Joint modelling of Echinococcus multilocularis and Echinococcus granulosus infection rates on dogs of the Tibetan Plateau

The Qinghai-Tibetan plateau has been described as a large meta-stable transmission focus for Echinococcus multilocularis. Infection rates in canid definitive host populations vary as a function of the availability of infected small mammal intermediate hosts which in turn varies as a function of complex interactions within a set of environmental variables. The infection status of dogs was monitored in 13 villages from Serxu County, NW Sichuan, China over a three year period. Each dog was dosed with praziquantel at the start of the study. Infection status was assessed using a copro-antigen ELISA and copro-PCR. This paper develops a temporal model that describes transmission to dogs and which accounts for uncertainty in dog infection status. Parameter uncertainty is assessed using Bayesian simulation techniques. The model was used to assess between village differences in infection pressure that might arise from heterogeneity in ecological conditions. The role of ecological variation on infection rates in dogs is discussed