RK39 ENZYME-LINKED-IMMUNOSORBENT-ASSAY FOR DIAGNOSIS OF LEISHMANIA-DONOVANI INFECTION

The rK39 enzyme-linked immunosorbent assay (ELISA) was compared with t he direct agglutination test (DAT) for Leishmania donovani infection i n the Sudan. rK39 ELISA proved more sensitive than DAT in diagnosis of kala-azar (93 and 80%, respectively); both tests may remain positive up to 24 months after treatment. For patients with post-kala-azar derm al leishmaniasis and individuals with subclinical infection, rK39 ELIS A performed as well as DAT but could detect infection 6 months earlier in similar to 40% of patients. Conversion in DAT and rK39 ELISA also occurred in leishmanin skin test (LST)-positive individuals, suggestin g active parasite replication (rK39 is an amastigote antigen) in these presumably immune individuals. In contrast to DAT, rK39 ELISA also de tected infection in randomly selected LST-positive individuals (in fou r of six) and endemicity (LST-negative) controls (in one of five). rK3 9 ELISA appears more sensitive than DAT and may prove an important too l in epidemiological studies.