Leprosy and MDT: eradication vs cure

Gurmohan Singh

 Chief Editor, India

Correspondence Address:
Gurmohan Singh
Chief Editor
India

The use of Multi Drug Therapy (MDT) for leprosy has been clouded with controversy since its inception, and perhaps understandibly so. The public health lobby views MDT as something which can be easily divided into Paucibacillary and Multibacillary based on the bacterial load. And so, no matter what the patient′s clinical disease dictates, if he is bacteriologically positive, he is given two years of MDT with three drugs. This is almost six times more than one in whom the bacillus is not seen.

Let us examine the relevance of "weakly" positive smears. There are many factors that influence the results of a smear. Who makes it? Who stains it? Who reads it? And what is the quality of the microscope?

The presence of one bacillus even in hundred fields makes the patients "diseased" for two years and he is put on three effective antileprosy drugs. If that lone organism is missed, he gets "cured" with only two drugs given for six months. No clinician can ever accept this. This is one reason why dermatologists and venereologists differ with public health leprologists in joint scientific meetings. Public health administrators assert and reassert that fixed duration MDT is extremely effective from PUBLIC HEALTH POINT OF VIEW. If we dermatologists read these four words, written in between lines, there is no bone of contention left. National Leprosy Eradication Programme has the target of reducing the pool of infection. This is why it lays stress on smear positive cases which are a threat to the community. Therefore, these patients are given three drugs for a period of two years. I am sure the programme would have recommended more frequent use of Rifampicin, had enough funds been available. I am made to understand that in the US, Rifampicin is given daily. Why not to my patients? It is justified because National and International bodies supply the drugs free of cost. This MDT regimen has been designed considering cost effectiveness for developing countries. I am sure, God forbid, if any of our colleague public health leprologists got the disease, he would definitely err on the higher side of his own recommended treatment.

What I wish to convey through these words is that we both are correct. The two of us have different objectives in mind. The public health administrator is interested in reducing the reservoir of infection and thus reducing the transmission and so development of new cases. I am sure, given properly, MDT as it is currently used is very effective from Public Health point of view. The clinical leprologist has, in addition, the patient and his disease in mind and not the bacterial load alone. He, therefore, wants to give treatment for a longer duration and with more frequent ′pulses′ of Rifampicin, depending on the patient′s pocket and clinical status.

The public health administrators divided treatment of leprosy into two broad categories. This was because they were aware that the field work has to be done by non-medical assistants who have only four months training in leprosy. It amazes me that we, highly trained dermatologists and leprologists, have also adopted this classification which was made primarily for the field worker. Knowing that leprosy is a spectrum, we are willing to allow a fine line between PB and MB to decide how long and with how many drugs a patient will be cured. Thus, therapy according to PB or MB should not be sacrosanct, but individualized with treatment intensity matching the disease severity.

Another question comes to my mind when I think about fixed duration MDT in BL/LL cases. I would like the readers of this editorial also to ponder on it and may be write back to the editor. BL and LL cases have very poor cell mediated immunity towards Mycobacterium leprae. In these cases many patients still harbour bacilli even after two years of fixed duration MDT. The proponents of FDT believe that the immunity improves with reduction in the bacterial load and that whatever organisms are left will be continually knocked down by enhanced immunity even after stopping the treatment. I would like to say that CMI in these cases seldom reaches normalcy. It always remains depressed. If any organism (may be even persisters) is left it is likely to multiply over the next many years. May I ask here if you would like to take a chance of leaving some organisms for natural immunity to deal with?

I shall request the readers to give all this a serious thought and reconsider whether we want to tow the line of treating cases as PB or MB without taking into account the wide variations that occur in the disease severity.