Noninvasive management of Indian visceral leishmaniasis: Clinical application of diagnosis by K39 antigen strip testing at a kala-azar referral unit

Firm diagnosis of visceral leishmaniasis (kala-azar) requires organ aspiration and microscopic examination of tissue specimens. To determine the usefulness of noninvasive diagnosis by strip test detection of anti-K39 immunoglobulin (Ig) G antibody in blood specimens obtained by fingerstick, 143 Indian patients with suspected kala-azar (fever, splenomegaly, anemia) were studied. Of 120 strip test-positive subjects (subjects with presumed kala-azar [group A]), amphotericin B treatment induced clinical cure in 119. Of 23 strip test-negative subjects (subjects presumed to have other diseases [group B]), 16 had other disorders diagnosed at entry, 4 responded to empiric antimalarial therapy, 2 were proven to have kala-azar, and 1 died elsewhere after undergoing splenic aspiration. Six months after treatment ended, all 120 patients in group A and the 18 assessable patients in group B were healthy. In a region in India where visceral infection is prevalent, strip test detection of anti- K39 IgG is a clinically promising diagnostic guide in persons with suspected kala-azar.