Field evaluation of two diagnostic antigen tests for Wuchereria bancrofti infection among Indian expatriates in Saudi Arabia

Two commercially available diagnostic tools (Tro-Bio ELISA and ICT card test) were used to detect circulating filarial antigen of Wuchereria bancrofti infections among Indian expatriate workers in Saudi Arabia. Daytime serum samples collected from 302 individuals (210 men and 92 women) were tested. Night blood surveys for microfilaraemia were restricted to those individuals who became positive for the trop-Bio assay test. The overall prevalence of filarial antigeaemia was 10.6% (32 individuals). Of these 32 antigen positive cases, microfilariae were found in 10 men (31.3%), with a mean microfilarial count of 105 mff/ml. No positive antigen results were found in control sera from 200 native healthy Saudis or from patients with helminthic infections (schistosomiasis, echinicoccosis, hookworm, ascariasis and trichuriasis). All 32 positive sera with the Trop-Bio ELISA showed a positive ICT card reaction (specificity and sensitivity 100%). It is concluded that, in Saudi Arabia and other Gulf states, where a continuous flow of south- and southeastern workers coming from areas endemic for bancroftian filariasis, the ICT card test may be useful in monitoring the potential risk of introducing bacncroftian filariasis to the host countries.