A filter paper technique for the detection of anti-filarial IgG4 in lymphatic filariasis.

In a previous study performed in south Sulawesi (Sulawesi Selatan), Indonesia, we established that the immunoglobulin G4 (IgG4) enzyme-linked immunosorbent assay (ELISA) is a suitable community diagnostic method and that it can distinguish areas of high and low prevalences within short distances. In an attempt to make this diagnostic tool more applicable in the field, a comparative study using serum and blood collected on filter paper was undertaken with 568 individuals living in 2 areas with different endemicity for brugian filariasis in south Sulawesi. In Mamuju district, where the microfilaria (mf) prevalence of the studied individuals was 18.4%, antifilarial IgG4 was present in 73.1% of the venepuncture samples and 72.5% of the filter paper samples, respectively. In Mangkutane district, where lymphatic filariasis is transmitted at a low level (mf rate 2.4%), antifilarial IgG4 was detected in 35.5% and 39.9% of similar samples, respectively. There was no significant difference in the IgG4 detection rate determined from venepuncture and filter paper samples from the same donors (P = 0.124), and the IgG4 values were highly correlated (p = 0.97, P < 0.001, n = 568). These results indicate that the filter paper technique for collection of blood samples is a suitable alternative to venepuncture for use in the IgG4 ELISA.