BASIC PRINCIPLES IN OCCUPATIONAL HYGIENE ????????

1
BASIC PRINCIPLES IN OCCUPATIONAL HYGIENE????????

• Day 3
• ?3?

2
12 - BIOLOGICAL HAZARDS 12-????
3
BIOLOGICAL HAZARDS????

• Biological Hazards - bacteria, viruses or moulds
  have the ability in the right conditions to
  rapidly replicate themselves.
• ????????????????????????????
• Focus on control is not only avoidance of contact
  with the agent but also on ensuring that
  conditions favourable for growth of the organism
  are prevented.
• ?????????????????
• ?,????????????????

4
BIOLOGICAL HAZARDS????

• The three main categories of biological agents
• ??????????
• Bacteria - single celled micro organisms that
  live in soil, water and air.
• ????????,????????????
• Viruses tiny parasitic organisms that can only
  reproduce within living cells.
• ?????????,???????????
• Fungi simple plants lacking chlorophyll and
  normal plant structures (e.g. leaves, stems etc).
• ???????,????????????(??,??)?

Dividing Escherichia coli bacteria ??????
Source Wikimedia Commons ??????????
5
Exposure to micro-organisms??????

• Individual to exposure to micro-organisms depends
  on state of immunity
• ???????????????????
• whether the individual has already experienced a
  particular illness
• ???????????
• immunisation levels
• ????
• individual resistance
• ?????
• Fatigue
• ??????
• age.
• ??

Legionella pneumophila multiplying inside a
cultured human lung fibroblast ???????????????
Source Wikimedia Commons ??????????
6
CONTROL DEPENDANT ON RISK GROUP????????

• Risk Group 1 - (low individual and community
  risk). An organism that is unlikely to cause
  human or animal disease.
• ????1 (?????,?????) ????????????????
• Risk Group 2 - (moderate individual risk, limited
  community risk). A pathogen that may cause human
  or animal disease and which might be a hazard to
  laboratory workers, but is unlikely to spread to
  the community, livestock or the environment.
• ????2 (??????,??????) ????????????,????????????
  ,?????????????????????
• Risk Group 3 - (high individual risk, low
  community risk). A pathogen that can cause
  serious human disease but does not ordinarily
  spread from one individual to another.
• ???? 3 (?????,?????)???????????,???????????????
  ?
• Risk Group 4 - (high individual and community
  risk). A pathogen that usually produces serious
  human or animal disease and may be readily
  transmitted from one individual to another,
  directly or indirectly.
• ???? 4 (?????,?????)??????????
• ?,???????????????????

7
Biosafety levels (1)?????? (1)

• Four Biosafety levels which give the containment
  precautions
• ??,???????????????????
• Biosafety Level 1 Little containment or
  segregation, precautions such as separation and
  labelling of waste materials.
• ??????1?????????????,???????????????????
• Biosafety Level 2 Staff have specific training
  in handling pathogenic agents, restricted access,
  sharps protection, biological cabinets for
  certain activities
• ??????2??????????????????,???????,????,?????????
  ??

8
Biosafety levels (2)?????? (2)

• Four Biosafety levels which give the containment
  precautions
• ??,???????????????????
• Biosafety Level 3 Biological safety cabinets or
  other physical containment devices, personal
  protective clothing and equipment. Double-door
  access zones.
• ??????3?????????????????????????????
• Biosafety Level 4 Separate building/ controlled
  are. Controlled ventilation maintaining it under
  negative pressure. All activities are carried out
  in Class III biological safety cabinets, or Class
  II biological safety cabinets with one-piece
  positive pressure personnel suits ventilated by a
  life support system.
• ??????4????/??????????,?????????????????????????
  3???????2?????????,????????????????????,??????????
  ?

9
Legionella???
X5000 Magnification of a large grouping of
Gram-negative Legionella pneumophila bacteria
X5000????????????? Source Wikimedia
Commons ??????????
10
Legionella???

• 1976 - an outbreak occurred among delegates
  attending an American Legion convention.
• 1976??????????????????
• Two patterns of disease in humans
• ?????????????
• Pontiac Fever (a mild flu-like illness)
• ?????(?????????)
• Legionnaires Disease. (pneumonia and flu-like
  symptoms. It is fatal in about 10 - 15 of
  cases).
• ????(????????,??????10 - 15)?
• It enters into the body when fine droplets of
  contaminated water are inhaled. The bacterium is
  not transmitted from person to person.
• ???????,????????????????????
• Legionella are widespread in natural fresh water
  including rivers, lakes, streams and ponds.
• ????????????,????,??,??????

11
Legionella???

• Areas most at risk include
• ?????????
• Cooling towers
• ???
• water storage tanks and calorifiers
• ???????
• hot and cold water services in premises where
  occupants are particularly susceptible (homes for
  the elderly, hospitals etc.)
• ????????????????(???,???)
• humidifiers and or washers that create a spray of
  water droplets and in which water temperature
  exceed 20C
• ???????????20???????
• spa baths and pools
• ????????
• fire sprinkler systems and fountains.
• ????????????

12
Legionella???

• Factors affecting growth include
• ???????????
• Water temperature - Temperatures in the range of
  20-45C favour growth (optimum temperature 37C).
  Proliferation of the bacteria is unlikely below
  20C, and the organism does not survive above
  60C.
• ??20-45C??????????(?????37C)??????20C,???????
  ?,?????60?,????????
• Water being stagnant favours multiplication.
• ???????
• The presence of sediment, scale and sludge.
• ??????????????
• The presence of other micro-organisms (algae,
  amoeba and bacteria) or a biofilm (a layer of
  micro-organisms contained in a matrix which may
  form a slime on surfaces).
• ??????(??,????????)????(????,???????????)?????

13
Legionella???

• Control prevent growth of bacteria and
  production of aerosols
• ??????????????
• Minimise the release of water spray
• ??????
• Avoid water temperatures between 20C and 45C
• ?????20C?45C??
• Avoid water stagnation
• ????
• Avoid use of materials that can harbour or
  support the growth of bacteria and other
  organisms
• ?????????????????????
• Keep the system clean
• ??????
• Use of suitable water treatment systems including
  biocides
• ??????????,?????
• Ensure that the system operates safely and
  correctly and is well maintained.
• ???????????,??????
• Sampling to assess water quality.
• ?????????

14
Humidifier Fever???

• Associated with exposure to many different types
  of micro-organisms including various bacteria and
  fungi found in humidifier reservoirs and
  air-conditioning units.
• ?????????????,????????????????????
• The micro-organisms have been found in both large
  ventilation systems as well as in small units.
• ?????????????????
• Significant concentrations of these organisms can
  be dispersed into the environment in the aerosol
  mist generated by the humidifiers during normal
  operation.
• ????????????,?????????????????
• Flu-like illness with fever, chills, headache,
  muscle ache and fatigue.
• ????????????????????
• Controls by ensuring that the bacteria and fungi
  do not multiply.
• ?????????????????????

15
Blood Borne Diseases?????

• The risk of occupational acquisition of a blood
  borne virus relates to
• ??????????????????????
• The prevalence of the virus in the patient
  population
• ??????????
• The efficiency of virus transmission after a
  single contact with infected fluid / tissue
• ????????/?????????
• The nature and frequency of occupational blood
  contact
• ?????????????
• The concentration of the virus in the blood.
• ????????

16
Blood Borne Diseases?????

• Protection comes from avoidance of blood to blood
  contact by precautions
• including
• ???????????????
• Wearing protective gloves and face masks
• ????????
• Covering cuts and wounds with a waterproof
  dressing
• ????????????
• Care with sharps
• ????
• Ensuring all equipment is appropriately
  sterilized
• ????????????????
• Safe disposal of infected material
• ?????????
• Control of surface contamination
• ??????
• Good hygiene.
• ?????????

17
Blood Borne Diseases?????

• Hepatitis B
• ????
• Hepatitis C
• ????
• HIV - (Human Immuno-deficiency Virus).
• HIV - (????????)?

18
Zoonoses ?????

• Zoonoses are infections that are naturally
  transmitted from animal to humans.
• ?????????????????????
• There are over 150 known zoonoses which range
  from ring worm to anthrax and rabies.
• ??????????????150??,????????????
• Zoonoses primarily affect people who work closely
  with animals
• i.e. farm workers, laboratory workers,
  vets, forestry workers.
• ?????????????????????,???????
• ???????????????

19
Zoonoses ?????

• Infection can occur through contact with
• ???????????
• Animal and animal products (meat, bone meal, fur,
  feathers, skins, wool)
• ???????(????????????????)
• Animal tissue body fluids (blood, saliva etc)
• ???????(??,???)
• Birth products (placenta etc)
• ????(???)
• Waste products (urine, dung, faeces)
• ??(?????????)
• Contaminated materials (ground, fencing, clothing
  etc).
• ??????(?????,???)?
• Infection may occur via inhalation, ingestion or
  through broken skin or contact with mucous
  membranes.
• ??????????????????????????

20
Anthrax???

• The disease is caused by the spore forming
  bacteria Bacillus anthracis.
• ??????????????????
• Many animals may carry the anthrax bacteria or
  spores including cattle, horses, goats and sheep.
  
• ???????????????,???????
• ?????
• Spore remain viable in animal products for long
  periods.
• ????????????????
• Cutaneous anthrax - (a skin disease).
• ????(?????)?
• Pulmonary anthrax (affecting the lungs).
• ???(????)?
• The main occupations at risk include agricultural
  workers, abattoirs, animal by product processing,
  vets and the wool and tanning industries.
• ??????????????????????
• ?????????????????

Source Wikimedia Commons ??????????
21
Leptospirosis ??????

• The main form of leptospirosis is Weils disease
  which is a potentially life threatening illness
  caused by the Leptospira bacteria passed from
  rats via urine.
• ????????????Weil????????????,???????????????
• Symptoms include flu-like symptoms such as fever,
  headache, vomiting, muscle pains, pneumonia and
  possible kidney failure and death.
• ???????????????????????????????????????????
• The disease may be transmitted through contact
  with rats urine or watercourses contaminated
  with it.
• ???????????????????

Source Wikimedia Commons ??????????
22
Salmonellosis?????

• Salmonellosis is the name given to an infection
  caused by any of the Salmonella group of
  bacteria.
• ????????????????????????????
• Salmonella bacteria may be carried by most types
  of farm animal.
• ??????????????
• Symptoms develop suddenly about 12 to 24 hours
  after infection and include malaise, headache,
  nausea, abdominal pain, diarrhoea and fever.
• ????12?24?????????,??????????????????????

23
Pandemics???

• An epidemic of an infectious disease that spreads
  over a wide geographic area and affects a large
  proportion of the population.
• ?????,????????????????
• A pandemic can start when the following
  conditions occur
• ??????????????
• Emergence of a disease, or a particular strain of
  a disease, new to a population
• ???????????????
• The agent affects humans, causing serious illness
• ????????,????????
• The agent spreads easily and sustainably among
  humans.
• ????????????,?????