Prevention of Tuberculosis: A Review of Guidelines [Internet]

Excerpt

Tuberculosis (TB) is an infectious disease caused by the bacteria Mycobacterium tuberculosis and is transmitted through the air by those who are infected with the bacteria (i.e., coughing). According to the World Health Organization, roughly a quarter of the world’s population is infected with M. tuberculosis and may be at risk for developing the disease. TB typically affects the lungs of a person (i.e., pulmonary TB) but can also spread to other parts of the body (i.e., extrapulmonary TB). Individuals with TB are categorized into latent TB infection (LTBI) and active TB disease.^, LTBI refers to an individual whom does not have TB disease and may not possess any symptoms but has the M. tuberculosis infection. Persons with LTBI cannot spread TB infection to others and are not considered infectious. However, those with the LTBI can develop TB disease if they do not receive proper treatment or have a compromised immune system. TB disease (also known as active TB) occurs when the TB bacteria begins to multiply and the individual’s immune system is compromised, leading to infection. Symptoms can progress right away or can develop long after infection, depending on the individual. Symptoms can vary between individuals who have TB infection but often experience weight loss, fever, fatigue, chills, excessive coughing and chest pain. In comparison to LTBI, persons with TB disease can spread the TB bacteria to others and are considered infectious.

TB continues to be burdensome in developing countries as the disease is associated with poverty, poor sanitation or hygiene practices and being easily transmissible from person to person. Although TB is more common and prevalent in low and middle income countries, high income, countries including Canada, still report cases of TB and it is considered an important public health matter. According to the Public Health Agency of Canada (PHAC), Canada has one of the lowest rates of active TB in the world. However, annual rates of TB have remained the same in the country since the 1980’s rather than steadily declining. In 2017, PHAC reported 1,796 cases of active TB in Canada with migrants and Indigenous peoples bearing the highest rates of active TB in the country and approximately 70% of cases being pulmonary TB.^, Migrants and Indigenous peoples are not the only populations that are at higher risk of TB infection in Canada. Workers travelling to areas with a high incidence of TB, and those individuals who are immunocompromised (e.g., patients living with HIV, children, infants) or workers (e.g., healthcare professional) who are in direct contact with immunocompromised people are also at high risk of TB infection. Additionally, homeless persons, prison staff and inmates are considered high-risk populations due to the proximity to others and conditions that enable the transmission of TB bacteria.

Prevention and infection control are necessary to reduce the spread of TB. There are a variety of preventative mechanisms used by public health organizations to reduce the transmission of TB. For example, the Bacillus Calmette-Guérin (BCG) vaccine, which is approved for the prevention of TB, may be administered at birth in countries with high incidence of TB. While educating health care staff about TB and screening health care workers for LTBI may be appropriate preventative measures to reduce the spread of TB disease in hospital settings. Depending on the setting and the population at risk, the interventions used for the prevention of TB may differ. There are multiple guidelines published about TB, and these guidelines may vary in quality and the topics covered. The purpose of this report is to review and critically appraise the evidence-based guidelines regarding interventions for the prevention of TB. This report is part of series of evidence reviews on TB guidelines. This report can serve as a guidance document to identify which guidelines include recommendations for specific prevention methods and specific populations of interest, and the strength of the guidelines.

This report is a component of a larger CADTH Condition Level Review on TB. A condition level review is an assessment that incorporates all aspects of a condition, from prevention, detection, treatment, and management. For more information on CADTH’s Condition Level Review of TB, please visit the project page (https://www.cadth.ca/tuberculosis).