Studies on etiological surveillance in filariasis-eliminated areas.

In order to screen a simple, economical and applicable etiological method, a comparison was made on McAb ELISA for detecting specific IgG4 and ICT for detecting antigens of Filaria bancrofti in serum and plasma. As a result, out of 59 microfilaremia cases, specific IgG4 was found in 57 (96.61%) and filarial antigens in 56 cases (94.92%), indicating McAb ELISA and ICT were both high sensitive and no significant difference existed between them ( P 0.05). No false positive result occurred by both methods in examining sera of 40 health persons from non endemic area, 30 cases with cysticercosis and 25 cases with clonorchiasis. In a field study, McAb ELISA and ICT were used in examination of 302 children born after the elimination of filariasis, 372 persons in filariasis eliminated area, 55 cases with advanced filariasis (41 with chyluria and 14 with elephantiasis) and 60 persons who had become negative from microfilaremia. Only one person in filariasis eliminated area was strongly positive for specific IgG4 and weakly positive for filarial antigens. However, no microfilaria was found in this case by repeated blood smear examination. The results proved that McAb ELISA and ICT both with high sensitivity and specificity were applicable in etiological surveillance in filariasis eliminated area, and the former was better for a large scale etiological monitoring in filariasis eliminated area and the latter was better in a case diagnosis.