Visceral leishmaniasis can cause large-scale and tenacious epidemics, with high case–fatality rates. Epidemics occur frequently in regions which are difficult to access, such as Libo Kemkem, Ethiopia (2005–06), Wajir, Kenya (2008), and Upper Nile, Southern Sudan (2009). Malnutrition is a well-known risk factor, and the epidemics flourish under conditions of famine, complex emergencies and mass population movements.
In Sudan a major epidemic of visceral leishmaniasis occurred from 1984 to 1994. As this was the first epidemic in the area, the population was highly susceptible. Some studies have estimated that the disease caused 100 000 deaths in a population of around 300 000 in the western upper Nile area of the country. In some villages, more than half of the population died from the disease.
In 1997, a new epidemic caused the number of confirmed cases of visceral leishmaniasis in Sudan to increase by 400% over the previous year. Treatment centres were overwhelmed and stocks of first-line drugs were depleted. The migration of seasonal workers and large population movements caused by civil unrest carried the epidemic into Eritrea and Ethiopia.