A simplified web of interactions involved in the ecology of hantavirus transmission.

(A) Seasonal epidemic and rodent dynamics in Hu County, 1984–2014. Apodemus agrarius capture rates (black line) and 95% confidence intervals (whiskers) are shown for 1984 to 2014. The blue line represents the number of HFRS cases. (B) Agricultural phenology and rodent dynamics. Time series of NDVI values of farmland (green line), rainfall (blue bars), and pregnancy rate of rodents (grey bars) [38] are shown. The timing of harvests (*) are denoted, as well as rainy seasons and breeding seasons (black dots). The NDVI value for farmland, which increases gradually during the growth period of crops and suddenly drops during the harvest season, was used to reflect the phenological changes of local crops. (C) Estimated seasonal transmission rate. Shaded regions are the 95% Bayesian credible intervals. Asterisks indicate agricultural activities for the spring harvest and wheat sowing, and autumn harvest and maize sowing. The agricultural activity may increase the risk of human exposure to rodents. (D) Hantavirus infections at the human-wildlife interface. The monthly number of HFRS cases from 1984 to 2014 are shown; the blue line represents observed cases, the red line represents the deterministic prediction from the model (using the susceptible and infected individuals in the first month in 1984 as initial conditions), and the black line represents the predicted outcome of the model without a vaccination campaign from 1994 to 2014. (E) An overview of the system. The series of models link environment to host population dynamics, hantavirus prevalence in rodents, and human demography. The model structures (solid lines) are established according to realistic ecological processes. Susceptible individuals, S, were divided into different age groups, births, B, deaths, D, vaccinated individuals, V, immune individuals, R, infected individuals, I, susceptible rodent hosts, SR, and infected rodent hosts, IR. The environmental forcing, δ, and resource availability, K, are incorporated into the model with parameters, which were considered to play a significant role in the fluctuation of rodent populations.