Transepidermal elimination: Role in leprosy transmission

Naveen Kumar Kansal

 Department of Dermatology and Venereology, All India Institute of Medical Sciences, Rishikesh, Uttarakhand, India

Correspondence Address:
Naveen Kumar Kansal
Department of Dermatology and Venereology, All India Institute of Medical Sciences, Rishikesh - 249 203, Uttarakhand
India

Sir,

I read with interest the Residents' Page article by Shah et al. on transepidermal elimination.^[1] Though transepidermal elimination in leprosy was mentioned only once, I would like to make a few comments about the significance of this phenomenon in histoid (and lepromatous) leprosy.^[1]

Nasal discharge from the untreated leprosy patient is considered the usual source of infection in the community and the cutaneous route is said to be unimportant. In tuberculoid leprosy, Mycobacterium leprae resides largely within the skin and the nerve and these patients are never considered infectious.

However, a number of workers have reported the presence of acid-fast bacilli in the epidermis.^{[2],[3],[4],[5]} Namisato et al. proposed transepidermal elimination as a mechanism for a “mass transport” of live leprosy bacilli in an untreated 35-year-old male lepromatous patient.^[6] The umbilicated/molluscoid lesion is one of the rarest morphological types of histoid leprosy. The fact that type 2 (pseudoisomorphic) Köebner's phenomenon has been reported in this form of histoid leprosy further substantiates the fact that viable bacilli must be eliminated transepidermally for this to occur clinically.^[7] Therefore, the skin may definitely be a portal for leprosy transmission, at least in the multibacillary cases. Studies are required to explore the contribution of cutaneous carriage and role of epidermal elimination of the bacilli in leprosy transmission. The need is acute as the multibacillary histoid and lepromatous cases are definitely a dreaded challenge to the elimination of this chronic mutilating disease.^[8],[9]

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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