Leprosy Mailing List – July 17, 2017
Ref.: (LML) Re-infection of lepromatous patients after release from MDT
From: Joel Almeida, Mumbay and London
Whole genome sequence analysis of M. leprae obtained from initial and relapse skin lesions demonstrated that reinfection with a different M. leprae strain can occur in lepromatous leprosy (LL) patients who remain in an endemic area after the conclusion of MDT (Stefani et al, 2017 in press, cited by Penna et al 2017, https://doi.org/10.1371/journal.pntd.0005725).
Exogenous re-infection was first postulated in the 1980's to explain supposed "relapses" among smear-negative BL and LL patients in an endemic area of India (Almeida et al, 1983, Int. J. Lepr 51(3):382-4, and 1984, Int. J. Lepr. 52(1): 16-19). The recent genome analysis lends support to that view.
So-called "relapse rates" among polar lepromatous patients in leprosy-endemic areas after MDT might be partly or wholly due to exogenous re-infection. For the interruption of transmission and the prevention of disfigurement, it seems important to identify polar lepromatous patients at diagnosis. They can then be protected against re-infection, by continued treatment, until they demonstrably develop specific immunity against M. leprae.
This is important for more than just the individual patient. It is crucial for leprosy control. One polar lepromatous patient is equivalent, in microbiological and epidemiological terms, to 10,000 or more TT or BT patients. Neglect of such microbiological and epidemiological realities renders our leprosy control efforts ineffective. It is a wholly avoidable error.
LML - S Deepak, B Naafs, S Noto and P Schreuder
LML blog link: http://leprosymailinglist.blogspot.it/
Contact: Dr Pieter Schreuder << firstname.lastname@example.org