An Expanded Transmission Assessment Survey to Confirm the Interruption of Lymphatic Filariasis Transmission in Wallis and Futuna

Abstract

Historically, the human prevalence of Wuchereria bancrofti infection in Wallis and Futuna (WAF) was among the highest in the Pacific and mass drug administration (MDA) against lymphatic filariasis (LF) either with diethylcarbamazine citrate (DEC) or the combination of DEC and albendazole had been implemented for decades. To determine whether LF antigen prevalence in WAF was lower than 1%, the infection threshold for elimination in an area where Aedes spp. are the principal vectors, we conducted the WHO-recommended transmission assessment survey in 2012. We present the results of a school-based survey, which targeted 1,014 students in all 13 elementary schools in WAF. From a fingerprick, the circulating filarial antigen (CFA) positivity was checked for grade 2-5 students using BinaxNOW filariasis test (immunochromatographic test). Of 935 children tested, three were positive for CFA in two schools. At the territory level, this was below the critical cutoff of nine cases, if the whole territory was considered as a single evaluation unit. The prevalence of CFA in WAF is less than 1%, reaching the goal for LF elimination set by the WHO. We were able to recommend stopping LF MDA and move to post-MDA surveillance to detect any recrudescence. This survey successfully paved the way for WAF to be validated as achieving LF elimination as a public health problem by 2020.