Histoid leprosy as reservoir of the disease; a challenge to leprosy elimination

In the month of January, 2006, India was declared to have eliminated leprosy. In an article by the Director General of Health Services, Government of India, the graphical representation of the progressively decreasing prevalence rate and new case detection rate for leprosy was quite encouraging and the goal of elimination by December, 2005 was supposed to be in sight. However, as dermatologists, from our day to day experience in dealing with the patients with leprosy, it was rather difficult to accept this contention. Histoid leprosy is an uncommon form of multibacillary disease, characterized by distinct clinical, histopathological, bacteriological and immunological features. It is quite rare and mostly occurs among patients with leprosy who had received dapsone monotherapy in the past. However, it was reported in previously untreated patients, as a manifestation of relapse several years after effective completion of an adequate course of MDT and in HIV infected patients with severe immunosuppression. As the bacillary load is very high in these patients, they can form a potential reservoir of the disease. While reporting a patient of histoid leprosy presenting as relapse following complete and effective MDT, it was appropriately stated by Ebenezer et al.: ‘occurrence of such cases reminds us that the road to elimination is not an easy one.’ Continued occurrence of histoid leprosy in areas of low endemicity and in areas from where leprosy has been declared as eliminated as in the state of Karnataka is a matter of concern. Moreover, the authors have been diagnosing histoid leprosy regularly (13 cases in 9 years) in their leprosy clinic in a smaller town of Karnataka, Bijapur, even though the total case load is not very heavy (Table 1). New cases of histoid leprosy turning up even in areas of low endemicity leave us in doubt, and raise few pertinent questions: