A devastating epidemic of visceral leishmaniasis occurred in Sudan 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 during this period. In some villages, more than half of the population died from the disease.
The epidemic in 1997 in Sudan caused an increase of cases of visceral leishmaniasis 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.
In south America, Brazil has experienced a significant increase in the number of cases of visceral leishmaniasis since 1999. Previously, rural epidemics were seen in ten-year cycles. Now, the disease has spread to urban areas. Drought, lack of available farmland, and famine have led to a large migration of the population from rural areas to the peripheral suburbs of large cities, creating densely populated settlements with minimal infrastructure and sanitation. Children under the age of 15 years are the most severely affected group. Dogs habitually kept in the domestic environment are the principal animal reservoir for the infection. Visceral leishmaniasis is also spreading in the north of Argentina and the areas bordering Brazil and Paraguay.
Epidemics of anthroponotic cutaneous leishmaniasis are of particular concern in Afghanistan, where decades of war and civil unrest have created conditions that favour the spread of the disease and make its control especially difficult. The disease flared up in 2002, with an estimated 100 000 cases in Kabul. Because of their low resistance to the disease, returning refugees and other displaced persons in Kabul are at higher risk of infection. Outbreaks of cutaneous leishmaniasis are occurring in different parts of the world, and have been well reported in the southern provinces of Sing and Beluchistan in Pakistan since 2004, in Ban, Islamic Republic of Iran after the devastating earthquake in 2003, and in the Sudanese refugee camps of Treguine and Koukou, Chad in 2007, Allepo, Syria.
Leishmania–HIV coinfection had been reported from 35 endemic countries. Coinfection with HIV intensifies the burden of visceral and cutaneous leishmaniasis by causing severe forms that are more difficult to manage. Visceral leishmaniasis interaction with HIV infection, as HIV-infected people are particularly vulnerable to VL, while VL accelerates HIV replication and progression to AIDS, poses major challenge in areas where there is high coinfection rate.
According to a WHO coordinated monitoring system involving 28 institutions worldwide - the number of new cases has declined in Europe since the end of the 1990s, mainly due to access to highly active antiretroviral therapy.
In other parts of the world, however, where there is limited access to such treatment, the prevalence is still high.
Post kala-azar Dermal Leishmaniasis (PKDL)
It occurs mainly in East Africa and on the Indian subcontinent, where up to 50% and 5-10% of patients with kala-azar, respectively, could develop the condition. It usually appears 6 months to 1 or more years after kala-azar has apparently been cured. But it can occur earlier. People with PKDL are considered to be a potential source of kala-azar infection.