MEDICAL MATTERS:Tuberculosis causes public health concerns, writes MUIRIS HOUSTON
SOME OF THE best descriptions of how devastating tuberculosis can be appear in James Plunkett’s classic novel, Strumpet City. Characters such as the destitute Rashers Tierney were typical of the residents of the 3,500 or so tenements in Dublin city around 1913.
Almost 50,000 families lived in accommodation of less than five rooms in our capital at the time.
Despite the many social changes since then, TB most certainly has not gone away. A report in a recent issue of the Irish Medical Journal (IMJ) outlines the challenges posed by multi-drug-resistant TB (MDR-TB) and is an indicator of how a different social dynamic is changing the face of the disease here.
The authors carried out a retrospective chart review of all patients treated for MDR-TB in St James’s Hospital, Dublin, and the Mercy University Hospital, Cork, between January 2004 and September 2009. These are two of the largest referral hospitals for TB in the Republic.
Some eight of 13 patients with the difficult-to-treat version of the infectious illness were foreign-born; six of these were born in Eastern Europe.
When they compared their data with previous years, no patients treated for MDR-TB in Ireland before 2001 were born in Eastern Europe but since 2004 nationals of these countries have accounted for almost 50 per cent of cases, Dr Joe Keane and his fellow researchers note.
Caused by the bacteria mycobacterium tuberculosis, TB is spread by droplets in the air. A person with infectious TB can expel TB germs when they cough or sneeze and people in the surrounding area can then inhale these.
Each person with active infectious TB infects on average 10-15 people a year. But many people who become infected never go on to develop the disease. Instead, the bug lies dormant in the body and the person is said to have “latent” TB.
The symptoms of full-blown TB are varied and depend on the organs affected. For the lungs, typical symptoms include cough, sputum which may be flecked with blood, tiredness and loss of appetite. Weight loss is also common and the patient may have a fever. TB can also infect bones in the spine and may infect the lining of the spinal cord, leading to TB meningitis.
New blood tests are attempting to displace the traditional skin test for TB called the Mantoux test. A blood sample is incubated overnight with TB antigens. If the cells get excited, they release interferon which can be measured. A positive test means that you may have either active or latent TB.
Although much handier to perform, the new tests are expensive and their reliability was recently questioned by the World Health Organisation (WHO) following the publication of research from Canada. The gold standard for the detection of active infection remains sputum analysis in a laboratory looking for the microbe’s presence.
MDR-TB is defined as resistance to at least isoniazid and rifampicin, the two most effective anti-tuberculosis drugs. So treatment of MDR-TB necessitates the use of second-line agents which are less effective and more toxic. The inadequacy of these second-line agents is manifest in MDR-TB mortality rates of between 11 and 37 per cent.
Treatment involves taking four antibiotics for two months followed by two drugs for a further four to seven months.
But WHO has just issued new treatment guidelines for MDR-TB, calling for an intensive phase of treatment lasting at least eight months. In addition, patients who have not been treated with second-line drugs for tuberculosis in the past should undergo 20 months of treatment.
Lengthy treatment like this isn’t easy on patients with MDR-TB or their carers. In two of the eight cases described in the IMJ, High Court orders had to be imposed on patients to ensure compliance with infection control measures. Because of the high public health risk, in the past patients have even had to be arrested.
Living conditions and treatment options may have improved since the 1913 lockout but TB continues to have a social impact.