Prevalence of Lymphatic Filariasis from 1999 through 2007 in Nauru, a Set of Solitary Island in the Southern Pacific

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As part of the Pacific Program to Eliminate Lymphatic Filariasis (PacELF), baseline surveys were conducted in 1999 and 2004 in Nauru to determine the prevalence of filariasis by rapid immunochromatotraphic test (ICT). In 1999, the survey demonstrated a filariasis prevalence of 0.26%, and Nauru was classified as a non-endemic country at the time. In 2004, the prevalence resulting from the survey was 1.66%. Since it exceeded 1.0%, this high prevalence warranted the implementation of Mass Drug Administration (MDA) according to WHO guidelines and gave rise to an urgent need to re-establish the filariasis policy in Nauru, as the target year for filariasis elimination in the Pacific is 2010. The present study was conducted to determine the current prevalence of filariasis, to decide whether implementation of the MDA program is necessary, and to compare the demographic characteristics of participants according to the ICT test results. Blood sampling and interviews, based on a simple questionnaire asking about filariasis-related symptoms, were conducted by trained health staff members. A total of 1,513 people were enrolled for the survey in January 2007. Filariasis positivitiy was detected in three subjects (0.2%) by ICT test. Nauru was reconfirmed as a non-endemic country and therefore did not require the MDA implementation. The prevalence did not vary significantly according to the demographic characteristics. The three seropositive cases did not have any filariasis-related symptoms. However, two of the three positive cases of filariasis lived in the same district and the other lived in a neighboring district. To assess the interruption of filariasis transmission, further surveys are recommended.