Improvement of the newly developed latex agglutination test (Katex) for diagnosis of visceral lieshmaniasis.
BACKGROUND
Different methods are available for diagnosis of visceral leishmaniasis (VL), among them the urine-based antigen detection assay, latex agglutination test (Katex), is a recently developed one. The main drawback of the test is false-positive reactivity in some of healthy individuals. The false positivity of the test can be removed by boiling the urine sample for 5 min before testing. In this study an attempt was made to improve Katex by removing unpleasant boiling process, which also decreases field applicability of the test.


METHODS
False-positive and true-positive urine samples were collected from VL patients and healthy individuals. Both samples were then treated by reagents including, sodium dodecyl sulfate, trichloroacetic acid, dithiothreitol (DTT), sulphosalicylic acid and also heating at 56 degrees C.


RESULTS
Findings of this study showed that DTT pretreatment significantly reduced the rate of false-positive reactivity of Katex where 73% of false-positive urine samples changed to negative after DTT treatment. However, the DTT treatment reduced the rate of true positivity by 14%.


CONCLUSIONS
These data indicate that DTT can be used to eliminate nonspecific reactivity in the Katex. This will improve the performance of Katex and make it a more convenient and field applicable test.
Hatam
Gholam Reza
GR
Department of Parasitology and Mycology/Parasitology and Mycology Research Center, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran.
Ghatee
Mohammad Amin
MA
Hossini
Seyed Mohammad Hossein
SM
Sarkari
Bahador
B
D000818:Animals; D000953:Antigens, Protozoan / Q000737:chemistry / Q000652:urine*; D004229:Dithiothreitol / Q000737:chemistry; D005189:False Positive Reactions; D006801:Humans; D007841:Latex Fixation Tests; D007893:Leishmania donovani / Q000276:immunology / Q000302:isolation & purification*; D007898:Leishmaniasis, Visceral / Q000175:diagnosis* / Q000469:parasitology / Q000652:urine; D011237:Predictive Value of Tests; D011933:Reagent Kits, Diagnostic
D000953:Antigens, Protozoan; D011933:Reagent Kits, Diagnostic; D004229:Dithiothreitol