DIAGNOSIS OF SYMPTOMATIC VISCERAL LEISHMANIASIS BY USE OF THE POLYMERASE CHAIN-REACTION ON PATIENT BLOOD

To diagnose symptomatic visceral leishmaniasis (kala-azar) using perip heral blood rather than tissue aspirates, a polymerase chain reaction (PCR) technique was developed for which the detection limit is 1 Leish mania-infected macrophage in 8 mL of blood. For Indian, Kenyan, or Bra zilian patients with parasitologically confirmed kala-azar, 57 of 63 c ases before treatment had blood that was PCR-positive (90% sensitivity ). None of 40 clinically healthy persons had PCR-positive blood (100% specificity). Twelve (92%) of 13 clinically cured Indian patients had negative PCR reactions 1-6 months after treatment. This PCR procedure can provide a parasitologic diagnosis for the vast majority of kala-az ar cases before therapy, may identify patients who have been successfu lly treated by chemotherapy, and should substantially reduce the need for invasive tests.