Long-term efficacy of single-dose mass treatment with diethylcarbamazine citrate against diurnally subperiodic Wuchereria bancrofti: eight years' experience in Samoa.

A single-dose of diethylcarbamazine citrate (DEC, 6 mg per kg body weight) was administered in three mass treatment campaigns to > 80% of the estimated total Samoan population (160,000) in 1982, 1983, and 1986. The effect of the drug was evaluated before and after each campaign by conducting four blood surveys covering 9600 to 13,700 people from 26-34 villages on each occasion. The drug reduced the prevalence of Wuchereria bancrofti microfilariae from 5.6% to 2.5% (a 55% reduction), while the transmission potential (the estimated mosquito infection rate if everyone is equally exposed to mosquito bites) dropped from 2.18 to 0.67 (a 70% reduction). The total number of microfilariae in the Samoan population is estimated to have been reduced by 80%. A spaced, single-dose treatment with DEC at a 1-2-year interval therefore seems to be an effective control measure against diurnally subperiodic W. bancrofti.

Geographic distribution of peptic ulcer disease in Western Samoa.

A survey of peptic ulcer disease in Western Samoa is described. As compared with New Zealand experience, an unusually high prevalence of peptic ulceration is documented. A remarkable and significant variation in the geographic distribution of cases is reported. Regions of high prevalence were significantly associated with disease onset at an earlier age and with increased frequency of a family history of ulcer disease. It is concluded that this genetic predisposition is unlikely to sufficiently account for the regional localisation of cases observed and environmental causes are under study.