Thousands of Years Later — a New Kind of Leprosy

By Carol A. Kemper, MD, FACP

Dr. Kemper is Clinical Associate Professor of Medicine, Stanford University, Division of Infectious Diseases, Santa Clara Valley Medical Center. Editor Stan Deresinski, MD, FACP, is Clinical Professor of Medicine, Stanford, Associate Chief of Infectious Diseases, Santa Clara Valley Medical Center. Peer reviewer Connie Price, MD, is Assistant Professor, University of Colorado School of Medicine.

Dr. Kemper and Dr. Price report no financial relationships relevant to this field of study. Dr. Deresinski serves on the speaker's bureau of Merck, Pharmacia, GlaxoSmithKline, Pfizer, Bayer, and Wyeth, and does research for Merck.

This article originally appeared in the January 2009 issue of Infectious Disease Alert.

Source: ProMED-mail post November 24, 2008; www.promedmail.org

Diffuse lepromatous leprosy (DLL) is an especially virulent form of multibacillary disease, occasionally seen in patients from Central and South America and Southeast Asia. Lucio's phenomena is a highly anergic and more severe form of DLL, resulting in extensive skin and subcutaneous involvement, with an abundance of organisms infiltrating tissues. Dermal infarcts occur, occasionally resulting in extensive necrosis, with histopathologic evidence of obliterative vasculitis of dermal and subcutaneous vessels. These extensive skin lesions increase the risk for superinfection and sepsis.

These authors from MD Anderson report on two such cases occurring in 2002 and 2007 at their facility, the first of which was so severe as to prompt transfer to the burn unit. The second occurred in an older Latino from Mexico, who presented with extensive skin lesions on his lower extremities. Within days, he became septic and died. Autopsy confirmed the presence of DLL, with diffuse AFB infiltrating blood vessels.

Having done gene sequencing on other organisms, the authors turned their hand to the organisms responsible for these two cases. Sequences of the 16S ribosomal subunit and five other genes were examined and compared to other mycobacterial cases, including M. leprae. The 16S ribosomal sequences were only 97.9% homologous with M. leprae — a huge difference, considering that gene sequences in other cases of leprosy are essentially identical. The five other genes reportedly showed important differences as well. The strain identified from these two individuals constitutes a new strain of leprosy — called M. lepromatosis.

Analysis of tissue from two other similar cases of DLL occurring in Singapore yielded this same organism. All four patients died of their disease. While its distribution worldwide has not yet been determined, the discovery of this new mycobacterial organism may explain some of the variation seen in cases of leprosy.