Tuberculosis (TB) is a bacterial infection which mainly affects the lungs.
Following a push towards eradicating the infection in the UK, Public Health England's senior TB specialist nurse uncovers some surprising facts exclusively for Nursing in Practice.
1. TB is a disease of past centuries and is almost eradicated now
About one third of the world’s population is infected with tuberculosis (TB). TB remains one of the world's top infectious killers. No country in the world has eradicated TB.
In the UK, in 2012, a total of 8,751 cases of TB were reported. The incidence of TB in the UK remains high compared to most other Western European countries. TB in the UK has remained relatively stable since 2005, following a rise in the previous two decades.
2. TB disease occurs only in the lungs
TB usually affects the lungs, but can also affect almost any other area of the body. Only 53% (4,563/8,659) of TB cases reported in the UK in 2012 where site of disease was known had pulmonary disease. Over one in five cases with pulmonary disease were also reported to have extra-pulmonary disease in at least one additional site.
3. Only people in certain risk groups can get TB
While TB in the UK now disproportionately affects people born in countries with a high burden of TB (such as Africa, South East Asia or Russia) certain ethnic minority groups and those with social risk factors, anyone who has close prolonged contact with an infectious case of TB can acquire the infection.
4. Anyone with TB disease can transmit TB
Not all people with TB are infectious. Infectivity depends on the site of disease. Only some people with TB in the lungs or larynx are infectious to other people. People with infectious TB usually cease to be infectious after a couple of weeks of the proper treatment. Left undiagnosed or if non-adherent to treatment, a person with infectious TB can infect up to 10-15 close contacts over the course of a year.
5. TB is easy to catch
Unlike some infectious diseases like influenza and measles, TB is not easily spread by casual contact. TB isn’t spread by touch, handshaking or hugging, or through bed linen or utensils. The TB bacterium is usually spread though droplets in the air released when a person with sputum smear positive or laryngeal TB coughs or sneezes.
Those who have had close and prolonged contact sharing the same airspace with an infectious case, particularly those living in the same household, are most at risk of becoming infected.
6. People with latent TB infection can spread TB
People with latent TB infection have dormant TB bacteria in their body. The only sign that someone has latent TB infection is a strongly positive reaction to the tuberculin skin (Mantoux) test and/or TB specific blood test (Interferon Gamma Release Assay (IGRA)). People with latent TB infection don’t have symptoms, and cannot pass TB onto others.
7. Everyone with latent TB infection will develop TB disease
Only about 5 to 10% of people infected with TB will develop TB disease at some time in their lives. About half of those who develop TB will do so within the first two years of infection. The risks of developing TB disease are much higher in people with weak immune systems than for people with normal immune systems.
If a person falls into high-risk groups for disease progression, the TB specialist team will discuss with them the option for preventive treatment.
8. Free TB treatment is not available for everyone in the UK
Regardless of a person’s status in the UK, everyone is entitled to free treatment for TB; this includes free hospital care. TB is treatable and curable. Early diagnosis and patient-centred treatment support strategies are essential elements to ensure a positive outcome for the individual and in cases of infectious TB, to minimise onward transmission of infection.
9. Multidrug resistant (MDR) TB is much more infectious
Patients with MDR tuberculosis are not more infectious than those with fully sensitive tuberculosis during the same time period. However, people with infectious MDR TB will take much longer than a couple of weeks to cease to be infectious once they start treatment. A longer infectious period does provide greater opportunity for transmission.
10. BCG gives full protection against TB in everyone
The BCG vaccine does not always protect people from getting TB. However, it is very effective at protecting young children who are at increased risk of exposure to TB infection against developing severe disease (e.g. miliary and meningitis). Efficacy in protecting adolescents and young adults has varied widely depending on location, ranging from 0% in South India to 80% in the UK.
It is now thought that previous infection with any mycobacteria can lower the protection provided by the vaccine. This indicates the importance of giving the BCG vaccine to eligible individuals as early as possible, ideally soon after birth.
Senior TB Specialist Nurse - Public Health England
Surinder Tamne works as a Senior TB Specialist Nurse for Public Health England at the Centre for Infectious Disease Surveillance and Control. She provides clinical and public health advice on tuberculosis prevention and control to health and allied professionals.