Epidemiological assessment of continuing transmission of lymphatic filariasis in Samoa

Abstract

Ongoing transmission of lymphatic filariasis (LF) was assessed in five Samoan villages by measuring microfilaraemia (Mf), circulating filarial antigen (CFA) and antibody prevalence. Compared to the other villages, Fasitoo-Tai had a significantly higher Mf prevalence (3·2%), CFA prevalence (14·6%) and antibody prevalence in children (62·0%) (P<0·05). Puapua had a significantly lower CFA prevalence (2·5%), no detectable Mf-positive individuals and significantly low antibody prevalence in children (7·9%) (P<0·05). Siufaga, previously believed to be LF-free, recorded >1% CFA prevalence and a high antibody prevalence in children (46·6%). Overall, antibody prevalence in children appeared to reflect the transmission dynamics in the villages and, in Siufaga, identified an area of ongoing transmission. The Filariasis Cellabs Enzyme-Linked Immunosorbent Assay (CELISA), based on recombinant antigen Bm14, to detect antibodies, could potentially be a promising diagnostic tool for inclusion in future surveillance in the South Pacific.

We would like to thank the staff of the Samoan Ministry of Health for approving this research and the World Health Organization, Samoa, for their participation in the field work. We would also like to thank Dr Petra Buttner for her statistical advice. We would like to thank Phil Bright, from the Secretariat of the Pacific Community, for providing the ArcGIS map of Samoa. Lastly, we would like to thank GlaxoSmithKline for their generous ongoing financial support of the LF support centre at James Cook University.