Filariasis serosurvey, New Caledonia, South Pacific, 2013

Lymphatic filariasis (LF) is a major public health problem in the Pacific. As the global prevalence of infection was not known in New Caledonia (NC), a serosurvey study was conducted by determining the prevalence of circulating filarial antigens, as recommended by the World Health Organization.

A cross sectional study on a 2 degree stratified sample was carried out from June to November 2013. Inclusion criteria were: individuals aged 2 to 80 y/o, who had been hospitalized or sought medical care for a non-infectious cause and who had been living in NC for more than 6 months. LF antigenic detection was performed using the immunocromatographic BinaxNOW filariasis card test (ICT). Among the 1,035 individuals tested, 7 were antigenic. The overall LF antigenic prevalence was 0.62% (CI 95% [0.60-0.63]). All patients were unrelated to each other; none of them presented clinical symptoms of LF. Four of the 7 ICT positive patients reported having travelled to LF endemic areas, 2 patients had never traveled outside NC and the last one had only traveled in non-endemic areas. For the 7 ICT positive patients, the research of microfilariae in blood smears and filarial DNA by PCR was negative.

The prevalence of filarial antigenemia in NC is less than 1%, the threshold that defines the filarial endemic areas for WHO. Nevertheless, as two patients who had never travelled outside NC and one who had only travelled to non-endemic areas were antigenic, we cannot conclude that NC is totally free of LF.