Once thought to be almost eradicated, TB is making a comeback. Why here and why now, asks Anne Dempsey
Tuberculosis is on the rise again in Ireland, according to the latest figures released by the National Disease Surveillance Centre. There were 395 cases reported in 2000, 378 in 2001 and 400 last year. This represents 17.1 cases per 100,000 of the population last year compared to 10.2 per 100,000 in 2001 and 9.6 the previous year.
The figures come hard on the heels of reported plans to phase out specialist tuberculosis (TB) services facilities at Peamont Hospital, Newcastle, Co Dublin. However, this is exactly the wrong move, says Prof Luke Clancy, the medical director of Peamont and consultant respiratory physician at St James's Hospital.
"If we are to eradicate TB, we need a TB centre of excellence. We need to preserve the embedded knowledge rather than dissipate it. In Ireland we have the best treatment results in the world because of the expertise that has been built up over 50 years. In countries like ours with a low incidence of TB, dismantling these structures is precisely the wrong way to go."
The demise of TB has long been trumpeted and has always been premature. Fifty years ago, medical students were told to avoid specialising in infectious diseases because it was literally a dying field. Public health leaders believed they had TB on the run, a rout which would soon show itself in declining statistics worldwide. In this they were massively incorrect.
Today the World Health Organisation estimates that by 2020 approximately one thousand million people worldwide will be newly-affected with TB, more than 150 million will get sick and 36 million will die of the disease. Despite the promises that it would disappear forever, it's clear that Mycobacterium Tuberculosis, the rod-shaped bacterium that causes TB, hasn't gone away.
The reasons why TB is still with us and gaining ground are discussed in a recently-published book, The Return of the White Plague. Edited by British-based geography teacher Matthew Gandy and infectious disease specialist Alimuddin Zumla, it gives the history and context of the disease, looks at the present global burden of TB, and advocates future action.
In past centuries, a litany of well-known artistic figures died of TB, including the Brontë Sisters, Anton Chekhov, Chopin, D.H. Lawrence and the fictional Mimi in La Bohème. The poet John Keats describes feeling blood in his mouth, fetching a candle to examine it and writing "I cannot be deceived, that drop of blood is my death warrant".
In researching early TB in Ireland, the Irish Red Cross Journal in 2000 notes that 12,000 young Irish adults died of TB in 1904. Mortality remained high in the 1920s and 1930s, and by the 1948 general election, the problem had become heavily politicised, with charges that the government had not responded adequately to the epidemic. "The fear and loathing surrounding TB is well-captured in Noel Brown's book Against the Tide," says Prof Clancy.
By the 1950s, the development of the Bacille Calmette-Guerin vaccine, (BCG) named after its creators, French scientists Albert Calmette and Camille Guerin, and better drug therapies had revolutionised treatment. BCG vaccination helps to prevent progression from infection to illness while anti-TB drugs may cure infected patients. Within 30 years, the rate of TB mortality in the developed world, including Ireland, had fallen by 90 per cent.
So why is it back? The new book on the subject is subtitled "global poverty and the new tuberculosis" and argues that all major societal change, including war, migration and land use, is also a public health event with its own pattern of diseases, so that responding with a medical model only will always be insufficient. So while TB seemed to be under control by the 1970s, it made a startling comeback in the 1980s arising, they say, from shifting patterns of poverty and inequality, the spread of HIV and the emergence of new virulent drug-resistant TB strains. Prof Clancy says up to one in three Irish people has latent TB today, and while this is distributed through the age range, the over 60 population account for 20 per cent of all latent infection which is triggered quite simply by contact.
"The reasons why some people are still contracting TB in Ireland is because they come in contact with it. Anybody can get TB. If a lot of people have it, then a lot of people will get it. Some 90 per cent of elderly people have latent TB, five to 10 per cent of younger people probably have latent infection. The more TB in the population the more people will contract it. There is also a proven link between smoking and TB in that smokers have more bacteria in the lung and are more vulnerable to reinfection.
"Years ago when our sanitoria were full of people with TB there seemed to be a preponderance of young, beautiful girls. I came to understand that because TB was in the population, popular, good-looking girls socialising with lots of people were more exposed to TB and so more likely to contract it.
"However, the decline in overall incidence is also closely linked with improvements in socioeconomic conditions. In earlier times, we were living closer together, sometimes three or four to a bed. If one member of the family got it, they all got it.
"Now people have their own rooms, space is better, we no longer spit. Today the most vulnerable to TB are older people, young adults in poor circumstances, adolescents where hormonal changes can trigger infection, susceptible infants and people with HIV. You are 200 times more likely to develop TB if you have HIV than if you didn't, and multi-drug resistant TB is linked to people with HIV who are more difficult to treat because they have drug intolerance."
About 10 people in Ireland per year die of TB, typically overwhelmed by the destructive effects of the disease which attack vital organs. "The infection wins", says Prof Clancy. Becoming complacent about TB has crucial consequences from primary care onwards.
"TB often goes unrecognised. We analysed delay in diagnosis, and found it was two to three months at GP level, and four weeks after the patient was admitted to hospital. If you think you have beaten TB, you're not looking for it. This delay adds to the progression of the disease and means that the person is infecting 10 others if they are left untreated."
Typical symptoms of TB are a phlegmy cough that lasts for three to four weeks or a change in an existing cough. Coughing up blood rings alarm bells and one in five TB cases is caught in that way. "Another cardinal one is night sweats experienced by men and women, where you are so drenched you need to change your night attire", says Prof Clancy.
Once correctly diagnosed and treated, TB is curable, with hospitalised patients staying three to four weeks, and needing to take their medication for up to six months. "Fifty per cent of people who contracted TB died before the advent of anti-TB drugs. Today, the outcome is good, the relapse rate is less than two per cent, though for a good outcome you need the right prescription, patient compliance in completing the full course of the drug and talking through the side-effects and toxicity.
"The global aspect of TB has a particular relevance for Ireland today, partly because we have a growing proportion of immigrants, some coming from areas where there is a relatively high incidence of TB. Symptoms of TB have increased in the East Region Health Authority where our immigrant populations have congregated. However, there seems to be little cross-infection as our migrants tend to stick together and not mix with the indigenous population.
"Misdiagnosis can happen when complacency creeps . . . We must not dismantle the structures, we need a centre that maintains an interest in the disease. TB has been called an orphan disease because nobody is caring about it. The Netherlands approach has been to increase the effort as the disease declines rather than the opposite.
"The main elements of a proactive programme includes direct government responsibility by law for the early identification and cure of patients with TB, including a properly-designed surveillance system with effective monitoring mechanisms in place," stresses Prof Clancy. "As this is only possible if specialised and well-trained TB health-care workers are available, the WHO advocates the recognition of a national centre of excellence to help achieve these aims. In Ireland we understand the problem and the solution but are slow to implement the necessary changes. The problem with history is if we don't learn the lessons, it repeats itself."
• The Return of the White Plague: Global Poverty and the New Tuberculosis, edited by Matthew Gandy and Alimuddin Zumla, published by Verso