The epidemic of visceral leishmaniasis in western Upper Nile, southern Sudan: course and impact from 1984 to 1994

Abstract

Background: Although endemic in parts of southern Sudan, visceral leishmaniasis (VL) had not been reported in Western Upper Nile (WUN) until an epidemic was confirmed in 1989. A combination of circumstances created conditions for transmission among a population of mainly Nuer and Dinka people who had no immunity. The civil war which restarted in 1983 has been a major contributing cause and continues to hinder provision of treatment, data collection and control measures.

Methods: Since the first of three clinics to treat VL was established in WUN in 1989, data on the epidemic and mortality have been collected in seven retrospective surveys of villages and among patients. Adults were interviewed about surviving family members and those who had died since the epidemic came. Survey death rates are used here to estimate mortality from VL and 'excess mortality' above expected levels.

Results: The surveys found high mortality at all ages and suggest an overall death rate of 38-57% since the epidemic started in 1984, and up to 70% in the most affected areas. Both methods of estimation suggest that around 100,000 deaths, among about 280,000 people in the epidemic area, might be attributable to VL.

Conclusions: This continuing epidemic has shown that VL can cause high mortality in an outbreak with astonishingly high infection rates. Population movement has been a major factor in transmission and poor nutritional status has probably contributed to the risk of clinical infection. Although over 17,000 people have been successfully treated for VL at the clinics in WUN, the disease is likely to become endemic there.

PIP: The syndrome of fever, wasting, and enlarged spleen or lymph glands resulting from visceral leishmaniasis (VL) is usually fatal unless treated. While VL is endemic in parts of southern Sudan, it was first reported in Western Upper Nile (WUN) during a confirmed epidemic in 1989 among a population of mainly Nuer and Dinka people who had no immunity. Civil war has been a major contributing factor to the continuation and spread of the epidemic, and continues to impede the provision of treatment, data collection, and control measures. The first of three clinics to treat VL was established in WUN in 1989. Data have since been collected in seven retrospective surveys in villages and among patients. Survey death rates were used to estimate mortality from VL and excess mortality above expected levels. Mortality was high at all ages. The overall death rate is estimated at 38-57% since the epidemic started in 1984, and up to 70% in the most affected areas. Approximately 100,000 deaths, among approximately 280,000 people in the epidemic area, may be attributable to VL.