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Infection control Biological Hazards Infectious Diseases Bacteria Parasites Viruses Prions Fungi Parasites INFECTIOUS DISEASE PROCESS • INFECTION: presence of microorganisms in the body that cause disease Staph. infection • NORMAL FLORA: microbes that are found in/on everyone. Many prevent disease Normal flora of mouth 6 Links to the Chain of Infection Portal of Entry Susceptible Host Causative Agent Reservoir Mode of Transmission • Control by stopping one link in chain Clinical stages of an Infectious Disease Infection Prodromal period Incubation Acute period Decline period Convalescence Causative Agents • Bacteria •Viruses •Hot tub rash Protozoa Giardia • •Glandular fever •Fungi •Helminthes Parasites Internal – Helminths (worms) Tape worms Nematodes – Protozoa Toxoplasma Giardia Histamoeba Cryptospiridium External Insects – Bed Bugs – flees Lice Bedbug Bedbug Feeding In bed bites Fleas Fleas are small, wingless bloodsucking insects (order Siphonaptera) with a characteristic jumping movement. The most important species are the rat flea, the human flea and the cat flea Their bites can cause irritation, serious discomfort and loss of blood. The rat flea is important as a vector of bubonic plague and flea-borne typhus. Cat fleas incidentally transmit tapeworms. LICE Lice are small bloodsucking insects that live on the skin of mammals and birds. Three species of lice have adapted themselves to humans: – the head louse (Pediculus humanus capitis), – the body louse (Pediculus humanus) and – the crab or pubic louse (Pthirus pubis) Characteristics of causative agents • Dose •Small : TB •Large : Leagonnella • Pathogenicity •Strong : TB, Bird flue •Week: Common cold Methods by which bacteria cause disease Adhesion. Many bacteria must first bind to host cell surfaces. Colonization. Some virulent bacteria produce special proteins that allow them to colonize parts of the host body. Helicobacter pylori is able to survive in the acidic environment of the human stomach by producing the enzyme urease. Colonization of the stomach lining by this bacterium can lead to Gastric ulcer and cancer. The virulence of various strains of Helicobacter pylori tends to correlate with the level of production of urease. Invasion. Some virulent bacteria produce proteins that either disrupt host cell membranes or stimulate endocytosis into host cells. Immune response inhibitors. Many bacteria produce virulence factors that inhibit the host's immune system defenses. For example, a common bacterial strategy is to produce proteins that bind host antibodies. The polysaccharide capsule of Streptococcus pneumoniae inhibits phagocytosis of the bacterium by host immune cells. Toxins. Many virulence factors are proteins made by bacteria that poison host cells and cause tissue damage. For example, there are many food poisoning toxins produced by bacteria that can contaminate human foods. Reservoirs • Animals • Insects • Rodents • Shell Fish Reservoirs • Environment Machinery & Equipment Environmental Surfaces Food Human Source / Reservoir of Infection Active carrier Convalescent carrier Healthy Carrier Incubatory carrier Casual or Chronic Modes of Transmission • Contact •(Direct and •Indirect) •Airborne •Vector-Borne • Solid material CONTACT DIRECT: immediate transmission • Person-to-person • Actual physical contact between source and person INDIRECT CONTACT: • Agent contaminate indirect object • Droplets spread (large particles that rapidly settle out on horizontal surfaces – usually within 3 feet of source) Direct transmission Staphylococcal infections Staphylococcus Ringworm AIRBORNE Organisms contained within droplet nuclei or dust particles (i.e. droplet nuclei of tuberculosis • Suspended in air for extended periods, may be spread through ventilation systems Diseases transmitted By Air Bacterial Tuberculosis Fungi Anthrax Histoplasma Legonella Candida Q – Fever Neisseria Psittacosis Streptococcus Clamydia Parasites Toxoplasmosis Viruses Influenza Measles Chickenpox Mumps Colds VECTOR-BORN • External vector-born transmission •mechanical transfer of microbes on external appendages (e.g. feet of flies) • Harbored by Vector-born •Inside vector • Ross river virus •West nile virus Hendra virus Hendra virus is a virus carried by fruit bats that inhabit Australia, Papua New Guinea, and surrounding islands. Rarely, Hendra virus spreads from fruit bats to horses, causing severe disease, and can then spread to people who are in close contact with infected horses. Four of the seven people who are known to have been infected (at the time of writing) have died. Figure 1. Distribution of flying foxes in Australia Australian local vector-borne diseases Mosquito borne – Ross River virus, Barmah Forest virus and Murray Valley encephalitis virus. – Possible Future Threats Chikungunya virus: a re-emerging threat Dengue fever and Malaria Tick borne – Australian tick typhus: Rickettsia australis, severe headache and conjunctivitis. Reservoir is in rodents and marsupials. – Flinders Island Spotted Fever: caused by rickettsiae R. honei, Tick Borne Lyme Disease PORTAL OF ENTRY The path by which an infectious agent enters the susceptible host • Respiratory Tract • Genitourinary Tract • Gastrointestinal Tract (Gut) • Skin/Mucous Membrane (eye) • Trasplacental (fetus from mother) • via blood Respiratory Tract Portal of Entry TB Flue Bronchitis Common Cold Legionnaires' Disease Whooping Cough Control Personal Hygiene Sanitation Vaccination Passive Immunity Active Immunity Antibiotics Isolation Quarantine SUSCEPTIBLE HOST A person or animal lacking effective resistance to a particular pathogenic agent Increase Resistance Good General Health – Nutrition – Well being Vaccinations Personal Hygiene Sanitation Good General Heath Nutrition – Needed for immune system – Plenty of energy – Vitamins dieing from infection A, B group, C – Minerals Iodine, Iron, Zink, –Dieing from CVD Dieting – Loosing weight lowers immunity – Less eating does not just reduce fat – More chance of dieing from infection Five Food Groups Bread &Cereals Fruit & veg. Dairy Meat Fats Healthy Diet Pyramid Good General Heath Factors that reduce Immunity – Stress – Cold – Flue – AIDs – Drugs But even a good may not protect against all infections Vaccination Ensuring the immunity of workers to infections or diseases caused by relevant infectious agents is an essential component of any firms occupational health program, to accomplish fundamental legal and moral duties: – Protection of workers from risk of the work place Tetanus Hepatitis A, B TB Flue Childhood vaccines – Age – immigrants Hygiene Wash hands – ASAP – Stops transfer to mouth – Stops transfer to environment (door handles etc. ) Hygiene Wash and disinfect cuts and scratches – Keep wounds covered Wear face masks – Minimise inhaling dust and pathogens Chemical Methods of Microbial Control Disinfectants – Used on non-living surfaces Antiseptics – Used on living surfaces Antibiotics – Used internally – Not much use for viruses and fungi Antibiotic resistance –Betadine Chemical Methods of Microbial Control Effective disinfection – Type of organisms – Chemical used – Proper dilution – Cleanliness – Contact time Floor disinfection Evaluating a Disinfectant Phenol coefficient test – Compared activity to phenol Exposure to Hepatitis B virus Contact with HB-positive blood or body fluid Meningococcus Direct contact with respiratory secretions Skin Infections and Diseases Scabies and Tinea Versicolor Scabies Female mites burrows into the skin where she lays eggs Skin-skin contact Clothing, bedding, towels Inflammatory elevation of the skin (red papules) Scabies S/S - intense itching - skin rashes - produces allergic reaction (eggs) - scratching may cause secondary infection Tx - Topical medications all over the body Tinea Versicolor Skin infection caused by a yeast Warm and humid environment Tinea Versicolor S/S - oval or irregularly shaped spots - pale, dark tan, or pink in color - sharp border - itching, worsens with heating and sweating Tx - Topical antifungal medications Ringworm Ringworm Fungal infection…not a worm! Skin-skin contact Ring-shaped, scaly itching patches on the skin Ringworm S/S - red raised itchy patches with defined edges, lighter in the center - take an appearance of a ring Tx - topical antifungal drugs Impetigo Impetigo Superficial skin infection Bacterial…Staphylococcus or Streptococcus Spread w/ direct contact w/ lesions , dressings Thick, yellow crust (commonly on the face) Impetigo - one or more pimplelike lesions surrounded by reddened skin - lesions fill w/ pus and later form a thick crust - itching Infected Wounds Infected Wounds Wound: break in the structure caused by an external agent Chronic open sores become infected Infected Wounds - swelling pain fever w/ infection bleeding or pus foul smell Hookworm? Traveling parasite Hookworm Cutaneous larva migrans Parasitic larvae found in dog and cat feces penetrate the outer layers of the skin and creep around underneath the skin Hookworm S/S - red itching eruption - serpentine track - painful Tx - Albendazole Other interesting stories… Leishmaniasis ???