Infection control Biological Hazards Infectious Diseases Bacteria Parasites

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 n. Portal of Entry n. Susceptible Host n. Causative Agent n. Reservoir n. 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 n Insects – Bed Bugs – flees n Lice

Bedbug

Bedbug Feeding In bed n bites

Fleas are small, wingless bloodsucking insects (order Siphonaptera) with a characteristic jumping movement. n The most important species are the rat flea, the human flea and the cat flea n Their bites can cause irritation, serious discomfort and loss of blood. n The rat flea is important as a vector of bubonic plague and flea-borne typhus. n Cat fleas incidentally transmit tapeworms. n

LICE n Lice are small bloodsucking insects that live on the skin of mammals and birds. n 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 n Adhesion. Many bacteria must first bind to host cell surfaces. n 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. n n 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. n 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 n 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 is a virus carried by fruit bats that inhabit Australia, Papua New Guinea, and surrounding islands. n 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. n Four of the seven people who are known to have been infected (at the time of writing) have died. n Figure 1. Distribution of flying foxes in Australia

Australian local vector-borne diseases n 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 n 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 n 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 n TB n Flue n Bronchitis n Common Cold n Legionnaires' Disease n Whooping Cough

Control n Personal Hygiene n Sanitation n Vaccination n Passive Immunity n Active Immunity n Antibiotics n Isolation n Quarantine

SUSCEPTIBLE HOST A person or animal lacking effective resistance to a particular pathogenic agent

Increase Resistance n Good General Health – Nutrition – Well being n Vaccinations n Personal Hygiene n Sanitation

Good General Heath n Nutrition – Needed for immune system – Plenty of energy – Vitamins dieing from infection § A, B group, C – Minerals § Iodine, Iron, Zink, –Dieing from CVD n Dieting – – – Loosing weight lowers immunity Less eating does not just reduce fat More chance of dieing from infection

Five Food Groups n Bread &Cereals n Fruit & veg. n Dairy n Meat n Fats

Healthy Diet Pyramid

Good General Heath n Factors that reduce Immunity – Stress – Cold – Flue – AIDs – Drugs n But even a good may not protect against all infections

Vaccination n n n 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 n Wash hands – ASAP – Stops transfer to mouth – Stops transfer to environment (door handles etc. )

Hygiene n Wash and disinfect cuts and scratches – Keep wounds covered n Wear face masks – Minimise inhaling dust and pathogens

Chemical Methods of Microbial Control n Disinfectants – Used on non-living surfaces n Antiseptics – Used on living surfaces n Antibiotics – Used internally – Not much use for viruses and fungi Antibiotic resistance –Betadine

Chemical Methods of Microbial Control n Effective disinfection – Type of organisms – Chemical used – Proper dilution – Cleanliness – Contact time Floor disinfection

Evaluating a Disinfectant n Phenol coefficient test – Compared activity to phenol

Exposure to Hepatitis B virus n Contact fluid with HB-positive blood or body

Meningococcus n Direct contact with respiratory secretions

Skin Infections and Diseases

Scabies and Tinea Versicolor

Scabies Ø Female mites burrows into the skin where she lays eggs Ø Skin-skin contact Ø Clothing, bedding, towels Ø Inflammatory elevation of the skin (red papules)

Scabies S/S - intense itching - skin rashes - produces allergic reaction (eggs) - scratching may cause secondary infection Ø Tx - Topical medications all over the body Ø

Tinea Versicolor Ø Skin infection caused by a yeast Ø Warm and humid environment

Tinea Versicolor Ø S/S - oval or irregularly shaped spots - pale, dark tan, or pink in color - sharp border - itching, worsens with heating and sweating Ø Tx - Topical antifungal medications

Ringworm

Ringworm Ø Fungal infection…not a worm! Ø Skin-skin contact Ø 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 Ø Tx - topical antifungal drugs Ø

Impetigo

Impetigo Ø Superficial skin infection Ø Bacterial…Staphylococcus or Streptococcus Ø Spread w/ direct contact w/ lesions , dressings Ø Thick, yellow crust (commonly on the face)

Impetigo - one or more pimple-like lesions surrounded by reddened skin - lesions fill w/ pus and later form a thick crust - itching

Infected Wounds

Infected Wounds Ø Wound: break in the structure caused by an external agent Ø Chronic open sores become infected

Infected Wounds Ø - swelling - pain - fever w/ infection - bleeding or pus - foul smell

Hookworm? Traveling parasite

Hookworm Ø Cutaneous larva migrans Ø Parasitic larvae found in dog and cat feces penetrate the outer layers of the skin and creep around underneath the skin

Hookworm Ø S/S - red itching eruption - serpentine track - painful Ø Tx - Albendazole

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