Comparative evaluation of blood and serum samples in rapid immunochromatographic tests for visceral leishmaniasis.
Rapid diagnostic tests (RDTs) based on the detection of specific antibodies in serum are commonly used for the diagnosis of visceral leishmaniasis (VL). Several commercial kits are available, and some of them allow the use of whole-blood samples instead of serum. An RDT is much more user-friendly for blood samples than for serum samples. In this study, we examined the sensitivities and specificities of six different commercially available immunochromatographic tests for their accuracy in detecting Leishmania infection in whole blood and serum of parasitologically confirmed VL cases. This study was performed in areas of India and Nepal where VL is endemic. A total of 177 confirmed VL cases, 208 healthy controls from areas of endemicity (EHCs), 26 malaria patients (MP), and 37 tuberculosis (TB) patients were enrolled. The reproducibilities of the blood and serum results and between-reader and between-laboratory results were tested. In India, the sensitivities of all the RDTs ranged between 94.7 and 100.0%, with no significant differences between whole blood and serum. The specificities ranged between 92.4 and 100.0%, except for the specificity of the Onsite Leishmania Ab RevB kit, which was lower (33.6 to 42.0%). No differences in specificities were observed for blood and serum. In Nepal, the sensitivities of all the test kits, for whole-blood as well as serum samples, ranged between 96.3 and 100.0%, and the specificities ranged between 90.1 and 96.1%, again with the exception of that of the Onsite Leishmania Ab RevB test, which was markedly lower (48.7 to 49.3%). The diagnostic accuracies of all the tests, except for one brand, were excellent for the whole-blood and serum samples. We conclude that whole blood is an adequate alternative for serum in RDTs for VL, with sensitivities and specificities comparable to those obtained in serum samples, provided that the test kit is of overall good quality.
Infectious Disease Research Laboratory, Department of Medicine, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh, India.
Dinesh
D
Kumar
Basudha
B
Khanal
Puja
P
Tiwary
Shyam Lal
SL
Mudavath
Narendra K
NK
Tiwary
Rupa
R
Singh
Kanika
K
Koirala
Marleen
M
Boelaert
Suman
S
Rijal
Shyam
S
Sundar
D000293:Adolescent; D000328:Adult; D000913:Antibodies, Protozoan / Q000097:blood*; D001769:Blood / Q000469:parasitology*; D002846:Chromatography, Affinity / Q000379:methods*; D019411:Clinical Laboratory Techniques / Q000379:methods*; D003955:Diagnostic Tests, Routine / Q000379:methods; D005260:Female; D006801:Humans; D007194:India; D007891:Leishmania / Q000276:immunology*; D007898:Leishmaniasis, Visceral / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D009390:Nepal; D010274:Parasitology / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult
D000913:Antibodies, Protozoan