CONTROL OF HYDATID-DISEASE IN WALES

Objectives-To evaluate the success of the south Powys hydatid control progamme by analysis of trends in cystic disease in humans and sheep a nd dog infestation. Design-A review of hospital admissions for human h ydatid disease in 1984-90, abattoir prevalence surveys of hydatid cyst s in adult sheep, arecoline acetarsol and coproantigen surveys of prev alence of Echinococcus infestation in dogs. Setting-All hospitals in E ngland and Wales, three abattoirs, and dog populations in mid and sout h east Wales. Subjects-Residents of England and Wales admitted to hosp ital between 1984 and 1990 with a new diagnosis of human hydatid disea se (International Classification of Diseases (ICD), ninth revision, co de 122) acquired in the United Kingdom. Results-The average annual inc idence of human hydatid disease in Powys, mid-Wales, fell from 3.9x10( -5) in 1974-83 to 2.3x10(-5) in 1984-90. Age specific incidence rates in Wales declined over this period only in children, and no cases occu rred in children (<15 years) in Powys. Two Welsh children who lived in Gwent and mid-Glamorgan were infected. Prevalence of hydatid cysts in old sheep from south Wales declined during the control period, but in 1993 prevalence of cysts was 13%. Prevalence of E granulosus infestat ion was zero in the control area in 1993, but it was 2.4% in Powys dog s outside the control area in 1989 and 9.2% in dogs in Gwent in 1991. Conclusions-Human hydatid disease has been successfully controlled in south Powys but cystic echinococcosis is still endemic in sheep in mid -Wales, and there is a focus of infection in humans, sheep, and dogs i n the bordering areas of Gwent and mid-Glamorgan. There is considerabl e potential for an upsurge in human cases if control measures are rela xed.