Epidemiology and chemotherapy of Echinococcus granulosus and Echinococcus multilocularis

Age-prevalence and age-intensity data of Echinococcus granulosus were collected in Xinjiang (northwest China). The frequency distributions of the number of tapeworms per dog and larval cysts per sheep were adequately described by the negative binomial model, suggesting that statistical distributions of parasites are invariably overdispersed. Infection pressure in dogs was determined to be 0.46 infections/year with a mean infection duration of 1.5 years; the infection pressure for sheep was 0.42 infections/year and the mean number of cysts increased linearly by 0.97 cysts/year. The prevalence of the parasite is presumed to be in an endemic state and not regulated by acquired immunity. Regular dog-dosing would readily drive the infection towards extinction.; Mean cysts weights in jirds inoculated with cystic material of Echinococcus multilocularis and treated for 5-day treatment regimes between 29-69 days post-inoculation were higher in praziquantel (PZQ)-treated and lower in mitomycin C (MC)-treated jirds than in controls. Although PZQ treatment enhanced cystic growth, ultrastructural studies showed that PZQ consistently damaged the germinal membrane.