Dear Dr Zignol ~
I write with reference to your letter to the Guardian of November 7th. You will recall, I’m sure, that you wrote in relation to a study that was recently carried out in West Africa by the West African Network of Excellence for TB, Aids and Malaria and which was reported by the Guardian on 3rd November. Your letter made it clear that you considered the “claims” which you reckoned the study had made to be “misleading and unhelpful”. Given the perilous state of the drug-resistant TB epidemic in the African region we took careful note of your comments and have equally carefully reviewed them in the light of the study itself. Unfortunately we have concluded that it was actually your letter which may have been misleading, and not the study.
We have decided to explain our misgivings to you and invite your further engagement on the matter. We are copying this letter to Sarah Boseley, the journalist who wrote the original piece, and we are also publishing it on the blog page of our website because we consider this wider topic to be a matter of immense public concern, which is still not being given the attention it deserves. As such we will welcome your response at your convenience, and in anticipation of this we also advise you that we will publish it on the same blog page for wider public consumption.
At first we wondered whether your letter might have simply been written in direct response to the journalist, i.e. you may have been challenging her journalism for not properly reflecting the study itself. After careful consideration, however, we don’t believe this to have been the case because you didn’t specifically call into question what the journalist wrote. What you did appear to call into question were the “claims” (a word which you used twice) that were apparently being made that rates of MDR-TB in West Africa are currently higher than WHO estimates; in other words you were challenging the actual content of the study.
Given that the estimates of the rates of MDR-TB for the African region generally are still being calculated to be below the global average (when we consider that the opposite is far more likely) we find such a conclusion to be a significant public health concern. We know, for instance, that TB epidemics thrive on weaker health infrastructures, and that weak health infrastructures in turn almost inevitably spawn MDR outbreaks in the course of time because of what will have been an anticipatable poor management of first line drugs. Our own view is that the African TB epidemic must be considered as such - to have a strong probability of having a significant proportion of MDR within it, with or without the benefit of any national surveys that may in any case be beyond local resource to conduct without immense outside help. Furthermore, the fact that HIV is considered by the WHO to be a risk factor for MDR development (as witnessed by its 2010 ‘strong recommendation’ for GeneXpert to be used to test for Rifampicin resistance in all co-infected patients) must surely only amplify this probability. As such we have been consistently baffled by the continuing low estimates of MDR-TB for the African region and are worried by the consequent lack of resource for the region to contain MDR-TB because we believe that they fly in the face of what should be the implementation of judiciously implemented precautionary principles to protect those most at risk of this disease.
But to return to your letter to the Guardian: you specifically stated that the study was claiming that “multidrug-resistant TB (MDR-TB) rates in west Africa ARE actually higher than estimates published by the World Health Organisation”. You then concluded that these claims “ARE both misleading and unhelpful” because there is a lack of epidemiological evidence for them. We have capitalised the word ‘are’ in both instances in order to emphasise its use since we are deeply concerned by what its employment seems to reveal. We would go so far as to suggest that the use of the word ‘are’ in this context may actually render your own letter, and not what you describe as the study’s claims, to be misleading or unhelpful (or possibly both).
In fact after evaluating the text of the study itself we could find no such categorical claims being made as your letter described. Rather we found suggestions, and we underline them accordingly for you in the following extracts. The authors of the study were “highlighting the possibility that drug resistance in West Africa is currently underestimated”. They further added that “the situation appears especially alarming in Nigeria”. They reasoned that “the presented MDR data … indicate that the drug-resistant problem in West Africa may be greater than currently assumed,” and concluded that “drug resistant TB could become a serious public health problem in West Africa if required control measures are not taken”. Could you help us understand what exactly caused you to react so negatively to what seemed a quite reasonable study which seemed to draw quite reasonable suppositions from the data it revealed?
Of course there were indeed some limitations to the study as your letter intimated, but actually these were adequately identified by the authors in the study itself. Certainly they didn’t seem to warrant such outright dismissal of the study as you made in your letter.
In fact even the Guardian (while its choice of wording may have been less judiciously chosen - it’s a newspaper after all and not a scientific journal), was hardly guilty of sensationalising the study. It in turn only reported that the study was “suggesting” that the seriousness of the epidemic had been “considerably underestimated”.
(We can identify only one significant inaccuracy, in fact, in the Guardian report - that XDR-TB has been found in new cases in both Togo and Ghana, when in fact these strains were actually pre-XDR.)
We did take some comfort from your observation that “west Africa remains a part of the world where MDR-TB surveillance data are most lacking”, particularly when we considered this alongside the study’s own conclusion that there is “an urgent need for country wide drug resistant surveys according to WHO guidelines”. But your letter doesn’t seem to draw this same secondary conclusion – in fact it seemed to us to do the opposite by implying that without any visible substantiation the rates of MDR-TB in the region may not even be on the rise at all so no survey would appear to be necessary. Why, otherwise, would this study have seemed to you to be so “unhelpful”?
The real problem is that so little has been done to facilitate better surveillance of MDR-TB for the region. You very rightly stressed in your letter that the collection of data is vitally important for all diseases, but I’m afraid that we found ourselves deeply troubled when you followed this by stating that “WHO estimates on MDR-TB are based exclusively on population-based surveys, such as those recently conducted in Nigeria and Senegal”.
First of all, we believe that this statement is misleading if not factually incorrect – at best WHO MDR estimates for the African region are based on surveys that are sometimes years out of date, or on single surveys from which trends cannot be evaluated, if any exist at all. In fact of the eight West African countries included in the study in question only two (Nigeria in 2010 and Senegal in 2014) have ever conducted an MDR study which surveyed both new and retreatment cases.
We can’t help adding a further observation in relation to South Africa, however, which may well reflect on the general assessment of MDR-TB in the whole of the region as well as on your statement that estimates are based so exclusively on population-based surveys. Until this year the published estimates for South Africa as published in WHO Reports have been based on a survey that was completed back in 2002 meaning that it has been hopelessly out of date for years: the trouble was that this population based survey was used in the WHO’s own Reports without any attempts at adjustment meaning that published estimated incident numbers of MDR cases for South Africa were year on year significantly less than the actual cases that were being notified each year to the national TB program (which I think all of us agree is an impossibility). This anomaly even now appears to have bizarrely lingered on into the current Report, despite a new DR Survey having been completed in 2014. The estimated number of MDR/RR-TB cases being quoted in the current WHO Global Report amongst pulmonary cases notified in 2015 was 10,000, whilst elsewhere the estimated numerical incidence of MDR/RRTB was suggested to be 20,000. Meanwhile the number of laboratory confirmed cases was over 20,000 (at 68% CDR this would suggest a more probable estimated incidence of MDR of around 30,000) and the number of cases started in second line treatment was over 13,000. These sorts of obfuscations (which of course in turn are being used to build a wider picture of the African MDR-TB epidemic) isn’t new and can hardly help to build any sort of true picture of the African epidemic as the crisis deserves.
Secondly, the reference you made to the 2010 Nigerian MDR prevalence survey should surely only amplify our collective concern and not reduce it. You will recall, I am sure, that the 2012 Nigerian TB prevalence Survey revealed five times the amount of prevalent sputum positive TB than was notified that same year to the Nigerian NTP (nearly half of which wasn’t sputum positive anyway). This meant that the following WHO Global Report in 2013 hiked the Nigerian prevalence rates by over 100%, incidence rates by over 200% and mortality rates by over 400%, with the regional rates for Africa hiked by 4%, 12%, and 44% respectively as well. The Case Detection Rate for Nigeria meanwhile was reduced from 51% to a terrifying 16% at a stroke. Whether not these hikes were accurate is beside the point; the point is that even in an HBC country like Nigeria, where expert opinion should be expected to be at least somewhere near the button (if not actually on it), a national prevalence survey can render previous estimates deduced with the help of expert opinion to be in an instant appallingly inaccurate. This 2012 survey doesn’t only show that TB estimates, even of drug-susceptible TB, can be terribly underestimated twenty odd years into a Global emergency, it also suggests the possibility that this could occur as easily in West Africa as anywhere. That 2012 Survey effectively suggested that the prevalent amount of sputum-positive TB might have been as much as ten times more than was being notified into the system in the course of that same year. The Guardian report was only suggesting that the rates of MDR-TB for West Africa might be three times higher (though that’s worrying enough if it’s near the truth)!
In the light of these considerations, surely it’s entirely reasonable for the authors of this study to have hypothesised, based on its findings, that the true levels of MDR-TB might just be higher than the WHO estimates? Might not a full prevalence survey of MDR-TB for the region reveal such an epidemiological underestimation? The truth is, of course, that we simply don’t know how much MDR-TB there is in West Africa and we will only ever know, of course, if a wider survey or surveys are conducted as they should be. Surely this study wasn’t in any way “unhelpful” in respect of encouraging this to happen, is it? In our view it is quite the opposite.
In conclusion your letter leaves us both confused and concerned because these uncertainties leave so many lives are at risk.
We are left very seriously wondering whether the WHO is yet taking the threat of MDR-TB to the African region as seriously as it could and should do. Furthermore we find ourselves fully agreeing with the study’s authors’ conclusions that “efforts [should] be put in place for containment of a potential west African TB epidemic at the earliest possible stage … as west Africa, with its 245 million inhabitants, is one of the poorest regions globally, whose fragile health systems can easily be overwhelmed by infectious disease epidemics, as seen in the recent Ebola outbreak.” It’s no secret that the WHO itself recently came under considerable criticism for its tardiness in responding to the Ebola outbreak in the same region. It would surely be a far larger tragedy if we are witnessing the same thing happening with MDR-TB at a much larger scale in slow-mo.
This isn’t just the responsibility of the WHO, of course, it’s also the responsibility of regional governments and donor nations, exactly as was identified in the Guardian piece when Ms Boseley quoted Professor Antonio, the principal investigator at the Medical Research Council unit in the Gambia who said that this study was “a wake-up call for the ministries of health and the governments to take MDR-TB seriously.”
It must surely be the responsibility of the WHO, however, to take a positive and proactive leadership role in this process.
We look forward to receiving your comments on the above, and will welcome corrections if or where we have made any misleading or inaccurate representations ourselves.
Chair and Co-founder - Moxafrica.