Tuberculosis (TB)

Causes

Tuberculosis (TB) is caused by a type of bacterium called Mycobacterium tuberculosis.

It's spread when a person with active TB disease in their lungs coughs or sneezes and someone else inhales the expelled droplets, which contain TB bacteria.

Although TB is spread in a similar way to a Cold or the flu , it isn't as contagious.

You would have to spend prolonged periods (several hours) in close contact with an infected person to catch the infection yourself.

For example, TB infections usually spread between family members who live in the same house. It would be highly unlikely for you to become infected by sitting next to an infected person on a bus or train.

Not everyone with TB is infectious. Children with TB or people with a TB infection that occurs outside the lungs (extrapulmonary TB) don't spread the infection.

Latent or active TB

In most healthy people, the immune system is able to destroy the bacteria that cause TB.

Butin some cases, the bacteria infect the body but don't cause any symptoms (latent TB), or the infection begins to cause symptoms within weeks, months or even years (active TB).

Up to 10% of people with latent TB eventually develop active TB years after the initial infection.

This usually happenseither within the first year or two of infection, or when the immune system is weakenedfor example, if someone is having chemotherapy treatment for cancer.

Who's most at risk?

Anyone can get TB, but those at greatest risk includepeople:

who live in, come from, or have spent time in a country or area with high levels of TB around three in every four TB cases in the UK affect people born outside the UK
in prolonged close contact with someone who's infected
living in crowded conditions
with a condition that weakens their immune system, such as HIV
having treatments that weaken the immune system, such as chemotherapy or biological agents
who are very young or very old the immune systems of people who are young or elderly tend to be weaker than those of healthy adults
in poor health or with a poor diet because of lifestyle and other problems, such as drug misuse , alcohol misuse , or homelessness

Medically Reviewed by a doctor on 22 Nov 2016

Articles for tuberculosis (tb)

Introduction

Tuberculosis (TB) is a bacterial infection spread through inhaling tiny droplets from the coughs or sneezes of an infected person. It mainly affects the lungs, but it can affect any part of the body, including the tummy (abdomen) glands, bones and nervous system.

Symptoms

The symptoms of tuberculosis (TB) vary depending on which part of the body is affected. TB disease usually develops slowly, and it may take several weeks for you to become aware that you're unwell. General symptoms include lack of appetite, weight loss, fever, night sweats and extreme tiredness.