key: cord-0040163-jhyc0iu8 authors: Aw, Tar-Ching; Blair, Iain; Babcock, Hilary M. title: Occupational Infections date: 2016-08-12 journal: Infectious Diseases DOI: 10.1016/b978-0-7020-6285-8.00072-1 sha: 9bbcdd811fd3796102226ad4563dcba7aae83714 doc_id: 40163 cord_uid: jhyc0iu8 nan TAR-CHING AW | IAIN BLAIR | HILARY M. BABCOCK 72 may acquire these infections. As the working environment becomes ever more complex, there is the potential for new occupational infections to emerge. Infections acquired occupationally may spread to other workers or the workers' families or social contacts. As with any infection, occupational infections are controlled by controlling the source of infection, its route of transmission and by protecting susceptible persons. Most occupational infections can be prevented if appropriate measures are implemented. Some occupational infections, especially those for which vaccines are available (e.g. hepatitis B), are more amenable to prevention than others (e.g. hepatitis C). Health education and preventive programs in the workplace provide a good system for minimizing the risk of occupational infections. The largest employer in the United Kingdom -the National Health Service -has a requirement for every healthcare facility to have access to an occupational health service. In the USA, both voluntary guidance and regulatory and certification requirements for healthcare facilities set standards for practices to protect employees from infectious hazards in the workplace, through infection prevention and occupational health programs. This has helped reduce the burden of occupationallyacquired infections in the healthcare community. 3, 4 In the US, the Occupational Safety and Health Administration (OSHA) also provides guidance and regulatory requirements for worker safety in other industries. These systems are not as well developed in some other industries where there is a recognized risk of occupational infections (e.g. in farming). This chapter includes primarily perspectives from the USA and UK and describes some of the guidance and structures for public health and occupational health practice that will be found there. Similar arrangements can be expected in most industrialized countries. The Centers for Disease Control and Prevention (CDC) in the USA have published guidelines for preventing the transmission of infectious diseases in the healthcare workplace. These are available at http:// www.cdc.gov/hicpac/2007ip/2007isolationprecautions.html and http://www.cdc.gov/hicpac/pdf/infectcontrol98.pdf. The US National Institute for Occupational Safety and Health (NIOSH), which is part of CDC, has also published research and recommendations on most aspects of work-related injury and illness including infections (see http://www.cdc.gov/niosh/topics/diseases .html). In the UK, the Health and Safety Executive (HSE) has a useful website that provides valuable guidance (http://www.hse.gov.uk/ health-surveillance/). The Australian Safety and Compensation Council (ASCC) provides policy advice on all aspects of occupational health and safety to allow local legislators to enact and enforce laws. Reports of occupational diseases are published frequently that demonstrate decreasing trends in most reportable occupationally-acquired infections in Australia. 5 The traditional model of infectious disease causation is the epidemiologic triangle. It has three components: an external agent, a susceptible host and environmental factors that bring the host and the agent together to produce an infection. 1 Occupational infections are defined by two of these components. Particular infectious agents or organisms may be associated with a workplace or occupational setting and specific work activities may predispose the worker to exposure, resulting in an occupational infection. Although difficult to quantify, occupational infections are probably uncommon when compared to those that result from non-occupational activities or environments. Infections can only be confidently attributed to occupational exposure as a result of careful epidemiologic investigation. Case reports, surveillance data and cross-sectional surveys may lead to a hypothesis that a particular infection is diagnosed more commonly in one or other group of workers. However, in order to accurately estimate an odds ratio or relative risk, a carefully designed, adequately powered, case-control or cohort study will be required. Assuming that bias and confounding factors can be adequately controlled, it may then be possible to satisfy the Bradford Hill criteria for causation. 2 Few infections have been subject to this rigorous approach. In the individual case where an occupational infection is suspected or when a source of infection is unclear, it is important to take an adequate occupational history. A workplace visit to assess the system of work can help confirm the likelihood of the infection being acquired through workplace factors. 3 A high index of suspicion will ensure that occupational infections are not missed. If an occupational source is not recognized there will be a continuing risk to other workers in the same work area, and the affected individual may be at risk of re-infection on return to work, especially if full immunity following the initial infection does not occur. A number of occupational infections that are of historical interest in higher-income countries are still found in low-and middle-income countries (LMIC), and staff who are traveling to work in those areas • Occupational sources of infection should be considered and actively sought in the evaluation of a patient with an infection. • Attributing an infection to an occupational source requires knowledge of the details of the patient's job duties, as well as pathogen reservoirs and likely routes. • Controlling occupational infections requires controlling the source of the infection as well as interrupting its route of transmission. • Most countries have regulations in place to minimize the risks of occupational diseases through safe work practice guidance, protective equipment use and immunizations. • Detailed information is provided in the chapter tables. can be acquired both at work and in the community, making attribution difficult. A range of data sources are available. The examples described here are from the USA and UK but similar systems may be found in other countries. It is a legal requirement in the USA and the UK for clinicians to report certain specified infectious diseases to local health authorities. In the USA, there are both national and state reporting requirements. The list of notifiable infections covers common infections (including viral hepatitis and tuberculosis) that may be occupationally acquired, as well as rarities such as rabies, anthrax and plague. Microbiology laboratories must also report micro-organisms of public health significance to local health authorities. Outputs from these surveillance schemes can be viewed at http://www.hpa.org.uk/infections/topics_az/ noids/menu.htm for the UK and http://wwwn.cdc.gov/nndss/ for the USA. In neither of these systems is the occupation of the case patient requested or recorded. Local and national health authorities may enhance the data that are collected as part of case investigation and management, and this may include occupation and other relevant risk factors. However, such additional data are not consistently collated, analyzed or disseminated and, when available, are susceptible to ascertainment and reporting bias. An exception is occupationallyacquired HIV in the US for which there is surveillance through a voluntary reporting system (http://www.cdc.gov/HAI/organisms/hiv/ Surveillance-Occupationally-Acquired-HIV-AIDS.html). Other occupational surveillance schemes in the UK also occasionally report occupational infections. Outputs from these surveillance schemes can be viewed at http://www.hse.gov.uk/statistics/tables/. In the UK, the Industrial Injuries Disablement Benefit (IIDB) Scheme provides benefits to employees if they develop a prescribed occupational disease. Diseases are prescribed when there is a recognized risk to workers in an occupation and where the risk is uncommon or absent in the general population. For some occupational diseases there is a strong association with occupation and the disease rarely occurs outside work (e.g. mesothelioma, coal miner's pneumoconiosis). However, most infections are common in the general population and it is difficult to establish a causal link with the occupation. In lay terms an infection will be attributed to an occupation if it is more likely than not to be caused by that occupation. In epidemiologic terms this means an attributable fraction (the proportion of the additional risk that can be attributed to the exposure in the exposed population) of 50% or more, which equates to a relative risk of two (a doubling of the background risk caused by exposure). Prescribed infections include: • anthrax where work involves contact with animals infected with anthrax, or the handling of animal products or residues; The control of any occupational infection requires a detailed knowledge of its epidemiology, clinical features, reservoir, mode of transmission, incubation period and communicable period. To prevent and control infection, measures are necessary to eliminate the source of infection and the route of transmission. Susceptible workers can be offered protection with personal protective equipment (e.g. masks, gloves), antibiotics or immunization. Many higher-income countries require employers to assess the risks from exposure to all hazardous substances (including biologic agents) and to implement measures to protect workers and others from those risks as far as is reasonably practicable. Following a workplace risk assessment, exposure to potential infection should be eliminated by changing working practices and removing hazardous products or waste. Residual risk is controlled by promoting good occupational hygiene and environmental hygiene, and by focusing on design and engineering controls. Staff training and provision and use of personal protective equipment (PPE) are key measures (Table 72-2) . All workers should be fully immunized according to the routine immunization schedule of their country. In addition, selective immunization may be recommended for groups of workers at increased risk 9, 11, 12 (Table 72-3) . Laboratory and pathology staff handle pathogens or potentially infected specimens, and mortuary staff are potentially exposed to infected cadavers. 13 There are many infections that can be acquired through work activities or from workplaces (Table 72- 5) . The recognition of occupational factors as an important component in the transmission of these infections will aid in the management of affected cases, and in prevention. Continuing vigilance for new occupational infections, advances in preventive measures and an experienced occupational health team working with infection control specialists are key to the successful prevention of these infections. References available online at expertconsult.com. Not recommended in the USA. In some countries, recommended for microbiology and pathology staff, mortuary staff and others at high risk of exposure Healthcare staff with varicella and nonimmune healthcare staff who have been exposed to varicella require active management (with vaccination, furlough and possibly postexposure prophylaxis) to prevent spread to vulnerable patients 17 Persons with influenza will be urged to stay at home, cough etiquette and enhanced hygiene will be encouraged, affected persons will receive a course of antiviral treatment, business continuity plans will mitigate the effects of absenteeism, nonessential services may be suspended, social distancing measures may be introduced National strategic plans and detailed guidance can be viewed at http://www.cdc.gov/ flu/pandemic-resources/ index.htm and https:// www.gov.uk/pandemic-flu Hepatitis B is a subacute viral infection of the liver. The initial illness may be severe and a chronic carrier state may develop, leading after some years to cirrhosis and hepatocellular carcinoma Hepatitis C is also a viral infection of the liver. The initial illness is often asymptomatic but 80% of those infected develop chronic infection that may result in cirrhosis and hepatocellular carcinoma Human cases and carriers are the source of infection and transmission is by the blood-borne route. Hepatitis B is also transmitted by the sexual route and vertically from mother to infant Healthcare workers and laboratory staff who are exposed to blood and tissues from infected patients are at risk. Other groups of workers such as tattooists and body piercers may also be at risk Humans are the source of infection and spread is by the blood-borne, sexual or vertical route Healthcare workers and laboratory staff who are exposed to blood and tissues from infected patients are at risk In the USA there have been 58 cases of documented HIV seroconversion following occupational exposure in healthcare workers with only one occurring since 1999. 21 In the UK there have been 5 with none occurring since 2004. 22, 23 Standard infection control precautions should be followed (including use of PPE and safe handling of needles and sharp instruments) for all patients Postexposure prophylaxis (PEP) with antivirals is recommended for healthcare workers who are exposed to HIV-infected patients' blood or body fluids. 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