Evaluation of the Og4C3 ELISA in Wuchereria bancrofti infection: infected persons with undetectable or ultra-low microfilarial densities.
The recently developed Og4C3 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 Og4C3 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 > 0.033). At microfilarial densities of < 1, 1-30, and > 30 microfilariae per ml of blood, the sensitivity of the Og4C3 was 72.2, 97.6 and 100%, respectively (chi 2-test for trend, P < 10(-6)). 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 Og4C3 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 < 1 microfilaria per ml.
Rocha
A
A
Departamento de Parasitologia, Centro de Pesquisas Aggeu Magalhaes-FIOCRUZ, Recife, Brazil.
Addiss
D
D
Ribeiro
M E
ME
Norões
J
J
Baliza
M
M
Medeiros
Z
Z
Dreyer
G
G
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000818:Animals; D000947:Antigens, Helminth / Q000097:blood*; D001938:Brazil; D002648:Child; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D005069:Evaluation Studies as Topic; D005260:Female; D005368:Filariasis / Q000097:blood*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012737:Sex Factors; D014958:Wuchereria bancrofti
D000947:Antigens, Helminth