Evaluation of a glycerol-preserved antigen in the direct agglutination test for diagnosis of visceral leishmaniasis at rural level in eastern Sudan

Three-hundred and eight patients with suspected visceral leishmaniasis (VL) were received at Doka Hospital (eastern Sudan) during the period September 2004 to October 2005. The sensitivity and specificity of a glycerol-preserved (GP) antigen for VL diagnosis was assessed against the results of repeated lymph node aspiration and readings from a direct agglutination test (DAT) employing standard formaldehyde-fixed (FF) or freeze-dried (FD) antigen. Despite 13 months of storage at ambient temperature (28–47 °C), the GP antigen mean titres obtained from these 308 patients were no different from those that were FD (P=0.945) and stored under similar conditions, but were significantly different (P=0.019) from those that were FF and kept continuously at the optimum temperature for storage (4–8 °C). Taking the parasitological result as the gold standard and using a pre-established titre of 1 : 3200 as the DAT cut-off, the GP antigen revealed a sensitivity (91/105, 86.7 %) and specificity (187/203, 92.1 %) comparable to that of FD antigen (92/105, 87.6 %, and 188/203, 92.6 %, respectively) and FF antigen (94/105, 89.5 %, and 188/203, 92.6 %, respectively). At a titre range of 1 : 400–1 : 800, statistically determined as the optimum cut-off for the three antigens, sensitivities of 92.4, 90.5 and 96.2 % and specificities of 90.6, 90.1 and 88.7 % were achieved for the GP, FD and FF antigens, respectively, at a peripheral hospital. Regardless of the antigen preparation used, DAT results obtained in the peripheral hospital were highly reproducible in the central laboratory in Omdurman (weighted kappa: GP=0.957, FD=0.979 and FF=0.936). With a diagnostic reliability comparable to formaldehyde fixation and stability under ambient conditions similar to freeze drying, glycerol preservation, by virtue of its high potential for reproduction, meets the requirements for the management of VL in developing countries.

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Dog-DAT: a direct agglutination test using stabilized, freeze-dried antigen for the serodiagnosis of canine visceral leishmaniasis

FEMS Immunology & Medical Microbiology ◽

10.1111/j.1574-695x.1996.tb00141.x ◽

1996 ◽

Vol 16 (3-4) ◽

pp. 235-239 ◽

Cited By ~ 17

Author(s):

Linda Oskam ◽

Rob J. Slappendel ◽

Eef G.M. Beijer ◽

Nel C.M. Kroon ◽

Cor W. van Ingen ◽

...

Keyword(s):

Visceral Leishmaniasis ◽

Agglutination Test ◽

Canine Visceral Leishmaniasis ◽

Direct Agglutination Test ◽

Freeze Dried

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Use of a Newly Developed β-Mercaptoethanol Enzyme-Linked Immunosorbent Assay To Diagnose Visceral Leishmaniasis in Patients in Eastern Sudan

Clinical and Vaccine Immunology ◽

10.1128/cvi.00313-07 ◽

2007 ◽

Vol 14 (12) ◽

pp. 1592-1595 ◽

Cited By ~ 5

Author(s):

Durria Mansour ◽

Elfadil M. Abass ◽

Mohamed el Mutasim ◽

Abdelhafeiz Mahamoud ◽

Abdallah el Harith

Keyword(s):

Visceral Leishmaniasis ◽

Immunosorbent Assay ◽

Leishmania Donovani ◽

Clinical Evidence ◽

High Reliability ◽

Agglutination Test ◽

Enzyme Linked Immunosorbent Assay ◽

Direct Agglutination Test ◽

Symptomatic Group ◽

Eastern Sudan

ABSTRACT Corroboration of serology results is essential for restricting the risk of inappropriate antileishmanial prescription. A direct agglutination test (DAT) and a recently developed β-mercaptoethanol-modified enzyme-linked immunosorbent assay (β-ME ELISA) based on the use of antigen prepared as described for the DAT were applied to 416 sera from two Sudanese populations with and without clinical evidence of visceral leishmaniasis (VL). Of 285 sera with the lowest antileishmanial DAT titers (≤1:100 to 1:1,600), 270 (94.7%) scored comparable minimum β-ME ELISA absorbance values (≤0.1 to 0.26). In 117 sera that demonstrated the highest DAT titers (1:12,800 to ≥1:25,600), 86 (73.5%) scored maximum (0.81 to ≥1.35) and 30 (25.6%) medium (0.27 to 0.80) β-ME ELISA absorbance values. VL diagnosis was established for 142 (44.1%) patients in the VL-symptomatic group (n = 322), based on positive microscopy for Leishmania donovani in lymph node aspirates or positive DAT (titer, ≥1:3,200). Of the 125 sera from the symptomatic patients for whom microscopy was positive for VL, 111 (88.8%) had comparable positive DAT and β-ME ELISA readings. In all 17 sera from the symptomatic DAT-positive patients for whom leishmaniasis was not established by microscopy but who responded favorably to antileishmanial therapy, absorbance values (≥0.27) indicative of VL were obtained by β-ME ELISA. Of 197 symptomatic patients for whom microscopy was negative for VL, 172 (87.3%) tested negative in β-ME ELISA and 180 (91.4%) in DAT. Based on the high reliability demonstrated here for VL detection, β-ME ELISA fulfills the requirement of confirming DAT results in patients manifesting suspected VL.

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Evaluation of the direct agglutination test based on freeze-dried Leishmania donovani promastigotes for the serodiagnosis of visceral leishmaniasis in Sudanese patients

Tropical Medicine & International Health ◽

10.1111/j.1365-3156.2004.01308.x ◽

2004 ◽

Vol 9 (10) ◽

pp. 1127-1131 ◽

Cited By ~ 11

Author(s):

Khalid A. A. Abdallah ◽

Bakri Y. M. Nour ◽

Henk D. F. H. Schallig ◽

Adil Mergani ◽

Zohal Hamid ◽

...

Keyword(s):

Visceral Leishmaniasis ◽

Leishmania Donovani ◽

Agglutination Test ◽

Direct Agglutination Test ◽

Freeze Dried

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Multicentre evaluation of a direct agglutination test prototype kit (DAT-LPC) for diagnosis of visceral leishmaniasis

Parasitology ◽

10.1017/s0031182017001378 ◽

2017 ◽

Vol 144 (14) ◽

pp. 1964-1970 ◽

Cited By ~ 9

Author(s):

E. OLIVEIRA ◽

D. OLIVEIRA ◽

F. A. CARDOSO ◽

J. R. BARBOSA ◽

A. P. MARCELINO ◽

...

Keyword(s):

Public Health ◽

Visceral Leishmaniasis ◽

Diagnostic Accuracy ◽

Antibody Test ◽

Agglutination Test ◽

Parasitic Infections ◽

Reference Laboratory ◽

Direct Agglutination Test ◽

Serum Samples ◽

Freeze Dried

SUMMARYIn this study, we assessed the sensitivity, specificity, and diagnostic accuracy of a previously developed direct agglutination test (DAT) using a freeze-dried antigen derived fromLeishmania infantumpromastigotes and composed in a prototype kit for visceral leishmaniasis (VL) diagnosis, named DAT-LPC. To evaluate DAT-LPC reproducibility, the kit was used to analyse 207 serum samples from VL patients and 80 serum samples from patients with other parasitic infections or healthy subjects in four laboratories from different public health institutions in Brazil. DAT-LPC showed sensitivity between 96·2 and 99·5% (P= 0·14), specificity ranging from 96·2 to 97·5% (P= 0·95), and diagnostic accuracy ranging from 96·5 to 99% (P= 0·34). The inter-laboratory reproducibility of qualitative results was classified as excellent (κindex: 0·94–0·97). The reproducibility of the end-titre results in relation to the reference laboratory, ranged from 31 to 85%. These results demonstrate an excellent performance of the DAT-LPC, and validate it for the diagnosis of VL that could replace the immunofluorescent antibody test as the routine diagnostic test in the Brazilian public health system.

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