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BIOLOGICAL HAZARDS

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					BIOLOGICAL HAZARDS
          …health hazards
           associated with
             exposure to
          biological agents
Definitions

   Biohazard – organisms or products of
    organisms that present a risk to humans
   Organism – a living thing, such as a germ,
    plant, animal, or human that may consist of
    several parts, with each part specializing in a
    particular function
   Microorganism – a minute organism, such as
    microbes, bacteria, cocci, viruses, molds, etc.
Development of Biosafety

   Army at Fort Detrick – Frederick, Maryland
    –   Researching biological warfare agents
   1941 – Chemical Warfare Services
    –   American Society of Microbiology served as advisors to CWS
   1970’s – Recombinant DNA technology
   1980’s - Appearance of HIV
   1991 – OSHA’s Bloodborne Pathogens Program (29
    CFR 1910.1030)
RECENT INCREASED AWARENESS
       OF BIOHAZARDS

               Newest subset of focus
               Contributing to awareness
                   Legionnaires’ disease
                   AIDS epidemic
                   rDNA technology
                   anthrax
               Specialists exist but their
                numbers are small
               S/H/E professionals have
                become involved
Occupational hazards…
   Healthcare
      –    Hepatitis, tuberculosis, infections
      –    Infections categorized as:
          Community acquired – transmitted to either patients or workers
           Occupationally acquired – resulting from worker exposure
           Nosocomial – hospital-acquired infections of patients

   Research facilities
      –    Q fever, hepatitis, typhoid fever, tuberculosis, dermatomycosis
      –    Percutaneous inoculation (needles/syringes, cuts or abrasions from contaminated items, and animal bites/scratches); inhalation of aerosols,
           contact between mucous membranes and contaminated material (hands and surfaces), and ingestion

   Agriculture
      –    Workers may be exposed to infectious microorganisms that are associated with the plants or animals
      –    Food and grain handlers, farmers, laborers – may be exposed to parasitic diseases
      –    Processors who handle animal products – may acquire bacterial skin diseases from working with contaminated hides, infected with
           contaminated fish, meat or poultry, Bacterial infections from exposure to feces from infected turkeys, geese, ducks, etc.

   Animal facilities/Veterinary practices
      –    Bites, scratches, parasites, diseases, allergens

   Biotechnology facilities
      –    Genetically engineered bacteria, fungi, plant and animal cells for development of products

   Miscellaneous occupations
      –    Workers maintaining water systems (legionella); pet shops; zoos; wood-processing facilities (fungi); sewage workers (bacteria, virus, parasites);
           forestry workers (Rocky Mountain spotted fever, lyme disease, viruses and bacteria from ticks, fungi); child care workers (bacteria (shingles),
           viruses (measles, chickenpox); public safety workers (bloodborne pathogens, viral respiratory diseases (influenza).
Biohazards are…

   Inherently different
    from chemicals,
    physical agents,
    carcinogens, etc.
   BUT, recognition,
    evaluation and control
    still can be applied
      Biological materials typically…..


   Have no threshold level of exposure, i.e., dose and
    response relationship
   Are ubiquitous in the environment so the idea of
    “permissible exposure limits” is inappropriate
   Are affected by biological competition rather than
    behaving in an additive or synergistic way
   Interact with the host and its environment to produce
    the adverse effects
          For illness to occur…..

   The agent must be pathogenic.
   There must be a reservoir of sufficient
    number.
   The agent must escape the reservoir.
   The organism must be able to move
    through the environment.
   There must be a portal of entry for the host.
   The host must be susceptible to the agent.
Factors affecting infection and
exposure
   Modes of transmission
    –   Contact (direct/indirect, zoonotic); vector-borne, airborne
   Routes of entry
   Infectious dose (infective dose)
    –   Number of microorganism
   Viability and virulence of agent
    –   Viability - Ability to replicate
    –   Virulence – Ability to cause disease
   Host susceptibility
    –   Skin disorders, immune system, vaccination allergy, infection
        of fetus, work practices
Classification of Biohazards
   Microorganisms                            Allergens
     –   Examples: viruses, bacteria,           –   Examples: from higher plants
         fungi, protozoa, algae                 –   Reactions: Dermatitis, rhinitis,
     –   Reactions: infection, exposure,            asthma
         allergic reactions                   Protein Allergens
   Arthropods                                  –   Examples: vertebrate animals
     –   Examples: crustaceans,                     (urine, feces, hair, saliva, dander)
         arachnids, insects                     –   Reactions: allergic reactions
     –   Reactions: skin inflammation,        Parasites
         allergic reactions, systemic
         intoxication, transmission of          –   Examples: ticks, hookworms,
         infectious agents                          pinworms
                                                –   Reactions: skin reaction,
                                                    inflammatory response, allergic
                                                    reaction
Some common biological agents


                   Bacteria
                   Viruses
                   Rickettsiae
                   Fungi
                   Parasites
                    BACTERIA

   Simple, one-celled
    organisms
   Cocci, bacilli, spirilla
   Some are pathogenic,
    some are harmless, some
    are even useful
   Broken skin is particularly
    vulnerable
   “Food poisoning” in mass
VIRUSES

     Smallest known
      organisms
     Living (?) non-cellular
      entities
     Are “obligate parasites” &
      cannot survive without
      living cells
     Common occupational
      exposures to animal virus,
      poxvirus & arbovirus
                    RICKETTSIAE

   Bacteria-like but smaller
   Are obligate parasites
   Transmitted to humans
    via bloodsucking
    arthropods (fleas, ticks
    & lice) or through the air
   Responsible for typhus
    and Rocky Mountain
    spotted fever
FUNGI

     Broadest spectrum
      among biological agents
     Are either parasitic or
      saprophytic
     Hypersensitivity due to
      inhaled fungal antigens
     Fungal disease is rare
      but includes ringworm &
      athlete’s foot
                   PARASITES

   Parasitic to plants or
    animals
   Diseases include
    malaria and other
    blood and GI infections
   Dermatitis and other
    skin-related ailments
    due to mites and
    chiggers, etc.
             Legionnaires’ Disease

   Caused by legionella pneumophila, a bacterium
   Presence possible if moisture, elevated temperature,
    oxygen and nourishment available
   Clearly can be transmitted through air and perhaps
    other ways
   Symptoms resemble a form of pneumonia and can be
    treated accordingly
   About 15% of known cases have been fatal
                  Tuberculosis (TB)

   Bacterial disease caused by Mycobacterium
    tuberculosis
   Some populations are at greater risk
   Transmitted by inhalation of infectious droplet nuclei
    suspended in air
   Symptoms
    –   Early on: fatigue, fever, weight loss
    –   Later: Hoarseness, cough, hemoptysis (blood-tinged sputum),
        lesions in respiratory tract
      Acquired Immune Deficiency
           Syndrome (AIDS)

   Caused by HIV, a virus
   Transmitted via sexual contact, sharing of
    needles and transfused blood
   Symptoms include tiredness, fever, night
    sweats, weight loss
   No single test as diagnosis
   Treatment (at present) cannot cure or restore
    the immune system
                          Anthrax

   Caused by spore-forming
    bacterium Bacillus
    anthracis
   Found in imported animal
    products
   Types of anthrax
    –   Cutaneous anthrax
    –   Inhalational anthrax
    –   Gastrointestinal anthrax
                Cutaneous Anthrax

   Most common naturally
    occurring infection

   Incubation period of 1-12 days

   Symptoms:
    –   small, raised bump
    –   ulcer with black center
    –   fever, headache, malaise
                 Inhalational Anthrax


   Most lethal form
   Incubation period of 1-7 and
    possible 60 days
   Symptoms:
    –   sore throat, fever, muscles aches
    –   respiratory failure and shock
   Fatality rate of approximately 75%
            Gastrointestinal Anthrax


   Follows consumption of raw or
    undercooked meat
   Incubation period of 1-7days
   Symptoms:
    –   sore throat, fever
    –   loss of appetite
    –   nausea & vomiting

   Fatality rate between 25%-60%
                  SUMMARY

   A tremendous variety of biological materials
    exists as potential exposure agents.
   Effects of bio-hazardous agents are subtle
    and slow in developing.
   There is increasing concern about, and
    interest in, biological materials.
   Bottom-line: biohazards are (and must be)
    treated with extraordinary caution.

				
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posted:12/9/2011
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