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You are in: Home > Chest Information > Chest Conditions > Tuberculosis > The Spread Of TB

The Spread Of TB

• How does TB spread?
• Who is more likely to catch TB?
• Countries with a high incidence of TB
• What do I do if someone I know has TB?

How does TB spread?

Active TB is infectious and can spread from one person to another. It is spread through droplets in the air when someone with active TB coughs or sneezes. However, it takes close and lengthy contact with an infectious person to catch TB.

Not everyone with pulmonary TB is infectious. Once treatment has started you will normally stop being infectious after approximately 2 weeks as long as you have taken all of your drugs as prescribed. You must, however, continue with the full course of your treatment. Pulmonary TB can also spread, through the bloodstream, and cause infection in other parts of your body.

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Who is more likely to catch TB?

Anyone can catch TB though some people are more at risk than others. This includes people who:

• Have had close and lengthy contact with someone with active TB (e.g. people who live in the same house or are a close family member and / or have had more than a total of 8 hours of close contact since the person became infected)
• Are homeless, sleeping on the streets or living in unhealthy / overcrowded conditions
• Have weakened immune systems due to illness (e.g. HIV infection) or treatment (e.g. chemotherapy, long–term steroid therapy or organ transplant)
• Have diabetes or advanced kidney disease
• Inject drugs or misuse alcohol
• Have been in prison
• Have a poor diet and / or are malnourished
• Have lived, worked or stayed for a long time in a country with a high rate of TB, such as southeast Asia, sub–saharan Africa and some countries in eastern Europe (see table below)
• May have previously been exposed to TB
• Have parents that come from a country with a high rate of TB

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Countries with a high incidence of TB

The table below shows a list of countries with the highest incidence of TB worldwide in alphabetical order:

Afghanistan	Ethiopia	Nigeria	Thailand
Bangladesh	India	Pakistan	Uganda
Brazil	Indonesia	Philippines	Vietnam
Cambodia	Kenya	Russia	Zimbabwe
China	Mozambique	South Africa
Democratic Republic of Congo	Myanmar	Tanzania

Further information about the epidemiology of TB, and about global TB control, is available from the World Health Organisation (WHO).

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What do I do if someone I know has TB?

If you have been in close contact with someone with active TB, and there is a risk you may have the infection, you will be offered screening by a TB specialist.

To catch pulmonary TB you usually need to have close and lengthy contact with a person who has active TB (e.g. you live in the same house or are a close family member and / or have had more than a total of 8 hours of close contact since the person became infected). Sometimes close friends or work colleagues who have spent a lot of time with an infected person will also be offered screening.

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