Epidemics and the Workplace

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Catherine Makison (Health & Safety Laboratory)

Introduction

During an outbreak of human infectious disease, the numbers affected will vary depending on the disease, location, susceptible population size, environment etc. When disease numbers exceed a set threshold for that illness it is considered to be of epidemic proportion, i.e., disproportionate to the norm. This article gives examples of micro-organisms that can cause disease of epidemic scale and how they are transmitted. It focuses on occupational health during an epidemic and how some industries, such as healthcare, are more susceptible to worker ill health than others. It covers infection prevention and control by good work and hygiene practices and using personal protective equipment.

Micro-organisms - disease and transmission; hazard and risk

Overview

Micro-organisms are microscopic organisms, subdivided into five main types: bacteria, fungi, protozoa, algae and viruses. Micro-organisms can be found in almost every environment and some can adapt to extremes such as high temperature, pH level and salinity. Most do not cause disease, and in fact human beings could not survive without them. People are protected by the physical barriers of their skin, by mucus secretions in the lung, and by their immune system. However, some species of micro-organisms (known as pathogens) do cause disease, examples of which are listed in Table 1.

Transmission

In order to cause human disease, micro-organisms need to enter the body. They can do this in a variety of ways, e.g., through ingestion (accidental swallowing or via hand-to mouth contact), inhalation, sexual intercourse, through the membranes of the eye, or through contact with broken skin. The latter two have been categorised collectively as contact for the purposes of the information in Table 1. Infections (termed zoonoses) can also be transmitted from animals to humans, sometimes directly or via vectors such as ticks or mosquitoes. The infected animals may be asymptomatic but act as a carrier of infection.

Pathogen survival

Pathogenic micro-organisms need to be viable (in a dormant/live state) in order to cause disease. As such micro-organisms released from an infectious source, e.g., in sneeze droplets or droplet nuclei from an individual suffering from influenza, or blood-borne viruses in body fluids, need to survive in the environment until they reach another host in which to commence infection. Environmental factors will all have an effect on the survival of pathogenic micro-organisms and will therefore influence the likelihood of infecting another individual. For airborne transmission these factors may include air turbulence causing dispersion and dilution, with humidity and temperature affecting survival through dehydration effects. Dehydration may also reduce survival on surfaces, but presence of organic loading may provide a protectant effect to prolong survival. Some micro-organisms have mechanisms to assist survival. For example, antibiotic resistant micro-organisms such as Meticillin- (formerly Methicillin) Resistant Staphylococcus aureus (MRSA) are often able to survive in hospital environments due to their ability to survive exposure to antibiotics. Additionally, bacteria that form spores, such as Bacillus species, can survive adverse conditions for longer. Bacillus anthracis (the causative agent of anthrax) spores are known to survive in soil for decades. The bacterium Mycobacterium tuberculosis (causative agent of tuberculosis; TB) has a protectant waxy cell wall that also makes it more resistant to disinfectants. After the pathogen has reached a new host, it must survive the individual’s immune defences in order to induce infection, but these will vary from person to person.

Incubation period

This is the time from initial exposure to the pathogenic micro-organism to the first signs and symptoms of the disease and varies between diseases. For example, the incubation period for TB is variable, but generally ranges from 3 to 12 weeks. In contrast, the incubation period for anthrax transmitted via inhalation is generally 1 to 6 days, although longer periods in excess of 43 days have been noted.

Hazard versus risk

It is important to distinguish between hazard and risk. The hazard is established by identifying how dangerous the micro-organism is in terms of the severity of disease if one becomes infected i.e. the hazard group of the micro-organism, and by how easily it is transmitted from one person to another. Risk can be determined by examining the circumstances in which the hazards arise, and the likelihood of exposure. This can then be applied to identifying at-risk populations or occupational groups.

Infectious dose and exposure limits

For disease to develop there needs to be sufficient numbers of the pathogenic micro-organisms to overcome the body’s defences. This number differs from pathogen to pathogen and infectious doses for some pathogens are unknown, further complicated by variation in susceptibility due to environmental/human metabolic factors. However, there are some well-known examples that illustrate how widely infectious doses may range. Via inhalation, the infectious dose of TB is very low, where 10 bacteria or fewer can initiate disease. In contrast, although anthrax is perceived as a major health concern the infectious dose for Bacillus anthracis via inhalation is regarded to be approximately 10,000 bacterial spores. While most strains of Escherichia coli require several thousand bacterial cells to cause infection via ingestion or hand-to-mouth contact, the verocytotoxigenic strains such as E. coli O157 that can cause severe infection require as few as 100 cells.

These factors add complexities to the exposure and risk assessment of pathogenic micro-organisms and as a result there are no numerical limits for workplace exposure to micro-organisms. Therefore, infection risk assessments for pathogens are based on probabilities.


Table 1: Disease causing micro-organisms and their routes of transmission

Name of Micro-organism Type of Micro-organism Disease Transmission Route Workers/ occupations likely exposed
Norovirus Virus Norovirus also known as Winter Vomiting Disease Ingestion All in semi-closed environments e.g. schools, cruise ships, aeroplanes, hospitals, offices, off-shore platforms, military bases, restaurants
Mycobacterium tuberculosis Bacterium Tuberculosis (TB) Inhalation Agriculture workers, healthcare workers
Influenza virus Virus Influenza (Flu) Droplet inhalation / contact – mucous membranes All sectors are at risk, but most at risk are healthcare workers
Bacillus anthracis Bacterium Anthrax Contact – mucous membranes or broken skin / inhalation / ingestion Agriculture workers, any work that requires use of animal hides e.g. drum skins, construction i.e. where animal hair has been used in plaster.
Escherichia coli strain 0157 Bacterium Cholecystitis, bacteraemia, cholangitis Ingestion Food industry
Human Immunodeficiency Virus (HIV) Virus HIV / Acquired Immunodeficiency Syndrome (AIDS) Contact – blood-borne Healthcare workers generally via needlestick injury
Severe Acute Respiratory Syndrome Coronavirus (SARS CoV) Virus SARS Likely inhalation / possible contact –mucous membranes Healthcare workers
Viral haemorrhagic fever (VHF) Virus Blood-borne viral haemorrhagic fever Via ticks from ruminants as amplifying host Healthcare workers, laboratory workers

Source: Overview by the authors.


Blood-borne viruses (BBV) such as HIV and VHF require direct contact with blood or body fluids. There are various occupations in which workers might be exposed to such agents and include needle exchange services, local authority services e.g. refuse collection, tattooing and body piercing, laboratory work.

Epidemics

The World Health Organization (WHO) describes an outbreak (also known as an epidemic) as the occurrence of individual cases of a disease, the numbers of which are ‘in excess of what would normally be expected in a defined community, geographical area or season’.

There are a number of organisations that record and follow outbreaks that occur:

• The European Centre for Disease Prevention and Control (ECDC) in Europe; • National agencies, such as the Health Protection Agency (HPA) in the United Kingdom; • Centers for Disease Control and Prevention (CDC) in the United States of America (USA); • The Robert Koch Institute (RKI, Germany) • The National Institute for Health and Medical Research (NISERM, France) • The Swedish National Institute of Public Health (SNIPH, Sweden) • The World Health Organization (WHO) internationally.

Other organisations, with similar interests, can be found on the Public Health Institutes of the World (IANPHI) website (www.ianphi.org)

Pandemics

A pandemic is defined as an epidemic that spreads to a much wider geographical area, i.e., encompasses several countries, and therefore the numbers of people who become infected rises further still.

Effects on workers and industry

There are three ways in which workers might be exposed to micro-organisms at work:

1. Exposure may result from deliberately working with biological agents. The main example is from working in a microbiology laboratory, but can also include where micro-organisms form part of the work process, such as in biotechnology. 2. Exposure may result from biological agents that are present as contaminants in the workplace material being handled, e.g., pathogens and allergens in materials being handled on farms, in municipal solid waste collection, sewage treatment. 3. Exposure is not a direct result of the work that workers do, but can result from indirect exposure. Examples include catching cold or flu from a work colleague, but also include micro-organisms introduced into the workplace via heating, ventilation and air conditioning (HVAC) systems, or pathogens such as Legionella bacteria via cooling towers, misting units or showers.

Even individual cases of disease in the workplace can impact significantly on an organisation, particularly in small to medium enterprises (SMEs), which cumulatively will have a negative impact on an industry and its economy. Outside the workplace, a disease epidemic may have major public health and economic consequences, and these may affect the workplace. For example, seasonal influenza may reduce the complement of staff fit to work and thus affect productivity. However, on rare occasions when the numbers of people that become infected reach epidemic proportions, this can cause great disruption to industry and the economy. The most likely scenario in which epidemics may affect the workplace is at the interface between public health and workers, as this is when there is likely to be the greatest contact with infection. This is therefore most likely to be healthcare workers, and this is reflected in guidance on infectious disease and occupational health. However, control of infectious disease is relevant to all industries.

Biosafety Levels, Hazard Groups and Containment Levels

For the reasons described above there are no workplace exposure limits for micro-organisms (biological agents), however studies have been undertaken to identify typical concentrations of micro-organisms in the air for example at various industrial sites as noted in Bioaerosols and OSH ERO- 10-06-c.9. Micro-organisms are categorised based on their ability to infect healthy humans in the workplace. This classification is variously termed Risk Groups (European Biological Agents Directive 2000/54/EC) [1], Hazard Groups (United Kingdom’s HSE Control of Substances Hazardous to Health 2002) [2] and Biosafety Levels (US Centers for Disease Control and Prevention; Biosafety in Microbiological and Biomedical Laboratories). [3] These are based on whether the biological agent is a hazard to workers, whether the agent is transmissible to the community, and whether there is effective treatment or prophylaxis available, and in each case classifies biological agents into one of four groups. This in turn determines the level of containment applicable and proportionate to control exposure and thus prevent infection. These controls include laboratory design, use of air extraction and safety cabinets, decontamination methods and protective equipment. Whilst this is mainly aimed at deliberate handling of biological agents in laboratories, the principles of classification apply to control of exposure to biological agents in the wider workplace.

The European Union (EU) Directive (2000/54/EC) on the protection of workers from risks related to exposure to biological agents at work dictates that Member States shall classify biological agents that are or may be a hazard to human health on the basis of the definitions outlined in Table 2. A list of micro-organisms and associated risk or hazard group can be found within the EU Directive (2000/54/EC). [4] The levels of containment required for activities, which involve working with biological agents, increase with a higher rating of the risk/hazard group, i.e. the more hazardous the micro-organism, the greater the containment requirement. Table 2 describes each hazard group, the corresponding containment level required and an example of a micro-organism categorised within that risk/hazard group.


Table 2: Hazard groups and containment levels required for micro-organisms used in the workplace

Risk/Hazard Group Description of Risk/Hazard Group Containment (Biosafety) Level Required Example

Micro-organisms

1 A biological agent that is unlikely to cause human disease. 1 The greatest majority of bacteria and fungi, including common soil bacteria such as

Bacillus species and skin-borne bacteria such as Micrococcus species

2 A biological agent that can cause human disease and may be a hazard to workers. It is unlikely to spread to the community there is usually an effective prophylaxis or treatment available. 2 Staphylococcus aureus including Meticillin Resistant strains of Staphylococcus aureus (MRSA); food poisoning agents such as most Salmonella species and E. coli strains
3 A biological agent that can cause severe human disease and presents a serious hazard to workers. It may present a risk of spreading to the community, but there is usually effective prophylaxis or treatment available. 3 Bacillus anthracis; blood borne viruses such as Hepatitis B and HIV; Mycobacterium tuberculosis; verocytotoxigenic strains of E. coli.
4 A biological agent that causes severe human disease and is a serious hazard to workers. It is likely to spread to the community and there is usually no effective prophylaxis or treatment available. 4 Blood-borne haemorrhagic viruses such as Ebola and Lassa Fever viruses.

Source: Adapted by the authors[5]


Examples of workplace infection risks and epidemics

Workers likely to be most affected by outbreaks of an epidemic proportion are those within the healthcare sector because of their close proximity to patients and consequently to their blood and body fluids. Workers within other occupational sectors are also at risk of infection and are perhaps less aware of such risks. The following text gives a few examples of occupations and risks of infections along with some relevant links to guidance.

Laboratory

Where laboratories propagate pathogenic micro-organisms for research or diagnostics purposes, this may create a risk of infection to laboratory workers particularly due to the high numbers of micro-organisms that can be generated. Whilst accidents can and do occur for example, one laboratory worker was diagnosed with SARS CoV after it was found that a culture of West Nile Virus had become contaminated with SARS CoV. It is unclear as to exactly how the worker became infected with SARS and was an exceptional case, but one that highlights the necessity for appropriate controls. Collins and Kennedy (1999) describe historical aspects of laboratory-acquired infections and provide facts and figures from data collated from around the world in their book “Laboratory-Acquired Infections: History, Incidence, Causes and Preventions, 4th Edition.

The types of controls used in laboratories depends upon the nature of the micro-organism, i.e. how dangerous it is to work with, which is highlighted by its risk/hazard category as outlined in Table 2. The risk/Hazard Group 2 organisms for example are handled in containment level 2 laboratories that have restricted access. Workers handling these organisms will wear lab coats and gloves. Where there is a risk of splash/aerosol generation and therefore a risk of infection via inhalation or inoculation, a respiratory protective device (RPD) and eye protection would be worn and micro-organisms would be handled in a microbiological safety cabinet to contain splashes and aerosols generated. The risk/Hazard Group 3 organisms would be handled in a containment level 3 facility, held at negative pressure so that when workers enter and exit the facility air flows into the containment level 3 laboratory to prevent micro-organisms escaping out into the neighbouring lab or corridor. Before entering the facility workers would put on appropriate PPE, which would likely include a dedicated lab coat (i.e. not the same lab coat that would be worn in the containment level 2 laboratory), two pairs of gloves, shoe covers and possibly eye protection.

Where possible, laboratories that propagate micro-organisms for research purposes will substitute pathogenic micro-organisms for non-pathogenic or less pathogenic micro-organisms in order to reduce the likelihood of infection to laboratory workers. This forms part of the hierarchy of control measures for laboratories.

The level of protection required by laboratory workers will differ depending on the laboratory type and use following risk assessment. Guidelines on health and safety in the laboratory and other relevant information are as follows: • The framework Directive 98/391/EEC (http://osha.europa.eu/legislation/directives/A/1/1) imposes a general duty on employers to ensure the health and safety at work of all employees. It requires risk assessment by the responsible employer to prevent risks to employees. The WHO’s Laboratory Biosafety Manual can be downloaded from the WHO’s website (http://www.who.int/csr/resources/publications/biosafety/Biosafety7.pdf) and provides useful information microbiological risk assessments, laboratory codes of practice, facilities, waste handling, equipment, safe handling of specimens, contingency planning and emergency procedures, transportation and training.

• In addition, The European Agency for Safety and Health at Work produced an expert forecast on emerging biological risks related to occupational safety and health. This document highlights the main emerging biological risks identified via expert survey, which includes occupational risks related to global epidemics. http://osha.europa.eu/en/publications/reports/7606488

• Biosafety-Europe. Containment level 3 and 4 laboratories: Legislative and regulatory framework. http://www.biosafety-europe.eu/d20public_300309.pdf

• European Council. Council Directive 98/81/EC of 26 October 1998 amending Directive 90/219/EEC on the contained use of genetically modified microorganisms. Official Journal, 1998, L330:13-31.

• EU-PPE Directive 89/686/EC.

• WHO’s Global Health Security, Epidemic alert and response: Laboratory Safety Manual. http://www.who.int/csr/resources/publications/biosafety/Labbiosafety.pdf

Healthcare

The main risk of infection to healthcare workers is from close contact with patients with infectious diseases, or indirectly through handling contaminated body fluids or clinical waste. Frequent examples include healthcare workers being infected by contact with patients during recent influenza epidemics and pandemic and healthcare workers in hospitals and care homes being infected by Norovirus, the ‘winter vomiting disease’. Less frequently, but with more serious consequences, is the potential for health care workers and carers to contract viral haemorrhagic fever during outbreaks through direct contact with infected body fluids. Examples include Ebola virus epidemics in sub-Saharan Africa, the re-emergence of dengue fever in the Americas and Asia, and Crimean-Congo haemorrhagic fever, which is endemic in all of Africa, the Balkans, the Middle East and in Asia.

The mode of disease transmission and how readily the virus infects individuals will affect the types of controls implemented by healthcare staff to help prevent infectious diseases spreading from patient to patient, patient to staff member, and worker to worker. For example a patient with multidrug-resistant tuberculosis will likely be isolated within a negative pressure suite. This negative pressure ensures that when doors are opened upon entrance and exit of the suite, air will flow into the suite thus preventing any airborne infectious material escaping the isolation suite. Before entry into the suite, staff will put on appropriate PPE e.g. apron, gloves, and respiratory protective device (RPD) as the bacterium is known to be transmitted through the airborne route. Conversely, influenza virus is thought to be transmitted mainly via contact with mucus membranes, but may be spread via the airborne route when in close contact with individuals suffering with the disease. Patients with influenza are likely to be isolated in a standard side room (i.e. without negative pressure). Healthcare workers caring for these patients will wear PPE as appropriate e.g. for routine checks e.g. temperature, blood pressure, etc. where workers will be close to the patient then PPE such as an apron, gloves, and surgical facemask to protect against splash are likely to be worn; however, when performing an aerosol-generating procedure e.g. bronchoscopy, staff would wear gloves, apron, eye protection and RPD. National guidance should be consulted for health and safety best practice for healthcare workers, which may differ slightly between countries. Some useful links to such guidance are as follows:

• An EU Directive was introduced in 2010 (2010/32/EU) implementing the framework agreement on prevention from sharps injuries in the hospital and healthcare sector concluded by HOSPEEM and EPSU. This legislation can be downloaded from http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2010:134:0066:0072:EN:PDF.

• The German Institute and Clinic of Occupational Medicine (Institut fur Arbeitsmedizin) conducts research and training of occupational medicine standards and outpatient clinic. It also carries out research on occupational skin diseases. Information on this can be found on their website www.ukaachen.de/content/folder/1018006.

• The International Section of the ISSA on the Prevention of Occupational Risks in Health Services (ISSA Health Services Section) undertakes activities at the international level, designed to further prevention of occupational risks in health services. More information on this can be found at http://health.prevention.issa.int/

• The French National Research and Safety Institute for the Prevention of Occupational Accidents and Diseases identifies and improves knowledge on occupational risks. It analyses their impact on health and safety at work and conducts research on how to prevent and control them. Further information on this can be found at www.inrs.fr

• WHO: Practical Guidelines for Infection Control in Health Care Facilities (http://www.smp-council.org.hk/mlt/english/mlt_message_infection_e.pdf). This document offers great background insight into the requirement for an infection control programme, to infection control practices. It highlights the required precautions based on airborne, droplet and/or contact risks through to premises management and facilities, e.g. having ventilation alongside cleaning, disinfection and sterilisation. It covers the care of health care workers and notes the risk to specific agents such as TB, HIV and SARS. It also includes procedures for putting on and removing certain face masks.

Agriculture

Farm and other agricultural workers are at risk of zoonotic infection from the animals and animal products they manage. Such workers are likely to be most affected by epidemics that are associated with an animal host/transmitter of disease e.g. avian influenza, swine influenza, TB.

Outbreaks of animal infections with Coxiella burnetii, the causal agent of Q fever, have resulted in infections in farm workers. Outbreaks of infection, mainly by verocytotoxigenic E. coli, have occurred in visitors to and workers on open farms, i.e., those where direct contact with animals is encouraged.

Controlling infection within agriculture may include the use of gloves and good hand hygiene. The use of RPD may be required where animals are positive for infection. Ensuring vehicles have in place air filters to reduce the numbers of micro-organisms entering the cabs of the vehicles will also help to reduce the likelihood of infection. The vaccination of animals e.g. vaccinating cattle again Leptospira hardjo or utilising Salmonella-free pigs and poultry will also protect workers.

The type and use of controls and PPE within the agriculture sector will vary depending upon the job and likelihood of infection based on risk assessment. Some guidance on occupational health for workers in the agriculture sector are as follows:

• European Agency for Safety and Health at Work: Biological Agents and Agriculture. http://osha.europa.eu/en/sector/agriculture/bio

• The German Institute and Clinic of Occupational Medicine (Institut fur Arbeitsmedizin) conducts research in occupational asthma and biological monitoring. Information on this can be found on their website www.ukaachen.de/content/folder/1018006.

• Food and Agriculture Organization of the United Nations: Agriculture and Consumer Protection Department. http://www.fao.org/ag/portal/agarchive/detail/en/item/161687/icode/?no_cache=1

• International Labour Organization: Safety and Health in Agriculture. Code of Practice. http://www.ilo.org/global/publications/books/WCMS_159457/lang--en/index.htm

Waste and recycling

Workers in the waste and recycling sector may be exposed to large numbers of micro-organisms in decomposing waste, but these are most likely to present an allergic rather than infectious hazard. Pathogenic bacteria such as food poisoning organisms may however be present. The controls required in this industry are likely to be similar to those required by workers in the agriculture sector i.e. the use of gloves and good hand hygiene. The use of RPD may be required where organic material is being sorted or turned as in the case of turning piles of compost. Ensuring that vehicles have in place air filters to reduce the numbers of micro-organisms entering the cabs of the vehicles will also help to reduce the likelihood of infection.

While no epidemics have been attributed to work in waste and recycling, some of the useful links to guidance on maintaining health and safety in the waste and recycling industry are as follows:

• The German Institute and Clinic of Occupational Medicine (Institut fur Arbeitsmedizin) conducts research in occupational asthma and biological monitoring. Information on this can be found on their website www.ukaachen.de/content/folder/1018006. • European Commission Guidance on the Revised Waste Framework Directive (2008/98/EC). http://www.apse.org.uk/briefings/12/1233%20European%20Commission%20guidance%20on%20rWFD.pdf

Offices

Office workers may be at risk of infection from their colleagues in the early stages of infections before the onset of overt symptoms, or if individuals continue working whilst they are symptomatic, especially with less debilitating illnesses such as colds. The greater trend towards open plan offices may dilute any infectious aerosols being produced by sneezing colleagues for example, however large open plan offices also generally contain more workers, which increases the likelihood of individuals coming into contact with an infectious worker. Measures to control infection transmission would include good hand hygiene and office cleaning procedures. If possible preventing staff from coming in to work when symptomatic may also reduce the likelihood of infection transmission.

Public transport

Drivers and passengers of vehicles are at risk of infection from other transport users. The greatest risk of epidemic or even pandemic infection in the office environment or for public transport drivers is likely to be influenza. Spread by droplets from sneezes, or from hand to mucous membrane contact with infectious agents picked up from surfaces. The potential for spread may be greater in these circumstances than in healthcare, where controls are more likely to be in place. Again, good hand hygiene, which is likely to include hand rubs, as hand washing facilities may not be available on some vehicles, will help to reduce infection transmission. It may be necessary to include surgical facemasks to protect against splash during epidemic outbreaks of Influenza for example.

The Institute and Clinic of Occupational Medicine (Institut fur Arbeitsmedizin) conducts research and training of traffic safety and occupational drivers. Information on this can be found on its website www.ukaachen.de/content/folder/1018006.

Risks associated with Legionellosis

Of special note is the infection risk from Legionella bacteria. The bacteria are infectious via inhalation, and can travel large distances (up to several kilometres) in droplets/aerosols of infected water. [6]. Free Legionella bacteria (i.e. not encapsulated within amoebae) can survive for a couple of hours within an aerosol. [7] Biofilms often build up inside water containment systems, which then become colonised with amoebae. These amoebae are then liable to become hosts for Legionella bacteria. When encapsulated within amoebae, these bacteria are protected from disinfectants. Large outbreaks have been associated with contaminated warm water systems such as industrial cooling towers and heating, ventilation, and air conditioning (HVAC) systems that provide optimum growth conditions for the bacteria. These water systems are often used in conjunction with air conditioning systems i.e. to cool warm air. The risk is not just for workers but also where the workplace activities affect the public, such as those downwind from emissions from contaminated industrial sources.

Links to relevant documents on Legionella are as follows:

• Legionella Control Association. http://www.legionellacontrol.com/legionella-control-association.htm

• Legionella Control Journal. http://www.lcj-online.co.uk/contacts.php

• The European Working Group for Legionella Infections. http://www.ewgli.org/

• European Legionnaires’ Disease Surveillance Network. http://ecdc.europa.eu/en/activities/surveillance/eldsnet/pages/index.aspx

• European Agency for Safety and Health at Work. Working Environment Literature Review for Legionella and Legionnaires’ Disease: A Policy Overview. http://osha.europa.eu/en/publications/literature_reviews/legionella-policy-overview.pdf [8]

Infection prevention and control

In order that workers are protected from infectious micro-organisms that they may be exposed to during the course of their work, a number of controls should be implemented based on the findings of a risk assessment. A hierarchy is advocated under the principles of controlling exposure to any hazardous substances, which might include changing work practices so the job/task/equipment that exposes workers to a source of infection is not needed any more; or modifying work to avoid creating hazardous by-products or waste. If this is not possible, then [[Hierarchy of prevention and control measures |controls]] should be applied to reduce the risk of infection to a level that will not harm people’s health. This includes physical barriers to prevent exposure, engineering controls such as exhaust ventilation systems to reduce airborne microbial burden by drawing air away from the person, and the use of PPE, which can include clothing, gloves, footwear and RPD such as appropriate facemasks (note surgical masks are not classified as RPD). This is supported by good hygiene practices such as thorough hand washing, avoiding hand to mouth contact, safe disposal of waste and the use of appropriate decontamination methods. Effective vaccines are available against some infectious agents and as such employers should offer workers the appropriate vaccination where assessment reveals that there is a risk of exposure to such biological agents. It is important to note however that vaccination must not be used as a substitute for the necessary precautions highlighted above.

Measures of infection prevention and control will vary nationally and between occupations. Measures are also likely to be task-specific based on risk assessment. The Biological Agents Directive (2000/54/EC) highlights some measures that may be applied to reduce the risk of infection. These include minimising as far as possible the number of workers exposed (or likely to be exposed), implementing hygiene measures such as not eating or drinking in working areas where there is a risk of contamination by biological agents, as well as providing appropriate and adequate hand washing and toilet facilities etc.

The WHO’s Practical Guidelines for Infection Control in Health Care Facilities (http://www.smp-council.org.hk/mlt/english/mlt_message_infection_e.pdf) offers a step-by-step guide on hand washing and hand rubs. It also discusses cleaning, disinfection and sterilization and PPE including RPE. The German Federal Institute for Occupational Safety and Health (BAuA) has a link on their website to technical rules for biological agents (http://www.baua.de/en/Topics-from-A-to-Z/Biological-Agents/TRBA/TRBA.html), which includes protective measures for activities involving biological agents in laboratories, sewage plants, agriculture and forestry, and healthcare facilities. Similarly, the French National Institute of Research and Security (INRS, http://en.inrs.fr/inrs-pub/inrs01.nsf/IntranetObject-accesParReference/Pdf%20Etudes-Recherches2011-2012-EN/$File/Etudes-Recherches2011-2012-EN.pdf) (http://en.inrs.fr/) carries out research on occupational hazards similar to the Health & Safety Laboratory in the UK, both of which offer guidance on best practice for most work sectors.

The European Centre for Disease Prevention and Control provides guidance on various aspects of infection prevention and control including, for example:

  • A tutorial on the safe use of personal protective equipment (PPE)[9]
  • Material relating to hand washing as a control measure.[10]
  • A Legionnaires' disease outbreak investigation toolbox[11]
  • A toolkit for investigation and response to Food and Waterborne Disease Outbreaks[12]

Social networking and mapping disease epidemics

Access to data via the Internet has greatly improved disease epidemiology and tracking in recent years. National and international disease outbreak alert sites provide valuable early warning of emerging epidemics. Forecasts on emerging biological risks are currently carried out and reported e.g. by the European Agency for Safety and Health at Work. [13] In future, social networking media such as Twitter and Facebook could provide early warnings of emerging infections, and Google launched Google Flu Trends to map pandemic influenza. [14] This could lead to improvements in preparedness not only for public health but also to reduce health hazards in the workplace.

The European Centre for Disease Prevention and Control (ECDC) is dedicated to the surveillance of infectious diseases in the EU and as such collects epidemiological data, maintains databases of such information, co-ordinates and operates dedicated surveillance networks, and supports national surveillance systems (http://www.ecdc.europa.eu/en/activities/surveillance/Pages/Activities_Surveillance.aspx).

It produces weekly reports highlighting current communicable disease threats as well as disease specific surveillance e.g. antimicrobial resistance and healthcare-associated infections (ARHAI), vaccine preventable diseases (VPD), and emerging and vector borne diseases (EVD) http://www.ecdc.europa.eu/en/activities/surveillance/disease_specific_surveillance/Pages/disease_specific_surveillance.aspx. The European Surveillance System (TESSy, http://www.ecdc.europa.eu/en/activities/surveillance/TESSy/Pages/TESSy.aspx) replaced data collection systems with Dedicated Surveillance Networks (DSNs) in order to provide experts with a single location for EU surveillance data (http://www.ecdc.europa.eu/en/activities/surveillance/european_surveillance_networks/Pages/european_surveillance_networks.aspx). A list of EU national competent bodies for health that feed into ECDC can be found at the following site: http://www.ecdc.europa.eu/en/aboutus/Competent%20bodies/Pages/Competent_bodies.aspx.


References

References

  1. EU-OSHA - European Agency for Safety and Health at Work. (no date). European Biological Agents Directive 2000/54/EC. Retrieved 19 June 2012, from: http://osha.europa.eu/en/legislation/directives/exposure-to-biological-agents/77
  2. HSE - Health and Safety Executive, Control of Substances Hazardous to Health Regulations 2002, 2002. Available at: http://www.legislation.gov.uk/uksi/2002/2677/pdfs/uksi_20022677_en.pdf
  3. EPA – US Centers for Disease Control and Prevention (CDC), ‘Biosafety in Microbiological and Biomedical Laboratories’, 5th Edition, December 2009. Available at: http://www.cdc.gov/biosafety/publications/bmb15/BMBL.pdf
  4. EU-OSHA - European Agency for Safety and Health at Work. (no date). European Biological Agents Directive 2000/54/EC. Retrieved 19 June 2012, from: http://osha.europa.eu/en/legislation/directives/exposure-to-biological-agents/77
  5. EU-OSHA - European Agency for Safety and Health at Work. (no date). European Biological Agents Directive 2000/54/EC. Retrieved 19 June 2012, from: http://osha.europa.eu/en/legislation/directives/exposure-to-biological-agents/77
  6. EPA - Environmental Protection Agency– (US), ‘Legionella: Human health criteria document’, 822-R-99-001, November 1999. Available at: http://water.epa.gov/action/advisories/drinking/upload/2009_02_03_criteria_humanhealth_microbial_legionella.pdf
  7. Hambleton, P., Broster, M. G., Dennis, P. J., Henstridge, R., Fitzgeorge, R. & Conlan, J. W., ‘Survival of virulent legionella pneumophila in aerosols’, Journal of Hygiene, Vol. 90, Iss 3, 1983, pp. 451-460.
  8. EU-OSHA - European Agency for Safety and Health at Work. Working Environment Information. Literature Review. Legionella and Legionnaires’ Disease: A Policy Review. 2011. Available at: http://osha.europa.eu/en/publications/literature_reviews/legionella-policy-overview.pdf
  9. ECDPC A tutorial on the safe use of personal protective equipment. http://ecdc.europa.eu/en/healthtopics/ebola_marburg_fevers/Pages/tutorial-ppe.aspx
  10. ECDPC Fight antibiotic resistance - it's in your hands! http://ecdc.europa.eu/en/press/news/_layouts/forms/News_DispForm.aspx?ID=1612&List=8db7286c-fe2d-476c-9133-18ff4cb1b568&Source=http%3A%2F%2Fecdc%2Eeuropa%2Eeu%2Fen%2FPages%2Fhome%2Easpx
  11. ECDPC Legionnaires' disease outbreak investigation toolboxhttps://legionnaires.ecdc.europa.eu/
  12. ECDPC Toolkit for investigation and response to Food and Waterborne Disease Outbreaks. http://ecdc.europa.eu/en/healthtopics/food_and_waterborne_disease/toolkit/Pages/index.aspx
  13. EU-OSHA - European Agency for Health and Safety at Work, ‘European Risk Observatory Report EN/3 – Expert forecast on emerging biological risks related to occupational safety and health’, 2007. Available at: http://osha.europa.eu/en/publications/reports/7606488
  14. Schmidt, C.W. ‘Trending now – using social media to predict and track disease outbreaks’. Environmental Health Perspectives 20, 2012, pp A30-A33. Available at: http://ehp03.niehs.nih.gov/article/info%3Adoi%2F10.1289%2Fehp.120-a30

Links for further reading

ECDC - European Centre for Disease Prevention and Control. Eurosurveillance weekly bulletin on latest disease data. Retrieved on 18 June 2012, from: http://www.eurosurveillance.org/

HSE - Health and Safety Executive, Infection at work: Controlling the risks. HSE Books, 2003. Available at: http://www.hse.gov.uk/pubns/infection.pdf

HSE - Health and Safety Executive, The management, design and operation of microbiological containment laboratories HSE Books, 2001. Available at: http://www.hse.gov.uk/pubns/priced/microbiologyiac.pdf

HSE - Health and Safety Executive. (no date). Biosafety web pages – with further links to guidance on controlling infections at work. Retrieved 19 June 2012, from: http://www.hse.gov.uk/biosafety/infection.htm

CDC - Centers for Disease Control and Prevention. (2011). Biosafety - Publications and Forms. Retrieved 18 June 2012, from: http://www.cdc.gov/biosafety/publications/index.htm

WHO – World Health Organization. (2012). Global Alert and Response (GAR). Retrieved 18 June 2012, from: http://www.who.int/csr/don/en/index.html