Alexander the Great, Seafaring, and the Spread of Leprosy

Ancient ships are commonly described as conveyors of merchandise, technology, and even ideas, but as conveyors of disease they are seldom mentioned in the literature. This is surprising because both passengers and crew typically had to endure poor hygiene, poor nutrition, and cramped quarters, especially on long voyages. All of these factors provided an excellent environment for the incubation and spread of disease. In contrast to ships, however, armies are commonly assumed to be likely human vectors for the spread of diseases, even if little or no evidence supports such an assumption. One such assumption concerns the army of Alexander the Great.

Alexander the Great (356–323 BCE) conquered much of the known world of his time. He was a consummate general, tactician, and statesman whose conquests led to the spread of Greek culture throughout the eastern Mediterranean. Some paleopathologists, leprologists, and historians have now bestowed another dubious honor on Alexander. ¹ They propose that members of his army may have contracted leprosy during the Indian Campaign (327–326 BCE) and then spread it to the Mediterranean region on their return. This opinion has been repeated without critical analysis since Johs Andersen first proposed it in 1969. Furthermore, Andersen proposed that Pompey’s army brought leprosy to Italy after his campaign against Mithridates of Pontus in 62 BCE. ² Yet the evidence does not support either assumption. Instead, I propose that cargo ships carrying young slaves from India to Egypt were probably the conveyors of this disease to the Mediterranean world.

Andersen’s theory is based on his argument that the earliest written description of leprosy in the Mediterranean region dates to around 300 BCE and the earliest osteological evidence for leprosy to about CE 500. Since publishing, however, the discovery of bones exhibiting leprous lesions from Egypt has pushed back the date of the earliest osteological evidence to about 200 BCE. ³ This does strengthen his argument because it places the earliest evidence closer to Alexander’s time. However, Andersen’s dating for the appearance of leprosy has not been universally accepted. A few scholars still believe leprosy appeared much earlier in this region, and the most ardent advocate of this theory is Mirko Grmek; he argued that ancient Egyptian, Mesopotamian, and Hebrew texts all describe leprosy. ⁴ So, my argument is two-pronged: leprosy did not appear in the Mediterranean region before approximately 400 BCE or so, and it traveled there via cargo ships, not via Alexander’s army.

The Many Manifestations of Leprosy

To understand why such divergent interpretations have been proposed, it is first necessary to understand the nature of leprosy. Leprosy, or Hansen’s disease, is a slow, progressive, and chronic infectious disease, which is produced by the bacillus Mycobacterium leprae. It can be difficult to diagnose in its early stages because it produces four different forms: indeterminate, tuberculoid, borderline, and lepromatous leprosy. The difficulty is further compounded because these different forms exhibit such a wide range of symptoms. Leprosy typically begins as an indeterminate form that can spontaneously heal, remain unchanged for long periods, or progress to a more severe form. Indeterminate leprosy produces poorly defined patches or macules that are slightly hypopigmented in darker skin and have a slightly reddish color in lighter skin. ⁵

If the disease progresses, it may develop into the second form, tuberculoid leprosy, which is associated with rapid and severe nerve damage, resulting in a loss of sensation, local paralysis, loss of sweat and sebaceous glands, and hair loss. Skin lesions are few; they are macular, have sharp borders, and are hypopigmented. Typically, there is also an enlargement of cutaneous nerves and peripheral nerve trunks with localized infection that may ulcerate in the area of lesions. However, nerve damage is often limited and infection usually heals without treatment. ⁶

The third form, borderline leprosy, is an unstable form...