Human infection with Wuchereria bancrofti in Matara, Sri Lanka: the use, in parallel, of an ELISA to detect filaria-specific IgG₄ in urine and of ICT card tests to detect filarial antigen in whole blood

Abstract

The ICT card test to detect circulating filarial antigen and an ELISA that detects filaria-specific urinary IgG₄ were each used to screen 473 subjects from a community in Sri Lanka where Wuchereria bancrofti is endemic. When the ICT test was used as the gold standard, the ELISA was found to have a sensitivity of 91.2%. However, far more of the subjects were found ELISA-positive than ICT-positive (76.5% v. 31.1%). The youngest children studied (aged 1-10 years) were similar to the adult subjects in terms of the prevalence of antigenaemia (33.8%) and the prevalence (72.1%) and concentration of filaria-specific IgG₄ in their urine. Therefore, especially as urine samples are easier, less painful and safer to collect than blood samples, the ELISA may be particularly useful to screen very young and school-age children, to estimate current levels of transmission in a particular area.