91福利

Alexander R Kaye, Giorgio Guzzetta, Michael J Tildesley

For many infectious diseases, the risk of outbreaks varies seasonally. If a pathogen is usually absent from a host population, a key public health policy question is whether the pathogen鈥檚 arrival will initiate local transmission, which depends on the season in which arrival occurs. This question can be addressed by estimating the 鈥減robability of a major outbreak鈥� (the probability that introduced cases will initiate sustained local transmission). We have devised an approach for inferring outbreak risks for seasonal pathogens (involving calculating the Threshold Epidemic Risk; TER). Estimation of the TER involves calculating the probability that introduced cases will initiate a local outbreak in which a threshold number of cumulative infections is exceeded before outbreak extinction. For simple seasonal epidemic models, such as the stochastic Susceptible-Infectious-Removed model, the TER can be calculated numerically (without model simulations). For more complex models, such as stochastic host-vector models, the TER can be estimated using model simulations.