Hydatid disease in New Zealand: changing patterns in human infection, 1878-1972.

Temporal trends in the prevalence and incidence of human hydatid disease in New Zealand were described with respect to the different phases in echinococcal control. The prevalence rate of human hydatid disease increased steadily from 1878 to 1954 despite some educational and legislative measures aimed primarily at controlling canine infections. There was not a marked reduction in incidence in young children and in Maoris until after the intensification of control activities by the voluntary committees in 1957, and the decline in incidence in all groups was maintained during the continuing national control programme. The incidence data were analysed by age, sex, race and residential history of patients, and by the site of hydatid cysts. Maoris were found to be at an unusually high risk of infection with Echinococcus granulosus, with incidence rates six times higher than those in non-Maoris.