Field validity, reproducibility and feasibility of diagnostic tests for visceral leishmaniasis in rural Nepal.
OBJECTIVE
To assess the field accuracy, reproducibility and feasibility of the formol gel test (FGT), the urine latex agglutination test (KAtex) and a rK39 antigen-based dipstick for the diagnosis of visceral leishmaniasis (VL) in rural Nepal.


METHODS
Patients with clinical suspicion of VL were recruited at Rangeli District Hospital (DH), a 15-bed government hospital located in south-eastern Nepal. FGT, KAtex and rK39 dipstick tests were performed on site and later repeated at a reference kala-azar diagnostic laboratory to assess reproducibility. Diagnosis of VL was confirmed by either a positive bone marrow aspirate examination or a positive direct agglutination test (DAT titre > or = 1:3200) in patients who later responded to anti-leishmanial therapy.


RESULTS
Of 155 patients initially recruited, 142 (85 with VL and 57 with another diagnosis) were included in the study. The sensitivity of the rK39 dipstick [89%; 95% confidence interval (CI): 81-94] was significantly higher than that of the KAtex (57%; 95% CI: 46-67) and the FGT (52%; 95% CI: 41-62). All three tests had a specificity of at least 90%. Agreement was higher for the rK39 dipstick (kappa = 0.87) than for the FGT (0.68) and the KAtex (0.43). All tests required < or = 20 min of actual work and < or = 40 min to obtain the results.


CONCLUSIONS
The rK39 dipstick was easy to do, more accurate and reproducible than other rapid diagnostic tests for VL in a DH of rural Nepal. It should be integrated into the field diagnostic algorithm of VL in this region and mechanisms to secure its availability should be found.
Chappuis
François
F
Travel and Migration Medicine Unit, Geneva University Hospital, Geneva, Switzerland. francois.chappuis@hcuge.ch
Rijal
Suman
S
Jha
Uma Kant
UK
Desjeux
Philippe
P
Karki
Bal Man Singh
BM
Koirala
Shekhar
S
Loutan
Louis
L
Boelaert
Marleen
M
D000328:Adult; D000953:Antigens, Protozoan / Q000032:analysis; D003955:Diagnostic Tests, Routine / Q000379:methods*; D004202:Disinfectants; D019353:Endemic Diseases; D005240:Feasibility Studies; D005260:Female; D005557:Formaldehyde; D006801:Humans; D007159:Immunologic Tests / Q000379:methods; D007841:Latex Fixation Tests / Q000379:methods; D007898:Leishmaniasis, Visceral / Q000150:complications / Q000175:diagnosis* / Q000453:epidemiology; D008297:Male; D009390:Nepal / Q000453:epidemiology; D015203:Reproducibility of Results; D012423:Rural Health; D012680:Sensitivity and Specificity
D000953:Antigens, Protozoan; D004202:Disinfectants; D005557:Formaldehyde