Disease Prevention_study notes.doc

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Dalhousie University
Health Promotion
HPRO 3335
Lesley Barnes

Pathogen Human Reservoir Portal of Exit Transmission Portal of Entry Establishment of Disease in new host Pasteurization Isolation Gowns Isolation Masks Immunizations Chlorination Surveillance Masks Hand washing Condoms Health education Antibiotics Quarantine Condoms Vector control Safety glasses Nutrition promotion Antivirals Drug Treatment Hair nets Sneeze glas Disinfectants Insect Repel. Safer sex Infectious Process 1. Causative Organism: exposure of a pathogen 2. Reservoir: where microorganisms grow—i.e. food tapeworms and salmonella; soil- tetanus; vaginal and mucous membranes; insects/ animals. 3. Mode of escape: Bug bites, sexual intercourse (genital tract), urinary tract, skin lesions. 4. Mode of transmission: Directly or Indirectly Indirectly • Insect; vector-borne illnesses (prevention is difficult) • Fecal-oral route (cholera & typhoid) • Airborne: coughing and sneezing droplets (i.e. measles and mumps) Directly • Skin to skin or mucous membrane to mucous membrane • From environment; i.e. rusty nail (tetanus) 5. Portal of entry • Some as a mode of escape 6. Susceptible Host Causative Agent Pathogens Viruses: • Subcellular, semi-living • Takes over DNA & RNA of another cell • Cellular walls are non-existent  Protein coat around DNA & RNA; uses mechanisms of that cell.  Blocking it before getting to a host cell is the prevention then anti-virals are used to destroy those cells. Structure: Different physical structures with no cellular membrane Destruction: No cells available to take over; and antivirals Classification: The size, shape, RNA vs. DNA viruses & what type of cells they took over (obligate parasites). Bacteria: • Single-celled, plant-like • Has a cell wall & living organisms  Chlamydiae: small, gram-negative, non-motile, intracellular  Rickettsia: Associated with anthropods, small and intracellular  Mycoplasmas: small and fragile.  Cell walls  Helps with digestion & can directly destroy other pathogens; helps with the production of vitamins  Pathogenic & non-pathogenic: can be in a dormant stage, doesn’t need a shot, more susceptible to be destroyed due to their structure. Classifications: types of toxins/enzymes they release, their staining & shape. Bacterial Shapes I. Spheres – cocci (coccus) A. Diplococci o Gonorrhea o Meningitis B. Staphylococci o Pyococci (pus inducing) o i.e. Boils C. Streptococci o Scarlet fever o Rheumatic fever o Strep throat II. Rods-Bacilli o Tuberculosis (can be dormant) o Tetanus o Typhoid fever o Salmonella III. Spirals – spirilla or spirochetes o Syphilis o Yaws o Lyme disease IV. Vibrios – comma-shaped *Intestinal disease, potassium levels and muscle o Cholera (dehydration) Toxins: Enodtoxin: liberated as the cell is integrating Exotoxin: secreted as the bacterium is growing & multiplying i.e. tetanus and antitoxins *Have to be trated very quickly to counteract the toxins Toxoid: A chemically modified toxin from a pathogenic microorganism, that is no longer toxic but is still antigenic and can be used as a vaccine. Rickettsia is named after Howard Rickets Fungi: • Single-celled or multicellular plant-like • Very persistent; but not severe  Not all pathogenic  We don’t develop an immunity to them i.e. athlete’s foot Classification a) Superficial (external) – athletes foot b) Systemic (internal) – lungs for beginning stages (i.e. type of pneumonia) and requires complex treatment. *Mycosis : another name for fungal infections, can be transmitted animal to human. Examples of fungi: Candida: yeast infection (treated with antibiotics or anti-fungal treatment) Pneumocystis: Fungal infection that impairs respiratory tract. *Fungal infections are typically opportunistic (i.e. after menstruation) Protozoa: st • Single-celled animals (1 category of animals) • Can be dormant; requiring intermediate hosts for a stage of development Transmitted: vectors – indirect transmission. (i.e. malaria) Examples: - Cryptosporidiosis - Amehiasis : aneba - Giardia: beaver fever - Toxoplasmosis: domestic cats in fecal matter - Trypanosomiasis - Trichomonas Parasitic Worms (Helminths): • Multi-cellular animals and live independently; can change markers on the surface and live for long periods. (there are various categories not easily identified) Classification 1. a) Nematodes – round worms • Pinworms • Ascaris • Hookworms • Whipworms • Trichonosis (found in pork) • Onchoceriasis – river blindness 2. a) Cestodes – flat worms (eats nutrients in intestinal walls causing abdominal cramping) • Tapeworms – found in pork, fish and beef; can be inches long or 30ft. long and causes abdominal cramping, diarrhea, swollen stomach. b) Trematodes • Flukes (aka liver flukes) • Bilharzia  Schistosmiasis (intermediate host fresh water snails that borrow in skin and blood stream impacting liver) Susceptible Host 1) Constitution Age: immune systems develops by ~18 months and decline by age 30. Sex: • Females – cervical mucosa is immature (females becoming pregnant i.e. rubella) • Circumcised men are more likely to avoid disease because they remove the skin where pathogens can develop. • Females – environment in vagina more susceptible to candida & STIs (physical structure makes females more prone) Hormones: Menstruation/hormone fluctuation Genetic factors: certain blood types are more resistant to things i.e. malaria or recessive trait in Jews for TB (O blood type and syphilis) Environment: Atmosphere: quality of air that we breathe  Humidity and temperature affect upper respiratory tract  Influenza in winter (Canada) because our upper respiratory tract changes from the dry and coldness Nutrition:  Protein in antibodies  Too much vitamin A affects the system *No food can boost the immune system but you can repair the immune system. Water and sanitation i.e. contaminated water Specie contact: zoonoses Previous Immunological Experience: Exposed previously to a pathogen (exposure artificial or original form?), species resistance Host Terminology Resistance: Ability to withstand a certain exposure Susceptibility: The frequencies and character to our response to a certain organism and the way it manifests. Immunity: cellular response (B & T cells and how they interact to an immune response) Parasite Factors Pathogenicity: ability to produce disease (constancy of condition)  Varies among species (low in zoonotic disease for us) i..e how likely this will cause disease. Virulence: ability to cause severe disease i.e. smallpox as high virulence Meningitis has a low virulence and influenza has a variable virulence Infectivity: The likelihood its going to pass from one person to the next i.e. vector salmonella is very low, but measles is very high infectivity Invasiveness: How likely is it to disseminate throughout the body rather than to get the disease i.e. syphilis and blindness *Tetanus ha
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