Evaluation of a rapid immunochromatographic test for diagnosis of kala-azar & post kala-azar dermal leishmaniasis at a tertiary care centre of north India.
OBJECTIVE
Definitive diagnosis of kala-azar requires demonstration of parasites by diagnostic protocols based on invasive organ aspirations. We evaluated in the present study the diagnostic utility of an immunochromatographic test (ICT) for detection of anti- rK-39 antibodies for the non-invasive diagnosis of kala-azar and post kala-azar dermal leishmaniasis (PKDL) at a tertiary care centre of north India.


METHODS
The study was conducted in the Department of Microbiology, All India Institute of Medical Sciences, New Delhi, from July 2003 to October 2004. Of the 120 samples tested, 57 were found to be positive by ICT; of which, 51 were diagnosed as kala-azar and 6 as PKDL. The controls included individuals from endemic (50) and non endemic (19) areas with malignancies, haemolytic disorders, chronic liver diseases, hypersplenism, portal hypertension, metabolic disorders and sarcoidosis. In addition, 47 sera from confirmed cases of tuberculosis, malaria, typhoid, filariasis, leptospirosis, histoplasmosis, toxoplasmosis, invasive aspergillosis, amoebic liver abscess, AIDS, leprosy, cryptococcosis, strongyloidiasis, cyclosporosis, patients having collagen vascular diseases and hypergammaglobulinaemia were also tested to check the specificity of the test.


RESULTS
Of the 51 cases with kala-azar 43 were males, children accounted for 25 per cent of these cases. All had fever of duration ranging from <1 month to 1.5 yr (median 4.5 months). All PKDL patients (n=6, 4 males) gave a history of having suffered from kala-azar in the past, and their slit skin test smears were microscopically positive for Leishman-Donovan (LD) bodies. The strip test was positive in all the cases of kala-azar and PKDL (estimated sensitivity 100%), all control sera were negative by the ICT (specificity 100%).


CONCLUSIONS
The rK-39 ICT is a highly sensitive and specific test, and may be suitable for a rapid, cost-effective and reliable field diagnosis of kala-azar and PKDL.
Mathur
Purva
P
Department of Microbiology, All India Institute of Medical Sciences, New Delhi, India.
Samantaray
Jyotish
J
Chauhan
Neeraj Kumar
NK
D000293:Adolescent; D000328:Adult; D000368:Aged; D000818:Animals; D000913:Antibodies, Protozoan / Q000032:analysis / Q000097:blood; D000953:Antigens, Protozoan / Q000276:immunology; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007159:Immunologic Tests / Q000379:methods*; D007194:India; D007223:Infant; D007891:Leishmania / Q000276:immunology; D016773:Leishmaniasis, Cutaneous / Q000175:diagnosis / Q000276:immunology; D007898:Leishmaniasis, Visceral / Q000175:diagnosis* / Q000276:immunology; D008297:Male; D008875:Middle Aged; D015800:Protozoan Proteins / Q000276:immunology
D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D015800:Protozoan Proteins; C079253:K39 antigen, Leishmania