LEISH-KIT, A STABLE DIRECT AGGLUTINATION-TEST BASED ON FREEZE-DRIED ANTIGEN FOR SERODIAGNOSIS OF VISCERAL LEISHMANIASIS

In order to increase the application potential of the direct agglutina tion test (DAT) for the detection of anti-leishmania antibodies in hum an serum samples, we developed an antigen based on stained and freeze- dried Leishmania donovani promastigotes. We describe here the evaluati on of the performance of the DAT based on this freeze-dried antigen. I t was shown that the freeze-dried antigen remains fully active, even a fter storage at 56 degrees C for 18 months. With a cutoff value of 1:1 ,600, the sensitivity of the DAT was shown to be 92% and the specifici ty of the test was 99.7%, which were comparable with the results found for the DAT based on liquid antigen. The major advantages of the free ze-dried antigen are that the production of a large batch of this anti gen allows reproducible results in the DAT over a long period of time and that the freeze-dried antigen can be stored at ambient temperature , which, as was shown, makes the test a valuable diagnostic tool for u se in the field.