Leprosy \[lepʹrə-se\]
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From the Greek *lepros*, "scaly," leprosy is a chronic infectious disease of man caused by *Mycobacterium leprae* and principally affects the peripheral nerves and skin ([Figure](#F1){ref-type="fig"}). The earliest known skeletal evidence for leprosy has been found in India and dates to 2000 [bce]{.smallcaps}. This finding suggests that the first textual references to leprosy are in ancient Sanskrit hymns of the *Atharva Veda*. The armies of Alexander the Great may have brought leprosy from India to western Asia circa 326 [bce]{.smallcaps}, and it spread further west when Roman armies campaigning in Asia Minor and Syria returned home (62 [bce]{.smallcaps}). The Romans referred to leprosy as *elephantiasis graecorum* and could distinguish between the similar symptoms of lymphatic filariasis, or *elephantiasis arabum*.

![Dorsal surface of the hands of a patient with a case of nodular lepromatous leprosy, which under the newer World Health Organization (WHO) standards, is classified as multibacillary (MB), leprosy.](ET-2112-F){#F1}

Norwegian physician Armauer Hansen identified the causative agent, *Mycobacterium leprae*, in 1873; however, it was successfully identified as a bacterium only in 1879 by a young German physician, Albert Neisser, who attempted to take credit for the discovery. Today, leprosy is also known as Hansen disease.

*Suggested citation for this article*: Etymologia: Leprosy. Emerg Infect Dis 2015 Dec \[*date cited*\]. <http://dx.doi.org/10.3201/eid2112.ET2112>
