Epidemiology

According to the World Health Organization (WHO), every year an estimated 10 million people develop TB, and there are an estimated 1.5 million TB-related deaths annually. (1)

• over 90% of TB cases occur in low and lower-middle income countries, but a global resurgence also affecting high income countries
• the majority of deaths (82% of HIV-negative and HIV-positive TB deaths) are in the WHO African Region and South-East Asia Region (2)
• countries of Asia such as India, China, Indonesia, Pakistan and Bangladesh have the largest number of cases. Note though that there have been striking increases in the number of cases in the former Soviet Union and in sub-Saharan Africa
• in parallel with a global epidemic of HIV, M. tuberculosis co-infection has become more common, ranging from less than 1 per cent in the Pacific islands, as high as 11 per cent in some areas of the UK, to over 60 per cent in countries such as Zambia, Zimbabwe and South Africa. TB is particularly devastating in areas with high prevalence of HIV infection (3)
• in the developed world, the disease is more common in some sections of society eg alcoholics, undernourished, ethnic communities, the elderly, and HIV positive individuals. The disease is also more common in patients after gastrectomy for peptic ulcer
• in 2021(4)
  • TB incidence in England was 7.8 per 100,000, below the World Health Organization (WHO) threshold for a low incidence country (less than or equal to 10 per 100,000 population)
  • TB incidence was not evenly distributed across the country and was concentrated in particular large urban areas
    • people with TB are concentrated in large urban areas, with the 2 highest notification rate local authority areas being Newham (London) at 41.4 per 100,000, and Leicester City (East Midlands) at 40.3 per 100,000
  • the majority of people with TB in England were born outside the UK
  • TB in England continued to disproportionately affect the most deprived populations
  • infectious pulmonary TB disease remained more likely in males, people with a history of imprisonment and people with a history of drug and alcohol misuse
  • social risk factors were more common in the UK-born population with TB, with drug or alcohol misuse and history of imprisonment more common compared with the non-UK-born population with TB
  • in the non-UK-born population with TB, homelessness, asylum seeker status and mental health needs were more common than in the UK-born population with TB
  • more than half (52.8%) of people notified with TB in England had pulmonary infection (that is, the lungs and respiratory tract) and are therefore at risk of transmitting infection to others
    • proportion has remained stable over time
    • pulmonary TB is much more common in UK-born people with TB, comprising 69.9% of TB notifications in this group, compared with 47.5% in non-UK-born individuals
    • a history of having been in prison was strongly associated with pulmonary disease, recorded in 74.1% of individuals with this risk factor

Reference:

• 1. World Health Organization. Health topics: tuberculosis [internet publication].
• 2. World Health Organization. Global tuberculosis report 2022. Oct 2022 [internet publication].
• 3. Dye C. Global epidemiology of tuberculosis. Lancet. 2006 Mar 18;367(9514):938-40.
• 4. UK Health Security Agency (March 2023). TB incidence and epidemiology in England, 2021.