Friday December 17 2010
TB had been virtually eradicated, but is now rising
London is “the TB capital of Europe”, The Daily Telegraph has reported. The newspaper says that Britain is now the only nation in Western Europe with rising levels of tuberculosis, with more than 9,000 cases diagnosed annually. In London, where 40% of UK cases are reportedly diagnosed, the number of cases has risen by almost 50% since 1999, up from 2,309 in 1999 to 3,450 in 2009.
The Guardian has also discussed the rising prevalence of the disease, which was detailed in a report on the modern TB situation in London, as well as the UK as a whole. The report’s author, Professor Alimuddin Zumla of University College London, attributes the rise to people living under “Victorian” conditions, with poor housing, inadequate ventilation and overcrowding in certain deprived areas of London.
Professor Zumla has also observed that the increase in TB cases has been predominantly among people born outside the UK, but who appear to have been infected here, rather than in their country of origin. He has called for the implementation of a London-wide strategy to help control the disease.
What is tuberculosis?
Tuberculosis is a disease caused by the bacterium Mycobacterium tuberculosis. Infection predominantly affects the lungs, though it can spread via the blood to affect other organs. Like other respiratory infections, TB is spread by airborne droplets passed on through sneezing and coughing. It is mostly spread through prolonged contact with an infected person. TB differs from other airborne infections such as colds and flu in that it is not typically passed on by short-term contact, such as when using public transport.
When initially infected, a person may have no symptoms and can remain without symptoms for a long time. However, if the person’s immune system is weak, the infection can progress to active disease and the person is likely to develop:
- a persistent productive cough that brings up sputum or phlegm, which may contain blood
- fever and sweating
- general symptoms of illness, such as fatigue
- weight loss
As such, the symptoms of TB need to be distinguished from those of chronic bronchitis, pneumonia or cancer, which are similar. The disease is usually diagnosed using X-rays and laboratory examination of sputum samples, and is treated with a combination of antibiotics over a prolonged period of at least six months.
Tuberculosis is known to occur more often in areas of deprivation, where poor living conditions, poor nutrition and poorer health are more common. Those with a depleted immune system and poorer general health are at increased risk, for example, people with HIV, alcoholics and those who are malnourished.
What is the basis for the current reports?
The news stories follow a narrative review authored by Professor Alimuddin Zumla, a consultant in infectious disease at University College London Hospital and the director of the Centre for Infectious Diseases and International Health at University College London Medical School. The review was published in The Lancet medical journal.
Professor Zumla discusses the history and resurgence of what was known in the Victorian times as consumption, or ‘the white plague’, due to the pale complexion of sufferers. In the 1800s up to 25% of deaths in Europe were attributed to TB. In the 1900s, however, improved housing, nutrition and economic status brought a decline in prevalence, which was then reduced greatly by the advent of anti-tuberculosis drugs in the 1960s.
By the 1980s, TB was considered to be almost eradicated in the UK. However, this is said to have changed again with the increase in travel and migration. The review suggests that the poorer socio-economic status and living conditions experienced by certain population groups have led to a gradual re-emergence of TB as a public health problem in Europe.
The review gives an overview of the modern toll of TB, saying that:
- Currently 1.7 million people die of tuberculosis globally each year.
- Incidence in the UK has gradually increased over the past 15 years, with more than 9,000 cases reported in 2009, a rate of 14.6 per 100,000 population. This is said to contrast with a general decline seen in other western European countries, with the UK being the only European country where TB rates continue to rise.
- In London, the number of cases has risen by almost 50% since 1999, up from 2,309 in 1999 to 3,450 in 2009. London now accounts for almost 40% of all TB cases in the UK.
- The increase in the number of tuberculosis cases in the UK has largely been in non-UK born groups. In 2009, these included black African (28%), Indian (27%), and white people (10%). However, 85% of individuals born overseas had lived in the UK for at least two years prior to being diagnosed, i.e. they were not recent immigrants. This suggests transmission may have occurred after they had arrived in the UK.
- Poor living conditions are known to be associated with TB and, in particular, the author considers prisons to be “ideal breeding grounds”. He quotes a four-year study (2004–07) of 205 prisoners with newly-diagnosed TB that demonstrated that, compared with all other cases in the UK during that period (29,340 in total), prisoners were more likely to be UK born (47% versus 25%) and to be white (33% versus 22%). Only 48% of prisoners diagnosed with active disease completed treatment, and 20% were lost to follow-up.
As the current figures reflect only reported cases, the true disease prevalence may be even higher. The narrative highlights the need for healthcare professionals in the UK, and particularly London, to have heightened awareness of TB as a possible cause of disease in their patients in order to improve diagnosis. The author also raises the problem of antibiotic resistance that has been observed in certain cases over the past 10 years, particularly those occurring among people in prison. This highlights the need for people to complete full courses of antibiotic treatment.
What does the author conclude?
The author says that the current situation in London has similarities with previous outbreaks of drug-resistant TB in the US in the 1990s, where a large amount of financial investment and government support was required to regain control of the disease through the clear establishment of clinical policy and protocol.
The author also says that there is now a need to implement the recommendations of a recent London tuberculosis service review, which has suggested steps such as standardising the various testing and treatment methods used in different areas.
What else do I need to know about TB?
The BCG (Bacillus Calmette-Guerin) vaccination exposes the person to a weakened Mycobacterium strain, causing them to develop immunity against TB. In the UK the vaccine is no longer given routinely, but is given to those expected to be at higher risk of disease, which includes certain professionals (for example, healthcare workers, and people working in homeless shelters and refugee hostels), immigrants coming to the UK from high-incidence areas and infants born into high-incidence areas such as inner London or whose parents come from high-incidence areas.
Anyone with a cough, productive or not, that has persisted for more than a few weeks should consult their doctor, as should any person with feverish symptoms, unexplained weight loss, general fatigue and loss of appetite. These could be signs not only of TB, but of other serious illness.
As stated, TB is a curable disease, as long as a prolonged course of antibiotics is followed. However, as with any antibiotic treatment, failing to complete a full course can lead to the development of antibiotic resistant strains of bacteria.
Tuberculosis is a ‘notifiable disease’ and, by law, government authorities must be informed of any cases identified. This information is gathered by the UK Health Protection Agency, which says that around 9,000 cases of TB are reported each year in the United Kingdom, with most cases occurring in major cities, particularly London. The HPA says it is committed to supporting the NHS and the Department of Health in controlling TB in UK.