Several species of canines serve as reservoir hosts of L. infantum (chagasi).Contemporary life has made itself felt even here, however—not as "progress" but in the form of the many small wars of Africas post-colonial era. In the Sudan, where civil war has been continuous since 1983, the violence has been concentrated in the more populated south, and kala-azar was concentrated there too. But the wars have driven a steady stream of refugees out of the region, and these traveled either across the southern border or into the remoter western part of the country called the Upper Nile, where both war and the disease that went with it had not yet penetrated.These refugees, moving at foot-speed, carried the disease with them, and when it arrived it hit the Upper Nile with a force comparable to smallpox hitting the American Indians. The isolated people of the Upper Nile had no access to medicine or education about the new disease among them. Worse, their immune systems were defenseless against this new pathogen, foreign to them though it came only from another part of their own country. One village at the center of the epidemic, Duar, was left with four survivors out of a population of a thousand, and from the late eighties to the mid-nineties a total of 100,000 died from the sickness in that region alone.
Another common name, kala-azar (Hindustani: काला आज़ार (Devanagari) کالا آزار (Nastaleeq) kālā āzār), is derived from kala which means black in Sanskrit, as well as in the languages descended from it, including Assamese, Hindi and Urdu; the word azar means Fever in Persian and Hindustani; as such the disease is named for the darkening of the skin on the extremities and abdomen that is a symptom of the Indian form of the disease. The agent of the disease was also first isolated in India by Scottish doctor William Leishman (who observed the parasite in spleen smears of a soldier who died of the disease in Dumdum, Calcutta, India - hence the name dumdum fever) and Irish physician Charles Donovan, working independently of each other. As they published their discovery almost simultaneously, the species was named for both of them—Leishmania donovani. Today, the name kala-azar is used interchangeably with the scientific name visceral leishmaniasis for the most acute form of the disease caused by L. donovani. The disease is endemic in West Bengal, where it was first discovered, but is seen at its most deadly in north and east Africa. It can also be found throughout the Arab world and southern Europe (where the causative organism is L. infantum), and a slightly different strain of the pathogen, L. chagasi, is responsible for leishmaniasis in the new world.