ENDEMIC KALA-AZAR IN EASTERN SUDAN - A LONGITUDINAL-STUDY ON THE INCIDENCE OF CLINICAL AND SUBCLINICAL INFECTION AND POST-KALA-AZAR DERMAL LEISHMANIASIS

Between April 1991 and April 1993, a longitudinal study was performed in the village of Um-Salala (1,430 inhabitants) in the endemic area of kala-azar (visceral leishmaniasis) in eastern Sudan. During the two y ears, a total of 92 kala-azar cases were diagnosed (male:female ratio = 1.8:1, mean age 6.6 years). The annual incidence rates were 38.411,0 00 and 38.5/1,000 person-years, respectively The ratio of clinical to subclinical cases was 1.6:1 in the first year and 2.4:1 in the second year. Post-kala-azar dermal leishmaniasis occurred in 48 (56%) of 85 k ala-azar cases that were followed-up for at least six months. Kala-aza r occurred only in previously leishmanin-negative individuals. The maj ority of the population had a positive leishmanin skin test result, pr obably due to previous exposure to Leiskmania major causing cutaneous leishmaniasis in their homeland in western Sudan from which they had m igrated in the 1980s. It was thus postulated that previous cutaneous l eishmaniasis might protect against kala-azar but this could not be pro ved.