. Stephanie Lewis, DVM, MS, DACLAM Clinical Veterinarian, ULAR July 22, 2009

Transcription

1 Laboratory Animal Health and Disease Dr. Stephanie Lewis, DVM, MS, DACLAM Clinical Veterinarian, ULAR July 22, 2009

2 Disease Paradox Strive for excellence in animal care and disease prevention so that disease research may be performed

3 Recognizing Disease Why does it matter? Ethical obligation Experimental studies need healthy animals Legal obligation

4 All animals should be observed for signs of illness, injury, or abnormal behavior by a person trained to recognize such signs as a rule, this should occur daily -- The Guide

5 Program of adequate veterinary care that includes daily observation of all animals to assess their health and well-being may be accomplished by attending veterinarian or their designee --Animal Welfare Act

6 Question #1 Who is the most important person(s) involved in the health surveillance of the laboratory animal population?

7 Causes of Disease Environmental Temperature Humidity Noise Overcrowding Lighting Air Exchange Contaminants t Air, water, bedding, feed Nutritional Genetic Cancer Infectious Diseases Viruses, bacteria, fungal, parasitic Idiopathic

8 Recognizing Disease

9 Recognizing Disease

10 Alopecia Assessment & Communication How much? Location? Wound How extensive? Location? Tumor Size estimate? Location? Prolapse How severe? Location?

11 Assessment and Communication Tools

12 Clinical Expression Clinical Expression: Clinical Signs Obvious (limping, hair loss) Subclinical No clinical signs!! Examples?

13 Classifying Disease Diseases may be classified by: By the body system affected (anatomically) Gastrointestinal, cardiovascular, etc. Area of body affected Local (ie broken bone, local dermatitis) Systemic (bloodstream) Their cause or origin (etiology) Bacterial, viral, etc.

14 Inflammation of meninges? Meningitis Classification? Anatomical Streptococcus pneumoniae isolated? Bacterial meningitis Classification Etiological Practice!

15 Disease Chronology Acute: rapid onset Hours to days Examples? Subacute: between acute and chronic Chronic: long duration Weeks, months, years Examples?

16 Acute or Chronic?

17 Acute or Chronic?

18 Categorizing Disease Morbidity rate Sick animals Expressed as a percentage Calculation: # of sick animals x 100 # of total animals *Sick animals near death termed moribund

19 Categorizing Disease Mortality rate Animals that die from disease Expressed as a percentage Calculation: # of sick animals x 100 # of total animals

20 Determining Severity Severity of disease depends d on: Number of host cells, tissues, organs involved Extent of damage done to those structures Importance of those structures Function, regeneration ability Typically the more specialized the cell, the more debilitating the disease process

21 Host Defense Skin and mucous membranes Primary defense mechanism Immune system Innate Non-specific Acquired Antibody response Vaccinations i

22 Immunodeficiency State t in which h the immune system's ability to fight infectious disease is compromised or entirely absent Primary: genetic disease process Over 80 recognized primary immunodeficiency syndromes Secondary: the result of particular external processes or diseases Malnutrition, aging, medications, caner, HIV

23 Inflammation ( itis ) Clinical i l Signs of Inflammation: Heat Increased blood flow with protective chemicals and white blood cells Redness Swelling Fluids, chemicals, and WBCs leak into space surrounding cells

24 Inflammation Pain Swollen tissue exerts pressure on nerve cells Chemicals released by degenerating tissues or WBC Loss of Function Due to pain, swelling

25 Question #1 Which h is more important t in medicine: i therapeutic treatment or prevention? PREVENTION!!

26 Preventive Medicine Pi Primary: avoids the development of a disease Most population-based health promotion activities are primary preventive measures Secondary: activities are aimed at early disease detection ti Increases opportunities for interventions to prevent progression

27 Primary Disease Prevention Quarantine Ensures newly arrived animals are not a source of disease Sanitation and hygiene Reduces risk of disease Periodic examination Daily observation Appropriate immunizations O f f Only given if they do not interfere with research

28 Primary Disease Prevention Proper waste disposal Upkeep of physical facilities Proper cage wash/rinse water temperatures (180 o ) Autoclave Light cycles Isolation Diseased or suspect

29 Secondary Disease Prevention Sentinel program (QA lab) Test a sample of mice that represent the larger population Necropsy (gross lesions) Histopathology (microscope slides) Serology (antibody detection) Parasitology (fecal float, tape test, pelt exam) Ancillary tests

30 Dogs Secondary Disease Prevention Physical exam, fecal exam Heartworm Test Primates Physical exam, fecal exam TB test Cats Physical exam, fecal exam Feline leukemia test

31 Question #2 What is the most important t tool in modern medicine for preventing infection?

32 Categorizing Disease Noninfectious Diseases Environmental Nutritional Genetic Cancer Idiopathic Infectious Diseases Viruses, bacteria, fungal, parasitic, pria Idiopathic

33 Noninfectious Disease Temperature Environmental Most animals comfortable at 70 o F Hypothermia/hyperthermia Humidity 30-70% 0% Prolonged dry or wet environment can contribute to disease Respiratory, ringtail, wet nose

34 Noninfectious Disease Noise Environmental Decreased breeding Immune system/hormone levels Sleep cycles Overcrowding Stress! Can affect just about every body system

35 Noninfectious Disease Lighting g Environmental Circadian rhythm (light/dark cycle) Air Exchange Particulate build-up Ammonia Respiratory disease Contaminants Air, water, bedding feed

36 Noninfectious Disease Nutritional Rare in research setting Husbandry: dominant animals in group housing Water is an essential nutrient Can be due to deficiency or excess

37 Noninfectious Disease Nutritional Common clinical signs: Skin conditions/changes in hair coat Growth abnormalities/malformation of bones Reproductive problems

38 Noninfectious Disease Genetic Hereditary Abnormalities Passed from parent to offspring via genes May be seen early or late in life Often intentionally maintained in research setting Even with excellent husbandry care, their lifespan is often reduced

39 Noninfectious Disease Congenital Congenital Diseases Diseases with which the animal is born May or may not be genetic origin Causes may be physical or environmental Can be a result of exposure to various environmental chemicals or nutritional deficiencies i i

40 Noninfectious Disease Degenerative Degenerative Diseases Usually associated with aging Infrequent concern to researchers as most animals are used when they are young May be an issue in long-term survival studies Many inbred animals develop degenerative disease early in life

41 Noninfectious Disease Cancer Cancer is unregulated proliferation (growth) of cells Often cells grow into mass (tumor) Another name for cancer: neoplasia The cause for most cancers remains unknown: Chronic irritation, radiation, chemical agents, drugs, viruses, and genes

42 Noninfectious Disease Cancer Cancer designation Benign: not extensively invasive Malignant: invasive i and often spread rapidly (metastasis) Many strains of mice and other rodents have a predisposition to spontaneously develop specific types of cancer

43 Infectious Diseases Infectious Diseases Viruses Bacteria Fungal Pria Parasitic Idiopathic?

44 Disease Transmission Direct contact Infected animals must touch Indirect contact t Aerosol Fomites Inanimate objects-mechanical means of transmission Vectors Living organisms that transmit disease

45 Disease Transmission Carriers Animals that show no clinical signs but are infected and can transmit disease Zoonosis A disease that can be transmitted from humans to animals or animals to humans Epizootic Sudden disease outbreak in a large Sudden disease outbreak in a large number of animals

46 Zoonotic Diseases Western equine encephalitis virus Venezuelan equine encephalitis virus Anthrax Avian Influenza (Bird Flu) Babesiosis Giardia lamblia Barmah Forest virus Hantavirus Bartonellosis Hendra virus Bilharzia Henipavirus Bolivian i hemorrhagic h fever Korean hemorrhagic fever Brucellosis Kyasanur forest disease Borrelia (Lyme disease) Lábrea fever Borna virus infection Lassa fever Bovine tuberculosis Leishmaniasis Campylobacteriosis Leptospirosis Chagas disease Listeriosis Chlamydophila psittaci Lymphocytic choriomeningitis virus Cholera Marburg fever Cowpox Mediterranean spotted fever Monkey B Creutzfeldt-Jakob disease (vcjd), Cryptosporidiosis Nipah fever Cutaneous larva migrans Ocular larva migrans Dengue fever Omsk hemorrhagic fever Ornithosis (psittacosis) Ebola Echinococcosis Orf (animal disease) Escherichia coli O157:H7 Oropouche fever Eastern equine encephalitis virus Plague Puumala virus Q-Fever Psittacosis, or "parrot fever" Rabies Rift Valley fever Ringworm Salmonellosis Sodoku Streptococcus suis Swine Flu Toxocariasis Toxoplasmosis Trichinosis Tularemia, or "rabbit fever" Typhus of Rickettsiae Venezuelan hemorrhagic fever Visceral larva migrans West Nile virus Yellow fever

47 Zoonotic Diseases Tuberculosis Salmonella Ringworm Q fever

48 Infectious Diseases Viruses Viruses Smallest and simplest biological entities Piece of nucleic acid (DNA or RNA) wrapped in a protein coat Cannot replicate on their own Requires host cell for replication

49 How small are they?

50 Important Viruses Mouse parvovirus Hardy virus in the environment, resistant to disinfectants, subclinical Mouse hepatitis virus Susceptible to disinfection, i subclinical i l except in immunocompromised and suckling Mouse norovirus Susceptible to disinfection, i subclinical i l

51 Infectious Diseases Bacteria Simple, once-celled organism Surrounded by a rigid cell wall Characterization of bacteria is based on shape, size, locomotion, capsule, oxygen requirements, staining etc.

52 Important Bacteria Helicobacter Subclinical infections Can cause GI disease or cancer Pseudomonas Common in water Can form biofilm Treat with acid water More dangerous to immunocompromised animals

53 Fungi Fungi: multicellular organisms Yeast: unicellular organisms Mold: branching multicellular hypha (many hyphae = mycelium) Fungi can reproduce sexually or asexually (budding from the parent cell) Fungal diseases are called mycoses

54 Fungi Superficial i Mycoses Infect skin, hair, and nails Ringworm

55 Question #3 At what age do you expect to see At what age do you expect to see ringworm in animals?

56 Fungi Systemic Mycoses Originate primarily in the lungs and may spread to many organ systems May be primary or opportunistic Histoplasma, Candida, Cryptococcus, Pneumocystis carinii

57 Prions Misshapen proteins Poorly understood Long incubation period (>18 months) VERY difficult to inactivate (Why?) BSE, Scrapie, Creutzfeldt-Jakob disease

58 Parasites Protozoa: single-celled Helminths: multi-celled Ectoparasite: outside the body (infestation) Endoparasite: inside the body (infection)

59 Parasites Life cycle lingo Each type of parasite normally lives at a specific location that fulfills its needs: predilection site Occasionally parasites attack the wrong host (aberrant host) or wrong location (aberrant site)

60 Protozoa Unicellular Include: Flagellates Ciliates Apicomplexans Amoebas Microsporidians

61 Protozoa Life cycle Two stages: Trophzoite Stage that actively feeds and multiplies Cyst Stage with a thickened membrane or Stage with a thickened membrane or thickened wall

62 Toxoplasma gondii

63 Helminths Multicellular Worm-like animals with differentiated tissues and organs Include: Trematodes (flukes) Cestodes (tapeworms) Nematodes (roundworms) Acanthcephalids (thorny-headed worms) Hirudineans (leeches)

64 Trematodes Flukes Flat worms Oral suckers for feeding Ventral suckers to attach to host Complex life cycle Adults in various parts of host s s body Life cycle require aquatic snails

65 Cestodes Tapeworms Long, highly segmented, flattened worms Found in the intestinal tract of definitive hosts (attach with hooks) Steal nutrients from host Segments are independent reproductive segments called proglottids

66 Cestodes Proglottids contain fertilized eggs Break off and passed in feces Appear in feces ( grains of rice ) Appear on fur around anus Most tapeworms require an intermediate host

67 Tapeworm life cycles

68 Nematodes Many classes and orders Nonsegmented, cylindrical worms Embryonated egg is the infective stage (larva in an egg) Life cycle may/may not require and intermediate host

69 Nematodes Common nematodes: Hookworms Roundworms Pinworms Strongyles Heartworms

70 Arthropoda Three important classes: Arachnids Mites, ticks Head, thorax, and abdomen fused Insects Lice, fleas, flies, mosquitoes Head, thorax, abdomen separate Pentastomes Worm-like as adults Has a mite-like larval stage with legs

71 Arthropoda What are we?! Arachnid Insect Pentastome

72 Quiz Question 1 You enter your animal room one morning to find many cages of sick mice. You checked the room thoroughly the night before and all the mice were fine. You describe the onset of disease as: a. Chronic b. Acute c. Subacute d. Subchronic

73 Quiz Question 2 You know a morbidity rate will help determine disease severity. 47 of 100 mice are sick. Your morbidity rate is: a. 53% b. 470% c. 47% d. 5.3%

74 Quiz Question 3 The following all are infectious causes of disease except: a. Helicobacter b. MPV c. Pasturella d. Vitamin C deficiency

75 Quiz Question 4 Which of the following is an etiological diagnosis? a. influenza b. diarrhea c. headache d. arthritis

76 Quiz Question 5 An animal that has a disease but does not exhibit clinical signs is described as: a. Subacute b. Subclinical c. Submarine d. Primary

77 Quiz Question 6 The specialized branch of the immune system than develops antibodies to disease and is stimulated by vaccinations is: a. acquired b. chronic c. innate d. stealth

78 Quiz Question 7 An inanimate object that can transmit disease is a: a. vector b. zoonotic c. fomite d. carrier

79 Quiz Question 8 The following is a: a. arachnid b. insect c. pentasome d. alien

80 Quiz Question 9 Helicobacter is a, while MPV is a. a. virus, virus b. bacteria, bacteria c. bacteria, virus d. virus, bacteria

81 Quiz Question 10 Primary disease prevention includes all of the following except: a. Sanitation and hygiene b. Quarantine c. Upkeep p of physical facilities d. Sentinel program

82 THANK YOU for your attention and all that you do every day for the care and well-being of our animals!!