RetourGeneral
Antimicrobial resistance (AMR) The loss of effectiveness of any anti-infective medicine, including antiviral, antifungal, antibacterial and antiparasitic medicines.
Grading of Recommendations Assessment, Development and Evaluation (GRADE) An approach to grading in health care that aims to overcome the shortcomings of current grading systems. For further information, see the GRADE website.¹
General hospital A health care institution providing medical or surgical (or both) treatment and nursing care for sick or injured people.
General population All individuals, without reference to any specific characteristic.
Health care-associated infection (HAI) An infection occurring in a patient during the process of care in a hospital or other health care facility, which was not present or incubating at the time of admission. HAIs can also appear after discharge. They represent the most frequent adverse event associated with patient care.
Health workers All people engaged in actions whose primary intent is to enhance health (as defined in Chapter 1 of The world health report 2006 – working together for health² ).
Household contact of TB patient An individual who is residing or who had resided in the same household as the infectious TB patient.
Infectiousness Probability of tuberculosis (TB) transmission from an individual with TB disease (usually pulmonary TB) to a susceptible individual through aerosols with droplet nuclei containing viable Mycobacterium tuberculosis while, for example, coughing, sneezing or talking.
Latent TB infection (LTBI) incidence The number of new persons identified with LTBI within a specified period of time.
LTBI prevalence The number of persons identified with LTBI at a given point in time.
Multimodal strategy Several elements or components (at least three, and usually five³ ) implemented in an integrated way, with the aim of improving an outcome and changing behaviour. Such a strategy includes tools (e.g. bundles and checklists) developed by multidisciplinary teams that take into account local conditions. The five most common components are system change (availability of the appropriate infrastructure and supplies to enable infection prevention and control [IPC] good practices); education and training of health workers and key players (e.g. managers); monitoring of infrastructure, practices, processes and outcomes, and provision of data feedback; reminders or communications in the workplace; and culture change within the establishment or strengthening of a safety climate.⁴
TB incidence The number of new and recurrent (relapse) episodes of TB (all forms) occurring in a given year.⁵
TB prevalence The number of TB cases (all forms) at a given point in time.⁵
IPC interventions
Hierarchy of infection prevention and control measures TB prevention and control consists of a combination of measures designed to minimize the risk of M. tuberculosis transmission within populations. A three-level hierarchy of controls comprising administrative controls, environmental controls and respiratory protection has been shown to reduce and prevent the risk of transmission and exposure to M. tuberculosis.
Administrative controls Administrative controls are the first and most important level of the hierarchy. These are management measures that are intended to reduce the risk of exposure to persons with infectious TB.
Environmental controls The second level of the hierarchy is the use of environmental controls to prevent the spread of infectious droplet nuclei and reduce their concentration.
Respiratory protection controls The third level of the hierarchy is the use of respiratory protection control. It consists of the use of personal protective equipment in situations that pose a high risk of exposure to M. tuberculosis.
Mechanical ventilation Ventilation created using an air supply or an exhaust fan (or both), to force air into or out of a room.
Mixed-mode ventilation A ventilation system that combines both mechanical and natural ventilation, providing the opportunity to choose the most appropriate ventilation mode based on the circumstances.
Natural ventilation Use of natural forces to introduce and distribute outdoor air into or out of a building. These forces can be wind pressures, or pressure generated by the density difference between indoor and outdoor air.⁶
Negative pressure mechanical ventilation system A mechanical ventilation system in which the exhaust airflow rate is greater than the supply airflow rate. The room will be at a lower pressure than the surrounding areas.
Positive pressure mechanical ventilation system A mechanical ventilation system in which the supply airflow rate is greater than the exhaust airflow rate. The room will be at a higher pressure than the surrounding areas.
Respiratory hygiene or cough etiquette The practice of covering the mouth and nose during breathing, coughing or sneezing (e.g. wearing a surgical mask or cloth mask, or covering the mouth with tissues or a sleeve, flexed elbow or hand) to reduce the dispersal of respiratory secretions that may contain infectious particles.
Respiratory protection programme A plan of action aimed at accomplishing an effective and sustainable use of particulate respirators by health workers in settings that pose a high risk for M. tuberculosis transmission. The plan includes activity details, responsibilities and timelines, and the means or resources that will be used. Examples of activities are policy development; education and training of health workers; respirator fit-testing; selection of respirator models and sizes; budgeting; procurement of respirators; and installation of signage in high-risk areas of a facility for mandatory respirator use, supervision and disposal.
Respiratory separation / isolation Measures aimed at decreasing or eliminating the risk of airborne M. tuberculosis transmission from infectious individuals to other persons seeking medical attention in a health care facility and health workers; such methods include use of individual rooms or designated units, or timing of care procedures.
Triage In the context of TB IPC, a simple and preliminary system of interventions for identifying people with TB signs or symptoms among those seeking medical attention in health care facilities. Triage is used to fast-track TB diagnosis and facilitate further separation or other precautions, when necessary, to minimize transmission from infectious patients.
Ventilation Provides outdoor air into a building or a room, and distributes air within the building. The purpose of ventilation in buildings is to provide healthy air for breathing by diluting pollutants originating in the building with clean air, and by providing an airflow rate to change this air at a given rate. Ventilation is also used for odour control, containment control and climatic control (i.e. temperature and relative humidity). Ventilation may also be used to maintain pressure differentials to prevent the spread of contaminants outside of a room or to prevent contaminants from entering a room.
Transmission of M. tuberculosis
Airborne M. tuberculosis transmission The spread of aerosolized M. tuberculosis caused by the dissemination of droplet nuclei that remain infectious when suspended in air over long distances and time.
Contagious (infectious) TB patient A patient with pulmonary TB disease (confirmed or undetected) who is able to spread infectious droplet nuclei containing viable M. tuberculosis while coughing, sneezing, talking or conducting any other respiratory manoeuvres.
Droplet nuclei Dried-out residuals of droplets of less than 5 μm in diameter. Respiratory droplets are generated when a person with pulmonary or laryngeal TB coughs, sneezes, shouts or sings. As respiratory droplets dry, before reaching room surfaces, they can become droplet nuclei, which are small and light enough to float in-room air for long enough to spread within confined spaces.
In contrast to droplet nuclei, droplets are generally more than 5 μm in diameter. Droplets settle faster than droplet nuclei and do not reach the alveoli when inhaled.
Person with presumptive TB A person who presents with symptoms or signs suggestive of active TB disease.
Risk of M. tuberculosis transmission The probability of passing M. tuberculosis to another individual. This may be influenced by factors such as the frequency of contact with the source person, proximity and duration of contact, use of respiratory protection, environmental factors (e.g. dilution, ventilation and other air disinfection), infectiousness of the source person and immune status of the exposed person.
TB patient An individual diagnosed with active TB disease (pulmonary or extrapulmonary).
TB symptoms General manifestation of active pulmonary TB disease, including cough for longer than 2 weeks, with sputum production (and could have blood at times), chest pains, fatigue, loss of appetite, weight loss, fever and night sweats.
IPC equipment
Air purifier or air cleaner A portable electrical indoor device intended to remove, inactivate or destroy potentially harmful particles from the circulating air.
Germicidal UV light (GUV) GUV is a modern term for UVGI (see UVGI). The word “irradiation” is removed from the abbreviation to help alleviate end-users’ fears of ionizing radiation, which GUV does not contain.
GUV fixture or luminaire An apparatus that distributes the GUV energy emitted from one or more sources. It does not include the sources themselves, but does include all the parts necessary for safe and effective operation, with the means for connecting the sources to the electricity supply.⁷
Particulate respirator (N95 or FFP2) A special type of closely fitted face cover that has the capacity to filter particles, to protect the wearer against inhaling infectious droplet nuclei.
The N95 respirator has a filter efficiency level of 95% or more against particulate aerosols free of oil, when tested against 0.3 μm particles. The “N” denotes that the respirator is not resistant to oil, and the “95” refers to a 95% filter efficiency.
The FFP2 respirator has a filter efficiency level of 94% or more against 0.4 μm solid particles, and is tested against both an oil and a non-oil aerosol.
(The performance of N95 respirators is approved by the National Institute for Occupational Safety and Health [NIOSH] of the US Centers for Disease Control and Prevention, and the performance of FFP2 respirators must comply with the essential health and safety requirements set out in European directives; that is, with “Conformité Européene” [CE].)
Recirculated air filtration Ventilation systems used in enclosed spaces, buildings, aircraft and vehicles, through which various proportions of outside air and recirculated air are mixed, conditioned and filtered before being fed into the enclosed space.
Respirator fit test A test protocol conducted to verify that a respirator correctly fits the user, to minimize ambient air leakage into the wearer’s respiratory tract. Qualitative fit-testing verifies the respirator’s fit using test agents, either detected qualitatively by the wearer’s sense of taste, smell or involuntary cough (irritant smoke), or measured quantitatively by an instrument. Quantitative fittesting uses ambient aerosols or artificially generated sodium chloride aerosols, and quantitatively measures aerosol concentrations inside and outside the respirator.
Ultraviolet germicidal irradiation (UVGI) The use of ultraviolet light C (UVC) to kill or inactivate microorganisms. UVGI is generated by germicidal lamps, and is capable of killing or inactivating microorganisms that are airborne or on directly irradiated surfaces. Low-pressure mercury-vapour lamps emit UVC.
Upper-room GUV GUV systems that are designed to generate high levels of UVC irradiance above the heads of room occupants, and to minimize UVC exposure in the lower or occupied portion of the room.
Intervention settings
Community setting In the context of health care, a setting (e.g. primary care or other health care facility at community level) where interventions aimed at maintenance, protection and improvement of health status are provided at or near to places of residence.
Congregate settings A mix of institutional (non-health care) settings where people reside in close proximity to each other. Congregate settings range from correctional facilities (prisons and jails), to homeless shelters, refugee camps, army barracks, hospices, dormitories and nursing homes.
Health care facility Any establishment (public or private) that is engaged in direct care of patients on site.
Health care setting A setting where health care is provided (e.g. hospital, outpatient clinic or home).
Inpatient health care setting A health care facility where patients are admitted and assigned a bed while undergoing diagnosis and receiving treatment and care, for at least one overnight stay.
Outpatient health care setting A health care facility where patients are undergoing diagnosis and receiving treatment and care but are not admitted for an overnight stay (e.g. an ambulatory clinic or a dispensary).
Settings with a high risk of M. tuberculosis transmission A setting where individuals with undetected or undiagnosed active TB, or infectious TB patients are present and there is a high risk of M. tuberculosis transmission (see above). TB patients are most infectious when they are untreated (e.g. before diagnosis) or inadequately treated (e.g. undiagnosed drug-resistant TB treated with firstline drugs). Transmission will be increased by aerosol-generating procedures (e.g. bronchoscopy or sputum induction) and by the presence of highly susceptible individuals (e.g. those who are immunocompromised).
Stratification parameters
High burden countries Countries with the highest absolute number of estimated incident cases, and those with the most severe burden in terms of incidence rates per capita. WHO has defined three lists: one for TB, one for MDR-TB and one for TB/HIV.⁸
High TB burden countries The 20 countries with the highest estimated numbers of incident TB cases, plus the 10 countries with the highest estimated TB incidence that are not in the top 20 by absolute number (threshold: >10 000 estimated incident TB cases per year).⁸
High MDR-TB burden countries The 20 countries with the highest estimated numbers of incident MDR-TB cases, plus the 10 countries with the highest estimated MDR-TB incidence that are not in the top 20 by absolute number (threshold: >1000 estimated incident MDR-TB cases per year).⁸
High TB/HIV burden countries The 20 countries with the highest estimated numbers of incident TB/HIV cases, plus the 10 countries with the highest estimated TB/HIV incidence that are not in the top 20 by absolute number (threshold: >10 000 estimated incident TB/HIV cases per year).⁸
High-income countries Defined by the World Bank as countries with a gross national income (GNI) per capita of US$ 12 236 or more in 2016, calculated using the Atlas method.⁹
High TB burden settings Countries or distinct parts of countries characterized by a high burden of TB (TB incidence >100/100 000 population).10 Low- and middle-income countries usually match this definition.
Low- and middle-income countries Defined by the World Bank as countries with a GNI per capita, calculated using the World Bank Atlas method,⁹ of US$ 12 235 in 2016. This group includes lowincome countries (GNI per capita <US$ 1005); lower middle-income countries (GNI per capita of between US$ 1006 and US$ 3955) and upper middle-income countries (GNI per capita of between US$ 3956 and US$ 12 235).
Low TB burden settings Countries or distinct parts of countries characterized by a low burden of TB (TB incidence <10/100 000 population).¹⁰ High-income countries usually match this definition.
1 See http://www.gradeworkinggroup.org
2 Health workers, in: The world health report. Geneva: World Health Organization; 2006 (https://www.who.int/whr/2006/06_chap1_en.pdf, accessed 18 December 2018).
3 Evidence-based care bundles. Institute for Healthcare Improvement; (http://www.ihi.org/topics/bundles/Pages/default.aspx, accessed 18 December 2018).
4 Guidelines on core components of infection prevention and control programmes at the national and acute health care facility level. Geneva: World Health Organization; 2016 (http://www.who.int/gpsc/core-components.pdf, accessed 18 December 2018).
5 Methods used by WHO to estimate the global burden of TB disease. Geneva: World Health Organization; 2018 (https://www.who.int/tb/publications/global_report/gtbr2018_online_technical_appendix_global_disease_burden_estimation.pdf?ua=1, accessed 18 December 2018).
6 Atkinson J, Chartier Y, Pessoa-Silva CL, Jensen P, Li Y, Seto W-H, (eds). Natural ventilation for infection control in health care settings. Geneva: World Health Organization; 2009 (https://www.who.int/water_sanitation_health/publications/natural_ventilation.pdf, accessed 18 December 2018).
7 International lighting vocabulary (CIE S 017/E:2011). International Commission on Illumination; 2011 (http://www.cie.co.at/publications/international-lighting-vocabulary, accessed 18 December 2018).
8 Use of high burden country lists for TB by WHO in the post-2015 era. Geneva: World Health Organization; 2015 (https://www.who.int/tb/publications/global_report/high_tb_burdencountrylists2016-2020summary.pdf, accessed 18 December 2018).
9 The World Bank Atlas method: detailed methodology. Washington, DC: The World Bank; (https://datahelpdesk.worldbank.org/knowledgebase/articles/378832-the-world-bank-atlas-method-detailed-methodology, accessed 18 December 2018).
10 Clancy L, Rieder HL, Enarson DA, Spinaci S. Tuberculosis elimination in the countries of Europe and other industrialized countries. Eur Respir J. 1991;4(10):1288-95 (https://erj.ersjournals.com/content/4/10/1288, accessed 18 December 2018).
