IB5 Flashcards
Workers at a waste-water treatment plant are at risk of contracting cryptosporidiosis.
(a) Explain how these workers might contract cryptosporidiosis. (4)
(b) Identify symptoms associated with cryptosporidiosis. (2)
(c) Outline specific control measures that these workers should use
to help reduce the risk of contracting cryptosporidiosis. (4)
(a)
an infectious diarrhoeal disease. It is caused by a protozoan parasite. It is transmitted by the hand-to-mouth route.
These particular workers could easily be in contact with faecal contaminated water, stagnated water, or equipment used in the process, the PPE if is not properly decontaminated and removed after used.
Also if one of the worker contract the diease he can spread it to his fellow-workers easily where there’s poor hygiene
(b)
Symptoms of cryptosporidiosis generally begin 2 to 10 days (average 7 days) after becoming infected with the parasite. The most common symptom of cryptosporidiosis is watery diarrhea. Symptoms include: Watery diarrhea, Stomach cramps or pain, Dehydration, Nausea, Vomiting, Fever , Weight loss
(c)
-Good occupational hygiene practices should be followed, especially washing with warm water and soap.
-Cuts and abrasions should be covered with waterproof plasters.
-Suitable protective clothing should be worn.
-A suitable disinfectant should be used – the parasite is resistant to most common disinfectants.
- prohibition of eating/drinking
in work areas
Cryptosporidiosis
Cryptosporidiosis is an infectious diarrhoeal disease caused by a waterborne protozoan parasite. It is a disease of humans and animals, including cattle and sheep.
(a) IdentifyTWO of the main types of biological agent.
(b) Outline the FOURspecial properties of biological agents.
(a)
• Fungi: Fungi include moulds and yeasts. Some fungi are able to cause infection on or inside the human body (e.g. athlete’s foot). Some fungi produce toxins (mycotoxins) that are harmful to humans.
• Bacteria:
Bacteria are simple single-celled organisms. They vary widely in shape and many have a tail (flagella) that allows them to move through liquid, Some (e.g. certain gut bacteria) are actually beneficial. Some bacteria can cause disease (e.g. Legionnaires’ disease is caused by the Legionella
bacterium)
• Viruses:
Viruses are micro-organisms but are not strictly alive. They are self-replicating molecules (genetic material
contained in a protein shell) that invade host cells, take control of the cell to produce more viruses, and then release these viruses to repeat the cycle
Hepatitis and Acquired Immune Deficiency Syndrome (AIDS) are two diseases of occupational significance that are caused by viruses present in human body fluids.
• Protozoa:
Protozoa are a very large and diverse group of single-celled organisms that all have a cell nucleus. They are therefore different to bacteria where no nucleus is present in the cell. Many diseases are caused by protozoans, perhaps the most notable being malaria. Sleeping sickness, giardia,
amoebic dysentery and toxoplasmosis are all caused by different protozoans
(b)
- Rapid mutation -, biological agents are subject to mutation; their genetic code changes over time, so changing the characteristics of the organism. However, unlike many organisms, some biological agents have a very high mutation rate. This means that their genetic code and their characteristics change quickly, making it very difficult for the human body to effectively recognise and attack them( HIV is constantly changing)
- Incubation period - there is usually a time delay between infection (when a person catches a disease) and when the first signs and symptoms of the disease become apparent. This incubation period can range from 1-3 days (for ‘flu) to many years (perhaps 30-50 years for Creutzfeldt-Jakob Disease (CJD)). biological agent may not be readily detectable
- Infectious : person (animal) with diesease i.e. capable of spreading the agent to others; Many diseases spread by making the carrier infectious When this is the case, an infected person poses a risk to anyone that he may come into cotnact with. a person may be infected with a disease and become infectious without showing any signs or symptoms of the disease (they are asymptomatic), Hepatitis C is an example of this type of disease.
- Rapid multiplication ; micro-organisms can multiply very rapidly when environmental conditions are right, It does not take long for a small number of agents (that might not present a risk of infection) to multiply to become large numbers that are capable of overcoming the body’s defences to cause infection.
Zoonoses are diseases transmitted from animals to humans. Two important zoonotic diseases are psittacosis and leptospirosis. For EACH of these:
(i) identify the animals associated with causing the disease in humans;
(ii) outline the mode of transmission from animals to humans;
(iii) outline methods of preventing infection of humans.
(i)
psittacosis: is most commonly associated with pet birds, like parrots and cockatiels, and poultry, like turkeys or ducks.
*
leptospirosis: the kidneys of infected rats (and other mammals, such as , Cattle Pigs Horses Dogs Rodents Wild animals)
(ii)
psittacosis
It can be transmitted to humans by breathing in infected material or occasionally by oral infection. Less commonly, birds infect people through bites and beak-to-mouth contact.
In general, people do not spread psittacosis to other people. However, this is possible in rare cases.
leptospirosis
- Contact with urine (or other body fluids, except saliva) from infected animals.
- Contact with water, soil, or food contaminated with the urine of infected animals.
The bacteria can enter the body through skin or mucous membranes (eyes, nose, or mouth), especially if the skin is broken from a cut or scratch. Drinking contaminated water can also cause infection. Outbreaks of leptospirosis are usually caused by exposure to contaminated water,
(iii)
Psittacosis :
- The disease is best prevented by isolating known infected birds
- Removing faecal material (before it has time
to dry out and become airborne),
- Preventing of creation of aerosols of faecal material during cleaning operations,
- Use of protective clothing
- And good personal hygiene
leptospirosis:
• Good pest control, such as getting rid of rats and avoiding rat infestations through good housekeeping.
• Washing cuts and grazes immediately with soap and running water.
• Covering cuts and broken skin with waterproof plasters before and during work.
• Wearing protective clothing (and laundering it).
• Good hand-washing after handling animals or contaminated material.
• Good hand-washing before eating, drinking or smoking.
• Early reporting of symptoms to a doctor.
• Carrying an alert card to provide additional information to the doctor about the risk.
Norovirus is a common cause of gastroenteritis that can spread rapidly in
closed communities such as hospitals, care homes and cruise ships.
(a) Explain how the virus is transmitted.
(b) Identify the symptoms of norovirus.
(c) Outline how the spread of the virus can be minimised.
(a)
- If an infected person doesn’t wash their hands before handling food, they can pass the virus onto others.
- Touching surfaces or objects that have the virus on them, then touching your mouth.
- close contact with someone with norovirus
(b)
Common symptoms:
diarrhea
vomiting
nausea
stomach pain
Other symptoms include:
fever
headache
body aches
(c)
• Frequent hand-washing, this can be encouraged by installing hand washing facilities stratigically, and promoting hand washing among employees and their family.
- raise awareness on the viruse among employee on the virus.
- Handle and prepare food safely by carefully wash fruits and vegetables before preparing.
- Avoiding the sharing of potentially contaminated articles, such as towels, clothing and PPE. Where applicaple provision of PPE laundering facilities.
- Disinfecting potentially contaminated surfaces (that an infected person has touched), especially After someone vomits and has diarrhea or displaying the symptoms,
outinely clean and sanitize kitchen utensils, counters, and surfaces before preparing food.
• employee involve in the disnfecting or PPE luandering process to be provided with rubber or disposable gloves.
Outline the means of controlling exposure to biological agents in a pathology laboratory.
Limiting the number of employees exposed and restricting access to authorised persons only by the use of security measures.
Minimising the potential for release of biological agents; through task design and engineering controls.
Displaying biohazard signs at lab entrances and on storage units.
Preparing emergency plans to deal with accidental release, spillage and worker contamination.
Decontamination and disinfection regimes and procedures that would be carried out both routinely and in the event of accidental releases.
Constructing rooms and surfaces for ease of cleaning.
Ensuring the safe collection, storage and disposal of waste; including sharps bins for all needles and incinerator disposal for all clinical and biohazard waste.
Safe handling and transport of samples, where necessary within containment.
Appropriate personal protective equipment; such as gloves, coats, overalls, eye protection and respiratory protective equipment.
Vaccination programmes where appropriate and health surveillance.
Hygiene measures; such as washing facilities and the prohibition of eating, smoking and drinking in the laboratory.
An appropriate containment level assigned to the laboratory and adherence to the criteria implied (a minimum of containment level 2).
Competent and trained personnel.
Water-sports instructors at a local water-sports centre are at risk of contracting Weil’s Disease (Leptospirosis). Give advice to these workers that outlines:
(a) The ill health of the disease.
(b) Why they might be at risk.
(c) Practical steps that they can take to minimise the risks to themselves.
(a)
Leptospirosis is a bacterial infection of the blood (initially) which results in ‘flu-like symptoms in the first instance (headache, fatigue, fever). It can lead to more severe effects in some cases; abdominal pain, jaundice and liver damage as the bacteria move out of the blood and invade internal organs. It can be fatal if left untreated.
(b)
The causative bacteria (Leptospira) are carried by rats (and other rodents) which continuously urinate and live close to water. The bacteria are carried out of the rat in urine and so may find their way directly into water, where they can survive longer than if allowed to dry out. If an instructor touches contaminated water, or wet urine, then they pick up the bacteria which can then enter the body through cuts and grazes, the nose and the mouth.
(c)
Staying out of the water when instructing (supervising training from land or from a boat).
Good personal hygiene practices, such as showering after immersion in water and always washing hands before eating.
Avoiding swallowing the potentially contaminated water.
Protecting the skin against water contact by wearing protective footwear, wet suits and covering existing cuts/abrasions with waterproof plasters.
Disinfecting cuts received whilst in the water before dressing the wound.
Seeking medical assistance in cases of illness and informing doctor about occupation/carrying card.
Looking for the sign of rat infestation and applying appropriate pest control methods.
(a) Define the term ‘biological agent’.
(b) Give FOUR examples of diseases caused by biological agents at work, and identify for EACH case the causative agent and an occupation particularly at risk.
(a)
A biological agent is a micro-organism, or microscopically small agent of biological origin, such as bacterium, virus, fungus that may cause disease or infection in humans. Bacteria, fungi, viruses and protozoa can all be biological agents, as can other similar types of biological material, such as cancer cells, DNA and single-cell parasites.
(b)
Legionnaires’ disease (Legionella) caused by the Legionella bacteria which can be contracted by people passing near to infected cooling towers (parts of air-conditioning units).
Weil’s disease (Leptospirosis) is caused by the bacteria Leptospira. This disease can be contracted from the urine of rats, so sewer workers, people who take part in water sports, excavations, etc. can be at risk.
Acquired Immuno-Deficiency Syndrome (AIDS) caused by the Human Immunodeficiency Virus (HIV). This is found in body fluids of infected individuals and is transmitted by direct body fluid transfer, so paramedics, doctors and nurses are likely to be at risk.
Hepatitis B, a liver disease, caused by the Hepatitis B Virus (HBV), again transmitted by body fluid contact. Again doctors, nurses and ambulance teams, as well as firemen and refuse disposal operators, are at risk
An enforcement inspection of a company has revealed the following data for a cooling tower.
Identify and explain, using the information presented below, the range of factors that increase the risk of Legionella growth and spread.
Legionella risk is affected by water temperature (does not grow well at temperatures below 20°C, grows well between 20°C and 45°C, killed at or above 60°C), the degree of stagnation, aerosol production and the presence of algae/scale/fouling.
The maintenance log shows the circulation rate is always below specification and there is a general trend of decreasing circulation rate over the period. Therefore there is a risk of stagnant water areas, which increases the risk of Legionella (stagnation encourages algal growth which acts as a nutrient for Legionella). Legionella growth is also encouraged by the presence of algae (a nutrient), sludge and scale (provides a haven in which to “hide”); the data towards the end of the log record (week 13) notes that algae is present (the tripping pump may also be evidence of fouling/filter blockage/scale build-up) - so this will encourage Legionella growth.
The addition of water softener was below specification in the early part of the period which may have allowed scale to build up. The filters were not cleaned monthly (except on one occasion) and the steadily decreasing circulation rate, pump tripping and presence of algae are all consistent with increasing filter blockage. Cooling water return temperature has also steadily crept up over the period so that it is outside specification and, by week 11, has crept within the range most suited to promote Legionella growth (20-45°C is best and it is unlikely to grow below about 20°C); thus, there is an increased risk of Legionella infection. Note also that there is no data recorded for the feed water temperature. It is likely that this was rising, mirroring the return water temperature.
The risk also depends on the likelihood of production of aerosols. The drift eliminator is designed to control aerosol production and this does not seem to have been working properly (damaged in some way) and could therefore result in aerosol production and a risk of inhalation of viable Legionella bacteria by the surrounding population
The biocide is needed to control Legionella viability. This was not added at the recommended rates on occasion, so concentrations may have fallen below those needed, which may have allowed Legionella to proliferate. Monitoring for the presence of viable Legionella bacteria (water analysis) is another control measure that does not seem to have been taken seriously during the second half of the period. This would have enabled early detection of the inadequacy of control measures.
The lack of measurements/action taken on certain weeks indicates that perhaps there was no “holiday cover”. There also seems to be an issue with making sure that sufficient stocks of biocide are always available and that maintenance on critical control measures is carried out promptly. This is not acceptable, provision should be made otherwise the risk will be greater.
(a)
Explain how, in a working environment, the hepatitis B virus may be transmitted to employees, identifying the types of occupation that present a particular risk.
(b)
As the health and safety adviser to a local authority, prepare a short report for departmental managers that outlines, with relevant examples, a strategy of measures to minimise the risk of hepatitis B infection.
(a)
The Hepatitis B Virus (HBV) can be transmitted to employees by transfer of body fluids. It is unlikely that direct sharing of body fluids or sharing of needles occurs in a workplace and therefore the most likely methods of transmission are through accidental contact with contaminated body fluids, through cuts and grazes and through needle-stick injuries. At risk occupations would be those where workers might expect to come into close contact with injured infected individuals, or come into contact with sharps (such as hypodermic needles) that have been used on or by infected individuals. This can encompass a lot of different types of worker, from health care professionals such as doctors, nurses and paramedics to bin men, social services and local authority house clearers.
(b)
At-risk occupations within the local authority and particular at-risk activities and workers must be recognised by departmental managers. This can be done through a simple risk assessment process where some questions are asked. Namely, does this work or occupation expose workers to the risk of contact with injured members of the public? For example, a normal office worker would not be considered ‘at-risk’. However, a first-aider would. Does this work or occupation expose workers to the risk of contact with contaminated sharps? For example, a civil works inspector would not, but a house clearance crew would be at-risk.
Information, instruction and training must be provided to at-risk workers. A basic level of information should be provided to all staff. This can be done by the provision of information on notice boards and leaflets distributed in communal areas. More specific training and information must be provided to at-risk work groups identified in the risk assessment process. Training and information should cover basic background information such as the nature of the virus, the symptoms of infection, the relative severity of the disease. There should also be information about the likely routes of infection.
Most importantly, the training and information must deal with the control measures that exist to prevent infection.
Decontamination and disinfection equipment and procedures must be put into place for at-risk workers and work areas. This would comprise the use of suitable disinfectants (hypochlorite based - as HBV is very resistant to non-aggressive cleaning agents) and the provision of suitable clinical waste bins for the disposal of contaminated cleaning material
Gloves must be used to prevent contamination of the hands with potentially infected body fluids. These gloves must present a suitable barrier to the passage of the virus. Nitrile gloves are to be preferred over latex, for reasons of employee sensitivity to latex (latex allergy).
In certain instances, the use of disposable aprons and eye protection would also be necessary to prevent contamination of clothes and face with body fluids.
Personal hygiene is an essential factor in preventing HBV infection. Hand washing before eating or drinking is necessary. Those in at-risk occupations must cover wounds.
Inoculations should be offered to all identified at-risk workers, however, there are issues with immunisation programmes; they do not guarantee immunity, and they may encourage bad practices because of feelings of invulnerability.
Workers must not smoke, eat or drink in potentially contaminated areas.
Sharps bins must be provided in areas where there is a recognised risk of needing to dispose of contaminated sharps.
All incidents where there is the potential for infection, e.g. needle stick injuries, must be reported.
A company that operates hotels and health spas is looking to minimise the risks associated with the Legionella
bacteria.
(a) In this scenario, identify specific sources of potential exposure to Legionella for BOTH employees and
guests.
(b) Describe the control measures that this company should implement to minimise people being exposed to
Legionella bacteria.
(a)
Sources of potential exposure to legionella at the hotel and health spa would include:
– The spa itself, i.e. the bubbling effect releasing legionella into breathing zone.
– Water storage calorifiers, where temperature is kept between 20°C and 45°C.
– Showers and spray taps releasing mists.
– Air-conditioning equipment.
– Foot bath sprays.
– Deadlegs in water supply lines which might lead to stagnation of water.
– Fire sprinkler systems.
(b)
Implementation of control measures to minimise the risks to people being exposed at the hotel and health spa should start with the appointment of a responsible person to manage legionella control for the complex, and to develop the legionella risk assessment.
Guidance specifies the requirement for routine disinfection of water systems with records kept of the cleaning and disinfection regime. Other controls include regular running of taps to remove stagnant water from deadlegs and minimising mists by cleaning valves/leaks to avoid sprays. Water treatment on spa and pools is necessary to control bacteria, and there should be regular testing to monitor chemical dosage to ensure that it is effective. Hot water temperatures should be maintained above 60°C and cold water below 20°C.
Systems should be designed to minimise the likelihood of legionella forming, with filters on air-conditioning systems regularly cleaned to avoid the build-up of bacteria and air intakes sited away from any potential sources of bacteria.
Finally, staff need to be trained in safe systems of work, including cleaning, and disinfection control.
A large indoor poultry farm is concerned about workers being exposed to the zoonose that causes the disease psittacosis (also known as ornithosis).
(a)
(i) Give the meaning of the term ‘zoonose’.
(ii) Identify BOTH the type and name of the biological
agent that causes psittacosis.
(b) Explain how the workers are likely to be exposed to the biological agent that causes psittacosis.
(c) Identify possible ill-health effects that could result from exposure to the biological agent that causes psittacosis.
(d) Describe control measures that could be put in place to help reduce the risk of workers contracting psittacosis.
(a)
(i) A zoonosis is any disease or infection that is naturally transmissible from vertebrate animals to humans. Animals thus play an essential role in maintaining zoonotic infections in nature. Zoonoses may be bacterial, viral, or parasitic, or may involve unconventional agents.
(ii) the type of agent is bacteria, the name is Chlamydia psittaci
(b)
- by disturbing the dry infected material such faeces it can be easily inhaled by the farmer.
-The feather contains the bacterium as well when the farmer is handling the infected animal they can contract the bacteria especially if not washing hands after handling
- Other potential sources of exposure include bird
bites, - mouth-to-beak contact,
- Human-to human spread is very rare.
(c)
- inflammatory illness of the lungs (pneumonia)
- fever
- muscle pain (myalgia)
- headaches
- dry cough
- inflammation of the liver, lining of the heart cavity , the heart muscle, and the brain can occur.
- liver disease.
(d)
- feeding birds properly, avoiding overcrowding,
- adequate ventilation systems including the use of high-efficiency particulate air (HEPA) filters to reduce the spread of contaminated air
- to clean cages daily. Do not stack cages. Position cages to prevent the transfer of feces, food, feathers, and other material from cage to cage.
- it is necessary to add the antibiotic (e.g., chlortetracycline) to their feed, consult a veterinarian for any treatment and subsequent testing that may be required
- training for workers who are at risk on how the disease can transfer from infected birds to people.
- Workers should keep infected birds in isolation and ensure these places are properly ventilated.
- All persons involved in the care of infected birds should wear protective clothing including gloves, eye wear, disposable surgical cap and a properly fitted respirator with N95 or higher rating
- Avoid dry sweeping, brushing or vacuuming when cleaning cages. Waste material should be removed frequently from the cage after moistening the material with a disinfectant.
- double-bag waste for disposal
- Chlamydia psittaci is susceptible to such disinfectants as quaternary ammonium compounds, isopropyl alcohol, 70% ethanol…..
- Discard items that cannot be cleaned appropriately.
A research laboratory undertakes necessary work with biological agents. These biological agents are categorized as extremely hazardous, being placed in the highest hazard group.
Outline a range of technical controls that should be used to minimize the risks to those working in the laboratory, where elimination or substitution of the hazard is not possible.
a)
•The separation of the laboratory from other activities in the same building.
• Input and extracted air to be passed through a HEPA (high efficiency
particulate air) filter
• Access via an airlock to be restricted to authorized persons by means of a security pass or swipe card
• The workplace to be sealable to permit
disinfection and to be maintained at an air pressure negative to the atmosphere
- All surfaces to be impervious to water, easy to clean, and resistant to acids, alkalis, solvents, and disinfectants
- Secure storage to be provided for the biological agents
- An observation window (or alternatively, CCTV) to be fitted so that the occupants can be seen at all times
- A microbiological safety cabinet with sealed front and glove port access to be used to carry out the work
- a facility such as an autoclave to be provided for rendering waste safe and finally the provision of appropriate and adequate handwashing facilities
The avian influenza virus can be found in chickens, ducks, geese, and wild birds. Poultry workers are at risk of becoming infected with this
virus.
(a) Outline how poultry workers can become infected by this virus.
(b) Identify the symptoms of avian influenza if contracted by poultry
workers.
A large poultry farm has a number of different locations where live birds
are kept. Vehicles transporting new stock birds and bird food access each location and poultry workers move equipment between the locations daily. Vets and external agencies frequently visit all the
locations.
(c) Outline control measures the poultry farm could use to minimize the risk of the virus entering their locations or spreading between the different locations.
(a)
- by disturbing the dry infected material such faeces it can be easily inhaled by the farmer.
- The feather contains the bacterium as well when the farmer is handling the infected animal they can contract the bacteria especially if not washing hands after handling
- when a person touches something that has a virus on it then touches their mouth, eyes, or nose.
- Other potential sources of exposure include bird bites,
- mouth-to-beak contact,
- Human-to human spread is very rare.
(b) conjunctivitis, influenza-like illness (e.g., fever, cough, sore throat, muscle aches) sometimes accompanied by nausea, abdominal pain, diarrhea, and vomiting, severe respiratory illness (e.g., shortness of breath, difficulty breathing, pneumonia, acute respiratory distress, viral pneumonia, respiratory failure), neurologic changes (altered mental status, seizures), and the involvement of other organ systems.
(c) - to clean cages daily. Do not stack cages. Position cages to prevent the transfer of feces, food, feathers, and other material from cage to cage.
- training for workers who are at risk of how the disease can transfer from infected birds to people. and how the virus spreads.
- Workers should keep infected birds in isolation and ensure these places are properly ventilated, to carefully and correctly dispose of any dead birds
- an active rodent and pest control system in place.g
- The need for rodent control and the prevention of other wild birds accessing the area
- The disinfection of boots, vehicles and equipment on both entry and exit is a basic requirement of infection control
- Discard items that cannot be cleaned appropriately.
- all the poultry sites are fenced with a controlled entry point.
• In-coming stock should be isolated from the rest of the flock. During the
period of isolation a testing and monitoring program should be
instituted.
• New stock should only be placed in facilities which have been de-stocked
and thoroughly cleaned and disinfected.
