TB or not TB?

That is the question. Most days I find myself studying a chest X-ray asking myself this question. Holding the X-ray up to the sunlight I hope the longer I look that I will see some cavity, apical consolidation or anything that would make me more confident to say ‘yeah this patient has TB’. It isn’t an exact science and while I believe that every doctor should be able to interpret basic investigations likely a chest X-ray and an ECG I haven’t spent much of the past four years GP training studying X-rays.

It’s a difficult call as TB treatment takes 6 months. Starting treatment without good evidence can mean other diagnosis are missed and often undermines confidence amongst the population in the value of TB treatment. Not starting treatment can deny a patient a chance of effective cure. When I do see some ‘good evidence’ including when I see miliary TB (diffuse infection) I am relieved as I can confidently make the diagnosis even though this particular finding carries a poor prognosis for the patient.

Tuberculosis is often thought to be a disease of the past in Ireland, associated with a time when large numbers of people spent several months in TB hospitals receiving treatment and getting fresh air. Globally however the incidence of TB continues to rise. There are about 9 million new cases each year and 2 million deaths, most in sub-Saharan Africa despite effective treatment being available for over fifty years.

While many major infectious disease are easily diagnosed using blood, stool or urine tests the diagnosis of TB is very tricky. The bacteria that cause the disease grow very slowly requiring special laboratory equipment and time neither of which are readily available in Africa. Some patients with TB in their chest will be ‘sputum positive’ that is the bacteria can be seen in their sputum under a microscope. However many are not, especially those patients that are HIV positive and in these patients the chest X-ray can lack any ‘typical’ TB changes.

I often wonder what the patients think of this uncertainty regarding TB diagnosis. I ask Muwewe a lady on St Monica’s ward how she feels about her recent diagnosis of TB. She explains that she has been coughing since August and having left sided chest pain. She came to the hospital in August and was treated for a chest infection. Her sputum studies were negative for TB and she got a little better on treatment. However when she went home the symptoms soon returned. This is another difficult aspect of TB diagnosis with patients often getting temporary improvement on ‘regular’ antibiotics such as penicillin and chloramphenicol.

As we chat I note from her records that Muwewe is 38 years old and weighs just 37kg. I am interested to know why she remained unwell for a further three months, losing weight, getting weaker, before returning to hospital. She lives in a village about 30km away which is a long distance here. She explains the problem was the transport that she could not afford it. Eventually as she became more unwell her teenage daughter brought her to the hospital on a bicycle. Her village is not that far from the tar road that links Katete to Mozambique and I don’t quite buy her assertion about the transport. Often patients delay coming to hospital and try traditional medicine first or live in denial of the problem.

Muwewe understands that her TB has been diagnosed on X-ray changes alone but is happy to start treatment. ‘I feel very free, not uncomfortable as I am not alone suffering from TB’. She is also HIV positive. HIV and TB have a powerful relationship. Whilst many of the opportunistic infection we associate with HIV only develop in the later stages when there is severe suppression of the immune system TB infection is very likely to affect the HIV positive patient at any stage.

She speaks openly about her HIV status explaining ‘I can not hide even my husband is positive and is on treatment’. The family survive on income her husband makes from decorating shop fronts and signs. In recent months however because of her illness Muwewe has found it increasingly difficult to care for her five children ‘since I have been sick, at home the work has been done by my children and my mother’. Encouragingly for Muwewe if she has TB she is likely to get better in the coming months especially as her HIV infection is not yet very advanced.

I talk to Emmanuel Sikateyo one of the senior nurses here at St Francis and TB focal person. With others he is responsible for registering all new cases giving adherence counselling, arranging directly observed therapy and follow up. He feels among the challenges to diagnosis is stigma surrounding TB and its association with HIV. ‘There is a lot of stigma, patients deny they produce sputum because they think in the back of their mind that the moment I am diagnosed with TB I am HIV positive, which of course isn’t always true’.

Emmanuel also feels that we could have higher sputum positive rates if greater care was taken to get adequate samples. ‘Sometimes us the nurses and the doctors are not keen to instruct the patients on how to give sputum and getting three good samples’. Time is probably one major factor in this shortcoming. He also alludes to the absence of specialist help to aid diagnosis including physicians skilled in the use of bronchoscopy (passing a camera into the lungs) to get washings which are more likely to be smear positive.

A further challenge facing Emmanuel and those involved in TB monitoring here is the number of patients from outside our immediate catchment area. ‘As a second level hospital we have an influx of patients because of seemingly better service than the government hospitals. We see these patients initially when they are ill, they come for review but as they get better they say ‘why should I come to St Francis to get my sputum examined as transport is expensive’. In this way patients get lost to follow and may not complete treatment with risk of severe illness or drug resistant TB. In recent years more people have a mobile phone (or at least a SIM card and occasionally access to a phone, or a family member or neighbour with a phone) and patients can be contacted this way if they default from follow up.

One of the encouraging facts Emmanuel tells me is that in recent quarters we have had a 90% cure rate for smear positive cases. Still there are many challenges including increasing numbers of cases since the start of the HIV epidemic. Emmanuel sees HIV and poverty as the main factors that contribute to TB in Zambia ‘if you look at our patients their social status is poor, usually crowded tiny houses where it is easy for TB to transmit, if they are lucky access to two meals in a day.’ Until these issues are addressed the question of ‘TB or not TB’ will continue to occupy the minds of health care workers in this part of Africa.