Prevalence, intensity, and fertility of ovine cystic echinococcosis in thecentral Peruvian Andes

An abattoir survey of 212 sheep of different ages was undertaken to determi ne the local epidemiological transmission patterns of Echinococcus granulos us in the central Peruvian Andes. Overall prevalence of the disease in shee p in this survey (which ended in July 1996) was 77.4%, with 96% of sheep ag ed greater than or equal to6 years being infected. Of 1165 cysts examined, 41.1% were fertile with a mean protoscolex viability of 73.2%. A logistic r egression model for the distribution of cyst fertility and type by age, loc ation and size is described. Mathematical modelling also determined that in fection pressure on sheep was 0.44 infections per year and that the mean nu mber of cysts increased linearly by 1.28 cysts per year. These data suggest that E. granulosus is in an endemic state in this area and control measure s could drive the disease towards extinction.