Ecological effect of Taenia saginata in beef imported from a high prevalence area into Norway.

A dynamic simulation model was used to assess the long-term effect of importing beef from an area with a high prevalence of Taenia saginata among cattle. The input of the model was from a Monte Carlo simulation model. The model predicted substantial increases in the prevalence of T. saginata in domestic cattle and in the incidence and prevalence of infections in humans that would last for more than one decade even if importation of infected beef was stopped after 2 years. The results were strongly influenced by various assumptions about proportion of human carriers infected abroad. Only in a scenario where 99% of domestic carriers are infected abroad did the simulation results show no dramatic ecological effect of importation of the beef. If the model's predictions are realistic, then an increase in the prevalence of T. saginata infections in cattle will be observed in and after 1999.