Evaluation of the Og4C3 ELISA in Wuchereria bancrofti infection: infected persons with undetectable or ultra‐low microfilarial densities

Abstract

The recently developed O g 4 c 3 ELISA, which detects circulating Wuchereria bancrofti antigen, appears promising for use in epidemiological surveys, but its sensitivity is unknown in persons with ultra-low microfilarial densities. We used the O g q c 3 to test the sera of 282 persons who were microfilaria-positive in 1-16 ml of blood, 18 persons who were microfilaria-negative but who had ultrasonographic or biopsy evidence of adult W. bancrofti infection, and 63 lifelong residents of a non-endemic area of Brazil. A total of 276 (97.9%) persons with detectable microfilaraemia tested positive (optical density >0.03 3). At microfilarial densities of <I, 1-30, and >30 microfilariae per ml of blood, the sensitivity of the O g q c 3 was 72.2, 97.6 and IOO%, respectively (X'-test for trend, PcIo-'). The assay was positive in 66.7% of amicrofilaraemic persons with evidence of adult worm infection and in one (1.6%) of 63 residents of the non-endemic area (specificity, 98.4%). Our findings support the increasingly widespread use of the OgqC3 for field investigations and epidemiological assessments. However, the sensitivity of the assay may be low in persons who are microfilaria-negative or with densities of < I microfilaria per ml.

Scope of detectability of circulating antigens of human lymphatic filarial parasite Wuchereria bancrofti with smaller amount of serum by Og4C3 assay: its application in lymphatic filariasis elimination programme

“…Considering the non-endemic normals and microfilaria carriers, the Og4C3-ELISA test was found to have 100 % sensitivity and 94.12 % specificity for detection of Mf carriers in sera samples. Comparison of finger prick dried blood spots (DBS) and sera samples by ELISA vis-à-vis the immunochromatographic test (ICT), carried out on Mf carriers (n = 91) and endemic normals (n = 97), showed a positivity of 88 (96.7 %) in DBS as against 86 (94.5 %) in sera samples and 88 (96.7 %) by ICT, amongst Mf carriers, with a statistically significant correlation in antigen units between sera and DBS samples (r = 0.959, p = 0.000) amongst the microfilaria carriers (Rocha et al 1996). But it is cost prohibitive for field use.…”

“…Antigen tests are more sensitive (Lammie et al 1994) and are used to assess the situation (Bal et al 2009;Das et al 2005;Melrose et al 2000;Nuchprayoon et al 2001;Shah and Mulla 2007;Steel and Ottesen 2001;Tisch et al 2001;Weerasooriya et al 2002) in different endemic countries. Antigen tests were also used to evaluate other methods of detection (Rocha et al 1996;Wattal et al 2007). Considering the non-endemic normals and microfilaria carriers, the Og4C3-ELISA test was found to have 100 % sensitivity and 94.12 % specificity for detection of Mf carriers in sera samples.…”

Comparison of tests for the detection of circulating filarial antigen (Og4C3-ELISA and AD12-ICT) and ultrasound in diagnosis of lymphatic filariasis in individuals with microfilariae

“…This technique allows for the identification of W. bancrofti antigens in serum, plasma and hydrocele fluid and does not show any cross-reactivity with other helminthic infections (More & Copeman 1990, Rocha et al 1996, TropBIO 1996, Rocha 2004.…”

Semi-Quantitative Scoring of an Immunochromatographic Test for Circulating Filarial Antigen

“…1,9 Though it is impossible to accurately determine the number of macrofilariae in vivo, this assertion is supported by studies that have shown a relationship between antigen levels and microfilarial densities in mf-positive individuals before treatment, 1,[15][16][17][18][19][20][21][22] and a relationship between antigen levels and microfilarial densities with the frequency of detection of worm nests by ultrasonography. [10][11][12]16,23 The original AD12 ELISA and the Og4C3-based TropBio ELISA tests are useful for quantitating filarial antigenemia.…”