Prevalence of soil transmitted nematodes on Nukufetau, a remote Pacific island in Tuvalu

BACKGROUND The population of Nukufetau, a remote coral atoll island in Tuvalu in the Western Pacific, received annual mass drug administration (MDA) of diethylcarbamazine and albendazole under the Pacific Elimination of Lymphatic Filariasis program in 2001, 2002 and 2003, with the last MDA occurring six months before a cross-sectional survey of the whole population for soil transmitted helminths (STH). METHODS A cross-sectional survey in May 2004 recruited 206 residents (35.2% of the population) who provided a single faecal sample that was preserved, concentrated and examined microscopically. RESULTS Overall prevalence of STH was 69.9%; only hookworm and Trichuris trichiura were diagnosed. Trichuris was present in 68.4% with intensity of infection being light in 56.3%, medium in 11.7% and heavy in 0.5%. Hookworm occurred in 11.7% with intensity of infection 11.2% being light and medium in 0.5%. Twenty individuals (9.7%) had dual infections. The prevalence of Trichuris was constant across all ages while the prevalence of hookworm was significantly lower in residents below 30 years of age. In the age group 5-12 years comparison of results with a 2001 survey 1 suggested that the prevalence of STH has declined minimally, due to sustained high prevalence of Trichuris, while hookworm has declined dramatically from 34.4% to 1.6%. CONCLUSION The results of this survey suggest that although the MDA appears to have reduced hookworm prevalence in residents below 30 years of age, there has been minimal effect on Trichuris prevalence. An integrated program to control STH is required.