Simulations on Prevalence of Echinococcus multilocularis in Hokkaido on the Basis of Vole Population Dynamics

In our study, we have investigated the influence of the intermediate host population density on the prevalence of Echinococcus multilocularis in the definitive host using a mathematical model of transmission. For the vole population (intermediate host) in Hokkaido, a model of population dynamics has been constructed in this paper which follows the seasonal and annual fluctuations. In the northeastern area, the vole density appears to fluctuate periodically with a 4 year cycle. The prevalence of Echinococcus multilocularis in the fox population (definitive host) can be affected by the density of vole through the fox ingesting infectious voles. Therefore we have prepared a food habit function of foxes and the logistic distribution has been proposed. The simulations which have been carried out using the mathematical model for transmission of Echinococcus multilocularis together with the vole dynamics have indicated that the prevalence in foxes is correlated and synchronized with the population dynamics of vole. In addition they have also made us recognize that it is necessary to introduce a suitable food habit function into the transmission model

A model for the transmission of Echinococcus multilocularis in Hokkaido, Japan

A mathematical model for Echinococcus multilocularis transmission would be useful to estimate its prevalence and manage control strategies. We propose a mathematical model which quantitatively describes the transmission of E. multilocularis in Hokkaido, Japan. The model takes into account the influence of the dynamics of both the definitive and the intermediate host populations, which show large scale seasonal variations as they are wild animals. The simulations based on the model clarify the mechanism for the seasonal transmission of E. multilocularis quantitatively, notwithstanding a lack of seasonal prevalence data. At present, human alveolar echinococcosis is prevalent throughout the mainland of Hokkaido. The risk of being infected with alveolar echinococcosis in the human population has been investigated by analyzing the seasonal fluctuation of parasite egg dispersal in the environment, which should be necessary for planning more suitable preventive measures against E. multilocularis.</p

STUDIES ON ECHINOCOCCOSIS XV : SECONDARY MULTILOCULAR ECHINOCOCCOSIS BY INTRAHEPATIC INOCULATION

Eight uniform strains of the mouse were investigated on experimental secondary multilocular echinococcosis by the intrahepatic inoculation of scolices. It is concluded that a part of scolices inoculated can develop fully to the multilocular echinococcus, but the susceptibility is not superior to that of peritoneal cases