Biological Agents


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A description of Biological Agents that could affect people in the workplace if Health and Safety protocols are not followed.

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Biological Agents

  1. 1. Biological Agents
  2. 2. Zoonoses Zoonoses are animal infections which may be transmitted to people in the course of their work. Common examples include: Brucellosis Q Fever Orf Psittacosis Anthrax Glanders
  3. 3. Brucellosis Caused by the bacterium Brucella abortus, which may infect people handling cattle or pigs or their carcasses in abattoirs Not very severe but involves loss of appetite, headache, insomnia and slight fever In the UK a policy of eradication has been pursued since the 60’s by destroying any infected cattle
  4. 4. Q Fever Known to occur in farm workers, abattoir workers and veterinary surgeons The causative agent, Coxiela burnetii, has been found in cows and sheep Not as serious as Brucellosis and takes the form of cold or `flu-like symptoms
  5. 5. Orf A contagious pustular dermatitis of viral origin, mainly affecting farm workers, shepherds, sheep shearers, butchers and abattoir workers Lesion enlarges and often becomes ulcerated, exuding fluid and pus Complete recovery occurs in about 3 weeks
  6. 6. Psittacosis A virus-like bacterium of poultry, game and other birds Can be fatal to man if untreated Illness sets in suddenly after an incubation period of 2 to 3 weeks with fever, headache and lethargy Pulmonary symptoms follow in a few days and mortality may be as high as 20%, particularly in the elderly
  7. 7. Anthrax  An acute infectious disease of farm animals caused by a bacterium  Transmitted to man by contact with infected hair, hides, excrement or products such as bonemeal  Fatal without treatment  Initial lesion rapidly becomes ulcerated  Treatment is by penicillin  Inhaling the pathogen causes pulmonary anthrax which is usually fatal in 3 or 4 days
  8. 8. Glanders An infectious disease of horses, donkeys and mules caused by the pathogen Pseudomonas mallei Transmitted to humans by nasal or mouth secretions from the infected animal Abscesses appear on hands, arms or face Lasts up to 4 months but is treatable with modern antibiotics
  9. 9. Zoonose Control Strategies Most common route of entry is via the skin, by way of open cuts, sores or abrasions which provide direct entry to bloodstream Other routes include inhalation of contaminated dusts, contact with conjunctiva of eyes, direct injection by cuts from infected animals or animal bites, and direct ingestion via hands
  10. 10. Zoonose Control Strategies First stage of control strategy is to assess those people at risk Factors to consider include: work being carried out susceptibility to infection of the workers how infections might occur how likely exposure to infection is
  11. 11. Zoonose Control Strategies First priority for preventing occupational exposure to zoonoses is to eliminate the infections from the animal stock, usually by protecting exposed animals through immunisation and improvement of their environment Workers should be protected by suitable environmental hygiene controls and wearing protective clothing including hand, arm, foot and leg protection
  12. 12. Zoonose Control Strategies Where animal products likely to emit infected dust are handled (e.g. wool, skin, hides, pelts), LEV and possibly RPE should be provided to prevent airborne infection Specific immunisation of workers may be necessary Clean & hygienic animal living conditions and disinfection of stalls will also ensure better hygiene in factory premises and will reduce probability of infection
  13. 13. Zoonose Control Strategies Automation to reduce human contact and enclosure of aerosol-producing activities will reduce exposure to infection Finally, medical checks, training and information, procedures, instruction and records will give added protection to workers
  14. 14. Legionnaires Disease  Caused by the bacterium Legionella pneumophilia  A type of pneumonia affecting the lungs and other organs  A number of conditions have been found to affect rate of growth: Water temp. in the range of 24-45o C. It does not survive about 60o C. Organisms may remain dormant in cool water Sediment, sludge, scale and organic material in water systems can act as a source of nutrients, as can organisms such as algae, amoebae and other bacteria Incorporation of Legionella in slime on surfaces can protect the organisms from biocides
  15. 15. Legionnaires Disease Infection caused by inhaling airborne droplets or particles containing Legionella, which are small enough to pass deep into the lungs and be deposited in the alveoli People at greatest risk include smokers, alcoholics and patients with cancer, chronic respiratory or kidney disease Initial symptoms include high fever, chills, headache and muscle pain. A dry cough soon develops and most patients suffer difficulty with breathing
  16. 16. Legionnaires Disease  Water systems potentially at risk include: Cooling towers Evaporative condensers Hot/cold water services where occupants are susceptible, I.e. health care premises Humidifiers and air washers creating a spray of water droplets above 20o C Spa baths & pools
  17. 17. Legionnaires Disease  Employers should manage the risk of Legionella by: Identifying and assessing sources of risk, taking into account potential for drop formation, water temperature, exposure probability and adequacy of control Implementing and managing precautions and keeping records of the precautions  Particular attention should be paid to populations which contain a high proportion of susceptible people (hospitals or nursing homes) and situations where there is a large number of such people at risk
  18. 18. Legionnaires Disease  Main aim of control measures is to avoid conditions where Legionella can proliferate and to avoid creating sprays or aerosols  Growth of Legionella can be inhibited by: Avoiding water temperatures between 20-45o C Avoiding water stagnation & slimes Avoiding use of materials which provide nutrient for the organisms Keeping the system clean and preventing a build-up of sediments Using appropriate water treatment chemicals
  19. 19. Sick Building Syndrome Occupants suffer from measurably higher incidence of illness than would be expected, for no readily identifiable reason Symptoms may include ear, nose and throat irritation; skin rashes; lethargy; headaches; respiratory infections and nausea Occurs predominantly in air conditioned buildings Victims tend to be in low status repetitive jobs and have little or no control over their working environment
  20. 20. Sick Building Syndrome Symptoms are more frequent in offices with large numbers of employees, and are also reported with greater frequency in the afternoons than in the mornings Cause is likely to be due to a number of factors, some of which may be biological, others not Airborne contaminants may cause SBS symptoms through several mechanisms, including toxicity, irritations, infection and allergy
  21. 21. Sick Building Syndrome Other factors include inadequate ventilation and low humidity Several “temporarily sick buildings” have been “cured” by increasing ventilation, amongst other measures Overall conclusion is that SBS is a complex phenomenon with a number of causes, possibly influenced by the victims reaction and attitude to the working environment
  22. 22. Leptospirosis - Weil’s Disease An infectious jaundice with symptoms of fever, jaundice, liver enlargement, haemorrhages and feverish relapses Causative organism is a spirochaete called Leptospira icterohaemorrhagiae Rats are the primary cause of the disease Found in the kidneys of rats and is excreted in urine
  23. 23. Leptospirosis - Weil’s Disease  There is evidence that the spirochaete can pass through intact skin  Persons at risk include: canal workers sewer workers agricultural workers rat catchers pig workers butchers
  24. 24. Leptospirosis - Weil’s Disease Primary control is through systematic destruction of rats in infested areas Prophylactic immunisation offers the best solution in sewer workers All “at risk” workers should carry a card warning of the dangers, stressing personal cleanliness and hygiene, explaining the need for protective clothing and alerting doctors to the possibility of the disease
  25. 25. Leptospirosis - Weil’s Disease It is essential that people subject to potential risk are: aware of the causes and symptoms given instruction in suitable first-aid precautions (e.g. covering existing skin wounds, cleaning and disinfecting all fresh wounds), notifying a GP if `flu-like symptoms occur and notifying public authorities if rat infestation is noticed in a work area
  26. 26. Fungi  Cause ill-health through inhalation of contaminated dust. Examples include:  Extrinsic Allergic Alveolitis is a type of pneumoconiosis of biological origin caused by exposure to organic dusts of vegetable and animal origin  Bagassosis is a similar disease to farmer’s lung resulting from exposure to spores present in the cellulose fibres of cane-sugar after the sugar has been extracted  Aspergillosis is an all-embracing term to describe the types of extrinsic allergic Alveolitis (asthma) caused by the spores of the Aspergillus fungus, found as a mould on cellulosic fibres such as hay, straw, jute, flax, hemp, sugar-cane
  27. 27. Fungi  Farmer’s Lung is a specific disorder caused by exposure to spores from mouldy hay.  The disease is result of hypersensitivity due to an antigen present in the dust.  Symptoms are often mistaken for `flu, with extreme shortness of breath on exertion  Recovery is swift following removal of the individual from the dust source  However, with seasonal exposures the disease becomes chronic, leading to pulmonary fibrosis, emphysema and bronchiectasis, by which time it may be irreversible
  28. 28. Hepatitis Those at risk include doctors, surgeons, nurses and porters Infection amongst health workers is a result of contact with blood or excreta of patients suffering from viral hepatitis or in whom the disease is still in its incubation stage Porters and refuse disposal are at risk from carelessly discarded syringes and other sharps - the problem is becoming worse with the increase in drug addiction
  29. 29. Hepatitis  Course of disease is similar to Weil’s Disease, but is usually much less severe and normally self-limiting with recovery in about 6 weeks  In about 5% of cases, chronic infectious hepatitis follows, leading to cirrhosis and possibly death  Persons exposed to risk can be protected with injections of gammaglobulin  In all cases, protective disposable gloves should be worn and hands and arms washed regularly with disinfectant
  30. 30. AIDS Acquired Immune Deficiency Syndrome Caused by Human Immunodeficiency Virus (HIV), which attacks the immune system Virus is found in most body fluids but is delicate and relatively easy to kill with heat and chemicals It has low infectivity and transmission is thought to be more likely with repeated exposure to infection rather than to a single contact
  31. 31. AIDS Occupational risk comes from accidental inoculation or contamination of a cut or abrasion with blood or body fluids of an infected person Doctors, nurses, dentists, laboratory and hospital staff are at some risk, since they may come into close contact with body fluids Other workers possibly at risk might include community, welfare, custodial and emergency service workers and first aiders
  32. 32. AIDS Many of the precautions taken against other infections, especially Hepatitis B, will be equally effective against HIV. They include: Prevention of puncture wounds, cuts and abrasions in the presence of blood and body fluids; and the protection of existing wounds and skin lesions Control of surface contamination by containment and disinfection Safe disposal of contaminated waste, especially sharps